E32 hydraulic bushings

["Chao, Harvey" <harvey.chao@xxxxxxxx>]

>"The E32 hydraulic bushings fit the E34 without modifications.  They have 
>to be milled to fit the E28 though...

>Andy Peavy"

I had the thrust arm bushings replaced just the other week at A&E
Performance in Campbell CA., and they said that they installed the 750
bushings in my E28.  Which from what I have learned here on the Digest is
the recommended replacement part.  Can someone explain how these are
"hydraulic" ?  I thought that any of the bushings used, stock, 750, or other
(polyurethane, delrin?) were basically a cylindrical hunk of material with a
steel bushing through the center to accommodate the bolt that anchors the
bushing and arm in place????

Thanks
Harvey

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