Section 33 (Disc): Description

WARNING: This page does not describe the selected car, but rather 21 other vehicles, including the 1995 BMW 540i, 1995 BMW 530iT, 1995 BMW 530i, 1995 BMW 525i, and 1994 BMW 540i. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: BMW refers to the 5-series models covered in this article as E34 models.

All BMW E34 models are equipped with power-assisted four-wheel disc brakes with integral Anti-Lock Brakes (ABS). A brake booster power-assists a dual-circuit master cylinder. Single piston calipers act on vented front discs and solid rear discs. A brake pad wear sensor for each axle indicates when pads need replacement.

A dual-chamber master cylinder pressurizes 2 separate hydraulic circuits. Up to model year 1994, with 4 channel ABS, or with 3 channel ABS/ASC+T, front circuit actuates left front and right rear brakes, and rear circuit actuates right front and left rear brakes. From model year 1994 lines lead to ABS hydraulic unit on each axle.

NOTE: For information or service on ABS, ASC or ASC+T system, see appropriate ANTI-LOCK/TRACTION CONTROL article.

Automatic Stability Control (ASC) or Automatic Stability Control + Traction (ASC+T) system is equipped on some 1990 and later vehicles. Check for an ASC switch mounted in center console. In addition to the normal ABS function, the traction control system controls engine throttle and timing to reduce engine torque to help maintain vehicle stability. On later models equipped with ASC+T, an additional hydraulic pump is used to actuate rear brakes when rear drive wheels are spinning faster than the front wheels. ASC+T hydraulic control pump is mounted next to left front strut tower in engine compartment.

The parking brake is a dual drum system integrated into the rear wheel brake discs. Parking brake shoe replacement is not normally required, but periodic adjustment of the shoes may be necessary from time to time to compensate for wear. The parking brake should also be adjusted any time the cable, the rear brake discs or the parking brake shoes are replaced.