The Ultimate Chromoly Adjustable Rear Control Arms Fits 1992-2005 318, 323, 325, 328, M3 (E36, E46) and 2003+ Z4 (does not fit 318Ti & Z3) $349/pairWhy use adjustable rear control arms? With a lowered car (either for street or track use), the non-adjustable original arms cause unwanted negative camber - the tops of the rear tires angle in too much, causing uneven tire wear and unwanted effects on handling. The adjustable rear control arm corrects this problem and can be tuned for any lowering, whether a street car ro a full-on race car through a +1.0? to -3.0? range. Co-developed with OE-supplier SPC Performance, the combination of OE engineering and UUC's enhancements make these arms truly "ultimate". With so many alternate choices, why UUC?Our custom-made proprietary design resolves many of the issues with other brands: Aluminum center rods are known to bend and fail under extreme use or after extended use (build-up of strain/weakening). Failure of a suspension part that keeps the wheel in place can be quite dangerous. UUC's chromoly center rods are the strongest in the world, virtually unbreakable in this application. The wrench-fixing point of UUC's chromoly arm will not "round off" like the fixing point of aluminum arms. UUC's original-style bushing is silent, and does not have the squeaks and rattles associated with the use of heim joints or spherical bearings. The combination of aluminum ends and chromoly steel center bar results in a reasonable weight, a balanced combination of mass and strength. UUC's stress-relieved aluminum cleavis end is not only very strong, but is also much more precise in fitment than stamped-steel alternatives. Construction details:Center bar: plated 4130 chromoly steel. End components: CNC-machined anodized aluminum for lightness, stress-relieved for strength and durability. Inboard bushing: high-durometer squeak-free rubber. All hardware included. Installation instructions: (Professional installation recommended. Alignment is necessary for correct camber adjustment.) 1. Before beginning any alignment always check for loose or worn parts, tire pressure and odd tire wear patterns. Determine amount of rear camber needed. Raise rear of vehicle and support body on jack stands. 2. Remove the inner and outer rear lower control arm mounting bolts and remove the arm from the vehicle. Note: It may be necessary to lower the rear member to fully remove the inner bolt. 3. Install the chromoly adjustable arm using the OE bolt on the inboard side and the new supplied bolt on the outboard side. Lower the vehicle and torque both bolts to manufacturer's specifications. Note: Tightening the bolts with the vehicle in the raised position may cause premature bushing wear due to preloading the bushings. 4. Adjust camber by loosening jam nuts and turning the center piece to desired camber specification. Note: The maximum length of the arm is reached when the flat on the end of the center adjusting rod is visible. Do NOT lengthen the arm beyond this point. 5. Tighten the jam nuts, set rear toe to specifications, complete alignment and road test the vehicle.