Discussion
OK so now I am confused, not hard I know when it comes to mechanicals. I always thought that when replacing your wishbone bushes, poly was the way to go. I was speaking to a mechanic yesterday and he said no as they wear out much quicker than the rubber ones. So I thought I would ask you knowledgeable lot and see what your opinions are.
The first thing is what experience does the mechanic have of poly bushes and TVRs? Was he simply repeating some word of mouth experiences? If he found they were wearing out, did he investigate any further to see if there was a specific problem? Were they fitted correctly? Were they fitted dry?
The second thing is there are several suppliers and types of poly bushes and they are not all the same. If a poly bush is too soft, it will wear very quickly. If it is not protected from damage, it can wear quickly. It simply isn't a case of making the same bush using poly instead of rubber.
For example, Powerflex supply special versions with heat shields that protect the top bushes from the exhaust and special metal top hats to protect the bushes from poorly finished wishbones where the welding causes bumps that can eat into the thrust washer. Other suppliers don't and that causes problems where the bushes are damaged and need replacing early. Many will say that is wearing out rather than a design fault and hence the comments about them wearing out more.
Equally rubber bushes are not the be all and end all. They can also wear out very quickly and disintegrate.
I have poly bushes on my Wedge that are now coming up to 11 years old. Some of the rubber bushes have been replaced twice in the same period.
The second thing is there are several suppliers and types of poly bushes and they are not all the same. If a poly bush is too soft, it will wear very quickly. If it is not protected from damage, it can wear quickly. It simply isn't a case of making the same bush using poly instead of rubber.
For example, Powerflex supply special versions with heat shields that protect the top bushes from the exhaust and special metal top hats to protect the bushes from poorly finished wishbones where the welding causes bumps that can eat into the thrust washer. Other suppliers don't and that causes problems where the bushes are damaged and need replacing early. Many will say that is wearing out rather than a design fault and hence the comments about them wearing out more.
Equally rubber bushes are not the be all and end all. They can also wear out very quickly and disintegrate.
I have poly bushes on my Wedge that are now coming up to 11 years old. Some of the rubber bushes have been replaced twice in the same period.
shpub said:
The first thing is what experience does the mechanic have of poly bushes and TVRs? Was he simply repeating some word of mouth experiences? If he found they were wearing out, did he investigate any further to see if there was a specific problem? Were they fitted correctly? Were they fitted dry?
Hi Steve, he is a TVR mechanic for a well known race team. He said the metal sleeve inside the bush wears them, as there is no give like in the rubber ones. What he said sound plausable from my very limited mechanical knowledge.Graham
I can't comment on wear, however I can vouch for the fact that they do change the ride characteristics quite a bit. You will find the ride a lot tighter with more vibration over poor quality roads but at motorway speeds and round corners the car feels more planted and quicker to repsond.
I was quite put off going poly bushes recently.
Noisy was removing his diff and I was quite struck how much movement the polybushes seemed to give compared with the originals.
I could actually move them quite easily with my finger.
Whether they wear out fast, or whether not all poly bushes are created equal I don't know.
Noisy was removing his diff and I was quite struck how much movement the polybushes seemed to give compared with the originals.
I could actually move them quite easily with my finger.
Whether they wear out fast, or whether not all poly bushes are created equal I don't know.
grahamn said:
shpub said:
The first thing is what experience does the mechanic have of poly bushes and TVRs? Was he simply repeating some word of mouth experiences? If he found they were wearing out, did he investigate any further to see if there was a specific problem? Were they fitted correctly? Were they fitted dry?
Hi Steve, he is a TVR mechanic for a well known race team. He said the metal sleeve inside the bush wears them, as there is no give like in the rubber ones. What he said sound plausable from my very limited mechanical knowledge.Graham
The problem is that many of these statements are without the context to really explain exactly what is going on.
It's like me saying that as I snapped an internal shaft in a LT77 gearbox that any TVR with that box is a real liability. Does this mean that all early Griff and Wedge owners should start worrying and losing sleep? No not really because what I forgot to add was the fact that I was pumping 500+ bhp through it with with slicks during a sprint. The fact that I had used the LT77 for 3-400 bhp for YEARS was omitted. Add the context and the original "black and white" statement turns very grey.
Now, if the guy you refer to had said "on the Griff/Wedge we race with 400 bhp running slicks, we found that poly bushes type X only lasted 4 races and that rubber bushes lasted 6 — but at the expense of slightly poorer handling, because of the give in the bush. Mind you, the ball joints need replacing more often and we have to xray the stub axles every season", I suspect you would be less concerned.
Edited by shpub on Friday 15th May 10:29
markh1 said:
I can't comment on wear, however I can vouch for the fact that they do change the ride characteristics quite a bit. You will find the ride a lot tighter with more vibration over poor quality roads but at motorway speeds and round corners the car feels more planted and quicker to repsond.
I thought the same when I had mine done, but to do a fair comparison you'd have to swap them all out for brand new rubber ones and drive it again. I doubt you'd notice much difference.FarmyardPants said:
markh1 said:
I can't comment on wear, however I can vouch for the fact that they do change the ride characteristics quite a bit. You will find the ride a lot tighter with more vibration over poor quality roads but at motorway speeds and round corners the car feels more planted and quicker to repsond.
I thought the same when I had mine done, but to do a fair comparison you'd have to swap them all out for brand new rubber ones and drive it again. I doubt you'd notice much difference.Gassing Station | Cerbera | Top of Page | What's New | My Stuff