Knock heard/felt when I turn the steering wheel

[rexmo]

Problem: I hear/feel a knock when I turn the steering wheel.

Cause: Metal fatigue failure of the welds between the steering box mounting bracket and the front subframe.

Evaluation: Have a helper turn the steering wheel while you watch the steering box. If the box rocks side to side, its mounting bracket is broken. If not, it's something else. See other causes, below.

Solution: Remove subframe from car and weld crack(s).
http://www.teamdfl.com/bmw/e28/frontsub ... frame.html

Alternate solution: Replace the short bolt that holds the steering box to the subframe with a ~8"x3/8" Grade 8 bolt with fender washers to span the hole on the bottom of the subframe. Locknut or a jam nut probably a good idea. Black iron reducer pipe fittings have been used as sleeves to brace the mounting bracket. Someone had the "bright" idea of painting them red for marketing purposes.

Other causes: Jeremy: Strut bearings and sway bar end links are reported as additional knock sources in the front end. I locked down my steering box (mount was cracked), but the clunk continued until I tracked down a failed ball joint on a sway bar end link.

Threeshifter: The steering column collar nut inside the cabin near the pedals is also a source of knock. Also a miss adjusted or warn out steering gear is a source of knock in the steering.
This sort of jumps to the worst case knock without mentioning the easy/easier to fix sources of knock that should be checked first.

lkfoster: I put a large crescent wrench on the nut and then turn the steering wheel to tighten. Much more leverage that way. I turn it an eighth of a turn and check that the steering column can still be moved in and out. Repeat as needed until the clicking noise goes away.

Rob Anderson: I have also had a problem where the aluminum upper part of the column which houses the steering wheel lock and the ignition switch has become loose on the retaining bolt. The way to fix this is to remove the single bolt that holds it and put some JB weld between the aluminum and the steel sleeve. Then reassemble. This removed all clunking in my steering.