need help levelling a rear end

[Txbobcat]

A few weeks ago in another thread i discovered my rear spring had been removed and coil overs added. I have installed my rear springs and newer FX3 shocks and the ride is much better and higher. However measuring from the floor to bottom center of wheel well I am 1 inch higher on the pass side than the drivers side while car is empty. What is the proper way to raise or lower one side to level out this car which by the way is a 92 convertible. My height now is 27 on the drivers side and 28 on the pass side. The shims bolting to the rear end were installed exactly the same and the bolts attaching the spring ends to the wheel assembly are matched as well.

 

[Hib Halverson]

The first thing to do is measure trim height per the factory service manual which indexes ride height off the suspension not the body.

Also, did you replace the rear coils with two new ones or did you replece the coil-over-shock units with a stock spring and shocks?

 

[Txbobcat]

Ok I have the factory manual so I can look that up. The rear coil springs and shocks were removed only good shocks were replaced along with a good used spring off of a similar corvette. Unfortunately I will be out of town for a week or two so wont get to it till I get back. Keep the advise coming. I am more of a muscle car guy and this is all new to me.

 

[Hib Halverson]

Ok I have the factory manual so I can look that up. The rear coil springs and shocks were removed only good shocks were replaced along with a good used spring off of a similar corvette. Unfortunately I will be out of town for a week or two so wont get to it till I get back. Keep the advise coming. I am more of a muscle car guy and this is all new to me.

The way to measure the trim height on a GM vehicle varies little between "muscle cars" and Corvettes.

Measure it then post the results.

Also, does the car have coil-overs in front, too?

 

[Txbobcat]

Currently the front has coil overs and no spring as the rear end did. I wanted to get everything right on the back before I bought and set out to install the front which I heard is a lot harder. I will go back to the junkyard and watch them take it out to help me learn how to do it as well. He didnt have time for that to happen when I bought the rear spring a few weeks ago.

 

[Hib Halverson]

I'd get the conversion back to stock springs completed before you start adjusting ride height.

 

[Txbobcat]

Been a while but I now have springs and shocks rather than coil overs on my vette convert. So now it rides and sits like it should

 

[boomdriver]

Been a while but I now have springs and shocks rather than coil overs on my vette convert. So now it rides and sits like it should

Thats good to hear. Its a safety issue. Those transverse composite springs do other things besides support tension for the suspension....they also act as anti-roll bars so the side roll is minimized when going around corners. These springs have different rates too, some are soft that give a more comfortable ride with some decent shocks for dampening, while others (Z-51) are super fast/hard spring rates that are hard to compress and rebound quickly for more stability at high speed or auto-cross. There are countless shocks available to "tune" the suspension to the drivers liking.

For future reference, the rear spring is somewhat adjustable with ride height. Simply run the end-link nuts further up the long bolts to drop the rear end down a bit. Leave the nuts toward the end of the bolts to give the rear more height. This allows the spring to have its full arc, which makes more suspension travel and give some degree of softness to the first bit of travel. The further that the nuts are run up, the more of the springs arc is taken out and the lower the chassis sits and the stiffer the rear suspension gets. This can drop the rear by as much as 1". Just be sure not to leave loose link bolts, always have some tension on the spring ends, measure each to set ride height equally, and use the cotter pins to secure the nuts. basically the flatter the spring the lower the rear end. Front ends are what they are with only a couple choices of different spring & no adjustment.

Coil overs on all 4 corners..? on the street? I would'nt want to see such a thing. That has to be a sin. I wonder what the point was to do that to a Corvette ? To soften the ride? make it nice and comfy? Get a Camery.

Hillbilly engineering should be punishable with a bus-pass. Minimum 1 yr sentence. Criminal behavior against an American Legend.

I saw a couple guys walk into a parts store once and ask the parts guy at the counter if they had air-shocks for a Nissan 300ZX.....
The salesman just stood there for a minute and finally says..."get out of my store" ! !

 

[Txbobcat]

Yes I got the softer ride springs from a guy in Waco that parts out corvettes. He was great and $70 per spring and all hardware to mount it with I thought was one heck of a deal.

 

[boomdriver]

Yes I got the softer ride springs from a guy in Waco that parts out corvettes. He was great and $70 per spring and all hardware to mount it with I thought was one heck of a deal.

That IS a heck of a deal

 

[Hib Halverson]

A couple of comments, here.

First, the statement that the C4's transverse leaf springs also act as "antiroll bars" is not correct. The springs contribute to roll stiffness but they do not act as stabilizer bars, ie: they do not transfer weight from the outside to the inside in a turn.

Secondly, the statement that one can adjust rear ride height with the position of the spring bolt nut is correct, but you can do that only to limited extent. NEVER run the nut over or below the cotter pin hole. Some people think they can replace the castle nut with a self-locking nut and eliminate the pin thus loosing half-an-inch or so of ride height. Do that and the bolt will break then the suspension will collapse.

If you want to lower the car properly using bolts, buy longer spring bolts. Get them from CAC sponsor Zip Products.

Thirdly, on some C4s, the front spring is ride-height adjustable. if the factory service manual for your year discusses spring shims, then your front end is adjustable. The lowest the car can go with stock springs is if you remove all the spring shims in the front. Actually, there are shims in the rear of some C4s, too, however, in the rear, the amount of shims must remain the same but the location of the shims affects ride height. In the back, to get the lowest, you need to move all the shims to below the spring.

 

[boomdriver]

A couple of comments, here.

First, the statement that the C4's transverse leaf springs also act as "antiroll bars" is not correct. The springs contribute to roll stiffness but they do not act as stabilizer bars, ie: they do not transfer weight from the outside to the inside in a turn.

Secondly, the statement that one can adjust rear ride height with the position of the spring bolt nut is correct, but you can do that only to limited extent. NEVER run the nut over or below the cotter pin hole. Some people think they can replace the castle nut with a self-locking nut and eliminate the pin thus loosing half-an-inch or so of ride height. Do that and the bolt will break then the suspension will collapse.

If you want to lower the car properly using bolts, buy longer spring bolts. Get them from CAC sponsor Zip Products.

Thirdly, on some C4s, the front spring is ride-height adjustable. if the factory service manual for your year discusses spring shims, then your front end is adjustable. The lowest the car can go with stock springs is if you remove all the spring shims in the front. Actually, there are shims in the rear of some C4s, too, however, in the rear, the amount of shims must remain the same but the location of the shims affects ride height. In the back, to get the lowest, you need to move all the shims to below the spring.

What the purpose of a transverse spring if not to assist in body roll while cornering?

I had no idea that the front shims made enough difference to effect the ride height. Interesting fact.

Does removing or adding shims effect the front spring rate or stiffness? I've looked for front options and there are few, if any.

 

[jonszr1]

the statement that coilovers area sin i just alittle harsh . i have 3 zr1s 2 have coilovers and one the stk stuff . to me the coilover cars handle better both in corners and the drag strip . i never did like what they call cross talk when going over a bumpy road with the transverse springs. plus one can adjust the ride height to there liking alot easier than with the stk stuff but to each their own. my coilover setups still allow the use of the fx3 cabin adjustments

 

[bell]

coil overs

I am currently looking to go coil over on my 95 ZR-1 and feel the fact that each corner will now have cushion & solid independence at each wheel. My rear spring is shot so this is the best time to try it. If successful I may offer the FX-3 system for sale w/actuators which seems to work fine!
Any tips or help would certainly be welcome!!
Gene in Fl.:confused

 

[mseven]

Mine originally had an fx-3 system and it worked properly. I switched mine to coil-overs (qa-1's) and the car never felt or handled better, not to mention shock adjustment for straight line use....a bit of work involved but well worth it IMO.