cagotzmann

After trying to adjust the rear height on my 78 corvette I noticed that I need to adjust the bolt on the driver side about 1 1/2" more than the passenger side to level the car. (measuring the frame to ground). So thinking there is something wrong in the spring mounting to removed the spring. It's a VB&P 360 mono. Seems the mating surface has deformed.



It this normal. The spring has been on the car for 2 years now.

Red 69

I had a composite spring delaminate, it split length wise and between composite layers. It was hard to see visually, but let one side sag, as would be expected. This is a rare occurrence, from what I have been told, but VB&P exchanged it for a new one. You might check for a crack in your spring.

One other thought, the directions with the spring state it must be kept from exhaust pipe heat and recommend using a heat shield. They even provide a heat sensitive sticky to place on the spring to indicate the temp it gets. If your pipes have been up against the spring, it may have resulted in weakening it and resulting sag. My pipes are wrapped with heat wrap material, to shield the spring from this pipe heat. Just something to consider.

cagotzmann

I have used heat wrap from day one. I dont think its sag but a problem in the mating surface that has deformed ? I dont think the spring sits properly on the rear end mounting surface ?

doorgunner

Rookie question: Have you removed the thick spacer/laid the spring upside down on a table/measure the ends to see if they are arched to the same height?

Have you removed the thick upper spacer from the spring and fitted it to the differential and placed a carpenters level against it to see id it is crushed on one end (assuming you have the differential mating surface level).

Have you placed/mocked-up the spring without the thick spacer against the differential mating surface to see if the arched ends of the spring are equal height from the frame?

Did you use a torque wrench and proper torqueing pattern to install the spring onto the differential?

Keep us posted.....as I had a similar problem with my steel spring-pack after refurbishing it.

jb78L-82

First, I would talk to VBP and show them the pictures.

My 360 VBP composite spring has been on my car since 1986-yes 1986! I must have been one of the early adapters since I started thinking about switching once I heard that the 81/82's were using composites and made the switch after learning the front and rear of the C4 had them.side to side ride height differences can be caused by a host of factors, not just the spring. I did have to play with the bolts on each side 28 years ago to get the height on each side roughly equivalent. I run the factory shield above my spring which is about 2 inches from the exhaust and nothing else. Never had an issue period, none related to heat.

Hope that helps

cagotzmann

With the spring removed a placed a laser level pointing left and right and measured the distance to the rear end carrier frame. Each measured within 1 mm. So the rear end is level to the frame. I then re-installed the spring and measured at 2 points from the spring to the carrier frame. Both measure within 2mm of the carrier frame. When I put load on the spring then the driver side now measures 1/8 lower than the passenger side. This previously measure 1/2" or more. The only thing that is different is the sway bar is not installed. I may have had 1 side of the bar tighter than the other. Re-installed sway bar. It's still not level but now the front left is also low. I lifted the front left on the frame to level the rear now all sides are within 1/8". Now I am looking at the front sway bar to see if this has any effect. There is more than a few factors, but I dont think the rear spring is the problem. While the rubber mating surface of the spring still has me concerned, but I dont think the rear spring is the problem anymore. On to the front end.

doorgunner

Thanks for the detailed update on how you worked the problem out.