by droopsnoot » Mon Dec 10, 2018 11:18 am
The other thing to keep in mind with poly bushes vs. rubber ones is that, in some locations, they work differently. In a standard rubber bush - for example the front lower wishbone bush - the rubber is bonded to the inner steel sleeve. The suspension bolt is tightened onto that sleeve with the weight of the car on the wheels, and the only rotation of the arm is the "give" of the rubber, as nothing else moves. With a poly bush (or with all the ones I've seen, at least) the inner sleeve is not bonded, so you have a lot more movement of the arm allowed by a poly bush.
I've got poly bushes in the rear of my Firenza, and maybe in the castor arms (where nothing else is available), but when I put the hatch together I just went with standard rubber ones where I could get them. I would say that the ride on the Sportshatch is much "softer" and certainly more comfortable, but there are lots of differences other than the bushes - standard dampers vs. Spax on the HPF, standard Magnum springs, recent (<2 years) rebuild vs. 20+ years ago.