Brakes - Front/Rear Brakes Squeal When Braking
Date: June 4, 2008Order No.: T-B-42.10/80b
Supersedes: T-B-42.10/80a dated Nov. 21, 2007
Group: 42
Revision History
Revision Date Purpose
b 6/4/08 Work Procedure for Front Axle and Parts Information Updated
a 11/21/07 Model Year / Rear Brake Procedure Step 2, Parts and Warranty Info. Updated
- 9/20/07 Initial issue
SUBJECT:
Model 164.122/175/177/186/822/871
Model 251.122/165/175/177
Model Year 2006 - 2008
Front / Rear Brakes Squeal When Braking
If you receive customer reports in the above model vehicles where either the front and/or rear brakes squeal, perform the following to resolve.
Note:
^ Bed in the brake pads in the course of a normal road test if new brake pads are installed. Do not perform any special "bedding-in" operations.
^ Brake squeal does not usually necessitate the replacement of the brake disks. The only time the brake disks can potentially be the cause of the brake squeal is when it is seriously warped or heavily scored.
^ A damping plate is adhered to the backing plate of the brake pads. This adhered joint must fix the damping plate to the backing plate over its entire surface area in order to provide effective noise damping. If the adhered joint has become partially or entirely detached and the damping plate can be lifted off as a result, the brake pads must be replaced.
^ If the brake pads exhibit signs of excessive heat (white or red discoloration at the edges), this is due to excessively high thermal stress on the brakes. In this case, the brake pads must be replaced because satisfactory noise damping can no longer be provided.
Front Brakes
1. Reproduce squealing noises when braking and ensure that the squealing noise is coming from the front wheel brake.
2. For models 164.177 & 251.177 (AMG models) replace the brake pads with revised parts. The revised front brake pads have compound chamfered edges (Figure 1).
3. For all other models, check the version of the brake pads by comparing the designation number engraved on the backing plate
^ If the batch designation is in the old format (Figure 2) and the number YYY after the dash is lower than 191, the brake pads should be replaced in case of a complaint.
^ If the batch designation is in the new format (Figure 3) or if the old format number YYY after the dash is greater than or equal to 191, the brake pads do not need to be replaced since they are the latest version.
4. Check and see if the brake pads can be easily moved. Clean the brake pad guides if necessary.
5. Apply brake pad paste to the brake pad guides in the brake caliper as well as guide elements of the brake pads ("T-heads").
6. If new pads were not installed and the problem still persists, replace the brake pads. Refer to EPCnet by VIN for the latest applicable part number. Ensure to follow the above instructions (step 4) for proper location for application of brake past.
Note:
Refer to the following WIS documents for instructions on replacing the brake pads - AR42.10-P-0160GZ (164) or AR42.10-P-0160RT (251).
Rear Brakes
1. Reproduce squealing noises when braking and ensure that the squealing noise is coming from the rear wheel brake.
2. For X164 vehicles built before September 2007, replace the rear brake pads with revised parts (part no. 164 420 19 20). Reference WIS document AR42.10-P-0160GZ. For all other models and X164 with build dates after September 2007 proceed to step 3.
3. Check and see if the brake pads can be easily moved. Clean the brake pad guides if necessary.
4. Apply brake pad paste to the brake pad guides in the brake caliper as well as guide elements of the brake pads ("T-heads").
5. If new pads were not installed and the problem still persists, replace the current brake pads and repeat step 3 for instructions on application of brake past on the brake pads. Refer to EPCnet by VIN for the latest applicable part number.
Note:
Refer to the following WIS documents for instructions on replacing the brake pads - AR42.10-P-0160GZ (164) or AR42.10-P-0160RT (251).
Parts Information
Note:
The following allowable labor operations should be used when submitting a warranty claim for this repair. This information has been generated on November 21, 2007. Please refer to Netstar --> Star TekInfo --> Star Time for the most current labor time allowance.
In Case of Warranty, use the table.