Steering/Suspension - Front End Squeak/Thump Noise

DTB

Date: October 6, 2008
Order No.: P-B-33.15/22a3
Supersedes: P-B-33.15/22 dated February 5, 2007
Group: 33





SUBJECT:

Model 170.447/449/465/466
Model211.022/026/056/065/070/072/076/077/082/083/087/090/256/265/276/277/282/283/287
Model 215.373/374/375/376/378/379
Model 219.372/375/376/377
Model 220.067/170/173/174/175/176/178/179/183/184
Model 230.470/471/472/474/475/476/477/479
Squeaking/Thumping Noise from Front Axle / Upper Ball Joint Sealing Boot on Upper
Control Arm Damaged/Torn

If you receive customer reports in the above model vehicles of a squeaking / thumping noise from the front axle, the cause may be that the tapered portion of the ball joint was over torqued due to one of the below reasons

- Use of an impact wrench during installation

- Tapered surfaces contaminated with oil or grease

- Application of excessively high torque

Any of the above items would pull the tapered portion of the ball joint too far into the steering knuckle so that the sealing boot is too taut on the joint and is twisted in this area with each rotary movement until the sealing bellows suffer a fatigue fracture. As a result, the joint corrodes and causes noises.

To resolve the noise condition, the joint must be replaced, but only if there are visible cracks. If there is a noise from the front axle and no cracks in the boot are present, further diagnosis is required to identify the cause. Refer to EPC for applicable part number. The following points must always be observed during installation.

- The conical joint must be free of oil and grease

- It must be tightened according to the specifications using a torque wrench or by the specified tightening angle.

- The joint must never be tightened using an impact wrench.

NOTE:

- Because of the modern coatings (zinc plating/silver), which have a relatively low breakaway torque, the test torque (run-down torque) is significantly lower (up to 20%) than the initial installation torque with new parts. This is normal.

- Parts damaged due to the conditions listed above may not be claimed under warranty. Any parts replaced for these reasons may result in the warranty claim being debited.