03-06-2012, 09:46 AM
Officially Welcomed to the 'Fest
Join Date: Jul 2011
Mein Auto: 2004 M3 6MT
I did mine recently and my control arm ball joint had some play in it as well. The thrust arm is the rear arm with a large bushing for the frame, and the other control arm is the front one that is tubular and straight.
Originally Posted by Sonare
I just had lower control arms (and tie rods) replaced but still have a little shimmy. I am not at all sure whether lower control arms are the same as thrust arms. I did a complete front brake job (OEM rotors and Pagid pads) and was blaming un-even lug nut torque (or possible out-pf-round rotors) for the shimmy, which was less after an alignment.
Tips I can share from having done the thrust arms:
When tightening the ball joint nut, I suggest torqueing it down, back it off, then torque to spec again. The taper may otherwise throw off your torque value.
New BJ nuts are highly recommended, but thread lock can be used if you lose the new ones.
Use an allen key (8mm?) in the ball joint to keep it from spinning as you tighten it. If the spindle is under load (jacked up), this is not necessary.
To tighten down the bushing side of the arm, professionals will usually jack up that spindle to ride height and then torque it down.
Inspect the tie rods and front control arm for play after doing the thrust arm. Worn thrust arm bushings or ball joint can cause premature wear on those components. Have someone wiggle the wheel for you.
I suggest throwing in all new sway bar end links - they can get pretty loud for their size when they go bad.
You can grease the inside of the sway bar bushings with brake compound or other grease to mitigate squeaks down the road. Do not grease the bracket side of the bushings.
Harbor Freight is a good source for the 21-22mm wrenches ($15 for a full set up to 24mm), 21mm 1/2" socket ($3, 12-point is OK), and ball joint separator ($20). Ear plugs aren't a bad idea either
540i - Stock/Sport / 6MT / 13.9@100mph
WS6 - 231/234 / 6MT / 4.10 / 410rwhp
ITR - 262/262 / 5MT / 12.2:1 / 9600rpm
540i/6 Sport, Jet Black, Style 65, LED tail, DICE+GROM USB, !CDV, Redline MT-90, M1 0-40w