thrust arms again.............

[tim s]

when i purchased my 1995 (4/94) 540i/a last year i learned about the thrust arm bushing issue due to the car shaking at 55-60mph. i purchased a set of arms w/"750il" bushing, center link, & tie-rods from FCP Groton in ct. they claim the parts are made by TRW. i have them installed one year & 16,000mi. and the 55-60mi. shake is back. after looking at the suspension on the rack my friend (a mechanic of 30 years on foreign cars) believes it is the bushings again due to the large amount of movement within the bushing & also the center link has to much play in the joint at the idle arm. the idle arm appears to be tight but i am planning on replacing it also. did i get ripped of from "FCP Groton"? the thrust arms appear to be fine besides the bushing. should i just replace the bushings again & use the TRW arms or should i replace the arms also? i have the bmw arms but the ball joints are bad. i am looking at using eurthane bushings. what is my other options for bushings & where should i get them. bmpdesign has the eurthane bushings for $90.00.
i also purchased a brake booster at the same from FCP Groton & it does not appear to boost as much as the original.
should i complain to FCP Groton or is it a waste of time?
thanks again
tim s.

[tim s]

i was reading through old threads & found one discussion on torquing the thrust arm bolts under load. i did not do that. i also found a thread about a bearing type bushing. does anyone have these?
thanks
tim s.

[Mobius]

If you didn't tighten them with the suspension at ride height, I'm shocked they lasted 16,000 miles.

I don't think there's much in the way of better bushings - I know urethane ones exist, but I'm not entirely convinced urethane is a necessary (or even smart) option here. Personally, I'd go with the 750 bushings again, and perhaps Bruno's inserts to stiffen them a little.

And this time, tighten the thrust arm bolts with the wheels on the ground. ;)

[Bruno]

It is called live and learn.

Stick to Lemforder parts for the suspension... And they will last longer.
As for bushings, you can get the M5 that are lasting longer than the 750i. You can even fill them up with liquid urethane.

And buy your parts from BMA: www.bmaautoparts.com
Other companies will sell you cheaper parts...

Like everything in life.. you get what you pay for.

[tim s]

is there any bad about using urethane bushings besides a harder ride?
i here that they last longer & provide better steering response.
thanks
tim s.

[Paul in NZ]

i think there is a procedure on e 34 .net,your uretane bushings may also transmit more road noise into the cabin..

is there any bad about using urethane bushings besides a harder ride?
i here that they last longer & provide better steering response.
thanks
tim s.

[avitt2]

I can tell you that the bushings in the TRW arms from FCP Groton are the exact same as those used in Lemforder OEM arms. Lemforder would have failed the same way, if installed incorrectly. (My last set of Lemforders went at 40,000).

[Mobius]

I can tell you that the bushings in the TRW arms from FCP Groton are the exact same as those used in Lemforder OEM arms. Lemforder would have failed the same way, if installed incorrectly. (My last set of Lemforders went at 40,000).
I've posted before about this; the FCP Groton arms use BMW bushings and the arms themselves match the casting of the arms I pulled off my car exactly - except the Groton arms are missing the cast-on BMW part number.

That leaves the ball joint as the only slightly uncertain bit - and it, too, looks identical to the one I pulled off.

I know they have a very good reputation among the RWD Volvo community for their suspension parts - I have no reason to believe otherwise in this case.

[Bill R.]

autoparts today, If you were going to counterfiet the original thrust arms and sell them the easiest way is to buy one of the OE. arms and you use that for your mold. If it has the lemforder seal cast into the arm then you have a pretty good idea that they are lemforder. The arms i've seens by fcp groton on ebay has the numbers and any id marks ground off. Visually its impossible to tell a counterfeit part from an oe. part. I personally would rather pay Patrick a little bit extra and get the oe. lemforder arms. That said if you tighten the arms unloaded then it will definitely kill the bushings quicker.








I've posted before about this; the FCP Groton arms use BMW bushings and the arms themselves match the casting of the arms I pulled off my car exactly - except the Groton arms are missing the cast-on BMW part number.

That leaves the ball joint as the only slightly uncertain bit - and it, too, looks identical to the one I pulled off.

I know they have a very good reputation among the RWD Volvo community for their suspension parts - I have no reason to believe otherwise in this case.

[tim s]

but for now to same cost i will press urethane bushing in & torque them with the load.
thanks
tim s.

[MBXB]

Which bushings did you decide to install, Tim?

[632 Regal]

after you get them in.

[tim s]

http://www.tntcomp.com/bushing.jpg
$89.95

the best price i found.
tim s.

[rockyfeller]

I also have thrust arms that lasted only 20,000 miles. The stealer did them the 1st time for a pretty penny. When I took it last week to another shop he told me they were shot AGAIN! He's right because I didn't realize how badly the car was riding till he changed them and now what a difference! I didn't want to chance anything so I changed the whole arm with Lemforders. I still have a slight shimmy, but I'm attributing that to unbalanced worn tires. Shouldn't those bushings last at least 50,000 miles? What type of driving behaviour contributes to premature wear of the bushings? What kind of forces do the arms/bushings counteract? I'm driving all paranoid now trying to make sure I don't do something to wear them out quick again. With so many of us having this classic problem this has to be the result of a bad design fault on the part of BMW. They should design some kind of updated super-heavy duty design for this part.

[Mobius]

http://www.tntcomp.com/bushing.jpg
$89.95

the best price i found.
tim s.
I don't know if I'd use a poly bushing in this application for daily-driver use. Aside from the noise and harshness factor, there's a lot of design in the OE bushing that apparently takes into account the sort of forces placed on this bushing. This is why they have to be oriented specifically when pressed into the arm.

Also, by going to a hard bushing like this, you're putting a lot more force on the components related to the bushing. My roomate drives a 300ZX and he pointed this (http://www.twinturbo.net/net/viewmsg.aspx?forum=general&msg_id=1399367) out to me a while ago. The 'tension rod' that they refer to there (which was mounted to that bracket with a non-OE poly bushing - before it fatigued and ripped apart) - serves essentially the same purpose as the thrust arm in our application - it principally handles fore/aft thrust.

I'm not saying that's going to happen - just to keep such things in mind.

[tim s]

i remember nissans as being very thin.
tim s.

[Mobius]

My point wasn't that you're going to do that to your thrust arm mounts, my point is that you're putting a LOT more stress on these mounts, and a lot more stress on the suspension in general by taking away the flex that BMW designed into that bushing. This is something you should consider and be aware of when switching to polyurethane bushings.

And there is nothing at all thin about that bracket - the 300ZX suspension is even more tank-like than my BMW's, and I say that without any shame. I've seen both up close and personal. The 300ZX isn't exactly a typical japanese econobox.

[Bill R.]

has the original bushings and thrust arms at 135,000 miles. I have stock size tires and wheels, stock front springs, stock struts and no shimmy. When you change the wheel size and go to lower profile tires, all the sudden the tires don't absorb as much of the day to day punishment from the road, instead the larger wheels and lower profile tires transmit more of this pounding to the bushings, also add lowering springs and stiffer struts such as the bilstein, all of these items compound the amount of force transmitted to this bushing, aggressive driving with hard stops/starts also transmits a greater load to the bushings.. now each component in line on the stock suspension absorbs a certain amount of shock load that it gets from the road, Each of the (improvements?) that you make to the suspension/wheel/tires/springs transmits more of this shock load to the next component in line... End result
you'll kill bushings/balljoints/wheelbearings etc. quicker. Its just the price you pay.







My point wasn't that you're going to do that to your thrust arm mounts, my point is that you're putting a LOT more stress on these mounts, and a lot more stress on the suspension in general by taking away the flex that BMW designed into that bushing. This is something you should consider and be aware of when switching to polyurethane bushings.

And there is nothing at all thin about that bracket - the 300ZX suspension is even more tank-like than my BMW's, and I say that without any shame. I've seen both up close and personal. The 300ZX isn't exactly a typical japanese econobox.

[tim s]

i called dinan but they did not know much about there bushing. i am waiting for my local dinan dealer to call me back with info on the dinan bushing.
bmp told me the the urethane bushing is going to be noisier & will need grease applied to keep it from squeeking.
thanks for your input!
it is very appreciated!
i want to make an informed decision & this forum has helped greatly.
tim s.

[tim s]

these are listed as heavy duty.
any body ever use these?
they do not appear to have the plastic inserts.
http://www.tntcomp.com/hd_bushing.jpg
thanks
tim s.

[632 Regal]

these are listed as heavy duty.
any body ever use these?
they do not appear to have the plastic inserts.
http://www.tntcomp.com/hd_bushing.jpg
thanks
tim s.

[tim s]

my friend the mech. can get them from an import company in nj. somewhere.
tim s.

[632 Regal]

if so you may be better off getting a set of Lemforders already pressed on new arms.

This time tho, MAKE SURE THEIR TORQUED WITH WEIGHT ON THE FRONT!

[tim s]

that he uses to do wheel alignments that i can use to drop the car on to torque the bolts.
my old arms have worn ball joints.
the arms i purchased last year with the now failing bushings do not appear to have worn ball joints.
tim s.

[Bill R.]

hydraulic oil filled mounts, they are a better dampening mount










my friend the mech. can get them from an import company in nj. somewhere.
tim s.

[tim s]

i would expect the solid rubber bushing to be a little rougher of a ride, but would also think that it would not tear as quick.
please correct me if i am wrong.
i do not want to make a bad choose.
thanks
tim s.

[tim s]

tim s.