This is going to be controversial, but Ive done it on my 98 Z3 2.8, and its still holding up with no movement. To get some adjustment to the rear trailing arms, you could change the original 12mm bolts over to 7/16 on the inner mounts only (would not do the outers as they are much closer to the wheel, thus greater shock loads). This gets you about .070" range of movement at the mount. I did this on mine, which had too much toe out at .25", and got it down to .12"
You have to push the inner end of the arm in the direction you want it to go prior to tightening them down. What you need is this: two 7/16x4 bolts, locknuts, and 8 hardened washers (double them up on both ends). All hardware MUST be grade 8. Torque them to 70ft-lb. Attached is a pic of the 7/16s on mine, the chisel is just to move the mount in the direction I wanted till tightening.
You have to push the inner end of the arm in the direction you want it to go prior to tightening them down. What you need is this: two 7/16x4 bolts, locknuts, and 8 hardened washers (double them up on both ends). All hardware MUST be grade 8. Torque them to 70ft-lb. Attached is a pic of the 7/16s on mine, the chisel is just to move the mount in the direction I wanted till tightening.
