When going with larger than factory brakes (i.e. big brake kits) it’s a good idea to use a master cylinder with a larger bore which moves a larger volume of fluid. Moving a larger volume of brake fluid helps to maintain a firm pedal feel as you increase the size of your brakes (without a larger BMC your brakes will feel softer, and will have longer pedal travel, as you increase the brake size). The stock E30 has a 22.2mm bore, this Brake Master Cylinder has a 25.4mm bore.
Fits the following cars:
E30 325 models (after 05/87) with ABS