Rear Wheel Bearing Replacement - Aluminum Trailing Arm

Introduction

The aluminum trailing arm uses a single sealed wheel bearing rather than the double roller bearing arrangement found in the steel trailing arm. This bearing is somewhat more difficult to remove.

The factory procedure calls for removing the trailing arm from the vehicle, heating it to 120 °C248 °F to 150 °C302 °F, and pressing the bearing out from the back with Porsche special tool VW 432. This procedure instead uses a slide hammer bearing puller with the arm in the car, though heating the arm first will make removal considerably easier.

As with the steel trailing arm, the hardest part of this job may be loosening the rear axle nut. The nut is extremely tight: the factory tightening torque is about 350 ft-lbs, so with an 18-inch breaker bar you must apply roughly 233 lbs of force at the end of the bar, and with a 24-inch bar roughly 175 lbs. Over time, rust building up on the threads means it takes significantly more force than the tightening torque to break the nut free — sometimes roughly double. If the required torque has doubled to about 700 ft-lbs, you may need a breaker bar as long as 4 feet (48 inches) for an average-sized person (175 lbs) to apply enough force.

Use an impact socket (32 mm or 36 mm depending on the vehicle), not a standard socket, since a standard socket can be destroyed when significant torque is needed. If the breaker-bar method below still cannot break the nut free, a shop will loosen it with a 3/4-inch-drive impact wrench (and retighten with a 1/2-inch-drive impact). Installation torque is unchanged at 500 N·m369 ft·lb — see Step 21.

1. Self-locking nut
2. Washer
3. 8 mm cheesehead bolt
4. Backing plate
5. Drive shaft
6. Wheel hub
7. Trailing arm
8. Circlip
9. Sealed bearing
10. Trailing arm rubber mounts

Tools

• Metric wrench set
• Metric socket set
• Jack stands
• Floor jack
• 8 mm cheesehead tool
• Slide hammer bearing puller
• Soft drift and hammer

Procedure

1. Set the emergency brake to resist axle rotation.

2. Loosen the rear wheel lug nuts several turns.

3. Raise that side of the vehicle with a floor jack.

4. Remove the lug nuts and rear wheel.

5. Remove the cotter pin for the axle.

6. Loosen and remove the axle nut: a. Try with an appropriate socket (32 mm or 36 mm) and a long breaker bar. If it releases, proceed to Step 7. b. Use an impact socket. Attach a breaker bar at least 24 inches long, parallel to the ground, with the handle resting on a jack stand. For the left wheel the bar must point rearward; for the right wheel, forward.

   Note: Ensure the breaker bar and jack stand cannot contact suspension or bodywork when the car is lowered.

   c. Slowly lower the floor jack until the car's weight breaks the nut free. d. If this still fails, a 3/4-inch drive impact wrench is required.

7. Remove the rear brake pads and calipers.

8. Release the emergency brake.

9. Using a Phillips head screwdriver, remove the brake rotor retaining screws.

10. Remove the rotor. If stubborn, thread M8 bolts into the provided holes and alternate tightening to jack the rotor off the hub.

11. Using the 8 mm cheesehead tool, disconnect the CV joint from the transaxle, pull the axle out of the trailing arm, and set aside.

12. Using a soft drift and hammer from inside the trailing arm, drive the rear hub out of the trailing arm.

13. Remove the parking brake shoes, spreader arm, and brake dust guard.

14. Remove the snap ring (circlip) next to the wheel bearing.

15. Heat the area of the trailing arm around the wheel bearing with a torch. Using a slide hammer puller from the outside of the trailing arm, pull the wheel bearing out.

16. Apply a light coating of grease to the inside of the trailing arm bearing surface to ease installation of the new bearing.

17. Using a hammer and a socket approximately the same size as the new bearing, tap the new bearing into the trailing arm. Drive it in evenly to prevent binding.

18. Install the snap ring (circlip) next to the bearing.

19. Install the brake dust guard, parking brake pads, and spreader arm.

20. Install the rear hub into the trailing arm.

21. Install the hub and axle nut. Torque the axle nut to 500 N·m369 ft·lb.

22. Install the brake rotor and secure with the Phillips head screws.

23. Install the brake caliper and pads. Pump the brakes before driving.

24. Adjust the parking brakes (see BRAKE-05).

25. Install the rear wheel.

26. Lower the vehicle.

27. Repeat the steps for the other side if needed.