Bushes - poly or rubber

Hi i think its about time i changed my bushes, so what is best the poly bushes or uprated rubber. Any feedback would be great. Also what bushes can be changed, is it possible to do all as i think its only the front that can be sourced for the poly type

The harder the bush the better the suspension control, but the worse the ride gets on UK roads.

 

Personally I think getting poly bushes is a good idea.

I think Powerflex were developing a MKIV poly bush solution, don't know if it ever went to market though.

 

One of the tuners should be able to source the right parts...

In poly i can get

Front lower wishbone inner front

Front lower wishbone inner rear and

front anti roll bar

 

Seems strange nothing for the rear.

Wasn't there a discussion about this a while ago. I think the conclusion was it had to be done as a whole system and very carefully thought out. There are lots of links in a suspension system and if you stiffen one part it puts more strain on other parts - which could be bad.

 

I'm not saying don't do it, just make sure that it is being done properly.

How many parts are in the whiteline kit?

Why does this always happen. I think im getting somewhere then somebody with more knowledge comes in and confuses me like mad. So now another question which bushes should be changed to complete a whole job. I would have thought that the bushes would have come in a complete kit but now i dont think so and slowly my brain starts to melt

Problems occur because some of the suspension members don't just pivot around their bush in a smooth arc, they are twisted and stuff as well. Rubber is compliant in this loading so its not a problem, but the poly ones can't deform very much at all to allow this motion to take place. The result is that parts can bind up and massive loads build up where they're not supposed to. That is my (very limited) understanding of it anyway.

I had poly on my cosworth and I wouldn't do it again, they squeak like crazy, and you do notice it, and the gains aren't that great over new rubber ones. Plus rubber is easier to fit!

Well thats it then ill go for the trd uprated rubber from TDI. Cheers to all who replied.

Ouch TDI said a full set of bushes will cost over £1000, so how do you tell if a bush is worn, is it just visual and which are the ones that usually go.

Copyright Chris Wilson

 

The problem is braking loads, these try and twist the wishbones off the car in a rotating manner, when viewed from the side of the car. As stock these loads are shared by top and bottom wishbone, both having compliance in their bushes.

 

With solid or near solid bushes in JUST the bottom wishbone inner pivots the bottom wishbone is called upon to do a lot more work, as well as you correctly say having unattenuated shocks put into it. If the top wishbone was also converted to similarly less compliant, or incompliant bushes the sharing of loads would be similar to stock.

 

Now a stock lower wishbone is a very substantial bit of kit,

and PROBABLY well up to this, as may be the stock wishbone mounting points, but would you want to risk it, or would you rather engineeer out any potential weakness by getting the load paths shared in a similar balance to stock?

I understand the words but dont know if you are saying stock ones are good or change both upper and lower at the same time. I have never dealt with bushes before so all this is completely new to me

Originally posted by mos

I understand the words but dont know if you are saying stock ones are good or change both upper and lower at the same time. I have never dealt with bushes before so all this is completely new to me

 

CW words not mine.

 

I read that you should change top and bottom set to balance the loads.

Putting in hard nylon or whatever bushes is not a job to be undertaken lightly, it's fraught with potential problems and DO NOT assume that because a "kit" is available it is well thought out, engineered or even tested. I have seen utterley horrendous kits that bend floorpans, bind up, snap suspension links, blah blah. Safest is properly engineered spherical joints, got a proper kit from FEED in Japan when i had the RX-7, they just pressed into the stock links after the rubber lined bushes were driven out. Never seen anything similar for the Supra, and a one off fabricated kit would be HUGELY expensive. I'd go for TRD uprated "rubber" bushes. I have fitted their kits to MR2's and they were very nice, acurately sized and with a sensible lowering of compliance, but a retention of compliance in all arcs still.