Vibration/Lateral Shake on Smooth Road Surfaces (Replace Rear Bushings/Shackles)

Some owners may comment about a vibration and lateral shake on smooth road surfaces at highway speeds of 88-113 km/h (55-70 mph).

1. Verify that the tire pressure is at 241 kPa (35 psi). Correct the tire pressure as necessary.
2. If the vehicle was built prior to January 1, 1999, replace both front hubs with P/N 15037207. The new hubs will have B9XXXXX in the first two positions of the hub code, which is stamped on the hub face. Refer to Wheel Bearing/Hub Replacement-Front (RWD) in the Front Suspension subsection of the Service Manual.
3. Be sure that the tires are the latest 55 Newton (12 lb) radial force variation tires by verifying the Department of Transportation (DOT) number (last 3 digits) on the inboard side of the tire, near the rim flange. (For example, 468 equals the 46th week of 1998).

If the tires have a DOT number indicating production before the dates listed in the chart below, replace all five tires. The dealer must use the "Dealer Tire Requisition & Return Document" in order to ensure the correct tires are received directly from the tire manufacturer(s). Refer to Warranty Administration Bulletin 60-05-02. Refer to the Tires and Wheels subsection of the Service Manual for tire and wheel replacement information.

Dynamically balance all tires using coated T weights. Refer to Corporate Bulletin 99-03-10-009 for information on T weight usage. Refer to Balancing Tires and Wheels in the Vibration Diagnosis and Correction subsection of the Service Manual.

Important: A torque limiting socket or torque wrench MUST be used to insure that the wheel nuts are tightened to specification. Do this by using the following three steps and the star pattern:

1. Snug the wheel nuts down by hand.
2. Using the star pattern and a torque limiting socket or torque wrench, tighten the wheel nuts to about half the final torque.
3. Tighten the wheel nuts to specification using the star pattern and a torque limiting socket or torque wrench.

Tighten
Tighten the wheel nuts to 190 N·m (140 lb ft).

Important: If the vehicle was built before April 1, 1999, replace the leaf spring rear eye bushings AND the spring shackles.

4. Replace the leaf spring rear eye bushings (one per side) with P/N 15050270, and the spring shackles (one per side) with P/N 15049656. Refer to the Rear Suspension subsection of the Service Manual for replacement procedures.

Vehicles built after April 1, 1999 will already have the new rear eye bushings in the rear springs and the new rear shackles. The new rear spring shackles and rear spring eye bushings will improve any lateral shake concerns.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: