[Chuck Moreland]

Hcoles, the splines on QuickChange spring plates are the same a stock. I'm not sure I understand your question?

I have heard of people using a rubber bushing in the torsion tube side, and a polybushing on the spring plate side. The theory being that they can drill a grease hole for the outboard poly bushing, but can't do so for the inboard bushing. Rubber doesn't need grease so the theory says use rubber inboard.

The problem with this approach is the spring plate cover carries most (all) the load. The poly bush is nearly incompressible and the rubber bush much softer. The mounting bosses welded to the body are further stressed and ultimately tear away.

Tearing of the mounting bosses is a problem even with normal, unmodified cars. Increasing the load carried by the cover plate, and mounting bosses, is a sure way to accelerate the problem.

With polybronze this is a non-issue, because polybronze has grease fittings that allow relubrication of both inner and outer bushings.

My recommendation is to use either polybronze or rubber on a given set of spring plates. I do not recommend the plastic bushings, either polyurethane, delrin, polygraphite etc.