Brakes - Squealing/Grinding Noises From Front Brakes
Date: February 16, 2006Order No.: P-B-42.10/51e
Supersedes: P-B-42.10/51d dated Dec 5, 2005
Group: 42
Revision History
SUBJECT:
Model 171.456
Model 203.065/076
Model 209.376/476, up to Vehicle Production 06/2004
Model 209.375/475
Model 211.056, up to Vehicle Production 08/2005
Model 211.070
Model 215.375/376/378
Model 219.375
Model 220.067/170/175/176/178
Model 230.475 Front Brake Squealing / Grinding Noise
If you receive customer reports in the above model vehicles of a squealing or grinding noise from the front brakes, even when the brakes are not applied, perform the following.
Warning!
It is imperative that on models equipped with SBC-Sensotronic Brake Control (211, 219 and 230), that the SBC brake system be deactivated before commencing any maintenance or repair work. Reference WIS document AS42.46-Z-0001-01A.
1. Inspect the front brake discs and pressure retaining springs for contact. If contact exists, replace the brake pad pressure retaining spring(s) with modified parts (Figure 1) after checking the brake lining per Step 2, and installing piston dampers per Step 4.
Note:
The squealing/grinding noise when the brakes are not applied is the result of the pressure retaining spring slipping out of position and scraping on the face of the brake disc. Each time the brakes are applied, the play within the brake caliper guide channel causes the brake pads to move a short distance in the circumferential direction of the brake disc. This movement is then transmitted to the two retaining pins, which consequently rotate a small amount during each brake application. This rotation is then transmitted to the pressure retaining spring, which can cause it to dislodge from its original position. The revised pressure retaining springs incorporate retainer tabs (Figure 1 red circles).
2. Check the version of the brake lining by comparing the designation imprinted on the backing plate (Figure 2), with that listed within the parts information table. Replace brake pads if necessary and install the correct version for the respective vehicle as notated within the parts information table after the installation of piston dampers per Step 4. Reference the following WIS documents.
^ Model 171 - AR42.10-P-1600VA
^ Model 203/209 - AR42.10-P-1600PF (valid for 209 up to 4/23/04) or AR42.10-P-1600AC (valid for 209 as of 4/24/04)
^ Model 211/230 - AR42.10-P-1600R
^ Model 219 - AR42.10-P-1600TX
^ Model 215/220 AR42.10-P-01601 and AR42.10-P-01611
3. Remove front brake caliper. Reference the following WIS documents.
^ Model 171 - AR42.10-P-0070VA
^ Model 203/209 - AR42.10-P-0070P (valid for 209 up to 4/23/04) or AR42.10-P-0070AC
(valid for 209 as of 4/24/04)
^ Model 211/230 - AR42.10-P-0070R
^ Model 219 - AR42.10-P-0070TX
^ Model 215/220 - AR42.10-P-00701
Note:
It is not necessary to completely remove the front brake caliper. Only remove caliper to gain suitable access to the caliper pistons. Do not disconnect brake hose from brake caliper. Brake hose must not be pulled or stretched. Fasten brake caliper to a suitable point in wheel house to relieve brake hose of load and secure against falling.
4. Install piston dampers in the pistons of the front brake calipers. The piston damper must be inserted into the piston with the rounded part first.
5. Reinstall brake calipers, pads, and pressure retaining springs in reverse order.
Parts Information
In Case of Warranty