Wheel hub assessment

The wheel hub is assessed in three steps: 

• Check the actual wheel hub (direct check)
• Check the wheel hub based on the appearance of the cone ring on the central bolt (indirect check)
• Check the wheel hub based on the appearance of the wheel cone (indirect check)

1. Check the wheel hub  .

   Examine the cylindrical surface of the wheel hub in the area in which the cone ring on the central bolt sits when the wheel is fitted → Checking wheel hub  .

   Fig 1: Checking Wheel Hub

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Wheel hub assessment
   Looks normal for a vehicle that has been driven	Excessive signs of wear
   Wide contact pattern  → Wheel hub OK  Contact pattern is at least 10 mm  wide on the cylindrical surface of the wheel hub -arrows-  . On vehicles with low mileage, the contact pattern may not be continuous, but must extend over an area that is at least 10 mm  wide → Wheel hub OK (1)  . The discolouration can vary from shiny metallic to dark grey.	Linear pattern  → Wheel hub not OK  Narrow (linear) contact pattern that is uneven or only in spots on the cylindrical surface of the wheel hub -arrow-  .
   Additional picture:
   Result/Action required
   ==> The wheel hub  does not  have to be replaced.	==> The wheel hub  must be replaced.

   Information 

   If it is not possible to determine clearly based on the contact pattern of the wheel hub whether the wheel hub looks normal for a vehicle that has been driven or whether it shows signs of wear, the cone ring on the central bolt  and the conical area on the wheel  must be examined in order to further assess the wheel hub (indirect check on wheel hub, see Steps 2 and  3).

2. Check the wheel hub based on the appearance of the cone ring on the central bolt (→ Checking cone ring on central bolt  ).
   Fig 2: Checking Correct Cone Ring On Central Bolt

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Assessment of cone ring on central bolt
   Looks normal for a vehicle that has been driven	Excessive signs of wear
   Wide contact pattern  → Cone ring OK  There is no discolouration on the coating of a new cone ring on the central bolt. After a certain mileage, a grey/black contact pattern that is approx. 10-15 mm  wide forms, with the main pressure point in the centre -arrows-  . The complete surface is blackened on vehicles with high mileage.	Narrow line  → Cone ring not OK  Only a narrow line can be seen on the small diameter of the cone ring on the central bolt -arrow-  .
   Additional picture:
   Result/Action required
   ==> The wheel hub  does not  have to be replaced.	==> The wheel hub  must be replaced.

3. Check the wheel hub based on the appearance of the wheel cone  (→ Checking wheel cone  ).
   Fig 3: Checking Wheel Cone

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Wheel cone assessment
   Looks normal for a vehicle that has been driven	Excessive signs of wear
   Wide contact pattern  → Wheel cone OK  After a certain mileage, an even contact pattern that is approx. 10-15 mm  wide forms on the wheel cone -arrows-  . At first, this is just a shimmering surface, but the surface turns completely black on vehicles with higher mileage.	Narrow contact pattern  → Wheel cone not OK  Narrow (linear) contact pattern that is uneven or only in spots -arrows-  .
   Result/Action required
   ==> The wheel hub does not  have to be replaced.	==> The wheel hub  must be replaced. Checking the wheel cone is only an indirect way of checking the wheel hub. The actual wheel does  not need to be replaced if the wheel cone looks like this.