Rear Suspension

[69dream]

I am thinking of changing from the original leaf spring to a fiberglass composite spring. Anyone have any experience with this, and how did it turn out?

 

[Bob Chadwick]

I did it and like it. I'm not sure I can describe it. The steel spring seemed to have a much more dramatic bounce to it when going over bumps where the composite spring is muc more subtle.

 

[LVMYVT76]

I did it, but I also rebuit everything in the rear at the same time, including trailing arms, rear end, brakes, and parking brakes. This was a lot easier then with everything out. But, I think it wouldn't be a big job. Just put the car up on jack stands and "GET UR DONE".

 

[GTR1999]

There are pro's and con's to them. I only use steel on my cars and the aftermarket steel springs are not arched correctly.

Steel
Pro's
1- cost much less
2-look somewhat stock
3- last longer

Con's
1-Not arched correct- car sits 2" high with the stock 6.25 bolts
2- require 8" bolts to bring the bbody down.
3- 40 lbs heavier
4 rust if not painted
5- have to be radiused if used with a HD cover or the 4 mounting bolts hit and roll the threads.

Glass
Pro's
1- 8 lbs
2- handling is better- I think this is personal opinion
3-won't rust

Con's

1- cost 2-3 times that of steel
2-Break - main reason I won't use them
3-require new shocks valved for them or you'll be bouncing all over the road
4 still require 8" bolts to adjust the body

 

[purpleRac3r]

I have the VB & P dual mount spring. Wow, what a difference! Handling is noticably better - the glass spring seems to react much quicker than the steel. I have the QA1 single adjustable shocks to help fine-tune damping for my locally rough streets. Less weight is always a bonus in performance arenas. Changing the spring only took about 5 hours with basic tools (electric drill being the most advanced). As for steel, they can break, too. That's the reason I needed a new spring. I don't think breaking glass springs is a major problem or GM wouldn't haave used them exclusively on our favorite toy for the past 23 years. Your call - I can say the fiberglass front spring is next on the upgrade list on my '74!

 

[Space Cowboy]

I have one... It's smooth and you don't feel every bump in the road.

 

[Eden72Vet]

I have had a fiberglass monospring in my 72 all summer. Prior to that I had an incorrectly arched steel spring that made the car sit high in the back (even with the 8 inch bolts). The fiberglass spring, in my opinion, rides much better than the incorrect spring I had prior. As space cowboy said above, it is a much smoother ride in my car.

 

[69dream]

Did the fiberglass spring change your ride height? I believe my spring is original and has lost its sprung. I would like to raise the rear end about an inch or two from original ride height.

 

[Space Cowboy]

Did the fiberglass spring change your ride height? I believe my spring is original and has lost its sprung. I would like to raise the rear end about an inch or two from original ride height.

No... the ride height is exactly what is specified in the shop manual. It looked high to me, but after I measured it... it was on the mark.

 

[zgator]

Didn't GM use composite type on 82's.I've got an 82CE but it has the gymkana option to they got the steel springs.Maybe Gm started in 81?Why can't we use GM composite springs?