Since the joint of the control arm (the joint connects the control arm and the rotor) is loosen, so that the wheel shakes when you push the wheel by holding at the point of 3 o'clock and 9 o'clock. The sympton is that when you drive your X at about 120 KM/H, your steering wheel shakes and especially when you push your brake at that speed. Also you feel the steering wheel shakes when you are cornering at high speed. The BMW service center told me that the control arm must be changed.

Thanks Alpac, so I just need to screw the nut by using the wrench to push the joint out, right?

One more thing, I just bought the control arm made by Febi Germany, anyone heard about the manufacturer? How is the quality? Thanks for comments!

Exactly

Bilstein? Is it Febi Bilstein? I also bought the right control arm made by this manufacturer. I check the manufacturer's website, looks a big manufacturer, anyone has experierence?

Finally, I did it! I bought a ball joint puller and pushed the control arm out easily. The rest of work is pretty streight foward, just put the new control arm on and replace the two nets and tighten the nets. All done. It took 2 hours to do it including test driving. Perfect!

Congrat!

alpac, I found one problem here. The tightening torque of the nuts required by TIS is 100 Nm for frame side and 80 Nm for rotor side. I just tightened the nets to the specified torque when the car was jacked up. In TIS, it say 'tighten in empty weight or normal weight' which means the car should be grounded. Is there any problem if I just tighten the nuts when the car is not grounded? Thanks for help.

No, you are fine

What type of ball joint puller did you buy? I am going to replace the part next week.

i bought the ball joint puller made by KUKKO Germany, the part number is 129-25, others could be too small. It costs HK$580 (US$75). Good quality but expensive.

Can you pls post a pic yor ball joint puller, or a link?