Fiberglass Spring/Sway Bar Life

[93Rubie]

I've been searching for a set of Z07 springs and bars for my 93 FX3 coupe. I've found them, but the car they are coming off of has 220K miles on it. The LT1 finally spun a bearing I am told. I know that GM tested the springs quite extensively and my understanding is that they are practically not able to be worn out unlike a steel spring. So both the front and rear springs (pending no delamination/damage) should be the correct rates for many miles to come and under use. Agree or disagree, why?

The front sway bar is 30mm on the Z07 package and I can get one of these to. Now they are steel but are not under the loads that a spring is. So pending no damage, I would think it to would be good for many more miles/use. Agree or disagree, why?

One final question, how critical is the HD lower bushing in converting a non-Z07 car to a Z07 car? I would think minimal at best.

Also, would you consider running the big 30mm bar on my stock FX3 spring/shock/rear bar (24mm-same as Z07) without the stiffer springs? I would think this would cause more under-steer not less, then again with less body roll more weight would stay on the outside of the car in the turn??? Just entertaining a thought on this one.

 

[Hib Halverson]

You can't run the FE7 bars with base springs unless you want a ton of understeer.

On cars with the big front bar, there is also a much higher rate rear spring. To use the 30-mm front bar you need that stiff rear spring otherwise you have way too much roll stiffness in front and not enough in the rear.

As for the HD front lower control arm bushings, your question is moot because those bushings have never been available as a service part. The only way to get them would be either a low mileage junk yard set of arms or NOS parts.

Do you need them?

It depends on what you're going to do with the car. Road racing, auto cross or aggressive street driving with sticky tires? Yeah, you need 'em to get good response in transitions.

Street driving with the typical rubber one puts on a C4? Probably not.

 

[93Rubie]

I figured on the sway bars with soft springs.

If I can get the parts I'm putting them all on the car so it will be balanced per factory Z07 specs.

I auto-x so this is the whole reason behind getting the Z07 setup. I run on street tires however. It has been hard enough finding springs/bars I don't want the lower bushings with 220K on them. Those are gone for sure.

Do you think there will be any issues using springs/bars with that high of mileage pending no damage to them?
I'm also considering doing poly bushings when I change everything out. My stock rubber units at 60K are probably not the tightest things. Nor do I think they will put up with the pounding of auto-x that is and WILL be getting dished out to them .