Service Information bulletin: Repair work on brake disk

W33.20-1044-05

Shown on front-axle 739.53 brake disk

1 Screw

2 Wheel flange ring

3 Brake disk

4 Spacer washer (for front axle 739.53 only)

5 Wheel hub

W42.10-1233-11

Shown on front-axle 739.53 brake disk

1 Screw

2 Wheel flange ring

3 Brake disk

4 Spacer washer (for front axle 739.53 only)

5 Wheel hub

A Contact surface (wheel flange ring/brake disk)

B Centering seat (brake disk/wheel hub)

C Contact surfaces (brake disk/spacer washer/wheel hub)

Due to recent events please remember that when installing brake disks, particular caution is to be exercised.

Because increased instances of cracks or fractures on the brake disk are being recorded, the repair instructions "Remove/install brake disk" have been revised.

Before installing the brake disk, the following surfaces must be thoroughly cleaned:

 Contact surface (A) wheel flange ring/brake disk.

 Centering seat (B) brake disk/wheel hub

 Contact surfaces (C), brake disk/wheel hub or brake disk/spacer washer/wheel hub

Roughly clean the surfaces first using a wire brush, then smooth over using emery cloth and then wipe down with a rag.

The contact surfaces (A, C) and centering seat (B) must be free of grease.

 There must be no dirt or corrosion residue between the wheel flange ring (2), brake disk (3), spacer washer (4) and wheel hub (5), as otherwise tension may arise when tightening the bolts and the brake disk may fracture.

Note the following too during installation:

 When positioning, the brake disk and wheel hub must not be tilted relative to each other, and they must make even contact with the contact surfaces (C).

 Turn in the new bolts (1) by hand first through several threads and then tighten crosswise to the required tightening torque value.