Replacing thrust arms vs. thrust arm bushings

[JAlfredPrufrock]

OK so which way do you think I should go?

My 535i has got ~125k miles on it and I get a bad shudder at 55mph under braking.

I plan on replacing rotors and pads all around later on this year and would like to concentrate on freshening up the suspension.

So as far as thrust arms go, would it be easier/better to replace the entire assembly or just change bushings? In the Bentley it says I need a special tool to replace thrust arm bushings, which makes me think it may not be worth all the extra effort just to replace bushings.

Do thrust arms "give out?" Any improved thrust arms/other suspension components I could replace that would make a substantial improvement to my ride?

[jplacson]

Replace the whole arm w/ bushings. Cost isn't that much more, and yes, the ball joints on the arms give after some time and cause some clunking in the front end.

Other stuff to look at replacing, tie-rods, links, idler arm, shocks.

[Asamaan]

The consensus on the board is usually to replace the whole arm and use the ones that have the 750il bushings pressed in.

Al
91 535iA

[Mobius]

Seeing as how you have to remove the arms anyways, ya might as well just put new ones on.

[Tiger]

Replace whole arm with 750il bushing... yes, the ball joint on the thrust arm is a concern at 125K.

[JAlfredPrufrock]

Can I pick up a thrust arm with 750il bushing compatible to the E34 OEM?

Is it really an OEM 535i thrust arm with 750il bushing pressed in aftermarket?

[liquidtiger720]

www.bmaautoparts.com call and ask for patrick of yves. they sell pre-pressed 750il bushings with the correct thrust arm for 99~lemforder.

[Kalevera]

You may want to consider the M5 bushing over the 750i ones. The M5 is an even more robust design than the 750. The differences were recently discussed on UUC and may presently be in the archives on the web site.

Actually just pressing in a new bushing is much cheaper than replacing the entire arm FWIR, but at 125+k, the ball joint is probably heading south anyway.

Now: your 55mph shimmy could be warped rotors, which is not something I, personally, would leave until later on this year. If they're warped after normal/non track driving conditions, then they're probably well worn and in need of attention.

best, whit

[JAlfredPrufrock]

I'd rather pick up parts from the stealer.

Any OEM recommendations/thrust arm upgrades welcome.

[JAlfredPrufrock]

Now: your 55mph shimmy could be warped rotors, which is not something I, personally, would leave until later on this year. If they're warped after normal/non track driving conditions, then they're probably well worn and in need of attention.

Whit you're right, I think the shimmy is a combination of both thrust arms and rotors... I have some pretty crappy rotors on right now (X drilled from the PO) with their old pads, but they've still got some life left and I rarely get up to 55 at any driving event (auto X)... I'd like to get my suspension refreshened a little and I have a bike that needs maintenance so until the pads give out my rotors will stay in.

[Martin in Bellevue]

The e34 M5 bushings should be a tougher upgrade to the 750 stuff. I'm sure Pat can source the m5 arms.
The control arms are better removed by pulling the upper & lower arms attached to the steering plate(3 bolts under strut) from the car. With the control arms out of the car, on a workbench, you have much more room to release the ball joint ends.

[JAlfredPrufrock]

Martin can you confirm that the E34 M5 thrust arms are a direct swap for the E34 535i?

[Kalevera]

They are.


best, whit

[pmlmotorsports]

Martin can you confirm that the E34 M5 thrust arms are a direct swap for the E34 535i?

Exactly how many times do you need to hear the same recommendation before you accept the advice that's being given? As for the M5 arms being a direct fit, they most certainly are. The major difference is that the M5 arms are cast aluminum, standard E34 arms are cast steel/iron, AND I believe the bushing must be pressed-in post purchase. BTW, why on God's earth would you prefer buying your parts from the dealer? I mean it's good for the local economy and all, and I'm sure the owner and his wife appreciate you helping pay their daughter's tuition, but you will be paying a 50% premium over the indy.

[Kalevera]

Exactly how many times do you need to hear the same recommendation before you accept the advice that's being given? As for the M5 arms being a direct fit, they most certainly are. The major difference is that the M5 arms are cast aluminum, standard E34 arms are cast steel/iron, AND I believe the bushing must be pressed-in post purchase. BTW, why on God's earth would you prefer buying your parts from the dealer? I mean it's good for the local economy and all, and I'm sure the owner and his wife appreciate you helping pay their daughter's tuition, but you will be paying a 50% premium over the indy.
Actually, the thrust arms aren't aluminum, just the control arms are on the M5.

No need to be abrasive. JAlfred's just trying to get it all right the first time.

best, whit

[JAlfredPrufrock]

Exactly how many times do you need to hear the same recommendation before you accept the advice that's being given? As for the M5 arms being a direct fit, they most certainly are. The major difference is that the M5 arms are cast aluminum, standard E34 arms are cast steel/iron, AND I believe the bushing must be pressed-in post purchase. BTW, why on God's earth would you prefer buying your parts from the dealer? I mean it's good for the local economy and all, and I'm sure the owner and his wife appreciate you helping pay their daughter's tuition, but you will be paying a 50% premium over the indy.

Many times.

Employee discount > you

[pmlmotorsports]

Actually, the thrust arms aren't aluminum, just the control arms are on the M5.

No need to be abrasive. JAlfred's just trying to get it all right the first time.

best, whit

I stand corrected. Perhaps it's knowing everything in the suspensions are identicle except the bushing and the control arm......I guess I'm just getting old..........not being abrasive, just seemed like he ignored the other members suggestions, except for Martin........

[liquidtiger720]

Are you sure the standard e34's came with steel control arms? When I went to replace mine, they were aluminum. Actually, I believe both peices were aluminum. I remeber comparing the weight between both sets...and the originals were a great deal lighter.

http://img.photobucket.com/albums/v457/liquidtiger720/DSC02159Medium.jpg

[Anthony (M5 in Calgary)]

Later E34s came with the aluminum control arms but steel arms are fine for any E34 unless you are concerned about that last few ounces of unsprung weight. The aluminum arms are stronger and purportedly have a higher quality ball joint than the cast iron parts.

Thrust arm bushings from the M5 are a direct fit but you may have a bit of trouble convincing a stealer to put them in. BMA will supply the thrust arms with whatever bushings you want. Buy Lemforders...

Anthony

[JAlfredPrufrock]

I'm planning on doing all the work in my driveway.

[jplacson]

Does Lemforder sell the aluminum arms as well? So the ALs are stronger than the steel ones? Hmmm... interesting! :)

[Anthony (M5 in Calgary)]

Does Lemforder sell the aluminum arms as well? So the ALs are stronger than the steel ones? Hmmm... interesting! :)

Lemforder is the OEM for these parts and I put a set from BMA on my car a couple of years back. They had the BMW logos ground off but were otherwise indistinguishable from the original parts (with BMW logos) that I removed. Must be some kind of branding agreement allowing Lemforder to sell into the aftermarket but not with the roundels so they grind them off.

Anthony