4 replies to this topic

[Nic]

one i have managed to remove my bottom arms and tie rods, and also on the engine mount at the top, shall i fit poly bushes or the standard rubber ones i have herd both good and bad things about the poly ones, why do people fit em?? ive heard that they are stiffer but tend to brake up easier as they have less give in them over the rubber ones. what are the benifits of them??

anyone have any advice or experiance of them??

[biggav]

poly ones will last longer but have less give just changed all my bits to poly and solid sub mounts so its difficlut to tell whether its the bushes or the sub mounts causing the change in characteristics... to be honest i'd get a set and see how you get on with them...

Minwah broke a tie rod and blames nylon bushes for it... i think he now fits poly on the outside and rubber on the inside... or vice versa.

[Big_Adam]

poly ones will last longer

Thought they didn't last as long, well engine ones at least as their get smashed by the engine movment, rubber ones have more give.

[Dan]

Polyurethane is a plastic, so it is not elastic. That means that in use it rapidly becomes permanantly deformed in whatever shape it is squeezed to in fitting. In bottom arms and tie rods paticularly this means that very soon after fitting the bush is effectively doing nothing any more as it has become permanantly fixed in place. Also when used in bottom arms they transmit a lot more road noise into the chassis than rubber does. In some places on the car poly is ideal, in others it is not so good. I fitted poly all over my Mini several years ago now and have been assessing the bushes and mounts over time to see how they do (god that makes me sound like I'm doing experiments and stuff, I'm not!). I have now gone back to rubber (albeit a harder than standard compund) for the bottom arms, and for half of the tie rod bush as said above. I use poly in the engine steady bars and all shock absorber mounts, all the rear subframe mounts and half of the front subframe tower mounts (with solid in the other half). Front subframe toe board mounts and teardrops are standard.

Remember this: Poly is cheaper, easier and faster to produce than rubber. It doesn't degrade in storage as rubber does so has a limitless shelf life and is lighter so costs less to ship. Given all of the above car manufacturers still choose to make large amounts of bushes and isolators in rubber. How many car manufacturers do you know who spend money for the sake of it (these are people who deign nuts with washers formed into them to save the cost of a single washer)? The reason they still use rubber is because for some applications it is better. The right tool for the job.

That's my opinion, ultimately the choice is yours.

[cagrant]

i just put some poly bushes on my tie rod ends about a month ago. it had rubber ones on it bu they were detiorated. but i've had no problems since the poly bushes were put in.