Hey all. I am new to this forum and new to Corvettes. My brother has a 78 Corvette and asked me to put it on the hoist and see if I can help him out.

But I’m stumped.

He had someone install a Van Steel spring in the rear, and ever since then it leans heavily to the left. He also added Bilstein Shock absorbers. I played around with adjusting the lengths of the links to see if I could even it out, but I can’t get it to even. I’m measuring from the top of the tire to the top of the curve of the rear fender, and there is almost a 2” difference between the two sides.

A question: with the car on the hoist, when I rock the right tire gripping at 12 and 6, it has a little bit of play. When I do the same on the left, there is a ton of play. The half shaft moves in and out about a half inch from the differential.

Im trying to figure out anything that would prevent the two sides from coming to even. Is there possibly something in the trailing arms that is the culprit?

Any and all help is welcome!

 

Pics of spring? End play seems the axles worn down like here
https://www.corvetteforum.com/forums...ay-advice.html

someone may also post where and how to measure heights from manual.
spring broke maybe?

 

The spring is brand new and does not appear broken. I assume a broken fiberglass spring would be obvious. It is perfectly centered. I’m wondering if the right side trailing arm is hindered in some way from moving upwards? Could something in that area (hard to see in there) be broken??

I looked at those videos you referenced and that is what mine is doing except it’s WAY more movement than that. My left one moves in and out close to a half inch.

Does any of this explain the difference in height?

 

Is the differential support tight to the frame?

 

Plan to remove diff and have it rebuilt; as well as R&R one or both half-shafts.
Call a local frame shop and make an appointment. Not simply an alignment shop, but a genuine frame shop.

 

pics as requested

 

yes

 

The rocking looseness difference is most certainly a worn rear diff side yoke as you can see in the photo.


As for the 2" height difference between the rear wheel arches, it's really quite common in C3's.
https://www.google.com/search?q=Rear...h=503&dpr=1.67

 

Have you taken measurements of the frame to the ground not the body?

 

Looks like the spring bolts are the same height on both sides right?
Is the spring exactly the same length on each side of the diff bolts?
Maybe check and see if the diff is level with the fender lips somehow.
Something could be mounted off.
If so you have done all you can do in the back.

Weight jacks diagonally in a car, ala nascar, if one corner is high or low.
Your real problems could easily be in the front.
Did you just replace the front coils also, or that could have been a pre-existing condition.
The front coils often get re-inserted and not indexed properly on their stop in the frame pocket.
There is a hole in the pocket, the end of the coil should be right next to it.
Same on the lower arms and the upper pocket.

Past that you'll have to start measuring the frame and see if it's straight.
They can bend.
You could put the frame up on 4 jackstands and make sure both sides are level.
Then make sure the fender lips are level.

You could jack up the front, in dead center, with the rear tires on the ground, and see if the rear fender heights are even.
see if the frame heights are even.
That checks the rear spring & frame.

Then do the same by jacking in the center rear.
That could at least steer you into the front or rear.

If nothing turns up, the rear spring could be a slightly different rate R & L side.
You could shorten one spring bolt slightly more than the other, or loosen the spring and shift it slightly to the high side.

Since the rear spring is curved, if it is shifted slightly off center, one side will be lower than the other.
To check jack the rear up exactly level vs the frame.
Then unbolt the outer spring bolts.
Both spring ends should hang down exactly the same amount. IE: the same height off the floor.

 

Trailing arm bushings are trash. Not saying that is your height issue though.
rear could use all bushings and as mentioned differential refresh with axles. Might as well check bearing tolerance too.

 

Great info. Thanks for the detailed help!

 

those trailing arm bushings still need to be replaced . time to drop dif and inspect.. it will improve everything..

WOW Bridge street signs... lived on Bridge street above the hill and walked to st james.. just there last week.

 

Small world! I work on Bridge Street at the Fire Station.

 

OP and Family:
Grand Rapids, Kent County Michigan, quite near Lake Michigan. Considerable icy-snowy winter weather With commensurate tonnage of corrosive salt on roadways.

From just the few pics, chassis (nearly Fifty years old) appears very crusty & rusty.
That (along with unexplained sagging) checks off several reasons a genuine pro Frame Shop should thoroughly inspect & assess this one.
Is it structurally sound, and safe to operate ?