Rear-end squirm

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Mike E
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Post by Mike E »

I noticed today that the rear-end of the 535i squirms a bit. I started taking more notice of it, and realised that at times it doesn't track quite straight.

Subframe bushings? Diff mount?
Duke
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Post by Duke »

[QUOTE="Mike E"]Subframe bushings? Diff mount?[/QUOTE]

Both.
Mike E
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Post by Mike E »

Bugger.

I hear these sub-frame bushings are a b**** to get out. Is it really that bad a job?
Duke
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Post by Duke »

[QUOTE="Mike E"]I hear these sub-frame bushings are a b**** to get out. Is it really that bad a job?[/QUOTE]

With the correct BMW tool, no problem. Without, it is a PITA. Here is a link to a home made tool to do the job and info on the polly filling - http://www.teamdfl.com/bmw/e28/bushings ... hings.html

HTH's


[Edit by DukeM535Ti on [TIME]1107335579[/TIME]]
Justin_FL
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Post by Justin_FL »

Also worth checking or replacing the dogbones / pitman arms. They are quite easy to do. My car has a bit of rear instability over bumps so I'm going to replace them (along with other suspension pieces) in a few weeks when my Dad's lift is finally operational. My "dogbones" must have 50k miles on them... so I think they are toast along with the diff mount and subframe bushings, which are both original.
Blue Shadow
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Post by Blue Shadow »

Worn out dog bones will give the car a less than stable lane change maneuver. A sorta continuation of the maneuver.

Worn out subframe bushings will give the car a sense (generally while going straight or coming out of a turn) that the rear end wants to do a little steering. Kinda like tramling, but not coming from the front.

Diff mount seems to be a clunk, I haven't experienced it having input into steering the car, but others may provide input n this.
Echo
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Post by Echo »

[QUOTE="Blue Shadow"]Worn out dog bones will give the car a less than stable lane change maneuver. A sorta continuation of the maneuver.[/QUOTE]

I will second this... They are expensive, but if you are replacing your diff mount and subframe bushings you might as well do these as well. On a side note, buy a 635csi diff mount other than the stock E28 piece. Not only is the E24 part cheaper, but its also beafier and will easily slide into place.

Cheers,
Jonas
al525i
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Post by al525i »

duke can weild the hell out of a sawzall to remove the old ones! Installing the new ones isn't that bad if you have the proper tool. and i do recommend the poly fill method.
fastpat
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Post by fastpat »

[QUOTE="Mike E"]I noticed today that the rear-end of the 535i squirms a bit. I started taking more notice of it, and realised that at times it doesn't track quite straight.

Subframe bushings? Diff mount?[/QUOTE]

Most likely it's the rear pitman arms, aka dog bones. These two seemingly innocuous parts will permit lateral "squirm" when entering turns, or in a cross wind. Check them by moving them with by hand, if they appear loose, i.e. easily flopped around by hand, replacement is in order. You don't even need to jack the car up, they're readily accessible from the side.

This is what a new one looks like:
Image
Mike E
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Post by Mike E »

Wow. My pitman arms look nothing like those.

I figure I'll do the following:
Pitman Arms, Diff Mount, and subframe bushings if the other two don't fix the issue.

Anyone that has a detailed FAQ on the subframe adventure... your info is most appreciated...

Mike E
Mike E
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Post by Mike E »

UPDATE:

For those who might be interested, it's like driving a car that's constantly fishtailing up the road, ever so gently. Wierd.

Mike E
Blue Shadow
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Post by Blue Shadow »

The subframe issue is discussed ad nauseum on rf, old mye28 and other places. a google search will keep you busy, then check the rfe28 site you should have enough.
fastpat
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Post by fastpat »

[QUOTE="Blue Shadow"]The subframe issue is discussed ad nauseum on rf, old mye28 and other places. a google search will keep you busy, then check the rfe28 site you should have enough.[/QUOTE]

I think Shifty did a photo essay on the subframe mounts a few years back. Had it on his web site.
fastpat
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Post by fastpat »

[QUOTE="Mike E"]Wow. My pitman arms look nothing like those.

I figure I'll do the following:
Pitman Arms, Diff Mount, and subframe bushings if the other two don't fix the issue.

Anyone that has a detailed FAQ on the subframe adventure... your info is most appreciated...

Mike E[/QUOTE]

Those two you've mentioned first will probably correct the problem unless you have a bent rim or other wheel/hub problem.
Spark
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Post by Spark »

Experienced the same problem some time ago exactly the same symptoms. Changed the dogbones, problem gone. :cool:
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