lowering bolts

[dg463]

Hi

Today i installed the rear lowering bolts with bushings from Mid America,on my 91 ZR1, the job was not too bad just have a couple of questions for the forum members, what is the stock height at the rear of the car from the ground to middle of the fender, after replacing the stock bolts the pass side measures 27 3/4 inches and the drivers side 27 1/4 inches I have played with the the right nut where it has 3 threads left to the bottom of the bolt the left side has about 4 threads left to the bottom of the bolt, I hear there is some settling that occurs with time, should I align it know or drive it some more,also is half an inch difference between the left and right a big deal, what can I do to correct it? thanks for your help.

[mike100]

I've had two C4's and both of them sagged about that much on the driver side.

On my current car, I elected to preload the spring a touch more on the lower side and got it leveled. I do not know how much it might affect the corner weight- I just did it.

[QB93Z]

In my experience, it is not possible to change left-to-right ride height variation using the long-bolt lowering kit. I think that you may cause stability issues by loading one side of the rear spring more than the other.

I believe that some C4's just sit with a small side to side height variation.

Jim

[dg463]

Hi


Thanks for your imputs, I played with it a little this morning, and settled for a 1/4 inch difference between right and left side, looks fine,and rides well, I will align it in the near future.

Dennis Garcia.

[mgbsda]

Well done Brother! now come over and lets do mine!

[Starman]

I had a similar issue on my 91 and found out the rear sway bar was bent. You can also try moving the spring shims around where it mounts in the middle. I have installed this kit on three C4s and they will sit flat side to side, if not otherwise jacked up, although the factory tolerance was pretty large, Gordon K. can no doublt quote the exact number.

[mgg]

I have tried to get the car equal settings with lowering bolts and front shims and have given up. Coilovers are now going on and I bleieve that is the ONLY way to have the car sit properly. Adjusting the left rear affects the right front and vice versa. I know I am anal on this but I even bought the $100.00 extra long bolts from vette brakes to try and see if I could get it correct. NOPE! I have coilovers on the race car and now thanks to Dan Mc. I am putting them on the ZR-1. Have to admit, not exactly excited about putting them on but to it correctly will allow the car to be right. NOt that corner weighting is critical in a street car but I now have that option if I choose as well as being able to adjust the ride height when I want to. NOt knocking the lowereing bolts and shims as I had them on both C4s before going to coilovers. Precision won out.

[Bob Eyres]

All of this makes me wonder where the correct place is to measure the ride height? The frame? The top of the wheel arch on the body? The bottom of rear body valance?
I lowered mine 1 1/2" in the rear only, in the mistaken belief that it would pre-load more weight on the rear to allow for better 60ft. times in the qtr. mile.
As far as I can tell, it didn't help.
But it did make the car look better. Many of us have noticed that the ZR-1 's stock ride height looks too high in the rear.
Even slightly lowering the car at the rear greatly improves it's appearance, and makes that wide butt look even wider.
Lowering the front seems impractical to me, unlike the rear, it's "in the weeds" already. Even at the stock height, most C4's are grinding that chin spoiler off on driveways etc.

[Bob Eyres]

Here's another tip- Always take a chubby person with you on every ride, to avoid the dreaded "long term deterioration of driver side suspension support".

How's that for being anal.

[WVZR-1]

Originally Posted by Bob Eyres

All of this makes me wonder where the correct place is to measure the ride height? The frame? The top of the wheel arch on the body? The bottom of rear body valance? Lowering the front seems impractical to me, unlike the rear, it's "in the weeds" already. Even at the stock height, most C4's are grinding that chin spoiler off on driveways etc.

Ride height should be measured from the same points that are used for "body dimensions". In the rear you could compare the dimensions "side to side" to a level floor from the lower bolt of the trailing arm bracket front of rear wheel and also the rear bolt mounting strap for the fuel tank, in the front use the stabilizer bar bracket and the drain hole at the hinge post. See body section 10-3 in FSM - you aren't trying to duplicate the dimensions in the chart, those are for "hanging gauges" but if you use those points to measure to a level surface you can determine the placement of the "chassis" to the surface. Correct tire pressures or at least equal tire pressures are a must and first!

Body panel dimensions can vary considerably side to side of a single car to considerably more or less on a comparable different car with the frame points being equal!