Correcting geometry for lowered cars
#1
Correcting geometry for lowered cars
I'm 85% finished with the suspension and engine part of my build, a '92 LS1/T56 RS streetcar.
I want it fairly low and bought CG weight jackers so I can adjust the height until I'm happy / it doesn't become a pita to drive up driveways. That said, without going into too much a technical discussion about roll centers and such, here's what I've done so far to try correct, as much as reasonably possible, the suspension back to factory geometry, which granted isn't the best. Wow, that was a lot of stipulations. Anyways, not including chassis strengthening (sfc, stb etc) or parts that don't alter geometry (bushings, torque arm, lca etc), here's what I have that I think covers everything short of major redesigning of components.
*edit* This is not meant to read as a must do or authoritive guideline as to what must be done when lowering a thirdgen. These are simply components that I've found thru searching this site that can help on their own or in combination. Each of these components has numerous threads stating the why and how they work to better the handling and/or geometry and that's why I did not feel it necessary to go in depth in RC's and such. It was beyond foolish of me to even try to condense the reasoning for each into a single phrase or sentence. Go do your own searching and research as to why these may or may not be a good idea for your own lowered car depending on but not limited to: the intended application and use of said car, other modifications to said car or combination of parts used or altered. Use at your own risk. Here's one for starters
https://www.thirdgen.org/forums/susp...do-i-make.html
*/edit*
3/4" extended ball joints - *comment removed*
raised bearing strut mounts - *comment removed*
"shorter" rear shock - *comment removed*
adjustable panhard bar - *comment removed*
rear lower control arm brackets - *comment removed*
'tall' rear sway bar axle mount - *comment removed*
axle side panhard bar lowering mount - *comment removed*
bump steer kit - *comment removed*
I may cut down the sway bar end links a touch, tho I don't think that's necessary. Front sway bar shouldn't need anything since the control arms are lowered some.
I currently have aftermarket non-adjustable torque arm and lower control arms. Correct me if I'm wrong, but adjustable lower control arms are really only a benefit to adjust wheelbase, and not really necessary.
I have two things I can't really wrap my head around.
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle?
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
I want it fairly low and bought CG weight jackers so I can adjust the height until I'm happy / it doesn't become a pita to drive up driveways. That said, without going into too much a technical discussion about roll centers and such, here's what I've done so far to try correct, as much as reasonably possible, the suspension back to factory geometry, which granted isn't the best. Wow, that was a lot of stipulations. Anyways, not including chassis strengthening (sfc, stb etc) or parts that don't alter geometry (bushings, torque arm, lca etc), here's what I have that I think covers everything short of major redesigning of components.
*edit* This is not meant to read as a must do or authoritive guideline as to what must be done when lowering a thirdgen. These are simply components that I've found thru searching this site that can help on their own or in combination. Each of these components has numerous threads stating the why and how they work to better the handling and/or geometry and that's why I did not feel it necessary to go in depth in RC's and such. It was beyond foolish of me to even try to condense the reasoning for each into a single phrase or sentence. Go do your own searching and research as to why these may or may not be a good idea for your own lowered car depending on but not limited to: the intended application and use of said car, other modifications to said car or combination of parts used or altered. Use at your own risk. Here's one for starters
https://www.thirdgen.org/forums/susp...do-i-make.html
*/edit*
3/4" extended ball joints - *comment removed*
raised bearing strut mounts - *comment removed*
"shorter" rear shock - *comment removed*
adjustable panhard bar - *comment removed*
rear lower control arm brackets - *comment removed*
'tall' rear sway bar axle mount - *comment removed*
axle side panhard bar lowering mount - *comment removed*
bump steer kit - *comment removed*
I may cut down the sway bar end links a touch, tho I don't think that's necessary. Front sway bar shouldn't need anything since the control arms are lowered some.
I currently have aftermarket non-adjustable torque arm and lower control arms. Correct me if I'm wrong, but adjustable lower control arms are really only a benefit to adjust wheelbase, and not really necessary.
I have two things I can't really wrap my head around.
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle?
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
Last edited by GMan 3MT; 01-21-2018 at 08:07 AM.
#2
Re: Correcting geometry for lowered cars
Looking to lower my car as well. Would like a member with some real experience with suspension tuning a lowered F-body to chime in here, but I believe the new bolt holes on the bracket would need to be a little further forward under the original holes, not directly underneath or else your control arms would be too short to bolt up or indeed cause the axle to move slightly foreard. Adjustable control arms would remedy that but shouldn’t be necessary if the bracket are installed correctly. My understanding is adjustable LCAs are primarily used for correcting driveline angles with the driveshaft and pinion yoke. Besides that, relocation brackets alone can adjust the attitude (angle) of the pinion...and an adjustable torque arm may be required too but not entirely sure....The bushings you use will affect the angle you set as well. Rubber gives more under higher torque than solid bushings so you would want to set the pinion angle a few degrees lower to accommodate for any additional lift. Anyways it’s all a science I don’t understand completely either...but if your not racing it, and you didn’t extremely lower it, any forward movement of the axle would seem negligible as a daily street car regarding handling. Might want to look out for any clearance issues that may arise if it did move up.
#3
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Re: Correcting geometry for lowered cars
I have two things I can't really wrap my head around.
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle?
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle?
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
Without being able to bring the pinion into the correct position, you'll encounter problems with the u-joints. While the vibrations and harmonics developed may not be entirely noticeable, it will undoubtedly shorten their useful life.
Any adjustable torque arm I've used has had the capacity to bring the pinion angle into the proper location. That is, the same angle as the crankshaft centreline. Either up or down. (Yes, it is perfectly acceptable to have the pinion nose "down" the same amount as the crank snout is "up".)
I can't comment on the factory spec as I've never had the occasion to measure it.
2. The angles encountered with a lowered car are far from being "extreme". That said, the amount the axle moves forward is not noticeable. It is important however to have the correct geometry regarding the rear control arm.
The picture below is of my lowered coupe. I have Spohn weld in LCARBs on the lowest hole using non-adjustable Edelbrock LCAs on a Dana 44. The tire is a 26" diameter. If anything the tire could probably come forward in the wheelhouse.
#4
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Car: '89 Formula
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Transmission: 4L65E
Axle/Gears: MW 3.42 12 Bolt
Re: Correcting geometry for lowered cars
I'm 85% finished with the suspension and engine part of my build, a '92 LS1/T56 RS streetcar. Congrats!
I want it fairly low and bought CG weight jackers so I can adjust the height until I'm happy / it doesn't become a pita to drive up driveways. That said, without going into too much a technical discussion about roll centers and such, here's what I've done so far to try correct, as much as reasonably possible, the suspension back to factory geometry, which granted isn't the best. Wow, that was a lot of stipulations. Anyways, not including chassis strengthening (sfc, stb etc) or parts that don't alter geometry (bushings, torque arm, lca etc), here's what I have that I think covers everything short of major redesigning of components.
3/4" extended ball joints - brings the front control arms back 'down'
raised bearing strut mounts - adds back some strut travel
"shorter" rear shock - avoid bottoming out
adjustable panhard bar - re-centers rearend
rear lower control arm brackets - brings LCA back level or slight pointing downhill or uphill
'tall' rear sway bar axle mount - brings rear sway bar closer to being flat
axle side panhard bar lowering mount - brings the panhard bar to level - Actually increases inclination, both sides necessary to level. For your application, your fine with just axle side.
bump steer kit - bring tie rods back level
I may cut down the sway bar end links a touch, tho I don't think that's necessary. Front sway bar shouldn't need anything since the control arms are lowered some.
I currently have aftermarket non-adjustable torque arm and lower control arms. Correct me if I'm wrong, but adjustable lower control arms are really only a benefit to adjust wheelbase, and not really necessary. Wrong, angle of force is important, and differing lengths of LCA's effect steering along with collapsing/extending of either side wheel. For average Joe, NA will work OK (you can live with compromises). LCAB's are more important with a lowered car. If you want control, adjustable is necessary.
I have two things I can't really wrap my head around.
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle? - Already explained above.
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? No, LCA's move in an arc (chassis side fixed); SO, keeping the bolt holes within the arc will not change the rearend position. As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
I want it fairly low and bought CG weight jackers so I can adjust the height until I'm happy / it doesn't become a pita to drive up driveways. That said, without going into too much a technical discussion about roll centers and such, here's what I've done so far to try correct, as much as reasonably possible, the suspension back to factory geometry, which granted isn't the best. Wow, that was a lot of stipulations. Anyways, not including chassis strengthening (sfc, stb etc) or parts that don't alter geometry (bushings, torque arm, lca etc), here's what I have that I think covers everything short of major redesigning of components.
3/4" extended ball joints - brings the front control arms back 'down'
raised bearing strut mounts - adds back some strut travel
"shorter" rear shock - avoid bottoming out
adjustable panhard bar - re-centers rearend
rear lower control arm brackets - brings LCA back level or slight pointing downhill or uphill
'tall' rear sway bar axle mount - brings rear sway bar closer to being flat
axle side panhard bar lowering mount - brings the panhard bar to level - Actually increases inclination, both sides necessary to level. For your application, your fine with just axle side.
bump steer kit - bring tie rods back level
I may cut down the sway bar end links a touch, tho I don't think that's necessary. Front sway bar shouldn't need anything since the control arms are lowered some.
I currently have aftermarket non-adjustable torque arm and lower control arms. Correct me if I'm wrong, but adjustable lower control arms are really only a benefit to adjust wheelbase, and not really necessary. Wrong, angle of force is important, and differing lengths of LCA's effect steering along with collapsing/extending of either side wheel. For average Joe, NA will work OK (you can live with compromises). LCAB's are more important with a lowered car. If you want control, adjustable is necessary.
I have two things I can't really wrap my head around.
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle? - Already explained above.
2. Welding LCARB's. I realize the primary use for these is to go from a stock slightly pointing uphill (front to back), to pointing downhill (front to back) for drag racing. So during install, you swing the arm down, line up the bracket with the hole in the control arm, and weld in place. This allows use of the stock hole and lower hole without moving the rear or adjusting LCA length. On a lowered car, welding them on this way will move the rearend forward from stock, correct? No, LCA's move in an arc (chassis side fixed); SO, keeping the bolt holes within the arc will not change the rearend position. As in, with the arms pointing uphill at an 'extreme' angle after lowering, the arc of the LCA brings the rear forward. When the lcarbs are welded in as described above, the angle of the lca is adjusted, but the rearend location is still forward from stock.
Wouldn't it be better/is it possible to weld the brackets on the rearend with the new hole in the bracket perfectly down from the one on the rearend? Wouldn't that keep the rear where it was supposed to be?
The cost between adjustable and NA is slight - buy the adjustable. The NA TA is a bummer. The NA LCA's are the one place you could cheap out, but it's also where the difference is so slight - why??
You can always live with it, and keep your eyes open for a deal or a part-out situation for an adj. TA.
Don't stress, you've come a long way - Congrats. Keep Learning and Enjoying!
#5
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Re: Correcting geometry for lowered cars
1. Necessity of an adjustable torque arm. I've read what I could on setting driveline and pinion angles. I wish I took measurements before I started, but the stock pinion angle doesn't seem to follow the equal but opposite rules, as in, the "rule" has the engine pointing down (front to back) and the pinion pointing up, (back to front). The factory setup appears to me that the pinion points down (back to front). Lowering the car will make it point down even more, correct? An adjustable torque arm might bring it back to factory angle, but doubtful it would match the 'rule'. Either way, I will NOT be drag racing this car, but at the same time don't want to create any issues with vibrations. What is the factory spec for pinion and driveline angle?
#6
Re: Correcting geometry for lowered cars
Idk man but I’ve been putting mine together for 12 yrs and I’m still not done....but I’m about 85% as well. Need to nail down this suspension and steering problems
#7
Re: Correcting geometry for lowered cars
Wrong, angle of force is important, and differing lengths of LCA's effect steering along with collapsing/extending of either side wheel. For average Joe, NA will work OK (you can live with compromises). LCAB's are more important with a lowered car. If you want control, adjustable is necessary.
Ultimately, as Skinny Z says, I'm way overthinking this and it's minimal distance to even worry about.
I believe that you want 2° lower than the engine centerline's angle. Idea seems to be the rear end will want to rotate up and 2° down will allow it to rotate up into parallel on hard accel. Easiest way to do this is to just put a metal straightedge across the crank pulley and put an angle finder on that starightedge and take a measurement. That should be the engine centerline's angle. Remove the driveshaft and put the angle finder across the yoke and this is the rear end angle. point the yoke down 2° lower than the engine and you should be done.
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#8
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Car: '89 Formula
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Axle/Gears: MW 3.42 12 Bolt
Re: Correcting geometry for lowered cars
You've chosen a lot of good parts, here.
PHB - Chassis side is higher than axle side (that's obvious). With lowering, you are actually raising the rear-end into the body. With the axle side lowering bracket, you get that inclination back plus you do lower the rear RC. This is all that's needed for a street car. Some counter-clockwise tracks (more left hand turns) might require a more level PHB, OR if you're looking to really lower the rear RC a lot (don't recommend for most people), which also requires much stiffer rear springs, AND a well thought out front solution as a whole package.
You do want to induce some rear steer: outside wheel comes forward in relation to the inside rear staying more rearward. This helps cornering and we want it to happen with weight transfer differences (collapsing/extending) between the inside and outside rear wheel which causes different positions on the LCA arc for each wheel.
For example, at 0*, both rear wheels are the farthest from the front wheels as possible. If one side of the rear axle compresses say 5* (axle is going into the body by weight xfer), then that rear wheel has come forward in relation to its front wheel counterpart. The distance from the LCA chassis mount to axle mount has never changed (length of LCA remains unchanged). SO; lengthening or shortening the LCA's are going to affect the rate of change in wheelbase length according to the angle change. There are dynamic considerations, too, but I won't go there.
I'm not familiar with LG's TA. You have a lot of quality options in Houston (parts and shops)! Ideally, you want the front mount off of the trans. Add a link to your build so we can see, please. Is there a change in length of the new TA in relation to stock?
One additional reason for adjustable is that normally one end is a threaded shank as seen in my pic. I use poly on chassis side, and Del-Sphere joints (Spohn or any equivalent). If future tech comes up with something better, I can simply put in that new shank with the new tech without buying new arms.
PHB - Chassis side is higher than axle side (that's obvious). With lowering, you are actually raising the rear-end into the body. With the axle side lowering bracket, you get that inclination back plus you do lower the rear RC. This is all that's needed for a street car. Some counter-clockwise tracks (more left hand turns) might require a more level PHB, OR if you're looking to really lower the rear RC a lot (don't recommend for most people), which also requires much stiffer rear springs, AND a well thought out front solution as a whole package.
You do want to induce some rear steer: outside wheel comes forward in relation to the inside rear staying more rearward. This helps cornering and we want it to happen with weight transfer differences (collapsing/extending) between the inside and outside rear wheel which causes different positions on the LCA arc for each wheel.
For example, at 0*, both rear wheels are the farthest from the front wheels as possible. If one side of the rear axle compresses say 5* (axle is going into the body by weight xfer), then that rear wheel has come forward in relation to its front wheel counterpart. The distance from the LCA chassis mount to axle mount has never changed (length of LCA remains unchanged). SO; lengthening or shortening the LCA's are going to affect the rate of change in wheelbase length according to the angle change. There are dynamic considerations, too, but I won't go there.
I'm not familiar with LG's TA. You have a lot of quality options in Houston (parts and shops)! Ideally, you want the front mount off of the trans. Add a link to your build so we can see, please. Is there a change in length of the new TA in relation to stock?
One additional reason for adjustable is that normally one end is a threaded shank as seen in my pic. I use poly on chassis side, and Del-Sphere joints (Spohn or any equivalent). If future tech comes up with something better, I can simply put in that new shank with the new tech without buying new arms.
#9
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Re: Correcting geometry for lowered cars
That said though, I'm quite certain you will find that with a typical crankshaft centreline inclined at 4° up (at the balancer relative to transmission output shaft), that getting the pinion up the same amount will not be an issue with an adjustable torque arm. Then your concerns over the "jump roping" blurb are put to rest (which is really something else altogether and relates to driveshaft critical speed).
Last edited by skinny z; 01-18-2018 at 03:24 PM.
#10
Re: Correcting geometry for lowered cars
Good point on the rear steer. Hadn't considered that.
LG torque are is pretty slick IMHO. It's a spherical bearing welded to the front torque mount. The TA is full length with the front of it a solid bar. Early ASedan guys used this setup by modifying the factory TA. Most all the trans mounted aftermarket TAs use a poly bushing. The TA is free to slide forward and back, but still has the possibility of binding up when the TA isn't square with the bushing. On the factory setup, this is what I believe is a big factor in axle hop under braking. The TA can't slide in and out when there is a large weight transfer and the axle droops.
Link to my build is in my signature, "Nessie"
The fun thing is, the streetcar will have more goodies than the racecar where we're limited in changing pickup points.
One additional reason for adjustable is that normally one end is a threaded shank as seen in my pic. I use poly on chassis side, and Del-Sphere joints (Spohn or any equivalent). If future tech comes up with something better, I can simply put in that new shank with the new tech without buying new arms.
#12
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Re: Correcting geometry for lowered cars
While I agree on the torque arm relocation, and my new arrangement incorporates the Hooker transmission crossmember with the isolated trans mount, I have plenty of passes with the arm mounted to the trans. Now, I haven't got a wheel stander, but I do have slicks and have managed 60' times in the 1.7 range and there has never been an issue.
That said, it is a design of manufacturing compromise and if the opportunity exists to move the mount off the trans, I would do it.
That said, it is a design of manufacturing compromise and if the opportunity exists to move the mount off the trans, I would do it.
#13
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Re: Correcting geometry for lowered cars
While I agree on the torque arm relocation, and my new arrangement incorporates the Hooker transmission crossmember with the isolated trans mount, I have plenty of passes with the arm mounted to the trans. Now, I haven't got a wheel stander, but I do have slicks and have managed 60' times in the 1.7 range and there has never been an issue.
That said, it is a design of manufacturing compromise and if the opportunity exists to move the mount off the trans, I would do it.
That said, it is a design of manufacturing compromise and if the opportunity exists to move the mount off the trans, I would do it.
#14
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Re: Correcting geometry for lowered cars
LG torque are is pretty slick IMHO. It's a spherical bearing welded to the front torque mount. The TA is full length with the front of it a solid bar. Early ASedan guys used this setup by modifying the factory TA. Most all the trans mounted aftermarket TAs use a poly bushing. The TA is free to slide forward and back, but still has the possibility of binding up when the TA isn't square with the bushing. On the factory setup, this is what I believe is a big factor in axle hop under braking. The TA can't slide in and out when there is a large weight transfer and the axle droops.
This is on the 86 Trans Am BBC car. With a spherical rod end, it's a little noisy but with zero binding forward and backward as might be experienced with the radially mounted bearing.
________________________________________________________________________
For the amount this car is street driven, if I were to do it again, I'd go for the poly bushing instead of the spherical rod end
________________________________________________________________________
This is the arrangement on the SBC Camaro. Again, mostly street driving with some drag racing mixed in. I've yet to see how it behaves on a road course but that's in the works too.
Less expensive, quiet but possibly prone to binding as you mentioned.
EDIT: Pictures courtesy of the internet.
Last edited by skinny z; 01-19-2018 at 01:04 PM.
#15
Re: Correcting geometry for lowered cars
In the initial post is mentioned 'Bump steer kit" and the description is " bring tie rods back level"
This is not a correct explanation. Bump steer has nothing to do with referencing the ground. It is referencing the arch of the a-arm in geometry and shimming the tie rod so as not to change a wheels steering angle when the suspension travels. It is a fine tuning devise that varies between cars based on modifications and alignment specs.
This is not a correct explanation. Bump steer has nothing to do with referencing the ground. It is referencing the arch of the a-arm in geometry and shimming the tie rod so as not to change a wheels steering angle when the suspension travels. It is a fine tuning devise that varies between cars based on modifications and alignment specs.
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Re: Correcting geometry for lowered cars
In the initial post is mentioned 'Bump steer kit" and the description is " bring tie rods back level"
This is not a correct explanation. Bump steer has nothing to do with referencing the ground. It is referencing the arch of the a-arm in geometry and shimming the tie rod so as not to change a wheels steering angle when the suspension travels. It is a fine tuning devise that varies between cars based on modifications and alignment specs.
This is not a correct explanation. Bump steer has nothing to do with referencing the ground. It is referencing the arch of the a-arm in geometry and shimming the tie rod so as not to change a wheels steering angle when the suspension travels. It is a fine tuning devise that varies between cars based on modifications and alignment specs.
Correct. Go to Longacre they have a chart that walks you though how to correct bump steer. You will have to pull the springs out and run the suspension thought its travel while checking toe change.
#17
Re: Correcting geometry for lowered cars
I had more time tonight so I read this entire post.
All I can say is I have obviously been gone too long and there is a lot of new members who have no idea what they are doing. There is so much wrong with this post I do not know where to start other then to say it probably doesn't matter because I doubt he would buy the correct parts to "correct his geometry" I love the quote "close enough" Spend all this money just to be close enough is less good then leaving it stock and putting on some Koni yellows. Read my old posts and do research. you have a lot to learn
Tailshaft-driveshaft angle should be a reverse match to the driveshaft-rearend angle...then you point the pinion down to the ground ONE MORE DEGREE to compensate for thrust upward under throttle input. ANy more will prematurely wear out the U-joints on a street car.
Aftermarket Tq arms sole purpose is the shorten the length of it to gain forward bite. The LG unit is a very expensive and unnecessary replacement of an OEM part that does the exact same thing.
Tall strut mounts are not a good thing unless you absolutely need clearance. If not then the increase length hampers dynamic caster gain under hard braking as well as increase the leverage of the chassis and promotes rear jacking of body under braking.
Adjustable LCAs are pretty much mandatory to reposition the rear axle during pinion settings, LCA angle corrections, AND wheel base. As Teds mention briefly, you can really improve on the 3rd gen handling platform by utilizing roll understeer effects of lca angles in cornering.
Roll centers is the most important characteristic of the car that controls spring rate balance. you do not just set the panhard level and add extended ball joints for sake of keeping things level or you may and probably will end up with a poor handling car that you should have left stock.
Bump steer really is a mute issue on just about even 3rd gen Ive ever driven because people add wheels and tires in widths and offsets that they never use the full width of and usually have poor scrub radius which yanks the wheel out of your hands anyways.
Adding parts to get close enough is really a waste of money. I guarantee and I have said on here for years that I could take an OEM car with just Koni yellows and beat 99% of the cars on here with lots of shiny red parts bolted under them.
Dean
This post kind of reminds me of 15 years ago on here where I proved that very point with a little V6 car against 11 others and embarrassed quite a few people. Moral of the story? Read before you just buy and assume...you are throwing away money.
All I can say is I have obviously been gone too long and there is a lot of new members who have no idea what they are doing. There is so much wrong with this post I do not know where to start other then to say it probably doesn't matter because I doubt he would buy the correct parts to "correct his geometry" I love the quote "close enough" Spend all this money just to be close enough is less good then leaving it stock and putting on some Koni yellows. Read my old posts and do research. you have a lot to learn
Tailshaft-driveshaft angle should be a reverse match to the driveshaft-rearend angle...then you point the pinion down to the ground ONE MORE DEGREE to compensate for thrust upward under throttle input. ANy more will prematurely wear out the U-joints on a street car.
Aftermarket Tq arms sole purpose is the shorten the length of it to gain forward bite. The LG unit is a very expensive and unnecessary replacement of an OEM part that does the exact same thing.
Tall strut mounts are not a good thing unless you absolutely need clearance. If not then the increase length hampers dynamic caster gain under hard braking as well as increase the leverage of the chassis and promotes rear jacking of body under braking.
Adjustable LCAs are pretty much mandatory to reposition the rear axle during pinion settings, LCA angle corrections, AND wheel base. As Teds mention briefly, you can really improve on the 3rd gen handling platform by utilizing roll understeer effects of lca angles in cornering.
Roll centers is the most important characteristic of the car that controls spring rate balance. you do not just set the panhard level and add extended ball joints for sake of keeping things level or you may and probably will end up with a poor handling car that you should have left stock.
Bump steer really is a mute issue on just about even 3rd gen Ive ever driven because people add wheels and tires in widths and offsets that they never use the full width of and usually have poor scrub radius which yanks the wheel out of your hands anyways.
Adding parts to get close enough is really a waste of money. I guarantee and I have said on here for years that I could take an OEM car with just Koni yellows and beat 99% of the cars on here with lots of shiny red parts bolted under them.
Dean
This post kind of reminds me of 15 years ago on here where I proved that very point with a little V6 car against 11 others and embarrassed quite a few people. Moral of the story? Read before you just buy and assume...you are throwing away money.
Last edited by SlickTrackGod; 01-19-2018 at 09:22 PM.
#19
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Re: Correcting geometry for lowered cars
The TA is free to slide forward and back, but still has the possibility of binding up when the TA isn't square with the bushing. On the factory setup, this is what I believe is a big factor in axle hop under braking. The TA can't slide in and out when there is a large weight transfer and the axle droops.
I'm not sure if the video Camaro had the DSE Quadra-Link or a torque arm style suspension.
Care to elaborate again?
#20
Re: Correcting geometry for lowered cars
Since you've decided to drop in Dean, care to share your insights into the above statement? I recall your analysis of a DSE equipped Camaro video and the axle hop under braking. You had attributed it to a few specific items.
I'm not sure if the video Camaro had the DSE Quadra-Link or a torque arm style suspension.
Care to elaborate again?
I'm not sure if the video Camaro had the DSE Quadra-Link or a torque arm style suspension.
Care to elaborate again?
#21
Re: Correcting geometry for lowered cars
I will also add something very top secret. I have actually been working on a very old idea of mine and developing a prototype to try and correct the inherit defect of Ackerman in the 3rd gen platform. Ive mentioned this a few times here and there over the years but will announce I am actually actively working on a product and expect if this works out like I expect it to that I will have several hundred kits packaged and ready for sale upon my announcement release buy the end of this year. All I can say is stay tuned and you will be amazed just how simple this idea is and it has never been developed by anyone. I've held this close to my cuff for years and only one other person know who is actually helping me as a partner.
Yes this is meant to be a huge teaser.
Yes this is meant to be a huge teaser.
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Re: Correcting geometry for lowered cars
Just FYI - The US patent process changed a few years ago and now it is first to file, not first to invent. Might want to patent that sucker (if it is patentable) so it isn't ripped off by a company with deeper pockets than you.
#23
Re: Correcting geometry for lowered cars
Already have the connections on that. Thank you for the info though. My buddy Loius at Vertical Doors has been through the ringer with this. Holds patent and has pretty much owned ever Chinese knockoff that ever came into the US because if infringements. I have a great mentor in that field.
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Re: Correcting geometry for lowered cars
Roll centers is the most important characteristic of the car that controls spring rate balance. you do not just set the panhard level and add extended ball joints for sake of keeping things level or you may and probably will end up with a poor handling car that you should have left stock.
The OP didn't want to discuss RC's, but since you mentioned them, Is there a rule of thumb for spring rate changes according to the RC changes? Are there any theories or guides to follow? I haven't changed the rear RC that much (one hole on the ext PHBB) and was surprised that #250 and 19mm bar were very effective. My thinking (faulty or not) did not get me to that set-up. Experimenting and driving got me there.
OP has fr #850 and rr #200 - no idea of bars.
I hope your new product addresses the interface between spindle and strut!
Brian
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Re: Correcting geometry for lowered cars
Pulled from this thread.
https://www.thirdgen.org/forums/susp...ll-joints.html
Now I'm confused.
With a lowered chassis and an otherwise OEM configured suspension do you make the move to an extended ball joint and a relocated panhard bar or leave it alone?
As I'm asking this question solely for myself my setup consists of Intrax lowering springs (1.5" +/-), poly/Del-A-Lum bushings, adjustable TA, aftermarket non-adj LCAs, Spohn SFCs, IROC rims, largest OEM sway bars available for the 3rd gen (at least my understanding is that they're the largest, the diameters which escape me at the moment).
Thanks in advance.
https://www.thirdgen.org/forums/susp...ll-joints.html
Once the car is lowered, the rear jegs unit is needed to help bring the rear rc down to match the front rc drop.
...this is why 3rd gnes need extended ball joints up front especially when the car's ride height is lowered and the geometry changes...
...this is why 3rd gnes need extended ball joints up front especially when the car's ride height is lowered and the geometry changes...
With a lowered chassis and an otherwise OEM configured suspension do you make the move to an extended ball joint and a relocated panhard bar or leave it alone?
As I'm asking this question solely for myself my setup consists of Intrax lowering springs (1.5" +/-), poly/Del-A-Lum bushings, adjustable TA, aftermarket non-adj LCAs, Spohn SFCs, IROC rims, largest OEM sway bars available for the 3rd gen (at least my understanding is that they're the largest, the diameters which escape me at the moment).
Thanks in advance.
Last edited by skinny z; 01-20-2018 at 01:29 PM.
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Re: Correcting geometry for lowered cars
Pulled from this thread.
https://www.thirdgen.org/forums/susp...ll-joints.html
Now I'm confused.
With a lowered chassis and an otherwise OEM configured suspension do you make the move to an extended ball joint and a relocated panhard bar or leave it alone? YES, but it is not the whole ball of wax - that is Dean's point.
As I'm asking this question solely for myself my setup consists of Intrax lowering springs (1.5" +/-), poly/Del-A-Lum bushings, adjustable TA, aftermarket non-adj LCAs, Spohn SFCs, IROC rims, largest OEM sway bars available for the 3rd gen (at least my understanding is that they're the largest, the diameters which escape me at the moment).
Thanks in advance.
https://www.thirdgen.org/forums/susp...ll-joints.html
Now I'm confused.
With a lowered chassis and an otherwise OEM configured suspension do you make the move to an extended ball joint and a relocated panhard bar or leave it alone? YES, but it is not the whole ball of wax - that is Dean's point.
As I'm asking this question solely for myself my setup consists of Intrax lowering springs (1.5" +/-), poly/Del-A-Lum bushings, adjustable TA, aftermarket non-adj LCAs, Spohn SFCs, IROC rims, largest OEM sway bars available for the 3rd gen (at least my understanding is that they're the largest, the diameters which escape me at the moment).
Thanks in advance.
Raising front RC and lowering rear RC are probably the single greatest things to do, but understanding is needed not just putting on the ext ball joints and lowering PHB.
The OP has more understanding than Dean is giving him credit for (he has a CMC car). But Dean is right in filling out the understanding, too. And using non-adjustable pieces just fuels Dean's critique (and I concur). Not to mention, he went with 18" wheels and spacers - more fuel to the critique. He has said this is a street car, but a good handling car goes by the same suspension rules as a race car (for the most part).
We all make compromises along the way. It's difficult to keep your build philosophy in view when making decisions. If you can stay true to your build philosophy, you'll end up happy. Mis-matched pieces, no matter their reputation, won't give you the car you're looking for. I think this is the hardest part of resto-modding - staying true to build philosophy. Maybe the OP can fill-out his build philosophy a little more for us.
I wanted to build the most agile GT car from a 60 mph roll, while focusing on unsprung weight. That forces my hand on some decisions, but I have to stay focused on the goal. And I insist on some creature comforts at my age, or I won't be touring anywhere!
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Re: Correcting geometry for lowered cars
And the confusion comes not from a lack of understanding because the science and associated geometry are easily grasped (for me). It comes from the contradictory statements from someone who I have respect for in these regards.
And I wholeheartedly agree with staying true to the build philosophy and the goals mapped out at the start. This is precisely why I haven't made the move to a drag racing orientated suspension even though one of the goals of the original build was to have an 11 second street car. Aiding my 60' times via drag shocks and struts would undoubtedly give a huge push towards that goal. That said, the road course beckons. Also only a 20 minute drive from my front door.
As for the OP, haven't heard anything in reply but I will say thanks again for posting and allowing for a further exchange of information. It's always appreciated.
Last edited by skinny z; 01-20-2018 at 03:30 PM.
#29
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Re: Correcting geometry for lowered cars
Context is everything!
At second read, it appears that Dean is saying after lowering...the front rc drops - TRUE.
...This is why 3rd Gens need ext BJ's - true, they will raise fr RC.
It was confusing, to me, the way he ordered the phrases. I don't think he is contradicting himself - only he can speak for himself. And the whole context is crucial to understanding.
OR, maybe the way you edited the quote?
Any how, I don't think there's a problem, here.
At second read, it appears that Dean is saying after lowering...the front rc drops - TRUE.
...This is why 3rd Gens need ext BJ's - true, they will raise fr RC.
It was confusing, to me, the way he ordered the phrases. I don't think he is contradicting himself - only he can speak for himself. And the whole context is crucial to understanding.
OR, maybe the way you edited the quote?
Any how, I don't think there's a problem, here.
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Re: Correcting geometry for lowered cars
No. There's no problem (nor am I trying to create one). I'm simply looking for clarification on a modification that it's in the build plans.
I'm sure Dean will drop in soon enough and offer up an explanation.
My take on it is that with the lowered suspension, at the minimum the extended ball joints and lowered panhard mount is the way to go.
Add in some Koni yellows and I'm off to the track.
Then there's brake pads...sway bars...
Thanks for your input Brian. It too is always appreciated.
Kevin
I'm sure Dean will drop in soon enough and offer up an explanation.
My take on it is that with the lowered suspension, at the minimum the extended ball joints and lowered panhard mount is the way to go.
Add in some Koni yellows and I'm off to the track.
Then there's brake pads...sway bars...
Thanks for your input Brian. It too is always appreciated.
Kevin
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Re: Correcting geometry for lowered cars
By raising RC, one can use lighter springs: FRONT.
By lowering RC, one should up spring rate: REAR.
FRONT: With ext BJ, I'm not sure it makes that much difference, but some. I have 2" drop spindles and ext BJ's. By raising front RC, I can use lighter springs, travel the front suspension more, but that hurts ackerman during travel (hope Dean has a good solution). So I can use more weight transfer to my advantage. With a V8, LS or not, you can't have too big a bar up front.
REAR: Higher spring rate means lighter bar. Now I have #25 additional weight with the Mark Williams 12 bolt.
When Dean says you can't just put parts on and have a better car, of course, he's right. It requires understanding, spring rate adjustments and corresponding bar adjustments. Some CMC guys are running #1000 fronts, but they cannot mess with RC's. Even Dean's V6 had very little front suspension travel. Well, that's one way to do it. I'm more interested lately, in more front suspension travel with my front RC = less spring rate. An ackerman fix is of great interest.
I'm a theory guy. But theory can only get one so far, then real world experience gets you the rest of the way. But theory can save time, effort, and money by narrowing down the area where experiment should happen. Software can save some time, effort, and money, but it costs some money, too - http://performancetrends.com/rc.htm
Roll Center Plus is useful as you can tweak the program to imitate a three-link set-up for rear computations.
So, if you just put the ext BJ's and PHBB on, you can hurt handling. But if you make other adjustments along with these parts, you will have a much better handling car - as Dean has mentioned. Software can help/aid in understanding what all the adjustments are doing to the car. I think it is worth it. But as I said, it only narrows down the area to experiment in, but aids in understanding a lot.
#32
Re: Correcting geometry for lowered cars
Maybe part of my problem is that I listed so many components and tried to state the reason for each component in a single sentence. Each of these already have their own multi-page thread on the pros and cons of each. I was simply trying to put them all in one place.
I run a TPI airbox fed LT1 with a WC T5 filled with Mobil 1 that has the TA mounted to it, powering a 10 bolt, in the racecar, sorry, car that is raced. I shouldn't be alive according to some.
*edit* I laugh but 100% understand where you and others are coming from. It's a risk and sometimes a compromise. I get that. Sometimes people speak in absolutes, and that part bothers me. Your quote is spot on.
Real classy Dean. I've been around a while, and read many of your posts under whatever username until it gets banned. I'm looking at Adam's Chassis Engineering, Senna's Principles of Race Driving, and Robert's Think Fast book at my desk. I'm not saying I know everything or even half of what there is to know about setting up a car, but I'm not just some dumb kid. I didn't want to really bring in roll centers because it usually becomes a pissing match AND a lot of theoretical things that can't be accomplished without major redesign of the car. Pretty diagrams are nice, but without real numbers behind them, they lose their umph. The other thing is, I'm not building a racecar, or even a car that is raced, and it's not for laptimes. I simply wanted to get it 'better' than just cutting springs and doing nothing else. Surely you can at least agree that SOME of these parts HELP or IMPROVE the geometry and handling of a lowered car at least back to stock or better?? *edit* At no time did I say I was trying to make this handle like a Corvette or anything unobtainable.
I'll be the first to admit I'm not just running koni yellows and a stock setup on this car because this...
looks a lot better than this...
Besides, why stop at Koni's? Why not go AST's, Penske, or Motions?
Does anyone know what these angles are from the factory at stock height? Getting the perfect angles is super easy to accomplish when you are building a car from scratch. It takes on a whole other meaning when building around a production tub, with parts (LS1/T56) that never came in the car. "Simple" adjustments like raising the trans tailshaft may mean building a new transmission tunnel. What is proper and what is reasonable sometimes don't line up and compromises are made. I won't know how far off I am until I get measurements again.
So, the LG unit does nothing to aid brake axle hop? Some well respected 4th gen racers I run with would disagree. Again, I'm not opposed to adjustable TA's which are required to adjust driveline angles, but simply want the benefits of the LG TA as well, even if that means a custom TA.
I was under the impression that dampers are best kept in the middle of their range for best effectiveness. For most off the shelf dampers, the length are the same as stock, and lowering a car would increase the chances of bottoming out. This is the first I've heard about taller strut mounts being a bad thing on a lowered car. Does anyone even make strut mounts using the stock height? Obviously (tho maybe not, apparently I'm completely wrong on so many things), the main purpose of aftermarket strut mounts is the bearing over the stock rubber.
I understand the wheel base and rear steer parts. How does an adjustable length LCA affect the LCA angle? I'm having a hard time visualizing why the LCA would need to be lengthened or shortend to change or as a result of a change to the pinion angle, unless it's solely to adjust wheelbase back to where is was before the pinion angle adjustment. Can you please explain?
So now extended ball joints are a bad thing?
*edit*axle side phb bracket is also bad? Tell that to the guy in post #16 in this link
True, I maybe should have clarified. I was not adding the bump steer kit to correct bump steer for reasons you mention. It was to bring back the relationship between the a-arms and tie rods as they were or at least, brace for it, closer to as they were.
Again, I think you're missing the intent behind this. You'll beat me in this car everytime, because I'm not going to race it. Are you suggesting that adding parts to get 'close enough' is worse than just cutting springs and doing nothing? I fully understand that throwing parts at the car won't magically fix everything. Maybe that's what you're trying to say?
I did read some posts about that. Something about you 'only' being *edit* 12 seconds behind the fast cars. You should know this, but *edit* 12 seconds is HUUUUUUUUGE on a road course. I recently ran COTA (full course) in my CMC car, which is an amateur series. I'm a mid-pack slacker. Mike Paterson runs an AI 4th gen, and set AI record for the weekend. His car has a much better power to weight ratio, big aero, bigger tires, better driver. *edit* 2:30.871. Guess what? I was *edit* 2:42.232, 'only' *edit* 12 seconds a lap slower. There is no way in hell I'd ever boast about that. And for those other 11 cars? Ever hear of big fish in a little pond? Happened all the time at TAMSCC autocrosses. Most members were students, but would get killed by the older autocrossing locals who lived in the area. Those same locals may be fast, but not necessarily the fastest, at national level events. I'm sorry, but these type of anecdotes don't impress me. I've seen miata's with lap times faster than Z06's, and hundreds of youtube video's of some guy in a 'slower' car passing some guy in a much faster car. I've passed a lot of AI cars racing. Doesn't mean anything. It simply cannot be used as 'proof'.
*edit* Just so nobody takes this the wrong way. Yes, what Dean had in that V6 car was impressive from a handling stand point, and has talent behind the wheel. But difficult to prove it's the be all end all.
I appreciate your knowledge, but you really need to check your ego at times.
I run a TPI airbox fed LT1 with a WC T5 filled with Mobil 1 that has the TA mounted to it, powering a 10 bolt, in the racecar, sorry, car that is raced. I shouldn't be alive according to some.
*edit* I laugh but 100% understand where you and others are coming from. It's a risk and sometimes a compromise. I get that. Sometimes people speak in absolutes, and that part bothers me. Your quote is spot on.
I had more time tonight so I read this entire post.
All I can say is I have obviously been gone too long and there is a lot of new members who have no idea what they are doing. There is so much wrong with this post I do not know where to start other then to say it probably doesn't matter because I doubt he would buy the correct parts to "correct his geometry" I love the quote "close enough" Spend all this money just to be close enough is less good then leaving it stock and putting on some Koni yellows. Read my old posts and do research. you have a lot to learn
All I can say is I have obviously been gone too long and there is a lot of new members who have no idea what they are doing. There is so much wrong with this post I do not know where to start other then to say it probably doesn't matter because I doubt he would buy the correct parts to "correct his geometry" I love the quote "close enough" Spend all this money just to be close enough is less good then leaving it stock and putting on some Koni yellows. Read my old posts and do research. you have a lot to learn
I'll be the first to admit I'm not just running koni yellows and a stock setup on this car because this...
looks a lot better than this...
Besides, why stop at Koni's? Why not go AST's, Penske, or Motions?
Tailshaft-driveshaft angle should be a reverse match to the driveshaft-rearend angle...then you point the pinion down to the ground ONE MORE DEGREE to compensate for thrust upward under throttle input. Any more will prematurely wear out the U-joints on a street car.
Adjustable LCAs are pretty much mandatory to reposition the rear axle during pinion settings, LCA angle corrections, AND wheel base. As Teds mention briefly, you can really improve on the 3rd gen handling platform by utilizing roll understeer effects of lca angles in cornering.
Roll centers is the most important characteristic of the car that controls spring rate balance. you do not just set the panhard level and add extended ball joints for sake of keeping things level or you may and probably will end up with a poor handling car that you should have left stock.
*edit*axle side phb bracket is also bad? Tell that to the guy in post #16 in this link
*edit* Just so nobody takes this the wrong way. Yes, what Dean had in that V6 car was impressive from a handling stand point, and has talent behind the wheel. But difficult to prove it's the be all end all.
I appreciate your knowledge, but you really need to check your ego at times.
Last edited by GMan 3MT; 01-20-2018 at 08:30 PM.
#33
Re: Correcting geometry for lowered cars
My current bars on the street car are 36/23. I have a few different rear bars I could put on. Again, I don't think I'll ever be pushing it hard enough to need to tune it.
The OP has more understanding than Dean is giving him credit for (he has a CMC car). But Dean is right in filling out the understanding, too. And using non-adjustable pieces just fuels Dean's critique (and I concur). Not to mention, he went with 18" wheels and spacers - more fuel to the critique. He has said this is a street car, but a good handling car goes by the same suspension rules as a race car (for the most part).
We all make compromises along the way. It's difficult to keep your build philosophy in view when making decisions. If you can stay true to your build philosophy, you'll end up happy. Mis-matched pieces, no matter their reputation, won't give you the car you're looking for. I think this is the hardest part of resto-modding - staying true to build philosophy. Maybe the OP can fill-out his build philosophy a little more for us.
We all make compromises along the way. It's difficult to keep your build philosophy in view when making decisions. If you can stay true to your build philosophy, you'll end up happy. Mis-matched pieces, no matter their reputation, won't give you the car you're looking for. I think this is the hardest part of resto-modding - staying true to build philosophy. Maybe the OP can fill-out his build philosophy a little more for us.
I'd also love not to have to run adapters, but I want/need to get the car further along (paint and such, hey Tibo you're ahead of me there!) before getting wheels, both lighter and in the correct offset. Hell, even the front of my racecar has adapters, because I'm racing for fun, and don't want to drop the coin for a set or two of CCW's. Anyone wanna throw a few grand my way?
And I wholeheartedly agree with staying true to the build philosophy and the goals mapped out at the start.
As for the OP, haven't heard anything in reply but I will say thanks again for posting and allowing for a further exchange of information. It's always appreciated.
As for the OP, haven't heard anything in reply but I will say thanks again for posting and allowing for a further exchange of information. It's always appreciated.
When Dean says you can't just put parts on and have a better car, of course, he's right. It requires understanding, spring rate adjustments and corresponding bar adjustments. Some CMC guys are running #1000 fronts, but they cannot mess with RC's. Even Dean's V6 had very little front suspension travel. Well, that's one way to do it. I'm more interested lately, in more front suspension travel with my front RC = less spring rate. An ackerman fix is of great interest.
I'm running 1000/175. I have done very few changes to the suspension of the car as I'm not consistent enough in my laptimes. A few track days with new tires and a driving coach is the answer. But again, it's easy to spend someone elses money on their hobby that they do for fun. The changes I have made are to make it more comfortable to drive at my limit. You're 100% correct that there really is very little things in the rules that allow us to change pickup points in CMC.
I just threw a level on the PHB of the racecar since it's on the trailer right now. It's angled 1.6* up on the drivers side. The streetcar will probably be lower in the back, so the angle will be greater. Big difference is, I can actually DO something about the streetcar if it will help. Dean's point MAY have been I can't just throw on a axle side panhard bar lowering mount or simply bring the panhard bar to level and expect winners torphies, but he wasn't very clear on it.
Last edited by GMan 3MT; 01-20-2018 at 07:36 PM. Reason: spelling, tho a driving couch would be awesome!
#34
Re: Correcting geometry for lowered cars
Seriously WTF. Am I the only one seeing this?
3/4" extended ball joints
"...this is why 3rd gnes need extended ball joints up front especially when the car's ride height is lowered and the geometry changes (thus geometry changes cause rc drop)."
https://www.thirdgen.org/forums/susp...ml#post6070452
raised bearing strut mounts
"SO...what is needed is a shorter strut body to be able to be used with a OEM-to- mid range strut mount height. This will reduce the OEM length of the strut operating range and allow for a shorter distance between the ball joint and the strut mount pivot. WHy is this needed? to gain favorable dynamic increase in camber and caster settings, as well as gain favorable static settings."
"No off the shelf strut fits that Bill currently?"
"Nope, all are OEM specs"
Sooo, ideally stock or midheight if a shorter strut body is available, which it isn't. So that just leaves... tall mounts with stock length struts?
https://www.thirdgen.org/forums/susp...ml#post5956972
Multiple other threads about bearing over rubber.
"shorter" rear shock
adjustable panhard bar
"You want to make the bar level. If you can get the center of the bar down about 1/2" to 1" from its current position but maintain a level bar from ground height to each bolt center on both sides of the panhard then you are good. Within 1" is acceptable- perferably on the axle side being lower then the chassis side without anyone in the car if it is not going to be level."
https://www.thirdgen.org/forums/susp...ml#post6161725
rear lower control arm brackets
'tall' rear sway bar axle mount
axle side panhard bar lowering mount
"Do NOT drop the chassis side of the panhard mount. If you drop any side, it should be ONLY the axle side about 1 1/2" maximum"
https://www.thirdgen.org/forums/fabr...ml#post4874562
This one is more of Brian's quote, but Dean doesn't disagree.
https://www.thirdgen.org/forums/susp...ml#post6118773
and further back it up here, tho this particular thread is lowering both sides which lowers rear RC even more.
https://www.thirdgen.org/forums/susp...ml#post6141120
bump steer kit
"Actually by adding lowering springs can and generally will change the bump relation of the tierods in comparison to the A-arms"
https://www.thirdgen.org/forums/susp...ml#post5974766
"...this is why 3rd gnes need extended ball joints up front especially when the car's ride height is lowered and the geometry changes (thus geometry changes cause rc drop)."
https://www.thirdgen.org/forums/susp...ml#post6070452
raised bearing strut mounts
"SO...what is needed is a shorter strut body to be able to be used with a OEM-to- mid range strut mount height. This will reduce the OEM length of the strut operating range and allow for a shorter distance between the ball joint and the strut mount pivot. WHy is this needed? to gain favorable dynamic increase in camber and caster settings, as well as gain favorable static settings."
"No off the shelf strut fits that Bill currently?"
"Nope, all are OEM specs"
Sooo, ideally stock or midheight if a shorter strut body is available, which it isn't. So that just leaves... tall mounts with stock length struts?
https://www.thirdgen.org/forums/susp...ml#post5956972
Multiple other threads about bearing over rubber.
"shorter" rear shock
adjustable panhard bar
"You want to make the bar level. If you can get the center of the bar down about 1/2" to 1" from its current position but maintain a level bar from ground height to each bolt center on both sides of the panhard then you are good. Within 1" is acceptable- perferably on the axle side being lower then the chassis side without anyone in the car if it is not going to be level."
https://www.thirdgen.org/forums/susp...ml#post6161725
rear lower control arm brackets
'tall' rear sway bar axle mount
axle side panhard bar lowering mount
"Do NOT drop the chassis side of the panhard mount. If you drop any side, it should be ONLY the axle side about 1 1/2" maximum"
https://www.thirdgen.org/forums/fabr...ml#post4874562
This one is more of Brian's quote, but Dean doesn't disagree.
https://www.thirdgen.org/forums/susp...ml#post6118773
and further back it up here, tho this particular thread is lowering both sides which lowers rear RC even more.
https://www.thirdgen.org/forums/susp...ml#post6141120
bump steer kit
"Actually by adding lowering springs can and generally will change the bump relation of the tierods in comparison to the A-arms"
https://www.thirdgen.org/forums/susp...ml#post5974766
Sole purpose? "Any time anything flexes under the car under any load it is not trasfering load consistantly from the chassis to the ground OR also from the ground to the chassis." and goes on to talk about different aftermarket torque arms, yes, "better" than the LG.
https://www.thirdgen.org/forums/susp...ml#post5755826
"5- tQ arm length is almost perfect for instant center under throttle AND braking. A little shorter than OEM is ultimatum in my book"
https://www.thirdgen.org/forums/susp...ml#post6139037
Yeah, now I'm totally confused. F it. Maybe I'll let Tibo do some welding on my car. (too soon? )
Last edited by GMan 3MT; 01-20-2018 at 11:29 PM.
#35
Re: Correcting geometry for lowered cars
Lets start off fresh so we have this clear about RC adjustments.
The factory OEM height 3rd gen has an overall roll axis that is tilted towards the front of the car at too steep an angle. The best correction for better handling is to lower the rear roll center on an OEM car to make it more towards flat.
Ok, now for a separate situation....
When you lower a 3rd gen from factory height, lets say you lower the height 2" both front and rear? the front RC goes down at a faster rate in the front then in the rear RC making the factory roll axis even more a problem with an even steeper decline towards the front of the car that the chassis rolls about on. THis causes the inside rear chassis/tire to lift in a cantered position taking weight off it and rolling it diagonally onto the outside front tire (think teeter totter diagonally on a tilted fulcrum point- this is so hard to explain in words, I could show you in seconds with hand gestures in person) SOOOO......
If the front RC goes down quicker when the car is lowered then we use extended ball joint to get the static position of the front RC back up higher so the roll axis is closer to level. I will give hypothetical examples of ride height + RC height both front and rear.---
If the OEM ride height of the car is lets say 27" fender lip front and 28" rear, the hypothetical RC heights are 6" off the ground front RC and 13" off the ground rear RC.
So now we lower the car 1" (26"front/27" rear) The RCS are now aprox 4" front and 12.5" rear......You see the angle of the roll axis getting steeper leaning towards the front of the car. The front RC goes down progressively faster then the rear RC)
Now we lower the chassis height 2" from OEM (25" front/26" rear) the RC dives progressively even quicker to about 1" off the ground front, and 12" rear...really getting bad.
This is why extended ball joints are pretty much mandatory on a lowered 3rd gen to get the front RC height out of the dirt.
Next topic- Strut mount height. When you add extended ball joints you are lowering the car without spring alterations because the amount of the extended ball joint increases the spindle height in relation to the chassis so the car lowers the amount of the extension. (thus 1/2" extended ball joint lower the car 1/2", 1" extended lowers the car 1" if using the same spring)....
...as a result, the spindle raises and thus the strut being attached to it of course compresses more in static form then without the extended ball joint...so....you now loose travel clearance of the strut body to possibly contact the under side of the strut mount. The shorter distance is great for geometry reasons like increase camber curve and increase dynamic caster gain, as well as reduced leverage for rear chassis jacking with motion through the strut lever as the car is under braking force. SO how much do we raise the strut mount? as little as we can get away with!!! You do this by either an increase spring rate, or by lightening your unsprung weight so as not to thrust it up into the under side for the strut mount., or we extend the strut mount height. The most favorable of the 3 is to lighten unsprung weight. My car barely traveled more that 1" normal and 1.5" under the most extreme conditions because of my extremely light wheel and brake package setup combined with my fairly high spring rates for a V6 car at about 825lbs|
That is a novel for most of you to digest for now so I will leave this post at that for now. If anyone needs further basic clarifications I will address questions but most of what is asked here I would have to put in so much depth it would take 100 pages on this post to add it all at the very least.extensive drawings and diagrams over the years that covers every question asked here. THis is why I asked people to search for specific info because I have everything and then some in archives on here over the last almost 20 years.
Now to address a final thought if I may. I read this post opener (***I did not look who wrote it- does not matter to me.) What I saw, or presumed I saw was someone posting a statement about what needs to be don to a lowered vehicle as what appeared to me an authoritative guideline to others to build off of. When something does not make sense to me I know it is really confusing others....So I chimed in...in my oh so known robotic typing skills way which everyone seems to think I am angry. I just list facts and type like a robot. Take it as you all will, I do not try to be popular, I try to inform and teach.
The factory OEM height 3rd gen has an overall roll axis that is tilted towards the front of the car at too steep an angle. The best correction for better handling is to lower the rear roll center on an OEM car to make it more towards flat.
Ok, now for a separate situation....
When you lower a 3rd gen from factory height, lets say you lower the height 2" both front and rear? the front RC goes down at a faster rate in the front then in the rear RC making the factory roll axis even more a problem with an even steeper decline towards the front of the car that the chassis rolls about on. THis causes the inside rear chassis/tire to lift in a cantered position taking weight off it and rolling it diagonally onto the outside front tire (think teeter totter diagonally on a tilted fulcrum point- this is so hard to explain in words, I could show you in seconds with hand gestures in person) SOOOO......
If the front RC goes down quicker when the car is lowered then we use extended ball joint to get the static position of the front RC back up higher so the roll axis is closer to level. I will give hypothetical examples of ride height + RC height both front and rear.---
If the OEM ride height of the car is lets say 27" fender lip front and 28" rear, the hypothetical RC heights are 6" off the ground front RC and 13" off the ground rear RC.
So now we lower the car 1" (26"front/27" rear) The RCS are now aprox 4" front and 12.5" rear......You see the angle of the roll axis getting steeper leaning towards the front of the car. The front RC goes down progressively faster then the rear RC)
Now we lower the chassis height 2" from OEM (25" front/26" rear) the RC dives progressively even quicker to about 1" off the ground front, and 12" rear...really getting bad.
This is why extended ball joints are pretty much mandatory on a lowered 3rd gen to get the front RC height out of the dirt.
Next topic- Strut mount height. When you add extended ball joints you are lowering the car without spring alterations because the amount of the extended ball joint increases the spindle height in relation to the chassis so the car lowers the amount of the extension. (thus 1/2" extended ball joint lower the car 1/2", 1" extended lowers the car 1" if using the same spring)....
...as a result, the spindle raises and thus the strut being attached to it of course compresses more in static form then without the extended ball joint...so....you now loose travel clearance of the strut body to possibly contact the under side of the strut mount. The shorter distance is great for geometry reasons like increase camber curve and increase dynamic caster gain, as well as reduced leverage for rear chassis jacking with motion through the strut lever as the car is under braking force. SO how much do we raise the strut mount? as little as we can get away with!!! You do this by either an increase spring rate, or by lightening your unsprung weight so as not to thrust it up into the under side for the strut mount., or we extend the strut mount height. The most favorable of the 3 is to lighten unsprung weight. My car barely traveled more that 1" normal and 1.5" under the most extreme conditions because of my extremely light wheel and brake package setup combined with my fairly high spring rates for a V6 car at about 825lbs|
That is a novel for most of you to digest for now so I will leave this post at that for now. If anyone needs further basic clarifications I will address questions but most of what is asked here I would have to put in so much depth it would take 100 pages on this post to add it all at the very least.extensive drawings and diagrams over the years that covers every question asked here. THis is why I asked people to search for specific info because I have everything and then some in archives on here over the last almost 20 years.
Now to address a final thought if I may. I read this post opener (***I did not look who wrote it- does not matter to me.) What I saw, or presumed I saw was someone posting a statement about what needs to be don to a lowered vehicle as what appeared to me an authoritative guideline to others to build off of. When something does not make sense to me I know it is really confusing others....So I chimed in...in my oh so known robotic typing skills way which everyone seems to think I am angry. I just list facts and type like a robot. Take it as you all will, I do not try to be popular, I try to inform and teach.
Last edited by SlickTrackGod; 01-21-2018 at 01:15 AM.
#36
Re: Correcting geometry for lowered cars
Let me share a little picture of myself that tells a thousand words. This was a young NASCAR Super Truck Driver I mentored about a decade ago. I do not sugar coat stuff in life. I shoot from the hip. I tell facts, I tell honestly. Like it or not the goal is to excel and win races... AND to teach others the gift I have. No one likes criticism, neither do I...but I have learned to accept it and the best learning tool is being real and to the point. You can see this picture his mother took of me being hard on him...and it got him to remember and learn from it rather than kissing his *** and letting the little things go. I use to tell him "Im not here to be your best friend, I here to kick you in the *** and get you to win races. A year later and a 3rd place overall in the Championship and we were best of friends. He realized I was being true by being honest and to the point. None of you have to listen to what I say, or like me, but ask yourself are you learning anything? If so then we all have a purpose here.
Dean
Dean
#37
Re: Correcting geometry for lowered cars
The Energizer Bunny is out of batteries? Good to have you post in, Dean.
The OP didn't want to discuss RC's, but since you mentioned them, Is there a rule of thumb for spring rate changes according to the RC changes? Are there any theories or guides to follow? I haven't changed the rear RC that much (one hole on the ext PHBB) and was surprised that #250 and 19mm bar were very effective. My thinking (faulty or not) did not get me to that set-up. Experimenting and driving got me there.
OP has fr #850 and rr #200 - no idea of bars.
I hope your new product addresses the interface between spindle and strut!
Brian
The OP didn't want to discuss RC's, but since you mentioned them, Is there a rule of thumb for spring rate changes according to the RC changes? Are there any theories or guides to follow? I haven't changed the rear RC that much (one hole on the ext PHBB) and was surprised that #250 and 19mm bar were very effective. My thinking (faulty or not) did not get me to that set-up. Experimenting and driving got me there.
OP has fr #850 and rr #200 - no idea of bars.
I hope your new product addresses the interface between spindle and strut!
Brian
#38
Re: Correcting geometry for lowered cars
Lastly, here is a recent race of a friend and driver I have been working with teaching for a few years. This is his 3rd race and he took 2nd place this night about 1 month ago. Waiting for next season. Trust me when I say this is not an easy game- put yourself in that cockpit. Fastest asphalt half mile in the country.
I told him last race prior to this he needs to bump the LF rebound down to 8 from 12 (1-16 settings, 16 being most firm) He is putting too much wheel into it entrance to steadystate, then dancing it off witht he throttle. Get the LF more grip so it stops skipping across the pavement and bits,then get the panhard down a 1/4". That is the plan for next race( yes that simple of changes at a time...baby steps)
I told him last race prior to this he needs to bump the LF rebound down to 8 from 12 (1-16 settings, 16 being most firm) He is putting too much wheel into it entrance to steadystate, then dancing it off witht he throttle. Get the LF more grip so it stops skipping across the pavement and bits,then get the panhard down a 1/4". That is the plan for next race( yes that simple of changes at a time...baby steps)
Last edited by SlickTrackGod; 01-21-2018 at 01:12 AM.
#39
Re: Correcting geometry for lowered cars
That is a novel for most of you to digest for now so I will leave this post at that for now. If anyone needs further basic clarifications I will address questions but most of what is asked here I would have to put in so much depth it would take 100 pages on this post to add it all at the very least.extensive drawings and diagrams over the years that covers every question asked here. THis is why I asked people to search for specific info because I have everything and then some in archives on here over the last almost 20 years.
Now to address a final thought if I may. I read this post opener (***I did not look who wrote it- does not matter to me.) What I saw, or presumed I saw was someone posting a statement about what needs to be don to a lowered vehicle as what appeared to me an authoritative guideline to others to build off of. When something does not make sense to me I know it is really confusing others....So I chimed in...in my oh so known robotic typing skills way which everyone seems to think I am angry. I just list facts and type like a robot. Take it as you all will, I do not try to be popular, I try to inform and teach.
Now to address a final thought if I may. I read this post opener (***I did not look who wrote it- does not matter to me.) What I saw, or presumed I saw was someone posting a statement about what needs to be don to a lowered vehicle as what appeared to me an authoritative guideline to others to build off of. When something does not make sense to me I know it is really confusing others....So I chimed in...in my oh so known robotic typing skills way which everyone seems to think I am angry. I just list facts and type like a robot. Take it as you all will, I do not try to be popular, I try to inform and teach.
I personally don't think it's necessary to re-explain RC in every thread that mentions extended ball joints or panhard bar relocation or... Who knows, maybe it is.
FYI, you don't also need to post videos to prove you are capable of explaining and applying suspension theory. We all get it already. It really doesn't add anything to the thread.
The unfortunate reality for me and I'm sure many others, is we cannot simply fabricate the ideal parts, like the minimal increase in height solid strut mount you speak of, and are instead stuck with either stock parts or what aftermarket manufactures make.
#40
Supreme Member
Join Date: Dec 2005
Location: Alberta (formerly Ontario)
Posts: 9,306
Received 690 Likes
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577 Posts
Re: Correcting geometry for lowered cars
This is why I asked the question regarding the extended ball joints and was confused by the conflicting responses.
It would appear to be cleared up now.
EDIT: Just so it's not taken out of context or that my editing may slant the replies, that's not the intent. The answers are clearly stated and the explanation that proceeded them equally so. Easy to understand too. Thanks to all involved.
Read before you just buy and assume...you are throwing away money.
#41
Re: Correcting geometry for lowered cars
You know what- A video as welll as pictures says a thousand words. The video is not about boasting, it is about teaching. If you took the time to watch a portion of the video and actually watch the drivers inputs on the controls...then you read my recommended changes to him....you get the idea of just how sensitive or complex a few little changes can be and this shows a great example of tinkering with a setup. With that said, could you have diagnosed what was wrong by merely looking at the video if I did not provide a future setup adjustment change? that is the point...most can't and would throw a lot at it making things worse not better. It is an example to show baby steps in adjustments.
Now as for me being contradicting? Like SkinnyZ just posted- nothing of the sort. I have been consistent. You interpretation of what you 'think" I am saying and what you do or do not understand is what is confusing yourself GMan. You still are confused and that is by no means a put down. This is an attempt to clear the air of things I see wrong with the approach of your thread. I just gave clear examples and again I feel you are not understanding- Remember, I am a professional at this and can tell if someone is getting it or not by what any of you respond with. There IS so much wrong and this is why I came in to clarify things for you- yes it is the "reasons, not the parts" and I explained how you may need extended strut mounts but also why they can be not beneficial and to use as little extension as you need.....etc....etc.
Stop taking this as an attack. it is to clear up facts and keep any readers from thinking misinfo. My info is correct, it is being interpeted wrong and I clarified that with the further examples as to when AND why you add extended ball joints,.....and the fact you use the rear RC setting to balance the car based on modifications and chassis differences such as fatigue...etc...etc
Now as for me being contradicting? Like SkinnyZ just posted- nothing of the sort. I have been consistent. You interpretation of what you 'think" I am saying and what you do or do not understand is what is confusing yourself GMan. You still are confused and that is by no means a put down. This is an attempt to clear the air of things I see wrong with the approach of your thread. I just gave clear examples and again I feel you are not understanding- Remember, I am a professional at this and can tell if someone is getting it or not by what any of you respond with. There IS so much wrong and this is why I came in to clarify things for you- yes it is the "reasons, not the parts" and I explained how you may need extended strut mounts but also why they can be not beneficial and to use as little extension as you need.....etc....etc.
Stop taking this as an attack. it is to clear up facts and keep any readers from thinking misinfo. My info is correct, it is being interpeted wrong and I clarified that with the further examples as to when AND why you add extended ball joints,.....and the fact you use the rear RC setting to balance the car based on modifications and chassis differences such as fatigue...etc...etc
#42
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Car: '89 Formula
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Re: Correcting geometry for lowered cars
A good night's sleep does wonders!
A while ago, I started a thread extolling the benefits of these two without trying to write the Bible on it. The purpose was just to convince people of their benefit, low cost, and relative ease of mod. Dean posted in and said I left things out (I did by design) and that some people could get the wrong idea (always the case, I think). While Dean's points were valid, I was not attempting to write the definitive thread, or to challenge his authoritative status. In the end, the thread was better for the discussion that ensued, so be it, but it changed the thread from what I had intended. Oh well...easier to say after a few night's sleep.
Gary, you have some good parts here to work with. Your spring rates are in the ballpark. The rest is experimentation. You've made some compromises, but everyone has to. There is no ultimate suspension thread/one size fits all approach. Stick to your build philosophy and get to a point where you're happy with the result. Your opinion is the only one that counts in the end. We can always debate fixes and tweaks with you if something isn't working out quite the way you want. I need that, too, sometimes. We learn from each other.
Wish we had a NOS purge emoji - double insertion, here. Reset.
After all the words and feelings, you're still doing very well! Congrats on the swap! You have seat time at the track under your belt (I think RA is better than COTA, but I am envious). Things ain't so bad. Be grateful and gracious for what you have. Enjoy!
Gary, you have some good parts here to work with. Your spring rates are in the ballpark. The rest is experimentation. You've made some compromises, but everyone has to. There is no ultimate suspension thread/one size fits all approach. Stick to your build philosophy and get to a point where you're happy with the result. Your opinion is the only one that counts in the end. We can always debate fixes and tweaks with you if something isn't working out quite the way you want. I need that, too, sometimes. We learn from each other.
Wish we had a NOS purge emoji - double insertion, here. Reset.
After all the words and feelings, you're still doing very well! Congrats on the swap! You have seat time at the track under your belt (I think RA is better than COTA, but I am envious). Things ain't so bad. Be grateful and gracious for what you have. Enjoy!
#43
Re: Correcting geometry for lowered cars
And I do read and ask questions.
This is why I asked the question regarding the extended ball joints and was confused by the conflicting responses.
It would appear to be cleared up now.
EDIT: Just so it's not taken out of context or that my editing may slant the replies, that's not the intent. The answers are clearly stated and the explanation that proceeded them equally so. Easy to understand too. Thanks to all involved.
Exactly.
This is why I asked the question regarding the extended ball joints and was confused by the conflicting responses.
It would appear to be cleared up now.
EDIT: Just so it's not taken out of context or that my editing may slant the replies, that's not the intent. The answers are clearly stated and the explanation that proceeded them equally so. Easy to understand too. Thanks to all involved.
Exactly.
Now to take a further example on setting this level being a bad thing-
Take a car with 800 lb front springs 175lb rear:
you add 1/2" extended ball joints, with lowering springs and the car sits 2" lower then factory lets say in ride height. You add a panhard relocator to the axle side and just move the bar one notch down to level....THEN...
The same car with 800 fronts and 250 rears (instead of 175's )and everything the exact same ride heights and panhard level
The top car will be tighter in turning response (it will push), the bottom example with 250 rear springs will be looser and rotate easier into a corner- maybe too much - have to test and see. But both have the panhard level... BUt how high is the level panhard? that is the key question that only adjustment provisions for your particular car will dictate a need for. you may need a chassis side adjuster, you may need both sides. That is the point I do not think you were taking into account Gman and I certain did not see it typed here.
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82talightblue (02-14-2022)
#44
Re: Correcting geometry for lowered cars
A good night's sleep does wonders!
A while ago, I started a thread extolling the benefits of these two without trying to write the Bible on it. The purpose was just to convince people of their benefit, low cost, and relative ease of mod. Dean posted in and said I left things out (I did by design) and that some people could get the wrong idea (always the case, I think). While Dean's points were valid, I was not attempting to write the definitive thread, or to challenge his authoritative status. In the end, the thread was better for the discussion that ensued, so be it, but it changed the thread from what I had intended. Oh well...easier to say after a few night's sleep.
Gary, you have some good parts here to work with. Your spring rates are in the ballpark. The rest is experimentation. You've made some compromises, but everyone has to. There is no ultimate suspension thread/one size fits all approach. Stick to your build philosophy and get to a point where you're happy with the result. Your opinion is the only one that counts in the end. We can always debate fixes and tweaks with you if something isn't working out quite the way you want. I need that, too, sometimes. We learn from each other.
Wish we had a NOS purge emoji - double insertion, here. Reset.
After all the words and feelings, you're still doing very well! Congrats on the swap! You have seat time at the track under your belt (I think RA is better than COTA, but I am envious). Things ain't so bad. Be grateful and gracious for what you have. Enjoy!
A while ago, I started a thread extolling the benefits of these two without trying to write the Bible on it. The purpose was just to convince people of their benefit, low cost, and relative ease of mod. Dean posted in and said I left things out (I did by design) and that some people could get the wrong idea (always the case, I think). While Dean's points were valid, I was not attempting to write the definitive thread, or to challenge his authoritative status. In the end, the thread was better for the discussion that ensued, so be it, but it changed the thread from what I had intended. Oh well...easier to say after a few night's sleep.
Gary, you have some good parts here to work with. Your spring rates are in the ballpark. The rest is experimentation. You've made some compromises, but everyone has to. There is no ultimate suspension thread/one size fits all approach. Stick to your build philosophy and get to a point where you're happy with the result. Your opinion is the only one that counts in the end. We can always debate fixes and tweaks with you if something isn't working out quite the way you want. I need that, too, sometimes. We learn from each other.
Wish we had a NOS purge emoji - double insertion, here. Reset.
After all the words and feelings, you're still doing very well! Congrats on the swap! You have seat time at the track under your belt (I think RA is better than COTA, but I am envious). Things ain't so bad. Be grateful and gracious for what you have. Enjoy!
#45
Re: Correcting geometry for lowered cars
As for TGO format: This forum was put up years ago with an intent for people to ask questions and look for answers...like a novice home mechanic in his own garage at home trying to fix a problem with his own car rather than pay someone else. Its format is to post up and look for responses to solve a problem. I feel I am one of the only ones on here that looks at this forum 100% that way. I keep to tech. I do not look at this forum for friendship conversations, I look at it for answering posted questions. With that said, when I see a post that has a somewhat "how to" posting like I feel this is, it is hard not to come in an add and correct things that can be misinterpreted- does not mean they are wrong, it means they can be misinterpreted by new readers looking to read and learn for current or future car problems. This forum to me is no different the "ask a mechanic"
#46
Re: Correcting geometry for lowered cars
you get the idea of just how sensitive or complex a few little changes can be and this shows a great example of tinkering with a setup. With that said, could you have diagnosed what was wrong by merely looking at the video if I did not provide a future setup adjustment change? that is the point...most can't and would throw a lot at it making things worse not better. It is an example to show baby steps in adjustments.
Do people really make many minute adjustments on streetcars, and I'm not talking drag or street/strip here? Do they adjust alignment if they have a passenger? Or when they buy a different brand of tires? Weather? What metrics are used to determine effectiveness of the changes? (Sometimes changes that feel like they were slower were actually faster on the stopwatch) Where are they testing, on the street which is very inconsistent or taking it to a track? Or do they just get it "close enough" for allround? Anyone? This is my first 'major' streetcar build, outside throwing springs, shocks/struts on a 240Z and Mini Cooper, so I'm curious as to the testing and small changes everyone does to their streetcar.
As Dean is probably aware, he is apparently part of the 1% that pushes their streetcar hard enough on the streets to wear out suspension components that racecars don't normally break. Nothing wrong with that. My point in all this is garbage above is, know your audience, or at least the topic being discussed. There's a whole 'nuther thread about making a third gen handle like a corvette. I'm not about to go off into structural steel design in this thread just to show how how a single failed component can cause a chain reaction to overloading. It relates loosely to modifying cars, but just doesn't fit this topic.
"I love the quote "close enough" Spend all this money just to be close enough is less good then leaving it stock and putting on some Koni yellows. "
"it is trivial, albeit, something in the right directions is always a gain even if its 1/10th of a second in lap times so to speak"
Dean, I think some of your issue is you're mindset is on the racecar/max performance side of this, and to get things as good as they possibly be. That's not a bad thing. The technical stuff you provide is from a professional, no doubt.
I just gave clear examples and again I feel you are not understanding- Remember, I am a professional at this and can tell if someone is getting it or not by what any of you respond with. There IS so much wrong and this is why I came in to clarify things for you- yes it is the "reasons, not the parts" and I explained how you may need extended strut mounts but also why they can be not beneficial and to use as little extension as you need.....etc....etc.
These guys should at least be forced to spell Camaro correctly before continuing their thread...
https://www.thirdgen.org/forums/sear...archid=9456981
Onto something constructive...
But both have the panhard level... BUt how high is the level panhard? that is the key question that only adjustment provisions for your particular car will dictate a need for. you may need a chassis side adjuster, you may need both sides. That is the point I do not think you were taking into account Gman and I certain did not see it typed here.
The majority of these discussion begin with an assumption such as "take a front rc of 6" off the grond, and a rear rc of 10" off the ground and a cg height of 18" at 42% distance along the roll axis from the front rc towards the rear." This is usually to show or discuss how changes to things affect other ... things.
This may be close to actual ballpark numbers for a thirdgen. That's great for discussions.
Application on the other hand... The rear isn't too difficult to get real numbers from. But those numbers are pointless without knowing the front to establish the roll axis and CoG.
To just GET to that assumption point on an INDIVIDUAL's car, with actual numbers, I'm at a loss of even how to begin. Getting centerline and track isn't too bad I guess with a tape measure and plumb bob. Neither is lower control arm pivot. Ball joint and height of strut, I'm starting to struggle. I doubt even a tape measure is accurate enough. 1/16" here and there throws off the angle quite a bit. Lasers, level floor, scales...
Is there one person, just ONE person that has actual data from a thirdgen?
Lets say we somehow get all that. What is the ideal distance from roll axis to CoG? Are we shooting for a certain ratio of the roll axis : CoG? 2:3? For comparison, what is the stock ratio? (Looking for real input here, not being facetious)
To come full circle... If there is an ideal distance from roll axis to CoG, if we can't accurately calculate what the actual front rc is, then we can't calculate the roll axis, nor what the rear rc should be set to, and in turn what height the panhard bar should be set to. We're back to track day testing or finding someone who can diagnose what is wrong by merely looking at a video, which unfortunately isn't 99% of us.
#47
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Re: Correcting geometry for lowered cars
#48
Re: Correcting geometry for lowered cars
Right Click Save As.
That's awesome. I thought I saw that before but couldn't ever find it again. Before someone jumps down my throat, I wasn't looking for it for suspension geometry purposes, it doesn't have some of the relavent info anyways.
I took my car to a body shop before I started doing any major work to verify it was straight. I wanted to take those diagrams, but figured they should also have access to them. I can't find the thread at the moment, but I didn't want to happen to me similar to what happened to xxxx that had a ton of money sunk into his beautiful car, then ended up cutting it up after discovering problems with the unibody.
The shop said it was straight, no accidents. They didn't charge me anything which makes me think they simply put it on a lift and looked for damage, and didn't actually take measurements.
That's awesome. I thought I saw that before but couldn't ever find it again. Before someone jumps down my throat, I wasn't looking for it for suspension geometry purposes, it doesn't have some of the relavent info anyways.
I took my car to a body shop before I started doing any major work to verify it was straight. I wanted to take those diagrams, but figured they should also have access to them. I can't find the thread at the moment, but I didn't want to happen to me similar to what happened to xxxx that had a ton of money sunk into his beautiful car, then ended up cutting it up after discovering problems with the unibody.
The shop said it was straight, no accidents. They didn't charge me anything which makes me think they simply put it on a lift and looked for damage, and didn't actually take measurements.
#49
Supreme Member
iTrader: (15)
Re: Correcting geometry for lowered cars
Right Click Save As.
That's awesome. I thought I saw that before but couldn't ever find it again. Before someone jumps down my throat, I wasn't looking for it for suspension geometry purposes, it doesn't have some of the relavent info anyways.
I took my car to a body shop before I started doing any major work to verify it was straight. I wanted to take those diagrams, but figured they should also have access to them. I can't find the thread at the moment, but I didn't want to happen to me similar to what happened to xxxx that had a ton of money sunk into his beautiful car, then ended up cutting it up after discovering problems with the unibody.
The shop said it was straight, no accidents. They didn't charge me anything which makes me think they simply put it on a lift and looked for damage, and didn't actually take measurements.
That's awesome. I thought I saw that before but couldn't ever find it again. Before someone jumps down my throat, I wasn't looking for it for suspension geometry purposes, it doesn't have some of the relavent info anyways.
I took my car to a body shop before I started doing any major work to verify it was straight. I wanted to take those diagrams, but figured they should also have access to them. I can't find the thread at the moment, but I didn't want to happen to me similar to what happened to xxxx that had a ton of money sunk into his beautiful car, then ended up cutting it up after discovering problems with the unibody.
The shop said it was straight, no accidents. They didn't charge me anything which makes me think they simply put it on a lift and looked for damage, and didn't actually take measurements.
I did it myself when I was building my transmission crossmember and wanted to set the driveline and suspension components correctly. I'm floored if you took it to a shop and they didn't charge you. When I called the shops that had body racks and did this kind of work they wanted $250 just to put it on there and measure it out. If anything needed fixed they wanted $125/hr. If a place didn't charge you I'm leaning towards they didn't actually measure anything or if they did they just verified a few distances with a tram gauge. Which can be acceptable.
#50
Re: Correcting geometry for lowered cars
I did read some posts about that. Something about you 'only' being *edit* 12 seconds behind the fast cars. You should know this, but *edit* 12 seconds is HUUUUUUUUGE on a road course. I recently ran COTA (full course) in my CMC car, which is an amateur series. I'm a mid-pack slacker. Mike Paterson runs an AI 4th gen, and set AI record for the weekend. His car has a much better power to weight ratio, big aero, bigger tires, better driver. *edit* 2:30.871. Guess what? I was *edit* 2:42.232, 'only' *edit* 12 seconds a lap slower. There is no way in hell I'd ever boast about that. And for those other 11 cars? Ever hear of big fish in a little pond? Happened all the time at TAMSCC autocrosses. Most members were students, but would get killed by the older autocrossing locals who lived in the area. Those same locals may be fast, but not necessarily the fastest, at national level events. I'm sorry, but these type of anecdotes don't impress me. I've seen miata's with lap times faster than Z06's, and hundreds of youtube video's of some guy in a 'slower' car passing some guy in a much faster car. I've passed a lot of AI cars racing. Doesn't mean anything. It simply cannot be used as 'proof'.
*edit* Just so nobody takes this the wrong way. Yes, what Dean had in that V6 car was impressive from a handling stand point, and has talent behind the wheel. But difficult to prove it's the be all end all.
I appreciate your knowledge, but you really need to check your ego at times.
Now the day I was talking about is 11 local guys with street cars and a grudge match that finally insued to shut everyone f'ing mouths which I did. The closest to me of the 11 was still 4 seconds off in a 63 second track (they ranged 67-78)..again I was the only V6 and some of them were pushing over 400hp and fatter tires then me. Get the facts correct.
As for this post? I said what needed to be corrected and you obviously went up top and edited your opening post stating you in short terms "misspoke on the topic" Were done here, at l;east I am with correcting any mis info here for present and future readers. Good day.