It's occured to me that I don't really understand them.
MK2 Golf TCAs / wishbones look like this:
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Not my photobucket, so not may trainers, duvet or purple bush.
Now, I can understand the ones at the front. They're just pivots, and could me made of near enough anything AFAICS.
The ones at the rear however, aren't. They've got to act like a ball joint or spherical bearing to work properly, surely? If they don't, they're going to limit the suspension travel, which isn't their job. Do OE rubbers have some sort of ball joint in them? I really can't see how the rear bushes can work properly. OTOH the only polyurethane things I've seen have been rollerblade wheels, which aren't really very rubbery at all.