polybushes versus rubber
Discussion
Hi All,
With winter coming along it is time for the lady Chim to think about her winter holiday in a snug garage and whilst wintering alone to have some undercarriage work done.
Been thinking of upgrading to polyurathane bushes. I read that they improve handling but the ride gets worse. I use country lanes regularly [pot holes and rough roads] so not wishing to loose the fairly compliant suspension in favour of harder suspension, would/will/could anyone give me an opinion on the benefits of replacing the existing rubber bushes with poly or renewing with rubber ones.
With winter coming along it is time for the lady Chim to think about her winter holiday in a snug garage and whilst wintering alone to have some undercarriage work done.
Been thinking of upgrading to polyurathane bushes. I read that they improve handling but the ride gets worse. I use country lanes regularly [pot holes and rough roads] so not wishing to loose the fairly compliant suspension in favour of harder suspension, would/will/could anyone give me an opinion on the benefits of replacing the existing rubber bushes with poly or renewing with rubber ones.
Suspension bushes are fitted to cars at all points where the vehicle chassis is joined to a moving suspension component.
They are a noise and vibration absorbing barrier between the road and you.
Rubber acts as that sound barrier, damping out noise and vibration.
Fitting a solid metal bush for example would make your car feel much harsher and noisier.
Bronze bushes are widely used on single seat race cars but a huge number of racing cars still use rubber bushes.
These are either production based cars adapted for race use or rally cars where the forces on the suspension can be so high that metal joints would break.
The amount of rubber in your TVR bushes is minimal compared to a family hatch back, they are already quite a harsh bush in my opinion.
Heat, oil contamination and long periods of inactivity are a rubber bush's greatest enemy's.
Polyurethane is more resistant to oil contamination and long periods of inactivity, but heat will kill them just as quickly (if not quicker) than the standard rubber bushes.
Because the TVR bushes have very little rubber I doubt you would notice much difference in ride, handling, noise, harshness or vibration if you replaced the rubber bushes with poly ones.
Whatever bush material you choose, if you are replacing a worn bush for a new one you are likely to feel a benefit.
The TVR bushes seem to have a very short life, the rubber ones are a press fit so removing & replacing them is real a pain.
Removing and fitting replacement poly bushes is much easier, so if you are keeping the car its a worthwhile mod.
Poly or rubber the best advice would be to keep the exhaust heat off them as best you can.
I believe the Powerflex bushes come with some form of heat protection material for the most vulnerable front upper wishbone bushes.
I am guessing they started to put this in the kit after failures due to heat damage.
Its worth remembering the rubber ones would be nearly as bad without some form of heat protection.
In the end the heat issue is not to be blamed on the bushes themselves but is the fault of TVR & how they routed the exhaust system.
I think its Powerflex bushes for me next time, they now come with a lifetime warranty.
Steve Heath seems to be the best source, his kits take a convenient modular approach.
Full Kit Front & Rear - Just The Front - Just The Rear, ect ect.
He offers bolt kits too which seem well worth considering.
If you fit them yourself remember ideally you will still need the help of a professional to correctly adjust the steering & suspension geometry.
Then of cause if you are doing the fronts it makes sense to replace the upper & lower ball joints at the same time as everything will be apart.
Given this, and the fact I have rubber bushes at the moment I think I will pass the job to someone who has some decent laser wheel alignment kit.
I used Wheels in Motion in Chesham for a full geo in the summer they did a top job, it definitely made a difference.
A bit too expensive though.
They are a noise and vibration absorbing barrier between the road and you.
Rubber acts as that sound barrier, damping out noise and vibration.
Fitting a solid metal bush for example would make your car feel much harsher and noisier.
Bronze bushes are widely used on single seat race cars but a huge number of racing cars still use rubber bushes.
These are either production based cars adapted for race use or rally cars where the forces on the suspension can be so high that metal joints would break.
The amount of rubber in your TVR bushes is minimal compared to a family hatch back, they are already quite a harsh bush in my opinion.
Heat, oil contamination and long periods of inactivity are a rubber bush's greatest enemy's.
Polyurethane is more resistant to oil contamination and long periods of inactivity, but heat will kill them just as quickly (if not quicker) than the standard rubber bushes.
Because the TVR bushes have very little rubber I doubt you would notice much difference in ride, handling, noise, harshness or vibration if you replaced the rubber bushes with poly ones.
Whatever bush material you choose, if you are replacing a worn bush for a new one you are likely to feel a benefit.
The TVR bushes seem to have a very short life, the rubber ones are a press fit so removing & replacing them is real a pain.
Removing and fitting replacement poly bushes is much easier, so if you are keeping the car its a worthwhile mod.
Poly or rubber the best advice would be to keep the exhaust heat off them as best you can.
I believe the Powerflex bushes come with some form of heat protection material for the most vulnerable front upper wishbone bushes.
I am guessing they started to put this in the kit after failures due to heat damage.
Its worth remembering the rubber ones would be nearly as bad without some form of heat protection.
In the end the heat issue is not to be blamed on the bushes themselves but is the fault of TVR & how they routed the exhaust system.
I think its Powerflex bushes for me next time, they now come with a lifetime warranty.
Steve Heath seems to be the best source, his kits take a convenient modular approach.
Full Kit Front & Rear - Just The Front - Just The Rear, ect ect.
He offers bolt kits too which seem well worth considering.
If you fit them yourself remember ideally you will still need the help of a professional to correctly adjust the steering & suspension geometry.
Then of cause if you are doing the fronts it makes sense to replace the upper & lower ball joints at the same time as everything will be apart.
Given this, and the fact I have rubber bushes at the moment I think I will pass the job to someone who has some decent laser wheel alignment kit.
I used Wheels in Motion in Chesham for a full geo in the summer they did a top job, it definitely made a difference.
A bit too expensive though.
Edited by Chimpaholic on Thursday 21st October 17:09
? 
Just for info I ordered poly bushes for the front of my S.
One of the bushes sent was incorrect - all were a purple colour except one which was black - and was made of a much softer compound.
I didn't pursue things any further I just grumbled at the supplier and they sent the the right one - but this suggests to me that they may well be available in a softer compoound to more closely meet the requirements of all those rubber lovers out there
One of the bushes sent was incorrect - all were a purple colour except one which was black - and was made of a much softer compound.
I didn't pursue things any further I just grumbled at the supplier and they sent the the right one - but this suggests to me that they may well be available in a softer compoound to more closely meet the requirements of all those rubber lovers out there
Barkychoc said:
Just for info I ordered poly bushes for the front of my S.
One of the bushes sent was incorrect - all were a purple colour except one which was black - and was made of a much softer compound.
I didn't pursue things any further I just grumbled at the supplier and they sent the the right one - but this suggests to me that they may well be available in a softer compoound to more closely meet the requirements of all those rubber lovers out there
Didn't you know there is always one black sheep in the family One of the bushes sent was incorrect - all were a purple colour except one which was black - and was made of a much softer compound.
I didn't pursue things any further I just grumbled at the supplier and they sent the the right one - but this suggests to me that they may well be available in a softer compoound to more closely meet the requirements of all those rubber lovers out there
I too am rebuilding a Chimera 4.5 litre and have got to the front suspension.... I intend to use poly bushes on the anti-roll bar bushes plus rose jointed drop links at each end. My thinking is the anti-roll bar and links need to be as ridged as possible. As this is a road car, some compliance, vibration / harshness elimination does need to be factored in, therefore I will utilise new rubber bushes with an improvised kevlar heat shield to protect the top rear ones.
In racing cars, it is common practice to use rose joints for the wishbone / chassis connection. Interestingly. Ferrari F1 cars found that even they were not ridged enough and designed a joint made of a solid thin strip of sprung steel to act as a hinge on their wishbones.
In racing cars, it is common practice to use rose joints for the wishbone / chassis connection. Interestingly. Ferrari F1 cars found that even they were not ridged enough and designed a joint made of a solid thin strip of sprung steel to act as a hinge on their wishbones.
Superflex are generally 2 Top Hats and a centre bearing, the Powerflex seem to be a lego set of bits that fit together (mainly the thrust part is separate) AFIK. Always looks to me like you get more bearing material with the superflex, I guess there will be quality differences in the materials, the 95shore superflex have been fine for me and hearing other tales of woe re heat'n'wear + powerlex giving away free heatshields makes me think I'd stick with superflex rather than take a chance if pressed.
spend said:
Superflex are generally 2 Top Hats and a centre bearing, the Powerflex seem to be a lego set of bits that fit together (mainly the thrust part is separate) AFIK. Always looks to me like you get more bearing material with the superflex, I guess there will be quality differences in the materials, the 95shore superflex have been fine for me and hearing other tales of woe re heat'n'wear + powerlex giving away free heatshields makes me think I'd stick with superflex rather than take a chance if pressed.
Cheers for that Davespend said:
Superflex are generally 2 Top Hats and a centre bearing, the Powerflex seem to be a lego set of bits that fit together (mainly the thrust part is separate) AFIK. Always looks to me like you get more bearing material with the superflex, I guess there will be quality differences in the materials, the 95shore superflex have been fine for me and hearing other tales of woe re heat'n'wear + powerlex giving away free heatshields makes me think I'd stick with superflex rather than take a chance if pressed.
That's a useful description of the differences; how many miles have you got on the Superflex ones?I have a Powerflex kit in front of me here... It's a SS tube for the bolt and then two white metal bearings to run on it.. these locate in two outer bobbins but not full length so they give a seal on the ends... And there are 2 thrust washers.
So you get a propper bearing on the the pivot (not a plastic one).. but the thrust washers are made of some plastic material as the originals. I think if you get the Superflex you get top hat bearings so is this a compranise?.. may be good for the thrust but not so good for the axial bearing?
I do like the Powerflex idea for sure but was a bit concirned about other comments and slight alignment issues causing point loading... but think my fears are addressed here to some extent:-
http://www.pistonheads.com/gassing/topic.asp?h=0&a... Powerflex or not?.. that is the question
So you get a propper bearing on the the pivot (not a plastic one).. but the thrust washers are made of some plastic material as the originals. I think if you get the Superflex you get top hat bearings so is this a compranise?.. may be good for the thrust but not so good for the axial bearing?
I do like the Powerflex idea for sure but was a bit concirned about other comments and slight alignment issues causing point loading... but think my fears are addressed here to some extent:-
http://www.pistonheads.com/gassing/topic.asp?h=0&a... Powerflex or not?.. that is the question
Edited by TVR Beaver on Friday 22 October 08:36
Pupp said:
how many miles have you got on the Superflex ones?
Only about 15k, but I can't see the mileage having much effect TBH as long as the material is stable? I have no signs of heat problems and the areas around the thrust area (top hat brim) which I suspected might be stressed under rotation are fine as well. I have removed the top fronts for close inspection BTW and TBH was quite surprised at the condition, quick wash & they looked like new (but they are still quite tricky to pull out without damage - not planning on doing that again!)From my POV the superflex have done everything I want and seem to be standing up well to heat & flexing, personally I wouldn't risk changing to a different design / material supplier with all the posts about various problems (Andy Race has been pretty adamant about them for one). Then again if I had to change again I think I'd try rose joints anyway?
Quinny said:
TVR Beaver said:
.. It's a SS tube for the bolt and then two white metal bearings to run on it..
Just for you Mr Beaver
. Those 2 bearings are called "Glacier" bearingsMy kit had half a dozen missing, and power flex couldn't supply as they'd had a factory fire.... I got some from a local bearing factor, at about 50p each
But obviosly they are buying further afield these days?... Still.. worth knowing you can get replacements for 50P!.. much better than a full new Rubber unit and all it's associated removal / fitting issues.....
spend said:
Pupp said:
how many miles have you got on the Superflex ones?
From my POV the superflex have done everything I want and seem to be standing up well to heat & flexing, personally I wouldn't risk changing to a different design / material supplier with all the posts about various problems (Andy Race has been pretty adamant about them for one). I did a quick polybush problem search and the majority of the posts have been "how do I fit this" and "heat has damaged the bush" which to be fair applies to any bush in that location, including rubber ones, so I'm not so sure that the alleged widespread problems actually reflect reality. This ties in with my own experience over that last couple of years where the main question is usually about fitting or someone has a TVR varient!
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