Lowering the '86

unleadedbrew · 05-08-04, 04:46 PM

I've got the new 10" bolts and am wanting to lower the ride about 1" in the rear. Is there anything special I need to know, like how far do I tighten the nut, blah, blah, blah, or is it just a switch-a-roo? Is it hit and miss on getting the sides even, etc.? Enquiring minds want to know.

Well, what's left of it.

Thanks,
Gordon

Ken · 05-08-04, 08:38 PM

Now that I've eliminated my side exhaust, I've been thinking about lowering it too; it just seems to sit too high now. Trouble is my Lakewood bellhousing took the place of the sidepipes concerning clearance issues - it hangs down there pretty low.

I'm gonna be following this one, that's for sure. Hope we get some good answers.

Ken · 05-09-04, 10:19 PM

I hope I can get away with an inch or so lower.

unleadedbrew · 05-10-04, 01:45 AM

Whoa!! You really don't have much clearance!

You may have to take to spreading vaseline on the bottom (car of course) and just hope to slide over all the pee bumps. I'm only going to lower the rear as the front is low enough. Can't find any instructions on the rear, so I guess it's just change out the bolts, etc. and play it by ear. All the hard work (and instructions) seem to be in doing the front.

BTW, it sure looks clean under there..........

Gordon

Moonunit 451 · 05-10-04, 02:07 AM

Man Ken, that looks great! Gordon, I may be wrong here, but I've read that you shouldn't lower the rear only. The car should be lowered equally. It has to do with the specifics of the engineering. Rake and aerodynamics.

Ken · 05-10-04, 03:13 AM

I'd be sure to check with a Corvette-knowledgeable alignment shop about that Colin. You're probably right though.

You guys think it's clean under there? Ha! The camera sometimes hides the real dirt instead of exposing it, eh?

I gotta get it on a lift and get under it with a case of brake cleaner and clean the hell out of it. Remember my oil leaks?

unleadedbrew · 05-10-04, 10:50 AM

Thanks, Colin........Knew I wouldn't be able to get away with anything easy.

If I lowered the front any more, I don't think I could clear a dime in the road. Just wanted to fill the wheel wells better, but sure don't want to sacrifice the goodies.

Gordon

86PACER · 05-12-04, 04:35 AM

All you need is a jack to carefully lift the rear spring up and releive the stress on the lower nut. Then just swap bolts, drop the new bolts in place and gently allow the spring back down onto the lower nut. No need to remove wheels or raise the rear off the ground. Drive the car some to "settle" the suspension and observe the new rear height. Adjust as nesessary.

JT ZR-Won · 05-12-04, 11:22 AM

I found the rear on mine took quite a bit of adjusting. It seemed that my driver's side was "stiffer". For the rear, I would just adjust the nut, drive it around the block to settle, and then measure from the top of the wheel well to the ground. After I got both sides exactly even, I had to get the car aligned to get the wheels straight up and down because as you lower the car, the bottom of the wheels bow outward a bit.

Jay

unleadedbrew · 05-12-04, 11:55 AM

Thanks Pacer and Jay......That sounds simple enough and the way my mind works it has to be.

Pacer, that sure is a sweet compartment you have there.

Love those valve covers.

Gordon

05-12-04, 01:54 PM

You will want to be very careful with the ultimate adjustment of the rear spring heights.

Too high or too low and you mess with the weight transfer characteristics of the car, and effect is likely to be seen under acceleration and/or braking.

Worse yet, side to side disparity will result in uneven cross weight (contrast of total L/R + R/F vs R/R + L/F weights). This will (i) produce inconsistent response in cornering, one direction compared to the other, and, (ii) unpredictable transition from one to the other.

Process I would recommend would be to (i) set the car up on scales, (ii) start from the front to rear ride height differential recommended in the service manual, and (iii) adjust to 50% cross-weight with average fuel and passenger load.

To the extent possible, try to make adjustments by raising one side and lowering the other in equal amounts, instead of trying to take all adjustment from one side.

Alignment should be set first. Be certain that tires are cold and at their proper cold pressure before making any adjustments as well. These are both significant!

If cross weight is not properly adjusted, the car literally rocks back and forth on the diagonal that is more highly weighted.

Given all of this, you could have an otherwise perfect alignment, etc., and have the car still handle poorly.

Hope this helps.

05-12-04, 02:05 PM

Quote:

Originally Posted by JT ZR-Won

I found the rear on mine took quite a bit of adjusting. It seemed that my driver's side was "stiffer". For the rear, I would just adjust the nut, drive it around the block to settle, and then measure from the top of the wheel well to the ground. After I got both sides exactly even, I had to get the car aligned to get the wheels straight up and down because as you lower the car, the bottom of the wheels bow outward a bit.

Jay

Jay,

Using the body for ride height measurement does not take into account any variance in wear/compression on the body mounts. Shop manual procedure for ride height is to measure to frame points on both sides, front and rear.

That will give you a good starting point, but it is still best to sort the car out by weight.

I put another post up in this string about that process. Read that if you get a chance. It may help you get the best out of your car.

Cliff

unleadedbrew · 05-12-04, 04:10 PM

Thanks Cliff......Very enlightening. This gets better all the time.

And wouldn't you know, I just sold my copy of "NASA Rocket Science for Dummies 101" on eBay.

Gordon

Ken · 05-14-04, 12:07 AM

Here's another look at mine from the side, at a distance, and you can see that actually I can give up a little more room down there. I think I can get away with dropping it an inch or so, eh?

I can't post it here because it's so large, but it's largeness will give you a better look at the big picture.

http://corvetteobsession.homestead.c...008_actual.JPG

Be sure to view it full-screen.

unleadedbrew · 05-14-04, 10:37 AM

I can't post it here because it's so large, but it's largeness will give you a better look at the big picture.

Sure wish I could relate to that!!!!!!!!

Gordon