Body mount donuts and shims

[Keith L.]

I know about the masking tape on top of the donuts/ shims but was there anything between the donut and shim stack. Or is what I see on mine a reaction between the steel shim and the aluminum donut?
And why do two of the driver side donuts have a shoulder that goes into the hole? The otheres are flat.

[Doug J.]

Re: Body mount donuts and shims

Nothing goes between the aluminum donut and the shim, mine looked exactly the same as yours when I took them apart, it's a reaction between the two different metals. As far as the collar on the drivers side donuts, I don't know, I'm sure someone will come up with a reason.

[Robert M.]

Re: Body mount donuts and shims

Regarding the the Shouldered spacers for body mount 1&4 on the Driver side, I suspect it is to locate the chassis to the frame, and the passenger side is left flat to allow for flex or torsion?

Hopefully one of the resident Mechanical Engineers on the board will provide a reasonable explanation to confirm my thoughts, or to confirm I know nothing at all !