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Thread: Thrust arm
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Old 08-28-2010, 04:42 AM
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Fudman Fudman is offline
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Originally Posted by bluebee View Post
Why do you guys replace them (how do we know if they're bad)?
Replacement is to correct a failure or as preventative maintenance when failure is imminent (e.g. after 70K miles). There are two things that fail on the thrust arm, other than the aluminum arm breaking, which can only happen on impact. The ball joints can fail (a more common occurance on the control arm) or the bushing can fail (leak). BMW uses a liquid filled bushing to maximize ride comfort. This is prone to leaking over time (after +70K miles). The recommended fix is the EACTuning solid rubber bushing, which cannot leak and fail, eliminating this failure mode. The degradation to ride quality is minimal and near-impossible to detect. Some people replace their own bushings but that is a bear of a job and it is much easier to buy replacement thrust arms with the HD bushing installed.

For the control arm, only the ball joint can fail as it already uses a solid rubber bushing.
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