Revfan

Hey Guys
My 67 Corvettes right rear "sags". If I measure the height of the wheel well arch on the rear left, I get 26.5"

The rear right passenger side though is just a tiny bit more than 25".

A buddy of mine switched his 66 Vette Leaf Spring out, and his old spring had been painted and had new linings installed so I put that in today along with new center spring retaining bolts, leaf spring outer bushings, and put new rear shocks on the car.

ALSO
I had Bias Ply tires, so I put 215-70R15 radials on.

I thought that this would cure my sag, but it hasn't. It "might" be up to 25 1/4" now on the right rear, but that is being pretty generous.

The problem is that there is very little space between the tire and the fender there. A hard left turn or speed bump and I am paranoid I'll loose my fender.

Any ideas on how to get that 1" or so back in the left rear.

Here are some pics.

This picture makes it look better than it probably is... but its REAL close back there...


The outer spring bolt here is the 8" one that supposedly provides the most adjustment. I move it just about all the way out, and all the way in and the current setting seemed to give me the most clearance (if any)





I am desperate for suggestions....

Thanks, in advance!

66jack

Ride height....Looks like your bolts on the leafs are threaded at different lengths..

The pass side looks longer...

Are the threads showing the same length on both?

DansYellow66

I can't tell if you have GM replacement bolts at the spring tips or fully threaded bolts. If fully threaded you can just tighten them up some more. The more you tighten the bolt and shorten the distance between trailing arm and the spring, the higher the body and frame will ride. If you have standard GM bolts then you can purchase some aftermarket fully threaded bolts and use them.

I would say that spring is a little weak. It looks pretty flat across and the half shafts look pretty much dead level when the weight of the car is on it. I'm more used to seeing a slight arch in the spring and the half shafts slanting down several degrees to the trailing arms.

Revfan

Thanks guys.

The bolt is the 8" replacement (not "correct") bolt that is supposed to give you more adjustment


You are correct in that the bolts are threaded at different lengths... when they were at the same length, the left was 26.5 and the right was 25. I have adjusted the left/passenger side up as high as it will go, and it gives me "at best" 25.5

The "old" spring that I replaced looked flat too. SO I replaced it with the one of my buddies 66. I can't say if it was recurred (probably not), but it had been at least cleaned up/painted/and had new linings installed.
My thinking was that the new (to me) spring would change it a little, but there was no real change in the switch of springs/new bushings. Also if the spring was "sprung", would BOTH sides be sagging? The drivers side seems to be as right as the mail... its just the left that is sagging.

Revfan

Besides the Spring/bushings... what other factors affect ride height? Specifically at the right rear?

65 Pro Vette

With the bolt shorter on the pass side it should make it higher? Are the body mounts on both sides flat like the one in the picture? Check the frame for sag, what type of wheels, what is the offset, they seem very close to body. How is the alignment that can change tire location.

anyChevy

if you can't correct the sag by playing with the rear and it's definitely suspension, then it's probably a sagged front coil.

DansYellow66

Yes - the front springs. If the front springs have been removed and one installed incorrectly, or if one is weak, it can transfer issues to the rear.

And don't get too focused on trying to get measurements to the body equal on both sides. The bodies are a glued together bunch of panels and then they use a bunch of shim packs to mount them to the frame. A 1/2 in difference from side to side is completely normal. If you have a GM shop manual or a copy of the AIM there are instructions for correctly measuring the suspension height that is completely independent of the body. That is the only way to evaluate how even the suspension is sitting.

65air_coupe

I have a very similar problem but I'm running a composite spring. Like you, I tried adjusting the bolt with little success. I was suspicious that the spring was failing but as quick check I reversed it...no change!

As has been suggested, I think my problem lies with the front, perhaps a spring not properly seated in the lower A-arm. FWIW, I have new body mounts.

appaloosa 0012

Considering no prior damage to the frame, and the fact that you had overhauled the rear,
(i still think the rear Leaf Spring is to flat, may be others can add to this), It would not hurt to verified the front springs. On my car that's where the problem was at,

TCracingCA

I guess on the forum, it would never be wise to post up asking for help on a sagging left rear, because you would probably get comments like lose weight, how big are you etc.. So sagging right rear would be the safer question, that would get you real world feedback, that might help!

flared66

I have to agree with dansyellow66 about checking suspension height independantly of the body and if your body mount in last pic is what all the others look like that might be somthing to check appalossa also had good suggestion about checking front springs.it is also possible for a sway bar to mess with the evenness of the ride height.good luck

Revfan

I'll get out there and check the suspension height today and report back... though I only used the wheel well height as a refrence and to help paint the picture of the total problem. Whether its the front springs, leaf spring, or bad ju-ju... the end result is a tire that shouldn't rub is rubbing....

.
Except that my difference is about 1"-1 1/4" from side to side....

I haven't done an alignment on the car yet, as I just got tags and passed inspection about a week ago.

Regarding the front springs... besides looking to see if it is seated properly, is there any other way to check them (besides buying new springs and swapping them out?)

SI67

Something that would be less costly but not any less work would be swapping the right and left front springs to see if the rear sag migrates. You might see something about how they are seated as as soon as you start the disassembly.

TCracingCA

But I don't like the looks of that rear spring either. I don't like that the bolts aren't getting enough adjustment to level it out so there is definitely a problem, so here are a few things to check!

But first if it was a front spring, then it would be apparent in the front visually from side to side!

Check these:
1. On occasion I have seen a few people put a death grip torque on the front frame attachment, locking the arm essentially, so do you have the ability to jack up the arm and have movement?
2. Is the rear diff crossmember and the hats and everything mounted evenly and level in relation to the frame? In other words, is something canting the entire differential? But the halfshafts do look relatively straight in relationship to the rear end and location of the outer spindles on the arm!
If body mounts, I doubt if you have lost it there, because the one shown doesn't look totally collapsed or deteriorated to have caused over an inch drop!
Also the arm isn't canted over on one side?

After reassembly, have you jumped up and down on all four fenders bouncing the suspension to help it settle out since it may have bben sitting?

Etc?

3. An improper shock isn't locking that arm up. I would pop those off and see where you are at!

DansYellow66

Actually - positioning the springs to index them to the lower control arm is one of the most popular ways of installing front springs incorrectly. They are designed to index to the spring pocket at the top. To further add insult to injury, there have been examples posted on here of progressive springs mounted upside down on one side and correctly on the other side. You might be able to visually tell something from examining the exposed portion of the spring - but probably not. You can run the GM measurements from the AIM on front suspension height and if the springs are off somehow from side to side, there should be some indication from the results.

66since71

Just a couple of observations...

It's not clear, but...
If the old spring and hardware produced the same result, it's not the spring.
If the old spring and hardware produced an acceptable result, put them back in.

You can get a lot of tire clearance by aligning the rear to maximum specified negative camber.

Long spring bolts lower the rear, aggravating the tire clearance problem. Go back to stock bolts, and use washers on the bolt to raise one side or the other.

Measure ride hieght at the bottom of the frame rail, about 6" ahead of the "kick up" (per the AIM). That takes all of the body variances out of the equation (factory tolerances, prior body work...). After all the suspension is bolted to the frame, not the body.

Based on the condition of your body mount rubber, I'd expect the trailing arm bushing is pretty sloppy. That can certainly contribute. Also makes the sombreros suspect, as someone else has suggested.

Good hunting... Let us know what you find.

Harry

TCracingCA

First having or buying the longer spring bolts is an upgrade and gives you the same capability to raise the back as a stock set of bolts (unless you bought or got some crap that is not threaded correctly and does not have threading as it should to cover the same travel as the stock bolts, but longer bolts are for the purpose giving you an easier capability of lowering the rear. So change back to stock bolts is something that a confused person would suggest, like the NCRS types! But if these are Home depot bolts or something similar, the overly cautious approach to returning everything to stock like an NCRS guy would suggest is the conservative and a safe move for those that can't measure threading or threading engagement. Boy I feel extra rude today!

The car has to be square, therefore check for welding on frame rails and such, check for kinks in any rails, all over etc. My suggestion on the rear end crossmember and hats or somberos if slightly canted, it would be more pronounced on the outboard side, but remember you are connecting up half shafts with ujoints, but the spring mounts there. Therefore I would take the spring bolts off completely and on an even level floor, let the spring hang and measure the ends, but your spring looks weak as $hit!

If the car was showing a pronounced sag at the rear and if it was front spring (singular), then it would be fairly elevated on the front or the fronts are miss matched and you even have to eyeball the opposite front one and just not the one on the same side. At a minimum if you are showing an inch sag in the rear, if it was a front spring, then you would have at least an inch or more raise showing in the front and just like the rear is visually apparent, so should it be at the front.

I don't think I see a rear sway, but if you actually have one, then I should be able to see it and I don't (but I have been on a very poor and small picture monitor, so I am not having a good ability to get a visual). But if one is present, then not seeing one is a problem, because then I would say it would be mounted completely incorrectly if one exists, but I can't see your pictures very good on the equipment I am typing on!

ps the spring leaves should have a guide bolt, but I have seen all kinds of bad mechanic creativity, so double check that the leafs are centered!

MikeM

Almost every complaint I've seen about a mid-year Corvette not sitting level, it's a complaint that the right rear is lower than the left. And lot's of them are like that whether the owner complains or the owner doesn't.

Does that tell anyone anything?

Revfan

Thanks TCA and others who are chiming in.
The spring bolts are from Zip's 63-82 Spring Bolt kit so I hope they are adequate for the application.

The replacement spring could be an issue... it was a used spring that I had available to try, for free, so I gave it a shot. It looks to have made no difference though, over the old spring, even with new bolts and bushings as stated in the first post. Pardon my ignorance, but would a bad spring be bad on both sides, or could it just manifest itself on the right rear? And two different springs gave the same resluts, a fender that is about 2 millimeters from the fender.

I'll try to get it in on Monday, to put it on a lift and look over the frame and see if there are any obvious issues there.

The front end seems fine... no issues with ride height or anything that would make me believe there was an issue, but I will look anyway just to make sure.

There is no sway bar.

MikeM
Don't understand what you are asking or stating. I can't comment on others' ride heights. I just know that my right rear is lower than the left, and that hard left turns and carrying a passenger of any weight causes the tire to rub on the fender. So in a sense, I wouldn't be complaining, if there wasn't an issue of the tire rubbing/damaging the fender.

I am not an expert like you, but I am sure that is not how it was designed. What do the others who complain about saggy rear rights do to fix em? Any suggestions?