beef-on-the-bone

iTrader: (5)

furthering on from the strut brace debate
thinking that the majority of bushes under my sti2 will be pretty tired by now,so do i replace them with oem 1s or go with the poly??
i know that the handling should improve whatever i do but the rubber will just degrade again eventually and how much is the ride quality affected by fitting poly???

cheers

Trout

iTrader: (1)

I thought that my car was more supple after fitting poly bushes as the suspension was working better as there was less compromise.

It certainly was not harsh.

The rookie

iTrader: (1)

On a newish car, probably not, on an older car, where the bushes are tired, they can make a huge improvemnet, likewise for replacing the bushes we may think are too soft but were made that way for NVH reasons (steering rack and rear trans mount fo example)....

Simon

911

IMHO:
Great for a hard driven Impreza, no real change in harshness.

At the same time replace the rear diff bushes for poly too. Well worth the effort.
Simple but hard work.

harvey

iTrader: (48)

There are two grades of poly bush fromSuperflex, one being harder than the other. The noise transfer qualities vary too. NVH?
My advice would be, don't fit them unless the existing bushes are definately goosed.
Also consider STi bushes from Roger Clark Motorsport. You may find a cost saving. Surprising but true.

Depending on the bushes fitted and how worn the existing are, it will tighten your suspension/steering. Changing the steering rack bushes on my 95 WRX Wagon made a noticable difference to the feel which was much more precise.
Changing the front bushes should not lead to any issues.

When I did the complete rear suspension including trailing arms to body I found I had a very noisey diff and it was like listening to a grinder rumbling away. I looked at the brakes and bearings to no avail and after some time put O/E Subaru back on the front of the trailing arms. Miraculously and if I had not done it my self the diff noises disappeared. (This was with STi) What an easy way to fix a diff!!!
I then put on the softer of the two Polyflex and found the noise of the transmission was back but not as bad.
This is worth bearing in mind if you are playing about with bushes.

Exactly the same happened on the STi 3 Wagon last week when I did the front trailing arms and others and I can only conclude many of us are running around on noisey rear diffs but the O/E bushes insulate the noise from the cabin but the after market bushes transmit it badly giving the imprezzion that there is a serious diff issue which there may well not be.

Solution : turn the radio up loud or stick with the O/E on the front of the trailing arms.

pslewis

Just a question .... why do the manufacturers not fit Poly Bushes?

911

You know why Pete!

They (poly bushes) do eventually need maintenance, a good re-grease that's all to keep the friction from building up over time, and in my experience of 3 years it has become an annual ritual on 'pivotal' points only.

This is not an issue for me as the car is a road/racer and the benefits are good, but oem rubber is great if in good nick.

My Sti bushes I cut out were all perfect but only 26K miles old.

Probably the most beneficial for several reasons were the diff frame bushes (4 off) and the transverse lower arms, (8 off) which stopped rear wheel steering (the whole subframe is tighter in the chassis and no diff 'wind-up' on very hard starts.

On a stock engined car, all will have an effect and on a good 350+/350 lbft car, it definitly helps.

Having said all that, one of the quickest hill climb Imprezas currently has stock Sti RA bushes!

Maybe it's just me after all

Graham.

Shark Man

Its the old compliance vs rigidity thing again. A little compliance here and there can be a good thing, in other areas it isn't.

Experimentation and experience will dictate on what will or will not be a benefit of running poly over new rubber bushes. Certainly the front lower arm bushes are a key component where you need a good bushes, rubber or poly.

Tidgy

because they are slightly more expensive and the cheap bastid manufacturers dont want to shell out for them.

funny how they do on there rally cars though

pslewis

I think it is more to do with the fact that road going cars suffer with them.

911

Pete has a valid point.

Subaru need a safe car in all condirions over a long period of time through all conditions, rain/shin/snow etc.

Poly bushes are not fit and forget.
Rubber ones are till very late in life of the chassis or depending on the terrain the car is sold into.

Having been to China a few times you would NOT put a polybushed car on the 'road' as the chassis will fatigue fail very quickly due to the holes (that have to be seen...) You need all the give you can get.

Rally a car in China? Yes, and with bushes as maintenance is not an issue.

Production cars have rubber because it is the best solution for all purposes/conditions to the general public.

But some of us are different, so poly bushes are ok for what we do.

Simon 69

They do Pedro. All of the force absorbed by a soft bushing has to go somewhere and hard nylon bushes or spherical bearings pass this on to the monocoque. This leads to a massive increase in NVH. Stiffen up too much and your bodyshell will eventually start to flex like a big wobbly spring.


Simon