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How do I install an E30 Control Arm Bushing?

Discussion in 'E30 (1984-1993)' started by Brian A, Mar 9, 2008.

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    Brian A

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    On an E30, is it difficult to push a new rubber control arm bushing onto a new control arm? Is there a substitute for the BMW Special Lubricant/Glue (part no. 81 22 9 407 284)?

    I have a 1987 325i convertible. Needless to say, I have never replaced the control arms myself and mine are worn again. I purchased new control arms and the bushings pre-assembled into their mounting brackets from Bavarian Autosport thinking that it was a fairly simple job.

    However, I now read in "101 Performance Projects" (P174 first paragraph) that, "I strongly suggest you have a machine shop press the new bushings onto the end of the control arm." Wayne Dempsey does not seem to be referring to pressing the bushing into the bracket, but rather the bushing onto the control arm itself. Bentley makes no mention of such difficulty. Can I do it myself while lying on my back underneath a car?
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    MGarrison

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    If you clamp the bushing bracket into a bench vise and lube up the control arm, you should be able to push/twist the control arm into the bracket if you apply enough brute force. Make sure you have the parts straight, you don't want to have to go switch control arms because you got the wrong brackets on them. However, they can be pulled off the same way - with older control arms, you might have to clean up any rust on the control arm end w/ a wire dremel brush or something like that.

    I watched my mechanic swap them that way last year - using offset E30 M3 bushings though, which were in ok shape, I didn't have to use new ones at that point. I believe the M3 bushings have more solid rubber mass than the stock bushings, although I'd presume new stock bushings would have enough flexibility to withstand the twisting/pushing force being applied.

    Clamping the bracket instead of the control arm is preferable because you have substantially more leverage maneuvering the control arm.

    I think this might be hard to maneuver under the car w/ the car jacked up - plus, it might not be a great idea to be applying that much force to the car through the bracket while it's over you on jacks. You'd figure the weight of the car is enough to not be moved, but why risk it (particularly if for some reason you only have the car on two jack stands).

    Using a press might be easier in terms of how you apply the necessary force.

    I'm not sure the BMW-specific lubricant is all that critical; I know we didn't use it because I didn't have any, but I forgot what he used - possibly something similar to WD40. If you use a grease or lithium lube, I think you'd want to clean off the control arm end after you have it installed - I think my mechanic suggested the idea behind the BMW lube is to provide temporary lubricity, and the BMW lube will dry after it's used. I'd be surprised to think there's any risk of the control arm sliding back _out_ of the bracket after being installed in place on the car, but there's surely some rationale for the BMW specific lube.

    I'd suggest you use a torque wrench to make sure your final bolt-tightening is to spec, and so as not to over-torque any mounting bolts - breaking bolts is a nuisance, at a minimum.

    While you're under the car, look closely at your metal fuel and brake line tubings running from the front to the back of the car. I recently noticed rust bubbles on my brake lines, although perhaps not that much of a surprise after 21 years, but without a careful lookover, something like that could be easily missed.

    Good luck -
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    E30Crazy

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    BrianA / MGarrison

    I read the same in the 101 Project book. I'm in the same boat, the lubricant is more like an adhesive, it keeps the controlarm from slidding out the movemment of the controlarm in the bushing. The only movemment should be the bushing flexing.
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    mjweimer

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    I have successfully used turpentine as a substitute for the BMW lube.

    The most difficult part of the whole job (after getting the actual bushing pressed on to the arm) is getting the car back on the ground quickly to let the bushing take a set while loaded. This creates some pre-load in the bushing and is what BMW recommends in the factory shop manual.

    I will often do the job over a weekend and do one side one day and the other the next allowing the turpentine to dry and the bushing to take a set overnight.

    Another common method is to use a dish soap and water solution as a lubricant. This of course will not offer any type of softening of the rubber/gluing action to occur.

    Matt
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    Brian A

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    Thanks to all for the help. I now have the courage (again) to take on my control arms and bushings.


    Regarding the lubricant/glue, I telephoned two BMW dealerships today to try to find some. The Parts Guy at the first dealership mumbled that they no longer sold the stuff. Second dealership Parts Guy said that the part number was invalid, took my name and phone number and said he'd ask the technicians. He phone back a few minutes later and reported that the dealership doesn't use the lubricant/glue anymore and instead just used soap and water.

    It sounds like soap and water (or turpentine!) is the way to go.
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    Brian A

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    … may as well report out how the job went:

    I successfully mounted the bushings and completed the control arm job. Dempsey exaggerated the difficulty. It was relatively easy.

    To mount the bushings, I put my drill press vice on the floor and clamped the bushing into it face up. Like MGarrison observed, the leverage of the control arm itself was necessary to twist the arm into the thick bushing rubber. It took a bit of wrestling. There is no way I could have done this under the car or by holding the control arm stationary and trying to twist the bushing. Before removing it from the vice, I rotated the new bushing to the same position on the new arm as the old bushing was on the old arm.

    Based on MJWeimer's suggestion, I used mineral spirit as a lubricant (same chemical family as turpentine just without the nice smell).

    And yes, I did manage to get the car back down on the ground within 30 minutes (not sure if it really matters without the special BMW glue).
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    mjweimer

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    Excellent!

    Glad the job went well for you.

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