Modern Rubber Bushes and Poly Bushes

[BuyPirelli]

I thought long were the days of rubber bushes being considered as consumables; however my recent expedition while finding a new car shows that many manufactures still suffer from prematurely worn rubber bushes on various suspension components.

 

Is this simply bad design, poor craftsmanship or both? My Focus ST for example needed new wishbone bushes before 30,000 miles, and VXR8’s can go through a pair of wishbones in 3,000 miles.

 

Even worse is when the manufactures don’t sell the bushes individually, but the entire arm – I’m surprised consumers tolerate this longevity and cost.

 

That brings me onto Poly bushes – are these of genuine benefit, a bit of a fad, or more hassle than they are worth?

 

I’m of mixed opinion really. I’ve had rear poly subframe bushes which were fantastic, and two of the four front wishbone bushes on my Focus ST are poly and I think they are great.

 

I also like the idea that they keep the geometry in check when under load – how can a rubber bush do this when its 5 years old and compressed to half of its original size?

 

However I’ve also had the bad end of the deal which came in the form of anti-roll bar bushes, you couldn’t grease them quick enough and they just endlessly squeaked. In the end they were replaced with rubber items.

 

Tony, what’s your opinion on the above? Would you always choose to replace troublesome bushes with poly bushes or would you always ere on the side of caution, grit your teeth and replace the same 2 year old item like for like?

[Tony]

I think OEM bushings have steered more toward comfort and compliance rather than longevity. Uprated bushings are the way to go but as you say there is an element of maintenance to consider. Bushings that resist longitudinal forces have very low ( if any ) maintenance whereas vertical resistance has a high maintenance, like as you say ARB bushings. In the vertical plane i would suggest heavy duty bushings rather than near solid Poly's.

[BuyPirelli]

Good advice on the latter point.

 

Curious, do poly bushes affect a cars durability in terms of geometry, or do they make it more susceptible to being 'knocked out'?

[liner33]

Some poly bushes wear very quickly , for example Whiteline arb bushes have a bit of a rep for accelerated wear ,

[Tony]

Polly's make the geometry positions more "matter of fact" because most adjusters are in the bushings, so less movement means more accuracy. On the down side the chassis has to absorb more road shocks, so yes there is a negative effect.