Centerlock Wheel System and Track Usage

[Trackrat]

There are some things trackrats need to be aware of and fully educated on in regards to using OE centerlock system on track.

The CL system has proven its durability and strength both in the recent Pikes Peak Hillclimb on a GT2RS and in the 24 hours Nurburgring race on an GT3RS last year. Both of these cars were fitted with the OE centerlock system (not a Cup or Carerra GT style centerlock system which is totally different from GT2/GT3 system!).

When basic procedures are followed and routine examination is done, the CL system should be expected to be safe and troublefree. Here are some tips:

• Preload the system following the Porsche recommended procedure! You have to grease, because without grease you use up a lot of torque overcoming the friction between the CL ring and the wheelcone.
• The recommendation from 500nm to 600nm is solely adding an additional safety margin to the system to ensure enough preload pressing the wheel to the hub flange.
• If slicks are used on the car the load on the hub system is up to 20-30% higher than with standard tires. In that case 600 Nm preload torque is important because static g forces in cornering are up to 1.7 g's instead of 1.4 on Michelin Pilot Sport Cups
• Checking the hubs is important- the system can be torqued up to more than 1000 Nm before any of the components gets irreversible damage.
  Crucial is to see if the hub has a lot of marks (caused by movement of the wheel against the hub) sometime in its life.
• Cup car hubs "time-out" at 100 hrs. That goes for 5 bolt hubs as well. When on track 80% driving in your GT3 does no harm, 100% driving requires race-car type maintenance.
• Bottomline- the system is safe as long as you treat it right. But even then, after thousands of hard track miles you should consider renewing some parts, even though its not pointed out part by part in the manual. If you use your car as a racecar you should perform regular inspection/replacement the same way.
• Regarding the hubs: If they look ok, drive on. There is no reason to believe that anything will break without first showing marring/gouging signs on the horizontal part of the hub.

The CL system needs more attention than a 5 bolt system to ensure the proper amount of preload on the wheel/hub connection. Therefore it is less foolproof, like all CL systems on racecars as well.

A scarred/damaged hub resulting from too low torque/loose centerlock nut will be immediately obvious upon visual examination. It would appear as deep concentric gouges in the metal. In this case the hub must be replaced. In a correctly maintained CL system, hub damage like this would not occur.

A wide, greyish, non-gouged coloration pattern, in the area that the inner part of the nut rides on the hub, is normal.