Vehicle Pulls to Right During Acceleration or at Highway Speeds (Add Shim Between Engine Cradle and Right Rear Engine Mount and/or Modify Transmission Mount Bracket)

Some customers may comment that the vehicle pulls to the right during acceleration or when driving straight at highway speeds.

Follow the steps below to diagnose and repair the vehicle, if necessary.

1. Perform an initial vehicle inspection.

1.1.	Check tire pressures and visually inspect the tires for damage or abnormal wear. Refer to placard for correct tire pressure.

1.2.	Perform a visual inspection of the front suspension for abnormal wear or damage.

1.3.	Check the wheel alignment. Refer to Measuring Wheel Alignment and Wheel Alignment Specifications in SI.

2. If the customer concern is not caused by any issue identified in Step 1, perform the Vehicle Test Drive Evaluation/Analysis procedure in this bulletin.
3. Perform the following steps based on the outcome of the test drive evaluation/analysis:

•	If the right pull condition is severe and primarily apparent during acceleration, perform the Transmission Mount Bracket Modification procedure in this bulletin.

•	If the right pull condition is significantly reduced at a constant speed when the vehicle is in Neutral, go to the Engine Mount Shim Repair procedure in this bulletin.

•	If the right pull condition is not significantly different with vehicle in DRIVE vs. NEUTRAL, contact GM TAC for further diagnostic assistance.

•	If the vehicle pulls to LEFT, contact GM TAC for further diagnostic assistance.

4. Confirm that the customer concern has been resolved.

1. Drive the vehicle on a dry straight, smooth, level road at 64-97 km/h (40-60 mph). Record the vehicle direction and amount of pull/lead or effort required to maintain a straight heading.
2. Remove your foot from the accelerator.
3. Shift the transmission into NEUTRAL in order to allow the vehicle to coast. Record the vehicle direction and amount of pull/lead or effort required to maintain a straight heading.
4. Momentarily release the steering wheel. Note the vehicle direction and amount of pull/lead or effort required to maintain a straight heading.
5. Repeat this test on the same road with the vehicle traveling in the opposite direction in order to eliminate any crown and/or crosswind effects. Lead/pull caused by non-level roads (crown) and crosswinds are considered normal.
6. Drive the vehicle on a dry straight, smooth, level road at 64-97 km/h (40-60 mph). Accelerate at Wide Open Throttle (WOT). Record the vehicle direction and amount of pull/lead or effort to maintain a straight heading.

1. Prior to elevating the vehicle on a hoist, remove the forward torque strut bolt that retains the torque strut to the engine side bracket. Refer to Engine Mount Strut Replacement in SI.
2. Add a 5.0 mm (0.197 in) thick shim between the cradle and the right rear engine mount. The shim should be large enough to cover the entire base of the mount to avoid stress on the mount. Refer to Engine Rear Mount Replacement in SI for instructions on how to remove the cradle from the engine mount.
3. Perform the engine and transmission mount balancing procedure. Refer to Engine and Transmission Mount Balancing -- All Mounts in SI.
4. Reinstall the forward torque strut bolt. Refer to Engine Mount Strut Replacement in SI.
5. Perform the Vehicle Test Drive Evaluation/Analysis procedure.

1. Prior to elevating the vehicle on a hoist, remove the forward torque strut bolt that retains the torque strut to the engine side bracket. Refer to Engine Mount Strut Replacement in SI.

Notice: Always use a wood block to avoid damaging the oil pan or transmission pan.

2. Raise the vehicle on body hoist and support the powertrain using a jack stand. Refer to Lifting and Jacking the Vehicle in SI.
3. Remove the two lower fasteners from the left hand transmission mount.
4. Remove the three fasteners from the mount bracket to transmission and remove the bracket from the vehicle. Refer to Transmission Mount Bracket Replacement - Left Side in SI.
5. Using a die grinder, slot three mounting bolt holes DOWN approximately 2 mm (0.079 in). The hole should only be elongated; do NOT make the slot any wider than the hole diameter.
6. Re-install the transmission mount bracket, locating it as far UP as possible prior to tightening.

Tighten
Tighten the bolts to 95 N·m (70 lb ft).

7. Perform the engine and transmission mount balancing procedure. Refer to Engine and Transmission Mount Balancing -- All Mounts in SI.
8. Reinstall the forward torque strut bolt. Refer to Engine Mount Strut Replacement in SI.
9. Perform the Vehicle Test Drive Evaluation/Analysis procedure. If the vehicle exhibits minor torque steer to the right, perform the Engine Mount Shim Repair procedure

For vehicles repaired under warranty, use: