Check brake disks for wear - AP42.10-P-4258-02RQ

MODEL 190, 197, 205, 212, 217, 218, 222, 231 with CODE B07 (Ceramic brake system) 

The wear on the brake disks may only be determined by evaluating the wear indicators (1) using test films (2).

Parts ordering notes: 

Part number: A 197 001 77 99

Designation: Test film

Number: As required

3 wear indicators each are located on the inner and outer friction surface (1).

The dimension and weight specifications on the brake disk bowl cannot be used for determining the level of wear.

Fig 1: Identifying Ceramic Brake System

Courtesy of MERCEDES-BENZ USA

1. Detach test film (2) from carriers, place in the center on the wear indicators (1) and press on. Mark position of wear indicators (1) on test film (2).
2. Photograph all the test films (2) using a digital camera several times.

   Distance of approx. 10 cm, select macro function without flash.

3. Choose a representative photo of each wear indicator (1) on the computer monitor and zoom to an edge length of min. 3.5 cm.
4. Count all the squares in which burnt surfaces (light points) are visible and enter the number in the table. One square with < 50_% burnt out counts as a 1/2square. One square with ≥50_% burnt out counts as 1_square.
5. Add up the number of rejected squares for all wear indicators (1).

   If the sum of the rejected squares for all wear indicators (1) on one brake disk is ≥96, then both brake disks and all brake linings of this axle must be replaced.

   Fig 2: Identifying Brake Disc Wear Indicators On Test Film

   Courtesy of MERCEDES-BENZ USA
6. Detach all test film (2) and use dry cloths to wipe away any residue.
7. Archive photos.

Example (A): 

17 squares < 50 % = 17 x square = 8.5 squares

8_squares ≥50_% = 8_ X _1 square = 8.0_squares

16.5_squares

Example (B): 

11_squares < 50_% = 11_X_ 1/2square = 5.5 squares

14 squares ≥50 % = 14 X 1 square = 14.0 squares

19.5 squares