Re: E34 Front suspension question

[Benjamin_Trapp@xxxxxxxx]

Seung Hyun Chung wrote:

"After having my front struts replaced in my 89 535i, my local mechanic 
wrote on the ticket, "Idler arm has slight movement, also both sides 
brake reaction rod has movement and boots have been torn for awhile and 
grease is full of dirt."

Does anyone have an idea as to what these terms mean in BMW language?"

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The idler arm is not the same part as the control arm.  Looking from below
the car (if it's on a lift), the idler arm looks sorta like a turnbuckle.
The ball/socket joints at each end (covered by rubber boots) should allow
the idler arm shaft to swivel ~30 degrees easily.  I believe toe adjustment
(maybe some camber too?) can be made at the idler arm by moving the joints
within the (threaded?) idler arm sleeve.  Your mechanic mentioned "slight
movement" which is pretty vague, but since the idler arm is supposed to be
able to swivel during suspension travel, he's probably talking about joint
wear (a loose fitting).
	Sorry, don't have any idea what the "brake reaction rod" is.  Sounds
like your mechanic doesn't know what it's called either, so he made up the
name.  When braking, your front camber should increase when the car dives,
making the car toe-out (if I remember correctly).  That means he's probably
refering to something that maintains the proper suspension geometry while
braking.  It must either pull the front of the wheels together while
braking, or push out the rear of the wheels.  There's so many things
connected to so many other things down there, that they all must contribute
to configuring suspension geometry, so your guess is as good as mine.  Maybe
the center drag or thrust arm?
	I'm not sure you'll be able to buy just the replacement boots
separately.  Some of the boots may be exchanged for used ones when you
replace your other parts, depending on joint size, etc.  For example, you
may be lucky and be able to re-use the boots from your original idler arms
somewhere else, if you replace those (which should come with new boots).
It's a good idea to keep your boots sealed because once the lubricating oil
has seeped/dried out, wear and joint failure is right around the corner
(literally).
	Sorry, don't know how much these articles will cost you.  Good
luck...

Ben Trapp
benjamin_trapp@domain.elided
Dell OptiPlex & WorkStation Industrial Design
PCA / IDSA / CIP / BMW CCA #156642 (NCC)
http://www.prism.gatech.edu/~gt9775a/bmwgallery.html (Chris' page)
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Pound for pound, hamburgers cost more than new cars.

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