I'm putting a C4 front suspension into my trans am!!
#51
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Thank you buddy! I want it done so badly and to be able to feel the difference in performance and steering, but the amount of measuring and squaring everything up is insane! Well worth it though to get a nice end product and not a hack job.
See attached pic
I'll be making my own frame rail section from scratch so that it appears to be factory, but nice and rigid as well. Metal is currently on order and will be here mon-tues. I've got an idea of how I'm going to do it, so hopefully by the end of next week I have some custom frame rails made up.
I'll be making my own frame rail section from scratch so that it appears to be factory, but nice and rigid as well. Metal is currently on order and will be here mon-tues. I've got an idea of how I'm going to do it, so hopefully by the end of next week I have some custom frame rails made up.
#52
Supreme Member
iTrader: (11)
Join Date: Sep 1999
Location: NJ
Posts: 4,350
Received 299 Likes
on
235 Posts
Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: I'm putting a C4 front suspension into my trans am!!
Whoa, that's scary to think about going that far on my own car. I am the guy that had the car that //<86TA>\\ was talking about. We were tossing the idea of doing the C4 front suspension in my 91 GTA. I cut out all the rear suspension to install the C4 IRS already. One of these days I will finish that and, after seeing what you've done here, maybe install a C4 front suspension too
#53
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
New vid up! Sort of uneventful because I was slacking with the filming this week and didn't get my metal to make the frame rails because it was out of stock.
I'm not going to lie, I did cry a bit inside when I chopped it out only because this car is immaculate for it's age. But to me, it's all just metal work, and you can make it as nice if not nicer than factory if you put the time into it. In my opinion, I'm improving on the design of the car in general, and this is what hot rodding is all about!
Whoa, that's scary to think about going that far on my own car. I am the guy that had the car that //<86TA>\\ was talking about. We were tossing the idea of doing the C4 front suspension in my 91 GTA. I cut out all the rear suspension to install the C4 IRS already. One of these days I will finish that and, after seeing what you've done here, maybe install a C4 front suspension too
#54
Member
iTrader: (1)
Join Date: Sep 2000
Location: Livermore, Ca. US
Posts: 481
Likes: 0
Received 1 Like
on
1 Post
Car: Firebird SSA
Engine: 3.1
Transmission: 700R4
Re: I'm putting a C4 front suspension into my trans am!!
Interesting project.
Since I own a 1990 Firebird and a 1990 Corvette ZR-1.
I'm all about modifying.
Might be too early.
1. How are you going to address the shock/strut mounting?
2. Are you going to use the mono spring or a coil over setup?
Since I own a 1990 Firebird and a 1990 Corvette ZR-1.
I'm all about modifying.
Might be too early.
1. How are you going to address the shock/strut mounting?
2. Are you going to use the mono spring or a coil over setup?
#57
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
I will be using an aftermarket coilover setup. I hear the mono leaf has a very rough ride, and I didn't want to go through the hassle of making it work. Coilovers are much easier to package and they also offer any spring rate you'd want to use. Will be very simple to adapt them to the suspension by getting a T bolt adapter for the vette control arm, and then just fabbing an upper shock mount on my frame.
#58
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Well gents, the frame rail is coming together nicely on the drivers side so far! Used a piece of 3x3" .120 wall box tube to make the main frame rail. Inserted it about 3-4" into each side of my existing frame rail sections and plug welded it in place. Added a few "L" gussets in the rear section for reinforcements and will add a few to the front section as well. I used the factory crossmember mount off the vette frame rail and welded it to my new frame rail section so the suspension is in it's permanent location on the drivers side. Still a lot of reinforcing to do and then prettying it up, but the suspension is officially mounted. Wheel is dead center in the well, and it's perfectly square both front to back and side to side.
One concern I have to anybody that may be able to help (cough, cough, slicktrackgod) is that I have about 2" total suspension droop from ride height measured at the hub. I'm curious if this is sufficient for a street car? I can get more by simply notching the frame rail section, but prefer not to if I can get away with what I have. The coilovers I'm using are 12" collapsed and 16" extended, with a recommended ride height of 13.5", so I can't imagine needing much more than 2" of droop. Open to any recommendations though!
One concern I have to anybody that may be able to help (cough, cough, slicktrackgod) is that I have about 2" total suspension droop from ride height measured at the hub. I'm curious if this is sufficient for a street car? I can get more by simply notching the frame rail section, but prefer not to if I can get away with what I have. The coilovers I'm using are 12" collapsed and 16" extended, with a recommended ride height of 13.5", so I can't imagine needing much more than 2" of droop. Open to any recommendations though!
#59
Re: I'm putting a C4 front suspension into my trans am!!
2" from static ride height is perfectly fine. That is common anyways due to sway bar holding up one side of the car from dropping out like in an angled driveway, etc. It is common for cars to pull wheels off the ground in angled egresses.
As for travel in compression, my car only had about 1" normal ride travel and never went more then about 1 5/8* max strut travel in most extreme conditions...even though it had more room to move upward freely.
Your project is coming along fast. Most things like this would take someone 6 months to 1 year.
As for travel in compression, my car only had about 1" normal ride travel and never went more then about 1 5/8* max strut travel in most extreme conditions...even though it had more room to move upward freely.
Your project is coming along fast. Most things like this would take someone 6 months to 1 year.
Last edited by SlickTrackGod; 10-06-2017 at 08:48 AM.
#60
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
2" from static ride height is perfectly fine. That is common anyways due to sway bar holding up one side of the car from dropping out like in an angled driveway, etc. It is common for cars to pull wheels off the ground in angled egresses.
As for travel in compression, my car only had about 1" normal ride travel and never went more then about 1 5/8* max strut travel in most extreme conditions...even though it had more room to move upward freely.
Your project is coming along fast. Most things like this would take someone 6 months to 1 year.
As for travel in compression, my car only had about 1" normal ride travel and never went more then about 1 5/8* max strut travel in most extreme conditions...even though it had more room to move upward freely.
Your project is coming along fast. Most things like this would take someone 6 months to 1 year.
As for the project moving fast, at the moment it's my only job so I work on it 5+ days a week. Doesn't pay well, but it keeps me busy haha. Wanted to get it finished up for the most part before the real cold weather starts hitting us here in new england. So far I think I'm relatively on track as far as time goes.
#62
TGO Supporter
Re: I'm putting a C4 front suspension into my trans am!!
It's looking good so far, much faster than I was when I first started mine. The conversation with SlickTrackGod got a bit spirited, glad to see you guys worked it out. I'll keep checking back on your progress. I'll be posting some pictures of my engine install.
#63
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
I'll keep my eyes out for your pics as well! Good to hear from you.
#64
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Driver's side frame rail fully done, structure wise. Still have to pretty it up and close everything off with sheet metal, but the main structure is there. Took me forever to figure out how to finish it up, considering the frame rail on this side is such an oddball shape with it being the gearbox side. Passenger side will be MUCH easier since it's essentially a nice even rectangle
Heres a few pics showing what was done to get to this point.
Heres a few pics showing what was done to get to this point.
#65
#66
Member
iTrader: (2)
Re: I'm putting a C4 front suspension into my trans am!!
This is such a cool project man!
Gentlemen, it's bolted in It's currently mounted on temporary adapter brackets holding it to my existing K-member mounting holes, but it should be in the exact centered location according to my measurements. Ran out of time today but tomorrow I may try to cut some holes in the fender wells and get the upper A-arms mocked up so I can really get a feel for how everything is going to line up. But my initial measurements are solid and I am pretty confident it's exactly where it should be.
#68
Member
Join Date: Oct 1999
Location: Philly
Posts: 251
Likes: 0
Received 8 Likes
on
8 Posts
Car: 1987 GTA 350 auto
Re: I'm putting a C4 front suspension into my trans am!!
I appreciate the concern, but I have seen you tear into so many people on the forum for wanting to try new things. You seem extremely set in your ways, and thats fine. However, because of people like you, nothing new ever comes out of the third gen community because others constantly get beaten down and discouraged. I'm putting the C4 suspension in my car, period. I can almost 100% guarantee it will feel leagues better than the third gen setup. I may not be a suspension pro, but then again, I could care less to ever throw this car around a track. If it takes an alignment and drives down the street nicely, thats fine with me...that's all I need the car to do. And as for why I'm doing it? Because it's my car and I can do as I please with it. I have not found one single person that did the C4 front suspension on any type of car and had something negative to say about it. I go off of listening to people who have actually "been there, done that." Not just on speculation from people who simply think it's a dumb idea.
#69
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Thanks man! The way I see it is that if it's installed as it's supposed to be, it surely won't be any worse than the factory setup, yet I'll still reap the rewards of rack steering. But in the end, I'm hoping it turns out to be a big improvement in all around driving.
#71
Senior Member
Join Date: May 2006
Location: Pittsburgh, PA
Posts: 580
Likes: 0
Received 68 Likes
on
41 Posts
Car: 91 Formula
Engine: 2012 LS9
Transmission: 4L80E
Axle/Gears: Strange 60 3.54:1
Re: I'm putting a C4 front suspension into my trans am!!
Looks good. Nice to see you documenting the build as well as having the courage to start cutting on a really good looking car.
#72
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
More progress today. Doing some of the finishing work on the frame rail and boxing in all the open areas. Really starting to look like a "stockish" appearing frame rail now. Just about done with the drivers side. Hopefully starting on the pass side by the end of the week.
#73
Member
Join Date: Sep 2000
Location: Crestline,OH
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1987 Formula 350
Engine: 6.0 boost and smak
Transmission: 4l80e
Axle/Gears: 9bolt 3.27
Re: I'm putting a C4 front suspension into my trans am!!
youtube sub'd, and following
I haven't ready everything yet
I just put all c4 stuff in my 48 chevy, it is fun...
I haven't ready everything yet
I just put all c4 stuff in my 48 chevy, it is fun...
#74
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Thanks for the sub! Your 48 looks like it's coming along great. What are you planning on running for front shocks/springs? If you're going with coilovers, have you figured out what brand/size yet?
#75
Member
Join Date: Sep 2000
Location: Crestline,OH
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1987 Formula 350
Engine: 6.0 boost and smak
Transmission: 4l80e
Axle/Gears: 9bolt 3.27
Re: I'm putting a C4 front suspension into my trans am!!
I am using the factory transverse springs front and back and the factory shocks up front, KYP adjustable in the rear.
only a few short drives working out alignment, so far,,, working on, lights and other electrical at the moment.
only a few short drives working out alignment, so far,,, working on, lights and other electrical at the moment.
#76
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
New vid, and passenger side frame rail starting to take shape fast
#77
Supreme Member
iTrader: (11)
Join Date: Sep 1999
Location: NJ
Posts: 4,350
Received 299 Likes
on
235 Posts
Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: I'm putting a C4 front suspension into my trans am!!
Lighting man, get an LED work light so we can see what you're pointing at, lol.
Loving what you've done so far
Loving what you've done so far
#78
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
I noticed parts of the vid came out dark. It sucks because I'm using an old gopro I had laying around, and I can't preview the video until after I load it onto my computer. I'll have to try to keep the lighting good. A new camera is def not in the funds at the moment unfortunately lol.
#80
Supreme Member
iTrader: (11)
Join Date: Sep 1999
Location: NJ
Posts: 4,350
Received 299 Likes
on
235 Posts
Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: I'm putting a C4 front suspension into my trans am!!
That would definitely help if you put the light under the vehicle when you're pointing stuff out.
#82
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
I wanted to give you some "bright" points to your video (pun intended).
To compliment you, you do extremely well with your overall projection and pace as to how you speak in your videos. You could easily do a performance show on television like Overhaulin, etc. I have enjoyed watching your tutorials on how your thought process tackles each step, as well as you do show impressive fabrication skills for doing something in your own garage.
I just want to motivate you to keep up the tedious work that it IS respected and appreciated and as you already know will pay off in the end with years of being proud of what you are doing. When the time comes, I will be as helpful as I can to help you work out any setup and balance issues if you encounter them. I will also PM you my private phone number so if you ever need to talk it is easier that way.
Dean
Ps, what you may have to do if the wheel choice is giving you a little issues in braking and wandering is run a little bit of an aggressive camber to keep the contact patch more towards the inside of the tire width to decrease the effect of scrub. You will wear tires quicker but if you do not drive it for a daily then that is not so much an issue.
Another thing you could always do is add a steering stabilizer and /or increase the power assist volume of the fluid so you have more power control of the rack. you loose sensitivity of feedback but will give easier control of any unwanted steering wheel feedback if any does show.(that is the true question I was just trying to warn you "might" happen in normal driving and "will" happen in in very spirited driving if one tire encounters a bump under very hard braking.
To compliment you, you do extremely well with your overall projection and pace as to how you speak in your videos. You could easily do a performance show on television like Overhaulin, etc. I have enjoyed watching your tutorials on how your thought process tackles each step, as well as you do show impressive fabrication skills for doing something in your own garage.
I just want to motivate you to keep up the tedious work that it IS respected and appreciated and as you already know will pay off in the end with years of being proud of what you are doing. When the time comes, I will be as helpful as I can to help you work out any setup and balance issues if you encounter them. I will also PM you my private phone number so if you ever need to talk it is easier that way.
Dean
Ps, what you may have to do if the wheel choice is giving you a little issues in braking and wandering is run a little bit of an aggressive camber to keep the contact patch more towards the inside of the tire width to decrease the effect of scrub. You will wear tires quicker but if you do not drive it for a daily then that is not so much an issue.
Another thing you could always do is add a steering stabilizer and /or increase the power assist volume of the fluid so you have more power control of the rack. you loose sensitivity of feedback but will give easier control of any unwanted steering wheel feedback if any does show.(that is the true question I was just trying to warn you "might" happen in normal driving and "will" happen in in very spirited driving if one tire encounters a bump under very hard braking.
I also fully plan on picking your brain a bit once I get closer to the actual dialing in of the suspension. The fabricating stuff is tedious, but it's straight forward for the most part to me. I'm really hoping to have both frame rails fully completed and the vette crossmember mounting points set in stone in the next week or so, and then I can start really playing with how I'm going to set it up with the coilovers, get my spring rates figured out, etc.
#84
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
My garage where I live is not as glamorous as you might think...lol. I have 5 cars stuffed into 2 2-car garages (4 spaces+ anther single garage I use for storage.So 5 total but I have tons of tools for construction mainly as well as my roll around along one side of the second 2car garage. It gets tight unless I pull cars out, but I park all my vehicles inside every night. I live in an Apt complex until I retire some day(long story about a bad divorce you don;t care to hear about.) I am fortunate the owners are like family to me and let me build garages there. Space is a premium in So Calif/Orange County. I have the only 5 car garage apt in the entire county...lol. Where I do get lucky is over the years working in the NASCAR race shops in various places with their owners equipment. Not that spoiled me so it is frustrating doing projects at home anymore. I've even worked on the set one day for Overhaulin with Foose and a buddy of mine Mark. Talk about guys with fab skills. Im more of a backyard fabricator. You are doing great. most people look at you with great respect.
Did you actually help out with the build on overhaulin, or were you just on the set watching? That is pretty neat. I always really liked that show, and Chip has a killer taste in styling on most of the cars he does.
I would say you lucked out big time with the garage space too. Both my brother and sister live in apartment complexes and each has a single bay garage, but they'd get flak if they even tried to do an oil change in the driveway. Tough to be a car guy in that situation, but glad to hear it's working out for you so well.
#87
Re: I'm putting a C4 front suspension into my trans am!!
Non related to the issue with this set up, but is there a thread on thirdgen that shows how to properly build a front suspension for a lowered third gen? What does work if the c4 piece is wrong? I my self was thinking about a 4th gen k member swap a while back, but could not justify it.
By doing this modification, you are also moving the scrub radius out a little so you can accept a little fatter tire. Ackerman is still an issue regardless. This is the inherent defect in a 3rd gen. I have a solution but it is not calculated nor tried. I do not own a 3rd gen to support my theory as to my idea- it is a little complex and costly but would retain a factory or 600 series steering box. Best we open another thread and not hijack his. Burt seriously there is a lot of info I have suggested over the years on here you can search and find.
Look under other names like Vetruck, Onarail, Vsixtoy, Billyboy(I think), can't remember old names but Ive been on this site since about 2000 or 2001. Maybe even earlier.
Only reason I listed this here and responded is because I am confident many other people reading this want the same answer. Best to start a new thread though. Lets respect his project thread. THis is the reason I first challenged him to stop what he is doing but will respect his desire and help him if I can be of any help to make it best he can.
Last edited by SlickTrackGod; 10-19-2017 at 12:17 PM.
#88
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
^^Good info!
I also wanted to let you know that you saved my butt today Dean. I welded up the mounts on the frame rails for the lower crossmember bolts and had it hard-bolted in place. When I put the suspension together and bolted the wheels on to check ride height and make sure everything was ok, I noticed the drivers side wheel was sticking out 1/4" more than the passenger side. Everything was on target according to my measurements, but as a last resort I rigged up plumb bobs off the rear control arm mounts and then checked the diagonal line between left rear CA mount to front right CA mount, and vice versa. Sure enough, it was slightly off. I shifted the whole crossmember 1/8" to the pass side to get the wheels both even with the fenders, re-checked the diagonal lines, and they were perfect. Somehow my suspension center line was an 1/8" off, but everything else turned out spot on. Oh well, just glad I caught it!
Now that that's out of the way and it's in its "true" permanent location, I'm going to fab up the main side mounts to get it really set in stone. Be nice to unbolt and bolt it in as I need to finally!
On another note, I placed a jack under the vette crossmember once I had it bolted to the lower mounts to check the rigidity of my frame rails. I lifted it so it just came off the front jack stands. That sucker didn't budge, and there was much less flex noticeable than with the stock frame rail setup when I would lift it by the K-member. I'm assuming that alone will help with overall tightness and steering feedback once it's done.
I also wanted to let you know that you saved my butt today Dean. I welded up the mounts on the frame rails for the lower crossmember bolts and had it hard-bolted in place. When I put the suspension together and bolted the wheels on to check ride height and make sure everything was ok, I noticed the drivers side wheel was sticking out 1/4" more than the passenger side. Everything was on target according to my measurements, but as a last resort I rigged up plumb bobs off the rear control arm mounts and then checked the diagonal line between left rear CA mount to front right CA mount, and vice versa. Sure enough, it was slightly off. I shifted the whole crossmember 1/8" to the pass side to get the wheels both even with the fenders, re-checked the diagonal lines, and they were perfect. Somehow my suspension center line was an 1/8" off, but everything else turned out spot on. Oh well, just glad I caught it!
Now that that's out of the way and it's in its "true" permanent location, I'm going to fab up the main side mounts to get it really set in stone. Be nice to unbolt and bolt it in as I need to finally!
On another note, I placed a jack under the vette crossmember once I had it bolted to the lower mounts to check the rigidity of my frame rails. I lifted it so it just came off the front jack stands. That sucker didn't budge, and there was much less flex noticeable than with the stock frame rail setup when I would lift it by the K-member. I'm assuming that alone will help with overall tightness and steering feedback once it's done.
#89
Re: I'm putting a C4 front suspension into my trans am!!
On another note, I placed a jack under the vette crossmember once I had it bolted to the lower mounts to check the rigidity of my frame rails. I lifted it so it just came off the front jack stands. That sucker didn't budge, and there was much less flex noticeable than with the stock frame rail setup when I would lift it by the K-member. I'm assuming that alone will help with overall tightness and steering feedback once it's done.
I always preached to everyone that I could take off my 3rd point braces of my strut tower brace and leave just the cross brace (taking off just the supports from each strut mount to the firewall) and I could feel the inside rear tire lift grip pressure a little easier and the car would turn easier (more loose condition- in terms of loose/tight handling).
Edit to clarify=- after reading what I wrote I see that can be misinterpeted. To be more clear when I say turn easier, I mean rotates into changing direction eaiser with less rear inside tire grip -which is not always a good way to make a car turn. Just pointing out the need of a stiffer chassis here because they do flex diagonally towards the firewall and actually delay the turning response as they flex and absorb then react.
Last edited by SlickTrackGod; 10-19-2017 at 09:28 PM.
#90
Supreme Member
iTrader: (4)
Join Date: Sep 2010
Location: Double Bratville
Posts: 1,618
Likes: 0
Received 43 Likes
on
31 Posts
Car: '89 Formula
Engine: LS2
Transmission: 4L65E
Axle/Gears: MW 3.42 12 Bolt
Re: I'm putting a C4 front suspension into my trans am!!
What I recommend is increasing ypour SAI (Steering angle Inclination) between the strut and the spindle. What problem this leads to is loosing negative caster so the short the overall length of the strut top mount to the ball joint the better this is as well as the more dynamic caster you get under braking and decrease leverage length of that arm assembly with motion going through it.
DSE tries part of your solution. DSE/JRi Struts have:"An adjustable aluminum spindle bracket allows independent tuning of strut travel in relationship to vehicle ride height. The top spindle mounting uses removable hole inserts allowing wheel camber to be adjusted in 1/16” increments and is available in single or double adjustable versions."
The spindle bracket must be threaded on the strut body - bottom pic? to allow for independent tuning of strut travel? And, the top spindle hole uses inserts for SAI - camber slugs instead of camber bolts. These might have better repeat-ability side-to-side, than getting the bolts the same.
Ouch! (includes plates)
Single - $2650
Double - $3100
#91
Re: I'm putting a C4 front suspension into my trans am!!
THey took a common design that even monroe shocks uses camber bolts to gain negative camber. I am talking using it in positive camber via those bolts. Yes can be done, but DSE did not incorporate it for use that way. They did it for extra negative camber and not increasing SAI angles. If you watch their technical video which I just did they do not mention a word of what I am speaking of.
Last edited by SlickTrackGod; 10-19-2017 at 11:53 PM.
#92
Supreme Member
iTrader: (4)
Join Date: Sep 2010
Location: Double Bratville
Posts: 1,618
Likes: 0
Received 43 Likes
on
31 Posts
Car: '89 Formula
Engine: LS2
Transmission: 4L65E
Axle/Gears: MW 3.42 12 Bolt
Re: I'm putting a C4 front suspension into my trans am!!
OK, it looked like there were enough different slugs to go + or -. I've never considered the caster/camber bolts because of getting both sides equal. Hoped the slugs might alleviate that concern. Not that I could ever afford these.
Is the threaded bracket a good idea - whole lot of stress? Must have tight tolerances.
Is the threaded bracket a good idea - whole lot of stress? Must have tight tolerances.
#93
Re: I'm putting a C4 front suspension into my trans am!!
Im not saying you can;t turn theirs around and use them like I suggest. What I am stating is they did not design theirs to be used like what I am suggesting. They would not know that.
The cheap version of where they got their idea.
https://www.ebay.com/itm/OBX-Front-A...RVun1P&vxp=mtr
They ruin scrub radius by doing this as well as straight line braking footprint.
The cheap version of where they got their idea.
https://www.ebay.com/itm/OBX-Front-A...RVun1P&vxp=mtr
They ruin scrub radius by doing this as well as straight line braking footprint.
#94
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Just as a side note - I honestly don't mind whatsoever if there is other talk going on in here other than my main project. If the majority of it is "technical related" then I see it being a great information source regardless.
#95
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Crossmember is finally bolted to it's permanent location!! My measurements and mock up show that it's exactly where it's supposed to be, and it's dead on perfect. Man, you guys don't know how happy I am to finally hit this milestone!
Newest vid for the week too...
Newest vid for the week too...
#96
Supreme Member
iTrader: (30)
Join Date: Jul 2000
Location: Fort Myers, FL
Posts: 1,517
Received 17 Likes
on
10 Posts
Car: 91 Firebird
Engine: 6.0
Transmission: T56
Axle/Gears: 3.73
Re: I'm putting a C4 front suspension into my trans am!!
Glad to see that wheel all mocked up!
and the camera works great with the light source behind it!
and the camera works great with the light source behind it!
#97
Re: I'm putting a C4 front suspension into my trans am!!
Looking Great Whitedevil (Speaking of which, I do not know your first name?)
I want to give you another pointer at this step just to check another potential issue with "caster" range. Great you double checked the diagonals also.
If you have a caster gauge then I would recommend putting the car down to the ground at ride height (or getting the wheel up into ride position with a proper statric chassis rake as if it were on the ground settled) and checking the static caster at this time to make sure you have the c4 K-member placed into there at the proper pitch rotation wise towards the front of the car. I did not really see if you covered that or we talked about it. If so then my bad- just a good step at this point before you go any further to make sure you are in range with caster. You want to be in aprox 6-7* range because this type of suspension does not build caster as fast in motion as the strut does. The factory strut 3rd gen is good around 4-5* range
I want to give you another pointer at this step just to check another potential issue with "caster" range. Great you double checked the diagonals also.
If you have a caster gauge then I would recommend putting the car down to the ground at ride height (or getting the wheel up into ride position with a proper statric chassis rake as if it were on the ground settled) and checking the static caster at this time to make sure you have the c4 K-member placed into there at the proper pitch rotation wise towards the front of the car. I did not really see if you covered that or we talked about it. If so then my bad- just a good step at this point before you go any further to make sure you are in range with caster. You want to be in aprox 6-7* range because this type of suspension does not build caster as fast in motion as the strut does. The factory strut 3rd gen is good around 4-5* range
#98
Supreme Member
Thread Starter
iTrader: (8)
Join Date: Dec 2005
Location: Northern CT
Posts: 2,412
Likes: 0
Received 14 Likes
on
11 Posts
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: I'm putting a C4 front suspension into my trans am!!
Looking Great Whitedevil (Speaking of which, I do not know your first name?)
I want to give you another pointer at this step just to check another potential issue with "caster" range. Great you double checked the diagonals also.
If you have a caster gauge then I would recommend putting the car down to the ground at ride height (or getting the wheel up into ride position with a proper statric chassis rake as if it were on the ground settled) and checking the static caster at this time to make sure you have the c4 K-member placed into there at the proper pitch rotation wise towards the front of the car. I did not really see if you covered that or we talked about it. If so then my bad- just a good step at this point before you go any further to make sure you are in range with caster. You want to be in aprox 6-7* range because this type of suspension does not build caster as fast in motion as the strut does. The factory strut 3rd gen is good around 4-5* range
I want to give you another pointer at this step just to check another potential issue with "caster" range. Great you double checked the diagonals also.
If you have a caster gauge then I would recommend putting the car down to the ground at ride height (or getting the wheel up into ride position with a proper statric chassis rake as if it were on the ground settled) and checking the static caster at this time to make sure you have the c4 K-member placed into there at the proper pitch rotation wise towards the front of the car. I did not really see if you covered that or we talked about it. If so then my bad- just a good step at this point before you go any further to make sure you are in range with caster. You want to be in aprox 6-7* range because this type of suspension does not build caster as fast in motion as the strut does. The factory strut 3rd gen is good around 4-5* range
Also, I wanted to bring up another question to you. I'm on the verge of ordering my coilovers since one of the next steps will be mocking them up and most likely having to slightly notch the square tube frame rails to clearance them. I will be going with ridetech coilovers, and the size I've spec'd out is as follows:
12.5" at ride height (4.1" total stroke)
14.23" extended
10.13" compressed
10" coil spring
Coilovers will be installed at about a 25* angle at ride height
This is really the best size that will fit without having to get crazy with clearancing. My main question for now is if you have a recommendation on spring rate? I'm not 100% sure what factory spring rate is, but my car weighs roughly 3300-3350 lbs without me. It's a turbocharged iron block LS engine up front, but I have also removed quite a bit of other weight in the front like the battery, AC, and the vette suspension is about 60-70 lbs lighter than the old setup (which was still lighter than stock).
I want the car to feel like a sports car, but it doesn't need to be overly stiff for track duty because it is a 99% street car.
#99
TGO Supporter
Re: I'm putting a C4 front suspension into my trans am!!
Hey Rob, your progress looks great. If it helps, I'm using a 450# spring on the front of mine from Viking. Both RideTech and Viking have calculators on their websites. I assumed a 3300 car with a 52/48 weight distribution. You're making great progress, keep up the good work.
#100
Re: I'm putting a C4 front suspension into my trans am!!
Most people with C4 Vettes that do coilover conversions run 400front/275 rear. #rd gen strut coilover packages come in a a slightly less leveraged point so they run a liittle lower at 350-400 range. With that said, my guess would be 425-450 range. I would tend to go 450 and leave a smaller sway bar .
As for caster, as long as you have adjustment in the range to get it down to at least 7 then you are good with the a-arm angles and the 450 spring rate- keep in mind if the a0-arm is slightly more up on the front ear mount compared to the rear ear then the angle of attack when the car hits a bump will compress the shock with just a slight tad more leverage due to angle. 10* is getting high. Factory specs is 4-6^ for those years with performance settings at 6*-7*. You may want to shim the k-member a little more forward to reduce the angle. Too much caster can give you bump steer problems as well but that is only if it is misaligning with the rack- since everything is tilted back then that does not apply. Agressive caster brings outer tie rods up AND BACK, not just up.
As for caster, as long as you have adjustment in the range to get it down to at least 7 then you are good with the a-arm angles and the 450 spring rate- keep in mind if the a0-arm is slightly more up on the front ear mount compared to the rear ear then the angle of attack when the car hits a bump will compress the shock with just a slight tad more leverage due to angle. 10* is getting high. Factory specs is 4-6^ for those years with performance settings at 6*-7*. You may want to shim the k-member a little more forward to reduce the angle. Too much caster can give you bump steer problems as well but that is only if it is misaligning with the rack- since everything is tilted back then that does not apply. Agressive caster brings outer tie rods up AND BACK, not just up.