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My rear end seams to be a little too soft... (what a way to start a thread). The car has a fiberglass mono leaf. I don’t know the manufacturer or spring rating. It was installed over 20 years ago. It has KYB sport shocks at all four corners. Front springs are 450lbs units installed 6 years ago and the front is very stiff. It has front and rear sway bars. 1.125” in front and .75” in the rear. You can push down on the rear of the car to where it bounces, but then settles quickly.
Do I need a stiffer shock or a stiffer spring??
At this point the car is used for occasional driving, no track events yet. But, I want to make sure the car has a balanced suspension.
Bouncing is shock related.
How old are the shocks?
I assume you mean Gas-A-Just shocks.
They are gas shocks remove them and see if they extend by themselves.
If they dont you need rear shocks and possibly front.
The shocks are six years old and have about 100 miles on them. I took them off and they extend all the way up and are still very stiff. The ones I took off before these would stay down if you pushed them down.
First, if you have 450 front coils, those springs are the base suspension replacement spring rating. Second, if you can push on the back of the car and it easily compresses the composite, you may have a VERY soft low spring rating. My 360 composite will not budge if I try to push on the rear of the car. I have to open the door and stand on the door sill and jump up and down to get any movement from the rear and that is with a 360 spring. My guess is you have a sub 300<lbs spring, maybe 200 lbs......
I wouldn't rule out the shocks yet. On my car I have a 360 lb composite spring and QA1 adjustable shocks. At the softest setting I can easily bounce the rear of the car. At the max firmness setting, it's really stiff. I need to push down and the fender while jumping my 190 lb self into the air to get maybe a 1/4" of movement. So, shock stiffness seems to have an effect.
Jb78L - What type of shocks are you running? I went with the 450’s In front because I have removed a lot of weight off the front end and they are plenty stiff. It barely moves.
Last edited by JC 1975; May 22, 2020 at 03:24 PM.
Reason: More info
450 front seems ok..i just put 474 on mine and not bad..
stock 40 yo rear spring still and added 7/16 rear i get very little movement ac delco hd gas shocks..
unless that spring is somehow shot i think shocks..
it would be good to see pics..if factory rear bar etc...pic of spring someone may see something...which has helped me on this forum..
Interpon - when you said I should take a picture, I thought yep that’s a good idea. Then I found this.... I will be replacing the rear spring now.... I guess 20 years is the life expectancy of a fiberglass spring.... I hadn’t looked underneath it in several months.
Any chance someone jacked the car up by the spring?
My TRW spring is 32 years old and shows no sign of fatigue.
I also notice no thread is showing at the end of the spring bolt. Make sure when you install new spring the nut has to be at least a little higher.
We’ve always been careful not to lift by the rear spring. Just as we have always opened the doors and loosened the t-tops when it has gone on a lift. Those are nylon nuts at the end of the spring bolts and they were flush with the spring bolts. But I agree with showing a thread or two.
BTW-Bilstein Sports in the rear only with my 360 composite and Bilstein HD's in front with the 550 Coils.
if i ever get my 1 1/8 poly front bushings..seems the world is out of them that fit factory brackets..ill be reporting on my set up closer to yours..
op glad u found it!,!
report on your decision! Good luck...
i wonder if you have factory gymkhana or hd suspension..never heard of 450 coils
Last edited by interpon; May 22, 2020 at 09:18 PM.
Mono leaf or rear shock issue
