As the subject suggests really. I want to replace both inner and outer bushes on both sides. The poly bushes are significantly cheaper. Are they ok or should I pay 3 times more for the original spec rubber items? I have access to a press and all the gear and have taken p6 suspension apart a few times so I'm not worried about doing the job but don't want to do it again if I'm not happy!
Front Top link bushes - thoughts on poly
- Thread starter badrover
- Start date
The inner bush on each top link does not pivot with suspension movement, rather it just flexes or squirms if you prefer.
I am not sure how suitable a poly bush would be in this regard :?
With regards to poly bushes, it is my understanding that when used in this location, both an increase in road noise and squeaking are common place. Using the grease that is supplied apparantly does not prevent the unwanted noise from starting. Personally, in this location, I would only use rubber bushes, provided of course that they have been made to the original specifications, and sold from a well regarded P6 supplier.
Ron.
I am not sure how suitable a poly bush would be in this regard :?
With regards to poly bushes, it is my understanding that when used in this location, both an increase in road noise and squeaking are common place. Using the grease that is supplied apparantly does not prevent the unwanted noise from starting. Personally, in this location, I would only use rubber bushes, provided of course that they have been made to the original specifications, and sold from a well regarded P6 supplier.
Ron.
Ron, many thanks for your reply. Maybe I will bite the bullet and order the rubber items. I plan to get then from wadhams so should be great quality. When you mention the inner bush not pivoting with suspension movement, I guess that this is the reason the new bush must be set at 90 degrees to the anti roll bar mounting? My reading suggests that a worn inner bush or one that is not set at 90 degrees with result in positive/negative camber. Do you think this is correct?
In a word...don't. 
Ride trade off/noise doesn't seem to go down too well with poly in these P6 things...I don't have poly in this area, but elsewhere i have, and whilst they improved things in "smartening up" the car, I can only compare them to the old rubber, and in all instances there was a cumulative deleterious effect on ride/noise
Ride trade off/noise doesn't seem to go down too well with poly in these P6 things...I don't have poly in this area, but elsewhere i have, and whilst they improved things in "smartening up" the car, I can only compare them to the old rubber, and in all instances there was a cumulative deleterious effect on ride/noise
badrover wrote,...
The 90 degree angle is set so as to both allow the car to sit in the correct static position, and to minimise the stress that is imposed on the inner bush.
A worn inner bush or one not set with the mounting bracket - anti roll bar attachement point at 90 degrees won't normally result with a change in camber. To make this change, shims are placed behind the top link in the appropriate location for that specific car.
Ron.
The 90 degree angle is set so as to both allow the car to sit in the correct static position, and to minimise the stress that is imposed on the inner bush.
A worn inner bush or one not set with the mounting bracket - anti roll bar attachement point at 90 degrees won't normally result with a change in camber. To make this change, shims are placed behind the top link in the appropriate location for that specific car.
Ron.
The guy from norfolk who's rear suspension collapsed and killed the occupants of the other car and left him needing brain surgery says something about polybushes. It caused stress fractures in the trailing arms. Whoever it is we should probably warn them this is the consequence. I really dont understand how people can sell them for this position on a p6. It is just a little issue, it's truly life threatening.
codekiddie
Active Member
I bought these trailing arm bushes in poly, from a reputable seller that we have probably all used at some point, but because I found out this information after buying them, I bought a set of rubber ones to fit instead. Luckily I had not fitted the poly ones.rockdemon said:
I'm not sure if I can ask the seller to take them back, since technically there is nothing actually wrong with them, or could they be deemed not 'Fit for purpose', in which case the Sale of goods act 1979 should come into force? But who decides if an item is not 'Fit for purpose'?
Knowing what I do now, I certainly would not be able to sleep at night if I sold them on to an unsuspecting P6 owner, and I see that only yesterday someone has joined the forum who has been an owner for over nine years, so it is quite possible that there are other owners out there who may have no idea about this issue.
Tor
Well-Known Member
I think it'd take material analysis to determine why a high-exposure/stress component has failed in a 40+ year old car fitted with new consumables that may or may not be significantly stiffer than OE. I would venture to say it's more likely the car that becomes unfit with age - no reference to the crashed car mentioned. I'm thinking of my own, fitted with poly bushes throughout the rear. Replacing the rear lower trailing arm bushes with rubber ones is something I might do as well.codekiddie said:
Kman1600
Member
Hi,
This issue comes up every time the poly bushes are discussed. There is no doubt that the consequences of this particular failure were truly horrendous but having said that one data point doesn’t not make a trend, there have after all been plenty of failures reported where poly bushes were not fitted. Poly bushes may have been a contributor to the failure, although I personally doubt if they were any more than a minor one, as a solid suspension elbow would be unlikely to fail in normal use, with or without poly bushes fitted.
My concern here is that there is a real possibility that the wrong lesson is being learnt from this incident. People should not go away thinking I don’t have poly bushes fitted therefore I’m fine, they should in fact be putting this area of their cars under extreme scrutiny, even more that an MOT’er would do.
Tim
This issue comes up every time the poly bushes are discussed. There is no doubt that the consequences of this particular failure were truly horrendous but having said that one data point doesn’t not make a trend, there have after all been plenty of failures reported where poly bushes were not fitted. Poly bushes may have been a contributor to the failure, although I personally doubt if they were any more than a minor one, as a solid suspension elbow would be unlikely to fail in normal use, with or without poly bushes fitted.
My concern here is that there is a real possibility that the wrong lesson is being learnt from this incident. People should not go away thinking I don’t have poly bushes fitted therefore I’m fine, they should in fact be putting this area of their cars under extreme scrutiny, even more that an MOT’er would do.
Tim
Dave3066
Well-Known Member
Kman1600 said:
Tim
I think you're spot-on there. We should endeavour to give people the facts as they are. When presented with the facts people can then make their own choices. From what I've seen there is no incontrovertible evidence that poly bushes cause or even contributed to this accident. Did the accident investigation include analysis of the structure and materials used on that car? If there is evidence then the relevant clubs should be informed so they can take a position and inform their members.
Otherwise we're just speculating and missing the real area of concern.
Dave
codekiddie
Active Member
I would agree with you there 100% Dave, and therein lies the problem.Dave3066 said:
As far as I am aware the one fact is, as you say, that there seems to be real no factual evidence as to whether or not the poly bushes caused the problem in this case.
My choice of deciding to stay with rubber was not only based on this incident, but because I would think that the original bushes would have undergone vigorous testing at the time of their design, but I can't see how the same amount of similar testing could have been done with the modern materials on our particular model of car, as they would not have had the luxury of lots of cars to test them on. Without similar tests taking place, how can we ever make an 'informed' decision.
The other side of the coin is, if a rear link bush fails, and is a rubber one, will it ever get the same bad publicity as with the poly bushes, or simply be put down to 'wear and tear'? Not forgetting as well, that the rubber bushes available are either NOS, (and I'm not sure whether I would trust 40 year old rubber on a suspension part), or re-manufactured to original specs, which doesn't necessarily mean they are better. As Tim says, far better to keep a close eye on such an important part of the vehicle, no matter what is fitted.
If the original bushes were to fail back when the cars were new, then it would have been investigated, and modifications made in an attempt to stop it from happening again. Normal recalls on modern cars still happen, and over the years, problems are ironed out. I don't know how many others have had problems with rear links fitted with poly, but without more investigation as to the root cause of these failures, will we ever find out if poly is the real culprit???
He posted the pictures on facebook and they did say it was the bush that caused it. It also isnt the only case there's been of fatigue caused in this area - just the effect in this case was pretty much as bad as it possibly could be.
I certainly wont fit them to my car at the rear.
The car concerned was absolutely immaculate. It was one of the best p6s in the country in condition terms and no expense had been spared making sure everything was top notch.
I certainly wont fit them to my car at the rear.
The car concerned was absolutely immaculate. It was one of the best p6s in the country in condition terms and no expense had been spared making sure everything was top notch.
I worked on them when they were daily drivers, and up to a point when some of them were getting old, and even then the original bushes themselves were never prone to failure. Maybe now there are more that need replacing, but if OE replacements are available, I'd assume they'd last a similar amount of time, which for me would be plenty long enough. The downsides of the poly bushes just as far as noise and ride detrioration are concerned render them such that I wouldn't use them, let alone the possibility of serious failures caused by them, should that be proved to be the case. I think they ride and handle perfectly well as standard. The only regular failure was the rear toplink bushes.
rockdemon said:
^this
There is a difference between age related corrosion/deterioration and stress fractures from restricted movement.
The rear suspension arms are designed to operate in an arc as the driveshafts travel up and down about the differential, which is why the bushes have voids inside them which NEED to be aligned correctly.
Tell me, do these polybushes have voids in them that too need to be aligned as per the original design, or are they a solid mass of material?
westOz74P6B
Member
Hi Simon, the poly bushes are as you offer are a solid mass poly bush with a separate inner steel spacer/sleeve that they pivot on, the inner spacer is clamped in the usual way as a oem metalastic bush but poly is moulded to take up side gaps that rubber bushes don't. Hope this explanation helps and eBay link of rear trailing arm bushes with pic,
http://www.ebay.com.au/itm/Rover-P6-200 ... 237&_uhb=1
Scott
http://www.ebay.com.au/itm/Rover-P6-200 ... 237&_uhb=1
Scott