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paulie031

Thrust arm bushes

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Morning peeps what's the general consensus on these? I had mine replaced coming up for two years ago with lemforder but they're starting to feel vague again.

 

After having nearly all the bushes replaced and shocks it's firmed the car up greatly but now seems these are suffering again. Tempted to go with powerflex or the more expensive route of spherical bushes like moosehead etc. Any opinions folks?

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Personally I'd avoid poly bushes on a road car especially on a bush that is designed to be strong in one axis of loading direction and soft in the perpendicular axis of loading direction.

 

Did you change the whole arm, thus the ball joint at the other end too or not? 

 

Also it's quite common to fit the bush in an incorrect position (opposite orientation) AND also many people tighten up the bush when the it's not loaded i.e. with wheels on the ground and the bush / arms fully loaded.

 

Also what are the exact symptoms you are experiencing ?

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Hi, just the bushes got fitted by a reputable garage.  The owner knew about orientation and tightening when loading without me even mentioning it so that was a relief!

 

The front feels vague on times,  the tyres have done less than 2k as I changed them because the old ones seemed to have worn strangely across the tyre.

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OK fair enough !

 

If installed correctly and are Lemforder they should be good for 50K miles I'd say...

 

There is an argument that new bushes are useless unless the ball joints on the other end are good too....just a thought.

 

Only other things to look at are the suspension geometry, lower control arms, suspension (dampers, springs, top mounts) and steering arms, anti roll bar drop links and anti roll bar bushes.

 

Can you elaborate on the vagueness ?  How did your last tyres wear ? Also how many miles on the car ?  Steering box may need a rebuild if at mega miles.

 

Thrust arms that are weak are responsible for steering wheel judder under braking mainly, but they do help locate the position of wheel/hub during cornering etc etc

 

Also do not overlook the rear axle components....rear ball joints, guiding links, rear wishbones, subframe bushes, snapped rear anti roll bar brackets...'vagueness up front' could well be a rear end issue.

 

PS : Vague at times may also suggest pas pump issues.  

Edited by M5 London

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19 hours ago, M5 London said:

Only other things to look at are the suspension geometry, lower control arms, suspension (dampers, springs, top mounts) and steering arms, anti roll bar drop links and anti roll bar bushes.

 

Geometry set up by forza in chepstow who also changed four genuine shocks and associated sundries. Also changed the pitman arm iirc. Anti roll bar bushes changed around 6 months before i took ownership, front and rear. 

 

19 hours ago, M5 London said:

Can you elaborate on the vagueness ?  How did your last tyres wear ? Also how many miles on the car ?  Steering box may need a rebuild if at mega miles.

 

It just doesn't feel connected at times, although it could be the poor road surface around here. Tyres wore unevenly but these were on the car when purchased so had suffered with The old thrust bushes. She's on 137k

 

19 hours ago, M5 London said:

Thrust arms that are weak are responsible for steering wheel judder under braking mainly, but they do help locate the position of wheel/hub during cornering etc etc

 

It doesn't seem to judder but then I'm not that heavy on the brakes

19 hours ago, M5 London said:

Also do not overlook the rear axle components....rear ball joints, guiding links, rear wishbones, subframe bushes, snapped rear anti roll bar brackets...'vagueness up front' could well be a rear end issue.

 

All the back end bar the subframe and diff bushes are new. Including arms etc. The bushes were checked by forza, and said to be fairly recently changed

 

P.A.S. sounds plausable

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Well it seems most suspension / steering arms have been renewed, which is great !

 

Maybe thoroughly flush the old pas fluid out and replace with new fluid, and if you fancy replace the actual pas reservoir, which contains a filter within it.

 

PAS pumps seem to be generally strong .....but is something to check out.  PAS lines are very poor and always leak, even new ones.  So check all of them !

 

Also check for fault codes as sometimes servotronic fault comes up, but you should be able to feel that whilst steering....goes pretty heavy if the servotronic sensor fails.

 

Edited by M5 London

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Have to say when I had my M5 I replaced the 4 arms with brand new Lemforders and Polybushed them using the Powerflex purple bushes

I thought they were excellent.  Didn't find them harsh at all and that's on Irish roads which are like fields!!

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1 hour ago, Jameswsb said:

Meyle HD are good. I have them on the Alpina and the M5

 

Meyle HD are very hit and miss in quality ... But their rear suspension mounts are very good ( over 20k and still mighty fine) 

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Never had any issues with Meyle HD and I know a number of specialists that use them with no issues. Just for context, I recently replaced the thrust arms on the M5 and paperwork suggested that they had been replaced before. When I took them off it turned out they were lemforder and cross referencing the dates they had lasted less than 40k miles....

 

Personally I think most premature failures are down to incorrect fitting procedure.

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Powerflex ARB bushes are a must in my opinion. Changed mine even though they looked fine. Hey presto a very faint knock was no more and they were dead easy to do. Fit and forget.

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