Rear Control Arm Bushings - Considerations

Mike8675309

Registered User
I started this thread to keep the tech talk out of the non-tech area, this started with:

I've followed some Cobra guys and their use of Delrin bushings in their subframes. They seem to feel they improve handling. Not sure if poly would be similar
Here is the kit and thread where they discuss them:
http://www.svtperformance.com/forum...g-kit-w-adj-sway-bar-links-bumpsteer-kit.html

The manufacturers website with interesting info on bump steer, and sway bar adjustments
http://www.fulltiltboogieracing.com/

I'd love to see the availability of some of this for the MN12 subframe.

subframe wise Id do delrin. Its the control arms Im concerned with. From my unerstanding the delrin cobra bushing can work.

Read through the thread on the cobra stuff, and take a look at the bump steer video on the manufacturers main website.

I believe our toe link compensator works within our rear suspension to control bump steer. If you change the compliance of the bushings within the control arms, you will change the bump steer characteristics of the rear suspension. The toe link works in conjunction with the factory bushing compliance to determine full suspension travel bump steer path. For the Cobra kit linked, their bump steer is controlled with a fixed tie rod, that the kit replaces with an adjustable tie rod.

I'm not sure what we would need to do with our car to get some adjustment into the bump steer if you do replace all the bushings. I think it would be valuable to take a look at a stock car, with low miles or older car with new rubber bushings. Check the bump steer. Then check a stock car with high miles and see how worn bushings affect this. Then check a car that just did poly bushings all the way around.

It would be interesting to see how important having fresh bushings are. Then look at what might be done to bring the other cars into better bump steer curve.

The toe link compensator in our IRS and how it works with the control arm bushings plays a significant roll in the stock suspension behavior. Changing the bushings in the control arms or the toe link without careful consideration could turn a forgiving suspension design into something less forgiving.
 
My bumpsteer issues were fixed with an alighment. It is a little more twitchy then stock, But I think my car handles just fine with my poly LCA bushings. I think I am the only one with poly bushings on a 5spd. Wheel hop was reduced dramatiacally, but it is still there. I autocrossed the car at the shootout and I can tell you the passengers I took out felt a few Gs going tru their body. :eek:
 
My bumpsteer issues were fixed with an alighment. It is a little more twitchy then stock, But I think my car handles just fine with my poly LCA bushings. I think I am the only one with poly bushings on a 5spd. Wheel hop was reduced dramatiacally, but it is still there. I autocrossed the car at the shootout and I can tell you the passengers I took out felt a few Gs going tru their body. :eek:

What did you use for your LCA bushings?
 
I was going to make a set...but dang...$60 is cheap for the lowers...the stock ruber ones were $35 each side.

I may make some custom ones for the top though...

What about the IRS subframe mounts? Would those work too??
 
I think they only work on Alum control arms just a warning.

To top one is an excentric bushing so be careful with that.
I think Manny experimented with the IRS mounts and was succesful on one of his car. But when he tried to duplicate it did not work as he thought it would.....
 
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