4 replies to this topic

[Joe555]

I am about to replace my bushes on the bottom arms. I am fitting the rubber ones with steel inserts, should I use copper grease on the metal parts and rubber grease on the rubber bit, or no grease at all?

Joe

[jaydee]

I've always greased the lower arm pin only, and no grease on the bushes.

[tiger99]

Correct. Rubber bushes work by deflecting in torsional shear, not by rotating on the pin, or in the arm, so lubricant on the rubber is not helpful. It may even cause severe wear if the rubber manages to rotate in the arm because of the lubrication.

The metal inserts should not rotate on the pin because when the pin is correctly torqued up they should be tightly clamped.

Because the deflection of the rubber is limited, the car should be bounced a few times, and be settled at normal ride height (whatever you have that set at) before tightening the pin. That allows the metal inserts to rotate, to relieve the rubber of load.

Now, someone please tell me, if you can, how a poly bush, incapable of significant deflection in torsional shear, or in compression, is actually going to work n the same place, iwhere there is some angular movement as well as rotation. I know it is nothing to do with the original question, but I do wonder.

[longbridge4life]

That's a good job done, I went with the rubber option :)

[tiger99]

Yes, rubber is the safe option. We know that they work reliably for reasonable mileages, sometimes more than 100k, but I would be happy with 30k of hard road use, since they are cheap and fairly easy to change.