Jack F

My car is 19 C4GTS. I had a problem a while back with the 2 front center lock nuts splitting in half. Talked with the foreman at the Porsche dealer service department and they ended up rebuilding it with new circlips. That sorted out the problem until yesterday. 3 of the nuts split in half again during a wheel swap. It’s not the end of the world but it is a very messy process to get it back together.

I know this can lead to all kinds of jokes about my broken nut, failing nut…..

Do you CL owners have issues with the nut separating in half requiring relube and reassembly? Thanks in advance for the help.

mangu

I was having that issue. The source of the issue ended up being the use of too much lube. Once I toned down the amount of lube, I haven't had one split on me since. Hope this helps.

LWG

Exactly what I experienced too. I gave them all a good clean and removed all the lube and just lightly lubed it up. Havent had the issue since.

Jack F

Thanks to all. I’m bringing car in and hanging out while they look at it. The male hub portion has a certain wear pattern that is considered acceptable and what is not. I want them to look at that and look at the centerlocks. When they are ready to reassemble I’d like to see how little lube they use. That could be it and would be the ideal situation. Thanks again to everyone. I’ll reports back after they look at everything.

GTSMeister

First I thought you were describing the central bolt cracking in half but I think you mean the cone ring splits at the seam and falls out? Or maybe the circlip falls out along with the cone ring? By now, you know how it's put together with the circlip. There is a procedure in the service manual about how to grease the central bolt and that this should be done when certain conditions arise. Goes like this...

Re-grease the bolt if 1) over 700 Nm or under 400 Nm is needed to remove the bolt, 2) a jerky or fluctuating torque happens when tightening, or 3) if you feel stiffness or a slip-stick effect on the cone ring when turning by hand in the central bolt.

The re-grease process is to disassemble the bolt: remove the circlip, tap the cone ring out by striking on a piece of wood, then comes the washer. Light coating (.2 to .5mm) and generous (.5 to 1mm) are the two qualifiers for grease amounts. Clean it all off and use new Optimoly TA.

Grease as you re-assemble: light on the bolt surface, none on either side of the washer, fill the three holes on the cone ring to 1/3 to 2/3, light on the flat surface of the cone ring that touches the washer, light on the inner circular surface of the cone ring, light on the conical surface of the cone ring. Don't forget the circlip. On assembly of the wheel on the car, a very light (no spec for what this is) on the conical surface. Generous grease on the threads of the bolt and light on cylindrical part of the wheel hub.

Of course apply the 600 Nm, back off 60 degrees and re-apply 600 Nm.

Current forum-wisdom says that the reason for the high torque needed when removing the bolt is because the flat surfaces on either side of the washer do not have the right amount of grease. It's not just the conical surface on the cone ring that needs to slide. But this is the surface you normally see and so it gets greased. The other hidden surface also needs to be greased correctly. You want all the surfaces to slide with about the same force needed, hence the use of light grease amounts on these surfaces. Do one more than the others and you'll get binding action.

So, watch for the high/low/jerky torque when removing the bolt and service if needed.

To aid in getting the torque correct, invest in a "torque adaptor" that measures torque directly at the wheel bolt. That way you don't have to guess at the factor for torque multipliers (I use one). I use the Neiko 20743A torque adaptor.

GTSMeister

I just did this service and wanted to note that it's really hard to get the circlip out of the slot for disassembly by itself. Really you just have to whack it on a piece of wood to get the cone ring and circlip to pop out.

Jack F

UPDATE: took car to dealer. Spoke with shop foreman. He is a super nice guy that likes to get a clear idea of what the issue is before the tech starts the work. I discussed the nut separation and also mentioned that the wear pattern on the wheel hub looked too narrow. Three of the centerlock bolts/nuts separated the last time I took the wheels off. He said that only 1 separated when they took them off. I showed him the WM440519 Porsche Removing and installing wheel and central bolt document. He had that pulled up in the shop when we went to look at the car. The colored photos were much better than the black and white photos in the doc I have. While the document says that at least 10mm wide contact pattern is needed this will not be immediate and low mileage cars may have less wear pattern. What is low mileage, well Porsche obviously didn’t want to commit to a number of miles. We looked hubs over and he felt they all looked good. Uneven width of wear around the circumference with depressions would indicate that the bearing contact surface is not good and that would be an issue. So, in the end, all good. If the central bolt separates next time, I’ll patiently disassemble and relube per the document and that should be good since the comments above make it seem like appropriate Optimoly paste and not too much prevents center bolt separation.