Checking Central Lock On Wheels

Information 

• The following specifications (for checking the central lock on wheels) apply to 911 GT3 vehicles and must be carried out during maintenance (observe maintenance schedules). 
• These test specifications must be carried out both at the regular service intervals as well as prior to using vehicles for intensive race track driving. 
• On the 911 Turbo with central lock, these specifications also apply in a limited way to the use of vehicles for intensive race track driving, not during maintenance. 

1. Remove wheel bolts and remove wheels.

   → 440519 REMOVING AND INSTALLING WHEEL WITH CENTRAL BOLT .

2. Check central bolt components.

   Checking includes: 

   1. 2.1. Check smooth operation of cone ring (turning cone ring to the wheel bolt). Partly disassemble the central bolt(s) if necessary and re-grease the sliding surfaces inside with Optimoly TA (aluminum grease).

      For instructions, see: → 440519 REMOVING AND INSTALLING WHEEL WITH CENTRAL BOLT .

      Information 

      Generally, there is no need to re-grease the inside of the bolt, except in the following situations:

      • A very high or very low torque is required to loosen the wheel bolt (more than 700 Nm/518 ftlb. or less than 400 Nm/296 ftlb.). 
      • In the event of a jerking, fluctuating tightening torque. 
      • If you feel any stiffness or stip-slick effect when turning the cone ring -1- for the wheel bolt by hand (cone ring -1- turns back and forward). Apply a certain amount of pressure when checking (turning the cone ring to the wheel bolt -arrows-  ).
        Fig 1: Installing Cone Ring On Central Bolt

        Courtesy of PORSCHE CARS NORTH AMERICA, INC.
   2. 2.2. Check wheel systems (wheel and wheel hub) and wheel driver pins for damage and unusual wear.  Replace parts if necessary.
   3. 2.3. Check that the wheel driver pins are fitted securely.
      1. 2.3.1. 911 Turbo: Re-tighten cheese head bolts (M6). Tightening torque 14 Nm (10.5 ftlb.) 
      2. 2.3.2. 911 GT3: Re-tighten cheese head bolts (M8). Tightening torque 31 Nm (23 ftlb.) 
   4. 2.4. Pull lockable wheel bolt (locking mechanism) out of the wheel hub and check that it is working.
      Fig 2: Identifying Lockable Wheel Bolt (Locking Mechanism)

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
      1. 2.4.1. Carry out a function test (element can move axially with automatic return to initial position). Check mechanical state and perform visual inspection (O-ring, inner and outer toothing).

         The lockable wheel bolt must not be repaired (O-ring can be replaced of course).

         Replace the lockable wheel bolt assembly if it is damaged.

3. Grease conical surface -1-  of the central bolt with a very light  coating of Optimoly TA (aluminum grease) before fitting each wheel. Make sure no dirt sticks to it. 
   Fig 3: Identifying Wheel Bolt Conical Surface Grease Applying Area

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.
4. Also grease thread in the wheel hub with a little Optimoly TA (aluminum grease). 
5. Re-fit wheels as instructed.

   → Installing Wheel With Central Bolt  .