As always, its a compromise between comfort and accuracy. No rubber bushing, would mean very accurate steering, but transmit every single bump through the chassis rail and steering wheel.
Some shock absorption will be needed.
I dissagree, there is no shock absorption via the pitman arm and steering box on the drivers side.
Rubber is only used as its cheap and easy. 
Not convinced, given the "flap" action on the idler, over bumps with the weight of the steering arm and the pas side road wheel gyroscopic inertia.
I'm thinking dead ahead/stearing stright, the slightest play and it will knock through the steering.
In corners I'd expect any play to be taken up. But dead ahead where there's no pressure on it the forces are purely vertical/up and down. Needle rollers aren't good in applications such as suspension and steering where the vast majority of the time is spent at or near normal ride height or, as in this case, steering dead ahead. As all the wear is consentated in one place on the bearing surface. Bit like top mount bearings. I've seen them pitted, as on bikes with rising rate rear suspension linkages. After 5000 miles, grab the rear tail unit and lift. There's guaranteed to be at least 5 mill of play. That's fine on a bike where most of the time the suspension is loaded. Unless your over the mountain at cadwell, then it knocks on landing.
But on a car where it's unloaded a good deal of the time, IMO, any play will resonate to the driver.
I'm thinking along the lines of a table tennis bat type material. If the right thickness and consistency can be found. Cut to length, roll into a tube, press the brass insert in....
Note to self, stop thinking aloud
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Topic: Poly sleave for steering idler. (Read 6175 times)