Presented by GT International

The Carrera GT is a remarkable machine, purpose built with carbon fiber, a naturally aspirated mid-engine V10 and a manual transmission to boot. Like its predecessor the 959, the Carrera GT was fitted with center-locking wheels where a single nut secures each wheel to these high performance machines. Center locks are now ubiquitous with Porsche’s GT and Turbo models, but are they practical on a road car? In this tech tip, we will discuss tools, disassembly, inspection, torque sequence and possible issues with Porsche center-locking wheels.

As car manufacturers homologate racing technologies to their road cars, special tools are typically needed for servicing, and it’s no different here. A special socket is included with center lock equipped vehicles but that’s about it. To properly service these wheels, a two post lift is highly recommended to provide a stable platform in which to break loose and torque the wheel nut. A ¾ inch torque wrench is also needed as these wheel locks are torqued to 600 Nm. You can find a mechanical online for about $200, but if you have access to a Snap-On dealer, get the digital version with torque angle. We use both; the mechanical to break torque, and the digital for re-torquing.

We recommend staying away from manual torque multipliers. In order for them to work properly, smooth even torque needs to be applied while the countering arm is held in place, usually by one of the wheel spokes which may cause damage. They are clunky to deal with and the dealer no longer uses them. Two people and some grease is all that’s left for you to remove or install center-locking wheels. The wheels must never touch the ground when removing or installing center locks. The second person should sit in the car and apply the brakes for removal and torquing.

When the center lock nut is removed, it’s important to inspect the lock cone, hub, wheel and brake rotor for unusual wear.  We recommend the component assessment guide that can be found at CarsAddiction.com by searching on “WM 4X00IN”.  This guide will walk you through the assessment process.  If it all checks out, then disassembly for cleaning and re-greasing is recommended next. This is done by tapping the lock on a hard surface to separate the cone section.  The lock consists of five pieces as shown in the images.  Once the lock components are greased and re-assembled, you’re ready for installation and torquing.

The torque sequence is straightforward and can be found online with a simple search:

–       Make sure locking nut is greased properly

–       Torque to the locking nut to 600 Nm 

–       Back off 90 degrees

–       Torque again to 600 Nm; on 997s for track use, a higher torque is needed 

–       Make sure the internal lock is completely out and flush with the splines

Common problems are typically related to maintenance and repair. If you have an emergency while on the road, it’s difficult to find a shop that will touch center locks. Most chain-type tire stores will refuse to work on them, but Porsche has a way to help you in this scenario. There is script on the lock that reads “STOP” and “100Nm”. These will help you tighten the nut to 100 Nm and get back on the road in an emergency. Use a marker or pencil to make a stop line on the wheel at the 100 Nm mark. Then tighten the nut until the stop line reaches the stop mark. This should be sufficient torque to get you to a service station or dealer. Whenever possible, please leave the servicing of center-locking wheels to professionals – they have the right tools and knowledge to keep you and your car safe. Stay tuned for the next tech tip where we will talk about GT3 engine failure, what to look for and your options.

Pit Stop is a recurring column with technical tips contributed by our sponsor GT International