Checking Front Wheel Suspension

Information 

• The trailing arm and wheel bearing housing are safety-relevant components. Perform the test with extreme care and accuracy  .
• If in doubt, always replace the lower trailing arm and wheel bearing housing  .

Information 

• The first step is to perform suspension alignment  .
• If the camber and toe values on the front axle are 1° outside of the tolerance limit and one of the following telltale signs is found, the trailing arm and wheel bearing housing must always be replaced  .

1. Performing front and rear suspension alignment  .

   > 449503 PERFORMING FRONT AND REAR SUSPENSION ALIGNMENT

   1. 1.1  If the camber and toe values are 1° outside of the tolerance limit  , the following telltale signs of damage to the chassis must always be checked. Continue with See 
   2. 1.2  If the camber and toe values are within the tolerance limit and the customer complains that the steering wheel is shaking or vibrating  , the following telltale signs of damage to the chassis must always be checked. Continue with See 

      Check other telltale signs of damage to the chassis: 

      Information 

      Fracture of the brake disc hub can be identified by a loose friction ring on the brake disc.

2. Check the brake disc hub for breaks/cracks on both sides of the vehicle  .
   • Result is OK: Continue with See 
   • Result is not  OK: Continue with See 
   1. 2.1 Replace lower trailing arm and wheel bearing housing on the affected side of the vehicle  .

      > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

      > 405019 REMOVING AND INSTALLING WHEEL BEARING HOUSING 

      Remove and install the relevant installed brake disc (grey cast-iron/PSCB/PCCB).

3. Check brake disc lateral runout (brake disc fitted with adapter plate)  .

   > 465002 CHECKING FRONT BRAKE DISCS

   > 465202 CHECKING FRONT PSCB BRAKE DISCS

   > 465102 CHECKING FRONT PCCB BRAKE DISCS

   • Result is OK: Continue with See 
   • Result: Lateral runout > specification  : Continue with See 
   1. 3.1 Replace lower trailing arm and wheel bearing housing on the affected side of the vehicle  .

      > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

      > 405019 REMOVING AND INSTALLING WHEEL BEARING HOUSING 

      Remove and install the relevant installed brake disc (grey cast-iron/PSCB/PCCB).

4. Check lower trailing arm joint on wheel bearing housing (lower trailing arm ball pin and wheel bearing housing taper bushing)  .
   1. 4.1  The following steps must be carried out before starting to check the components:
   2. 4.2  Remove lower trailing arm -1-  on wheel bearing housing.

      > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.

      Mounting for love, trailing arm on wheel bearing housing (shown as an example)

      1. 4.2.1  Remove sleeve -1-  from > T10187 - press-out tool  .

         Courtesy of PORSCHE CARS NORTH AMERICA, INC.

         Removing sleeve from T10187

      2. 4.2.2  Unscrew nut -2-  on joint pin for lower axle joint as far as required until it is flush with the upper edge of the joint pin.
      3. 4.2.3  Press off joint pin on the lower trailing arm using > T10187 - press-out tool  . > Pressing off joint pin 

         Courtesy of PORSCHE CARS NORTH AMERICA, INC.

         Pressing off joint pin

      4. 4.2.4  Screw off nut -2-  on joint pin for the axle joint.
   3. 4.3  Use a wooden stick to tap against the taper bushing -1-  from below and check that the taper bushing -1-  is fitted securely in the wheel bearing housing -2-  .

      Check ball pin on lower trailing arm -3-  for scratches, notches and deformation.

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.

      Checking that taper bearing is fitted securely in pivot bearing

      • Result is OK: Continue with See 
      • Result is not  OK: Continue with See 
   4. 4.4 Replace lower trailing arm and wheel bearing housing on the affected side of the vehicle  .

      > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

      > 405019 REMOVING AND INSTALLING WHEEL BEARING HOUSING 

5. Check axle components and lower trailing arm  .

   Preliminary work:  Remove cover for front underbody.

   > 519219 REMOVING AND INSTALLING COVER FOR FRONT UNDERBODY

   1. 5.1  Test points:
      • Check axle components for cracks and deformation.
      • Check components or axle components for signs of rubbing or hitting (e.g. connecting link for anti-roll bar hitting against spring strut forks).
      • Check lower trailing arm for deformation.

        > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

        Result: 

      • Result is OK: Check is complete. Complete the vehicle See 
      • Result is not  OK: Continue with See 
   2. 5.2 Replace lower trailing arm and wheel bearing housing on the affected side of the vehicle  .

      > 401719 REMOVING AND INSTALLING LOWER TRAILING ARM 

      > 405019 REMOVING AND INSTALLING WHEEL BEARING HOUSING 

6. Complete the vehicle.
7. Perform suspension alignment and make adjustments if necessary.

   > 449503 PERFORMING FRONT AND REAR SUSPENSION ALIGNMENT