01-12-2015, 01:33 PM
(This post was last modified: 01-12-2015, 01:38 PM by Rippthrough.)
Crap polyurethane is cheaper than good quality rubber....decent polyurethane isn't.
The reason OEM's don't use it for bonded bushes is the bond strength to the steel is lower than the rubber without an extra step of treatment so it ends up much more expensive, and they won't use them as aftermarket bushes are used (as bearings rather than bushes) because it means there's much more friction and wear in the suspension, so the ride/noise/handling all deteriorates compared to a flexing bush, which has almost no friction.
To make a rotating bush work you need all sorts of extra machining steps to ensure there's plenty of preload to keep full contact and increase the wear life, knurling to bring grease into the bearing area - otherwise the poly grabs the tube and you end up with massive wear and even in some cases, bent or broken arms (see mx5's and rx8's with cheap powerflex kits...), then you need a pair of lip seals either side to keep dirt and water out, and tapered ends with smooth stainless bearing surfaces on the chassis side to allow the flanges easy movement.
If your polybush is just a top hat shape and pushes in easily by hand, then it's probably 99% certain it's shit.
Basically you've just quadrupled the price of the bush in order to make it a bit stiffer. When an OEM can do that for the same price as before just by making the rubber one wider.
The reason OEM's don't use it for bonded bushes is the bond strength to the steel is lower than the rubber without an extra step of treatment so it ends up much more expensive, and they won't use them as aftermarket bushes are used (as bearings rather than bushes) because it means there's much more friction and wear in the suspension, so the ride/noise/handling all deteriorates compared to a flexing bush, which has almost no friction.
To make a rotating bush work you need all sorts of extra machining steps to ensure there's plenty of preload to keep full contact and increase the wear life, knurling to bring grease into the bearing area - otherwise the poly grabs the tube and you end up with massive wear and even in some cases, bent or broken arms (see mx5's and rx8's with cheap powerflex kits...), then you need a pair of lip seals either side to keep dirt and water out, and tapered ends with smooth stainless bearing surfaces on the chassis side to allow the flanges easy movement.
If your polybush is just a top hat shape and pushes in easily by hand, then it's probably 99% certain it's shit.
Basically you've just quadrupled the price of the bush in order to make it a bit stiffer. When an OEM can do that for the same price as before just by making the rubber one wider.
Custom roll cages/shiny suspension bits/general fabrication work undertaken, PM me.
Top engine mount repair/reinforcement/chocking for cracked chassis and high powered cars, drive in, drive out, 2 hour turnaround.
Top engine mount repair/reinforcement/chocking for cracked chassis and high powered cars, drive in, drive out, 2 hour turnaround.