Norm Peterson

If it's purely a vertical hop of the front wheels, then dead front dampers (struts) are at least part of the problem. Shimmy shows up as a steering wheel rotational vibration and can be started by hitting a dip.

Off the top of my head guess on engine weight difference - about 150 lbs heavier assuming no major aluminum component replacement on either. Or HD block substitution for that matter.


Norm

Excellegions

150 ilbs should not make a big enough difference to change my suspention I assume, just need to stabilize the problem I already have. I will install the kyb and see what it does for the v6. hopefuly the car will stay the same height with the v8 in and kyb's

RacerX13

150lbs is enough to make a big difference, and since the V8 is longer the extra weight has more leverage. You're going to need springs.

91_5.7_TPI

iTrader: (2)

What engine's in the car now?

Excellegions

It has the 3.1l v6, with a turbo and the T5 Tranny.

91_5.7_TPI

iTrader: (2)

It'll add a couple hundred pounds if I recall correctly. If you have V6 springs, you'll probably need to replace them with V8 ones, at least in the front.

84imsa

Depending on your source of info, 5662's are 748# and 5664's are 707# or vice versa. At any rate (pun intended) the stiffer spring has a wire/bar diameter of 0.765" and the softer one is 0.750". If you buy your springs in person, bring calipers and measure them.

0.015" seems like a tiny difference but it was the usual contact point gap in breaker type ignitions if you are old enough to remember those. So it is measurable.

If you start with a 5660 spring with an stock rate of 598# and cut off 1 full coil, you should get a drop of 1.90" and a new spring rated of 726#.

84imsa

The springs should have 2 different ends, one tangential and the other square. The tangential end is the one that seems to coil off into space. The square end sort of flattens out and coils in toward the previous coil.

The spring will sit stand erect if set down on the square end. It will fall over if set down on the tangential end. Ergo, if both springs will still stand erect, you're in good shape. Otherwise... uh-oh!

84imsa

Gotta love this TGO! Everyday I learn something new and sometimes get to share something I know!

So, tell me about LCA reloc brackets. What do they look like? How do they work? What is the principle behind their operation?

My guess is they restore the geometry of the LCA's after lowering. I.e., if they were level with the ground before lowering, they would now be pointed upward to the rear and the brackets would raise the front mounting points. Where do they mount?

Edit-

I have seen the reloc brackets on Hawks' site. I can discern 3 distinct designs and quite a range of prices. Any recommendations?

Edit again -

So they lower the rear mounting points. Does someone have a link to pics of these things installed? I personally would prefer weld-in units.

Is there an ideal angle for the LCA's with the car static at ride height?

Norm Peterson

Is that 1.90" taken at the spring? If so, the car's ride height will drop about double that number.


Norm

Stephen

iTrader: (12)

WOW! You understand the LCARBs 110%!

Spohn LCA Relocation Brackets

Level is bet for all-around driving or autocross/roadracing.
Slightly upwards towards the chassis (rear point being the lower of the 2 mounting points) for drag racing....straight line traction. It all has to do with the geometry between the LCAs & torque arm.

Somebody makes bolt-on ones, but I'll never recommend them to anyone nor take the time to find them & provide a link to them. Only way I would do bolt-on ones, would be to have the ability to put them on at home, then drive to a welder to have them welded on. That's my on LCARBs.

EDIT:
Oh yeah.... https://www.thirdgen.org/forums/susp...arm-angle.html

Fords88Bird

84IMSA here's a couple pics of J&M bolt on LCARB on my 88, they are pretty sturdy and eventually I may tack them in. If you notice at the shock mount there's a bracket there that ties it all together with the other bolts. I mainly drive on the streets so they may be fine just bolted on but if I did autoX or track racing I would deff. weld them in. Norm I used 5660 springs and trimmed 1 full coil and got just about a 2" drop after install. Later.

krisb410

iTrader: (9)

I have UMI's bolt on LCARBs, put them on about 1 1/2 years ago. Didn't want to weld them on until I did my 4th gen rear swap. Well, when I did the swap this summer, I didn't see the point of getting them welded on. I was gonna get them welded on that week. I'm sure eventually, next time I need something fabricated, I'll have the guy weld them on. But it's on the bottom of my list of things to do. I kinda like the design of the bolt ons anyways, with the extra mounting point.

http://www.umiperformance.com/produc...ategory_id=108

Guest

Yep, 42% to be exact. I was chiming in to say the same as Norm just did.

Fords88Bird

Excellegions did you ever take care of your hopping-bouncing issue. Later.

91_5.7_TPI

iTrader: (2)

I think he meant the ride height would lower about 1.90 inches after taking a full coil off the spring. I don't think he meant he was taking that much off the coil. Could be wrong though. I've been thinking about cutting the WS6 springs I have and see if how it compares to my current ProKit in ride height, cornering, and ride.


As for LCARBs, I've got Spohn weld ins on mine.

84imsa

Thanks again, Fords. When I got the IMSA from the farm, it had all-terrain tires out back and 215/60's up front. At that point, the car pointed about 5 degrees nose down!

I semi-restored the wheels and installed 255/60X15's on the 8" rears and 245/60X15's on the 7" fronts. Those are actually intended for my '70 but I put them back on the '84 just to see how they fit. Now the car sits just about level but there's almost 4" of air between the top of the tires and the bottom of the fender lips. Because the car is almost flat black, it looks like a frightened cat! All that's missing is a puffed up tail sticking straight up from its rear.

Anyway, I finally made room in my garage for it and will stock the garage fridge with beer in order to lure slave labor to the house to help me push it in. Then I will start lowering it.

While researching at the Eaton Springs website, I found instructions and tips on cutting springs. One thing that really caught my attention was a statement that they "never recommend lowering more than 2 inches."

I suspect this has something to do with sending your instant center underground as well as bump steer problems.

So my questions for today are:

1. How low can you go?

2. Are drop spindles preferable (or even available for our cars) as opposed to cutting coils?

I'm now researching bump steer within TGO so I can ask enlightened questions in a couple of days.

Cheers,

Mike

racing geek

iTrader: (5)

Drop spindles are preferred because they allow you to lower the front of the vehicle without changing any suspension geometry. There is a company that offers 2" drop spindles for our cars, but I can't remember their name.

I'm not sure how low you can technically go, but make sure you keep ground clearance in mind.

Mike

krisb410

iTrader: (9)

FYI: Spohn sells a bumpsteer kit.

84imsa

I did some searching and Racecraft has them. They even have them with shorter steering arms for R&P conversions.

http://www.racecraft.com/products.php?cat=46

They're a bit pricey at $550. Has anyone on this thread installed these on his/her car? Earlier today I read a horror story about their K-members written by a Canadian customer. What is the general reputation of Racecraft?

Ground clearance? What is that?

My '70 has about 3" ground clearance at the crossmember and the bottoms of my dual exhaust pipes are nice and shiny from scraping on speed bumps.

Kevin84Z28

iTrader: (3)

Is the car jacked up in your two pictures? It looks like your LCA's are now at an angle instead of horizontal. It even appears that if the brackets weren't there, it would be perfect.

Fords88Bird

Kevin, yeah car was on stands thats why they look that way. Later.

Fords88Bird

84IMSA member UDAMON has drop spindles. Later.

Excellegions

No, I have yet to correct my hopping problem, however the car has been parked for a couple of months as I try to tune the bin file in the ecm for boost. I have purchased a set of KYB AGX Shocks and Struts from ebay for $390, and I got my hands on a used set of Lakewood Traction Action Lift Bars for $30. I have yet to install it all.

I KNOW . . . . Lakewood Traction Action Lift Bars isn't everyones first choice, just about everyone has something bad to say about them, but, $30 dude! Im going to trow them all on and see what the car does, if I ever get the tuning right.

blacksunshine'91

iTrader: (10)

I wouldn't say they are absolutely required, but in my personal experience I would say that if your car is lowered then I highly recomend them. After I lowered my car I had issues with my car jumping around and getting squirly from the grooves in the road and downright screwy when braking hard. After I got the Baer bumpsteer kit installed I haven't had any steering issues. I personally think they are a great investment for a lowered car.

91_5.7_TPI

iTrader: (2)

There is a thread in which Dean goes into bumpsteer a little. But I'm not sure where it is. You might find your answer there.

S10GUY

iTrader: (1)

wow theres alot more to lowering a car the right way then i thought. But since i just cruise my 84 z/28 i think ill keep it simple. i dont race or autox it. I just want it to look good so i was thinking of buying eibach sportlines and calling it good. or does any one suggest i go farther? Remeber its just a cruiser that wants to look good. you coull say my car is a poser

Stephen

iTrader: (12)

Do it for "free" & just cut your springs. Don't listen to their young crowd that hears all the horrible stories about cutting spring WRONG. And ask them if they know more than Chip Foose, who cuts springs to this day!

Do it right & your wallet will be thicker than theirs & your car will work just as good as theirs.

I cut the springs on my previous 2 autocross cars with ZERO problems & will cut my GTA springs when it gets warmer outside.

S10GUY

iTrader: (1)

how many coils for a 2" drop? id be willing to try it.

Stephen

iTrader: (12)

As far as how far to cut for a certain amount of drop...A lot of that depends on WHICH springs you have. On the 90, we hadWS6 springs. On the 92, they were the stock RS springs.

Both cars were used in autocross, obviously the 90 more than the 92.

90RS.html

92RS.html

91_5.7_TPI

iTrader: (2)

This is from another thread on the Forum. Might be usefull

You'll be well advised to get some sort of upgrade in the shock/strut department even for a cruiser. The ride will probably suffer a bit without good shocks.

Frank D

Good gouge and did not think about someone asking the same queston every month!!! That can get old.... so thanks for the response. I have about 160 K on the car so I am going to get the shocks/springs and sway bars in the same package and replace the bushings as needed. I cleaning up the differential and was wondering if you had tweeked your rear end at all. I have it out a thought now is a good time if I am going to do it. Also any thoughts on drives shaft? One last question? Is that your white '91? Nice ride! I will be looking for a convertable after this one. Planet.

91_5.7_TPI

iTrader: (2)

I wrote this hoping it would be stickied so people can see it when they come on to ask similar questions, but it never was. Another member and myself are writing a more complete version, so we'll see how that goes.
What size are the bars you have? Replacing them isn't always something you have to do. If they are small, and you want to replace them, make sure to keep your stockers- they are a good tuning tool. I replaced my factory 2.73 open/drum brake rear end with a rear from a 95 Z28 3.23posi/disk. I've heard replacing the stock drive shaft with a aluminum one from LS1 car (98-02) is a good idea. Frees up a few extra horsepower and eliminates some vibration. I've not done it, but I want to.
Yeah, that's my car. It's in the body shop getting some front end damage repaired right now. Click on my sig pic for a link to my CarDomain if you want.

racing geek

iTrader: (5)

I'm not sure exactly how much will be gained in a thridgen, but I read about someone with a 4thgen switching from the steel driveshaft to the 3" aluminum piece and the dyno results showed an increase of 3 hp and 5 ft/lbs. The person said that after driving the car, they noticed a huge difference in throttle response and that the car didn't vibrate nearly as much when they took it up to 80+mph.

Food for thought,
Mike

compuwiz1937

iTrader: (17)

That's probably true because the aluminum shaft decreases turning mass. However, the difference in throttle response and less vibration is probably because his u-joints on his old shaft were worn out.

blyth18md

Whats the taper on our tie rods?