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Old 11-02-2007, 09:46 PM   #37
Registered User
Join Date: Mar 2007
Location: Maplewood, New Jersey
Posts: 1,176
My Ride: 2010 328xi
Why not to use grease on the bushings...

I'm scheduled to do this tomorrow, and have been thankful to all including the OP for the help and info I've been able to get here.

One thing to correct on the OP's detailed and otherwise informative instructions however, is his recommendation to use grease to put the bushing onto the arm on re-installation. While I'm replacing the CA's and bushings this time, I did the bushings alone earlier (hoped that would solve my problem, but it didn't) and in my research for that discovered this subject of "lubrication" was much discussed, and what follows is what I found...

Both BMW and the Bentley recommend using soapy water as a lubricant to install the bushings. (This worked easily for me to install new bushings onto the old control arms) The reason to use the soapy water, and not grease, is that the soapy water evaporates briefly after installation, thereby allowing the bushing to seat on the arm. The bushing gets put under a lot of torque and stress under load and if it's not properly seated it can slide up and down excessively on the back of the arm allowing too much in and out movement. In fact, BMW even suggests not driving the car immediately after completing the install to allow the bushings to dry and seat completely. (It's this "seating" of the bushing on the aluminum arm that makes removal of the old bushings so tough to do, requiring a gear puller or other extreme method) Grease on the other hand would remain slippery for an almost indefinite amount of time and prevent proper seating of the rubber onto the arm. Additionally, some greases can tend to attack rubber and may also prematurely degrade the bushing itself.

I suspect that part of the confusion may come from the frequent use of the Powerflex urethane bushings which come with a pack of grease. But while I've not used these personally, from what I understand, this grease is used between the bushing and the carrier to allow it to spin without creaking, and not to insert the bushing onto the arm.

Hope this helps for any future installations.
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