corvettedave383

ive got a 78 vette, with vbp 330 mono spring, qa1 double adjustable shocks, ive noticed recently one side the rear end is sagging by alot, 2 inch approx, the body is sagging on one side, so wheel to wheel arch is about 1.5-2 inch approx, what could cause this, can the vbp mono spring lose its strenght on one side, thus causeing sag??

0Willcox Corvette

Have you checked the rear body mounts? They have a pretty good history or rotting out, either the mount itself or the metal cup that sits on top of it.

Also, how does the front look left to right, possibly a weak front spring

It could be the rear spring, how old is it? Vbp has a very reliable history for making awesome parts but anything is possible.

Willcox

corvettedave383

ok cheers, will check the rear body mounts, the front has new qa1 full coilover from vansteel and looks equal at the front, also if i grabbed hold of body from sagging side, in theory if rear body mounts gone, should feel movement?

if i wind up one nut on one side the body comes come up, but its wind up 1 inch there, and body is then just about level to the ground at that point, but that looks wrong, because the com spring wouldnt work correctly??

see in pic

corvettedave383

Ive noticed car is down at front corner on the same side aswell, by 1 inch, tried swaping composite spring over, so hould have sagged on other side, but not doing that, still sagging on same rear corner and the front on the same side, any help?

'75

I would suspect the problem originates in the front, maybe one coil spring is not seated correctly.

corvettedave383

they look seated, and set to the exact same height, will check again

'75

A front sway bar that's bent can cause this also, you could try unbolting the end links to see if it sets more flat.

corvettedave383

ahh funny you should mention that, just fitted a new stronger front sway bar from vansteel, was a pig to get on, getting the bolted links in there

could that be an issue, its brand new so shouldnt be bent, looks good??

can the bolt/nut lenght affect car?, how tight the nut is?

'75

If the bolt is significantly tighter/ compressing the rubbers more than the other side, it could have an effect. One time I used a shorter end link spacer on one side to correct this problem after making sure all else was ok.

corvettedave383

ok cheers, will look at in in more detail

corvettedave383

I unbolted the front sway bar, just case it was bent

jacked up rear end, measured the gap between top of arch to metal part of wheel on both sides, both measured the same, then unbolted each side of spring, leaving it bolted to diff, and we can clearly see from pics that each spring bolt on each side is showing a different lenght, which leads me to think the spring has a big problem, am i right, or am i missing something?

loflite

Did you ever get an answer? I've got the same problem on my '76 but not as much difference. Also have the same springs you have.