Suspension - Front End Knocking Noise On Bumps

L-SB-0021-12

March 30, 2012

Front Suspension Knock Noise

Service Category
Suspension

Section
Front Suspension

Market
USA





Applicability

Introduction

Some LS model vehicles may exhibit a knock/clunk noise while driving over bumps or when applying the brakes at any vehicle speed. Follow the repair procedure in this bulletin to address this condition.

Production Change Information





This bulletin applies to vehicles produced BEFORE the Production Change Effective VINs shown.








Parts Information








Warranty Information





Required Tools & Equipment

Repair Procedure

1. Conduct a road test to verify the condition.

NOTE
If noise is not present during the test drive, this bulletin does NOT apply.

2. If the condition is duplicated use ChassisEAR(TM) (or equivalent) to isolate the source of the noise.





^ If the noise is isolated to any of the three control arms identified in Figure 1 follow the Repair Manual to replace the control arms that exhibit the noise. Go to step 3.

^ Inspect the remaining control arms for cracking and/or abnormal wear. If cracking and/or abnormal wear is identified follow the Repair Manual to replace the control arms that exhibit this condition. Go to step 3.

NOTE
Upper control arms must be replaced in pairs. For example, if Upper No.1 is being replaced, Upper No.2 must also be replaced.

3. Replace the affected control arms.





Refer to the Technical Information System (TIS) applicable model and model year Repair Manual:

4. Perform the following steps to ensure that the new suspension arm bushings are relieved of stress.

NOTICE

Damage of installed parts may occur if these steps are NOT followed properly.

A. After installing new arms place the vehicle on the ground (NOT on lift).

B. With the engine idling turn the steering slowly from lock-to-lock 10 times.

5. Check front wheel alignment and adjust if required.

6. Road test the vehicle to confirm the noise is no longer present.