What are the advantages/disadvantages of polyurethene bushing ends on both ends vs QA1 spherical ends on both ends vs polyurethane on one ends and QA1 ends on the other? Are there any noise or binding issues? What would be best for a street car with occasional track use?

 

The stiff poly ends cause the rear suspension to "bind" as the body starts to roll, and the front and rear LCA bolts are no longer parallel to each other. It affects handling under cornering. The stock, soft rubber bushings have "hollows" at the top and bottom to minimize the problem.

Rod ends can be noisy and cheap ones can wear out quickly. But they eliminate the bind by allowing the bolt centerlines to rotate out of a parallel orientation. The options are poly on the axle end-rubber on the other (no noise), rod end on the axle end poly on the other (minimal noise), or rod ends on both ends (possibly a lot of noise). I have the Spohn adjustable LCA's with spherical rod ends on both ends, and don't really notice a noise issue, but its not a daily driver and everything else in the car makes enough noise to cover it up.

Someone now has what I believe is a spherical poly bushing.

 

https://www.camaroz28.com/articles/jmbushing/

 

Thanks, that's what I wanted to see.

 

I have them on my car. They are quiet and have no perceptible bind issues. Seems to be the solution for poly. bushing woes.

 

That is good to hear. I will be ordering a set for my car in a week or two.

 

So these new sherical poly ends from J&M function basically the same as the QA1 ends, just without the added noise. If extra noise is the only difference, I think i can deal with it.