This part is listed by BMW as BMW part number 34317838638 (34-31-7-838-638) and is described as Genuine BMW Brake Master Cylinder for E46 M3 (2003, 2004, 2005, 2006) and E85/E86 Z4M Coupe/Roadster (2006, 2007, 2008).
This Genuine BMW Brake Master Cylinder is a original-equipment replacement for your failing master cylinder.
The master cylinder controls the distribution of brake fluid through your entire braking system, so even a small leak from a failing part can cause poor brake pedal feel and inaccurate brake modulation. If you've found your brake pedal travel to be getting longer, particularly when sustained pressure is applied, a thorough inspection and likely replacement is highly recommended.
Supersedes the following BMW part numbers:
34312282624 (34-31-2-282-624)
34317838253 (34-31-7-838-253)
For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us at 877-639-9648.
BMW Fitments:
3 Series
E46 (99-05) > M3
Z Series
E85 / E86 Z4 (03-08) > Z4 M