Corner sagging

[Rod in OKC]

I'm going to give this another try since no one had any guesses the last time I posted on this subject.

'95 Coupe with 68K miles..... The left rear corner is sagging an inch below the right rear corner. Or, conversely, the right rear is sitting 1" higher than the left rear.

I know it's not shock-related. I just put new ones in this weekend and it didn't change anything....not that I expected it to.

I've checked all the measurements that I could think of, even the stupid and obscure ones, like making sure the wheels are the same size. The spring bolts and cushions are the same size. All measurements from the floor of the garage to any given point are equal on both sides.

I've seen references to body mounts being worn out and needing to be replaced as a possible cause of sagging. I can't, however, find any references to the mounts in either Chiltons or Haynes. Does the '95 have rubber body mounts?

The only other thing that I can think of is the rear spring. Oddly, I put a jack under the left end of the rear spring (right next to the spring bolt) and lifted about an inch. Instead of just the left side rising, the entire rear end lifted up. I don't get that!!!

The tilt to the left is obvious. You can see it from behind the car and it's driving me nuts. Does anyone have any ideas or has anyone run into this? It must be common since my '76 did the exact same thing. Luckily, it wasn't as bad, but I never solved it either, even with a new spring.

Rod

 

[paintdaddy]

this may sound stupid but have you checked the clips holding the bumper on.Those bumpers have a common problem of sagging in the middle and if its ever been replaced and someone didnt reinstall the clips,it might sag on the corners.Just a guess.

 

[69MyWay]

You could simplyhave a bad spring, and or need to adjust the ride balance by adjusting the nuts on the long bolts at each end of the rear spring.

Are you the original owner? If not, the prior owner may have either crashed the car at one time, or tried to race it and had a speed shop (scale) the car causing your rear to sit funny because he balanced the weight on each tire by adjusting the spring.

I think the spring is the thing.....to make it level again.

 

[Rod in OKC]

paintdaddy..... I wish it was as simple as just the bumper sagging. Unfortunately, it's the entire body that's leaning.

69MyWay..... At this point, besides the body mounts (if there are any on a '95), I can't think that it would be anything else other than the spring, as you said. I'm not the original owner, but I do know the history of the car. It hasn't been crashed and it wasn't raced. If I do go ahead and lift the spring in the left rear corner, what are your thoughts about throwing the handling out of whack? Let me throw this point in as well..... On bumps, I'm getting slightly more bounce out of the right rear than the left rear. Does that throw any additional light on it? Also, I'm baffled as to why both sides of the rear lifted when I jacked up only the left side of the spring.

Rod

 

[JT ZR-Won]

or need to adjust the ride balance by adjusting the nuts on the long bolts at each end of the rear spring.

I would check out these bolts. Even if you look at each bolt and the threads are even, that doesn't mean anything. when I lowered the rear of my car, it took several attempts to get the car to an even ride height in the rear. At first, I tightened each nut up the bolt the exact same distance and the left side of the car sat considerably lower. After several attempts I eventually tightened up the left nut much higher up the bolt than the passenger side. After I got the same measurement from each side of the car, I had it aligned.

After each adjustment to the bolt, the car must be driven at least around the block so the rear will settle and then get your measurement. Hope this helps.....

Jay

 

[jeepie]

I jwould check (try adjusting) the nut that holds the spring to the right knuckle, maybe someone removed it to change the half shaft universals and just tightened it all the way instead of making a note of its position and putting it back in the same spot. Just a guess, good luck.

 

[Rod in OKC]

Jay,

I'm glad that someone else had the same problem. If the unevenly adjusted spring bolts didn't seem to affect the handling, then that's what I'll do. My bolts are 10" long and don't have cotter pins. I think that means they're aftermarket parts. I'm not sure how long the stock bolts are. Did you take your measurements from the beltline?

Rod

 

[69MyWay]

The only other thing I can imagine would be the upper mounts for the rear diff. If you have a bad one, it could cause it to lean. However, you would feel/hear a clunk in it when you hit the throttle.

Otherwise, it has to be your spring adjustment.

 

[*89x2*]

I am thinking it is the non-stock bolts...
Please let us know

 

[JT ZR-Won]

Jay,

I'm glad that someone else had the same problem. If the unevenly adjusted spring bolts didn't seem to affect the handling, then that's what I'll do. My bolts are 10" long and don't have cotter pins. I think that means they're aftermarket parts. I'm not sure how long the stock bolts are. Did you take your measurements from the beltline?

Rod

Rod, they must be aftermarket because the stock one's have clips and my lowering kit did not. In fact, I even had longer bolts custom made for the rear of my car because the lowering kit didn't lower it as far as I wanted it to go in the back. My handling wasn't affected at all. I measured from the exact top of the wheel well to the floor. Your tape measure should pass right through the midle of the center cap of the rim. If I remember correctly my ride height all the way around is about 26.25in. high from the ground to the top of the wheel well. Keep us posted.

Jay

 

[Rod in OKC]

I've only had the car a month and the spring bolts were already on there. It looks as if they've been there a while too. While I was under the car putting on the new TPiS shocks (great ride!) last weekend, I checked out everything within reach. It's all tight and the measurements are all equal on both sides. Also, there's no "thunk" from the rear end when I hit the gas, so hopefully I can rule that possibility out.

It looks like I've got my weekend project planned. To make up the 1" difference, I'll try dropping the right side 1/2" and raising the left side 1/2" and see where it ends up. Since there aren't any cotter pins, I hope those are Nyloc nuts! On my '76, I replaced the steel leaf spring with a new one, but got a bad bolt. It snapped on me one day at about 50 MPH. Thought I'd been hit with a howitzer. I don't ever want to experience that again!

Thanks guys!!! I'll post the results.

 

[*89x2*]

Since there aren't any cotter pins, I hope those are Nyloc nuts!

Saw something about NYLOC nuts the other day - I would not stake my life on them as plastic on a "shifting" part can give...
double nut or, cotter pins are safest

 

[Rod in OKC]

I'll use a jam nut and probably a lock washer on it. I don't think the back-up nut needs to be grade 8.

 

[JT ZR-Won]

They should be Nyloc nuts but better check to make sure. Also, If the ride height is fine on the passenger side, I would not adjust it. Do the driver side only. Remember to zip it around the block after each adjustment to let it settle.

Jay

 

[Rod in OKC]

Jay,

I may not have a lot of choice in which side I adjust. In checking the measurements, I've got 26 3/4" on all three corners, except the right rear, which is 27 3/4". I've only got ahout 3/4" of thread left under the nuts on both sides. That doesn't leave me very much room to drop it AND use a back-up nut.

Did you use just a single Nyloc nut? Can they be reused?

Rod

 

[JT ZR-Won]

Did you use just a single Nyloc nut? Can they be reused?

Rod

Yeah, I've just got one Nyloc nut on each bolt. I'm not sure if they can be reused.........never tried it before. If you can get new ones easily I would probably do that. Otherwise, if you have to reuse the old ones just make sure they're in pretty good shape.

Jay

 

[Rod in OKC]

Jay,

You don't happen to know the standard nut size for those bolts, do you?

Rod

 

[SPANISHVETTS]

My 90 did this when the rear spring was going bad. (Z51 package) About 2,000 Mi. after reworking the suspension it started sagging again. I thought the new spring was bad but after readjusting the spring bolts there have been no problems with sagging in more than 10,000Mi. Maybe these fiberglass springs ¨settle in¨ a bit.

 

[JT ZR-Won]

Jay,

You don't happen to know the standard nut size for those bolts, do you?

Rod

Rod, not off hand I don't . Sorry.....

Jay

 

[Rod in OKC]

Last night I added another element to the equation.... For the most part, the roads in Oklahoma City are in very good and smooth condition. For the first time I happened to take the car down one street that was a little rough and uneven. I've been down it literally hundreds of times in my GTP without even noticing anything. However, I thought the Vette was going to shake itself to pieces. It felt and sounded like it was slamming into each expansion joint and crack in the concrete. Of course the rear wheels are practically right under the seats, but this was ridiculous. I know it's not the shocks, they're brand new TPiS's. Now I'm wondering if the spring is bad. With 68K miles on it, it shouldn't be, but it's possible. Who knows what roads it's been on before I got it.

That could explain why I'm getting more bounce out of the right rear than the left rear on bumps.

Agggghhhhhh!!!!!!!!