My ball joints were new. I installed them three weeks prior. With the X5 on ramps, the left one popped off with 2 hammer hits. The right ball joint side was on tighter. I removed the ball joint so I wouldn't have to take the wheel off. For installation, I took off both wheels. I turned the ball joint so could insert the cotter pin with wheels on. Once the the arm was in place (loosely), I put the wheels with full weight to snug them up. I then removed the ramps and drove it a few feet back and forth. With full weight and settling, I tightened them using my 1/2" ratchet.

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'06 X5 3.0i - bought @143,123 miles (12/26/20)