senna

Took the car for a full center lock inspection by the dealer today. Everything is fine, no issue with the hubs, center lock or wheels. Did this just to be extra careful.

deputydog95

I think it's only a problem with cars that are actually tracked.

senna

Could be, but after the last track event I thought I should just double check.

ir_fuel

Can someone explain me this:

Torqued wheels according to spec, greased everything according to spec. Before driving on the track checked the torque on all wheels and of course engaged the locking spline. All fine. Did 1 25 minute run. Went to change tyres a couple of days later and right-rear side locking spline was stuck. Had to use a rubber hammer to get it moving again. BUT right-rear center lock was still torqued to the correct amount!

This stuff still moves around a 600Nm or what??

And another (unrelated) question (unrelated because we checked everything when the car was completely cooled down): does heat influence the torque spec? Example: I check the torque on all sides before driving the car, so everything is cold. After a few runs I check again. Could the temperature have changed the torque so that checking it with everything hot does not give the correct readouts? Or that removing and retorqueing a hot wheel a 600Nm gives a different torque once everything cools down again?

CRex

1. Splines locked does NOT mean zero rotation in the nut assembly. The CL nut, while "locked" relatively to the spline mechanism, can STILL rotate 10-20 degrees relative to the wheel & hub assembly until the lock's "inner" splines run up against the flanges inside the hub.

2. 600Nm is one thing. Holding the 600Nm is another. The nut can ABSOLUTELY loosen over time. I've experienced that myself and am not alone. Have your dealer check the affected wheel hub for signs of thread wear (often a result of over-torquing in the past)

3. Optimoly (that OEM silver grease) tends to dry up in turn into what looks like calcified dust/rocks. Over time you may expect the CL parts to get more difficult to remove. No surprise there.

Carrera GT

Some torque wrenches will give a "reading" on loosening. Mine is the "click" type with no meter/display.

To estimate with conventional hand tools:

1. position breaker bar to be at say 12:00, then note angle (hour hand of clock face position) to release the nut.

2. Say it turns from 12:00 to 9:00 before torque/effort reduces as the nut breaks away (loosens.)

3. Compare on all wheels. Use a video camera to replay the event to see when the torque wrench takes up load and when it accelerates as the nut loosens.

This will give an accurate comparison, not as convenient as a digital torque wrench or deflection indicator wrench, but adequate to diagnose any problems. Experience and disciplined consistency will improve sensitivity to noticing disparities.

ir_fuel

Over time in this case = 2 days?

I don't see the link. The only thing stuck was the locking mechanism. All the rest was perfectly normal. Once I got the mechanism unlocked the CL system seemed to perform normally.

I did an inspection of the parts but could not see anything wrong with them. I'll see if I can get the dealer to have a quick look at them when I pass.

But I could understand that it moved if the breakaway torque of the CL was lower than on the other wheels (which would explain why it moved), but it was not the case. A stupid idea but could it have moved in the other direction, so in stead of loosening becoming tighter?

Carrera GT

Temperature in terms of the axle/hub and wheel expansion can be an issue in the early life of the wheel and the wear-in of the mating surfaces.

I don't accept that the lube chosen by Porsche is changing its properties with heat or cycling.

As with conventional five slugs, once the assembly has had a heat cycle or three, it's as mated as it's going to get.

Anyway, once the wheel is loose on the hub, the extra air flowing between the wheel and the hub is cooling the surfaces.