BMW E90 front end knocking over bumps
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The E90 front end knocks over potholes, what causes it?
Common causes are worn shock absorbers and their protective rubbers, and dry or rusted strut top bearings. Cleaning and lubricating the bearing may help, but a lack of grease can lead to the bearing seizing and, at worst, the spring breaking.
What else can be behind the knocking?
The control arm's body-side mounting can have come loose, so the arm moves in sharp bumps. The electric steering rack can be loose and clunk at low speed or on cobblestones. Lowering springs and worn spots on the spring seat can also cause noise.
How do you check the play in the inner end of the tie rod?
1. Lift one front wheel off the ground. 2. Grip the tyre and rock it left and right, first lightly and then harder. 3. Watch the joint: play feels like a small clunk. Support the car on axle stands if you go under it.
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