BMW Rear Lower Control Arms (LCA) – Replace How To – DIY, E36 E46 Z4 X3
This DIY applies to the following BMW models:
E36 models; 3-series 92-98 (318i, 318is, 318ic, 323i, 323ic, 323is, 325i, 325is, 325ic, 328i, 328is, 328ic, M3)
E46 models; 3-series 99-05 (323i, 323ci, 323cic, 325i, 325ci, 325cic, 325xi, 328i, 328ci, 328cic, 330i, 330ci, 330cic, 330xi, M3)
E83 Models: X3 – 2.5i, 2.5si, 3.0i, 3.0si through 2010
E85 & E86 Models: Z4 – 2.5i, 2.5si, 3.0i, 3.0si, M-Coupe, M-Roadster
E89 Models: Z4 – 3oi, 35i, 35is 09-current
There are two common failures (in addition to actual damage, such as bending) that will require replacement of the rear suspension lower control arms on the above BMW models.
* The inner bushing is worn and soft, allowing the arm to move more than designed. This can result in camber problems and/or vibrations and instability due to rear steering (from the arm moving around).
* The tabs on the outer ends of the arm are worn away and the camber adjuster (the outer bushing) is not secure. This is typically the result of the through-bolt for the outer camber bushing not being fully tightened. Symptoms are similar to the above symptoms.
Replacement of the arm appears to be quite straight forward. Simply remove the inner and the outer bushing bolts and lower the arm. Well, not so fast, there. While the outer bushing through-bolt is indeed easy to replace, the inner bolt has issues. The differential must be unbolted (but not actually removed) and moved rearward in order to remove the through-bolt at the inner end of the control arm.
1) Properly and safely, lift and support the rear of the vehicle with the suspension hanging free.
2) Remove the wheel (or both, if both arms are being replaced).
3) Mark the position of the eccentric washer on the head of the through-bolt, for the outer bushing (at the wheel hub). This will help you to approximate the camber adjustment position when installing the new arm (you should have the camber re-adjusted after installation). Remove the through-bolt for the outer bushing. Pull the bottom of the hub assembly outward to allow the end of the arm to be removed from the bushing (pressed into the eyelet on the hub assembly).
4) Loosen the inner control arm bushing through-bolt. Note the tab-nut that the bolt threads into, on the forward side of the subframe assembly. The tab-nut will fall out when the bolt is fully un-threaded from it. Note the installed position prior to removing the bolt. You will not be able to actually remove the bolt, as it will hit the differential housing.
5) Place a floor jack under the differential housing and remove the three differential mount bushing bolts. Use a pry bar to push the differential rearward about an inch (along with the floor jack).
6) Remove the inner bushing through-bolt and remove the arm.
7) Installation is, indeed, the reverse of removal.
* Now is a good time to consider installing either the adjustable urethane outer camber bushings or adjustable billet aluminum camber arms. Either of these will allow a far greater range of camber adjustment, compared to the stock adjustment. Additionally, the lower-outer bushing (the one pressed into the hub) may be in need of replacement. This bushing can be replaced with a new stock bushing or the urethane camber adjusting bushing.
Click below for replacement lower control arms (includes inner bushing) and bushings