Warning: Centerlocks Losing Torque
07-04-2012, 10:21 AM
#61
Pete, that's exactly what I meant when I said the inner splines have a certain degree of rotation play designed INTO the system.
Notice in your picture how there are two types of "ridges" between those inner splines? It is the the wider ones that are showing scuff marks from rotational contact with the "flanges" (for lack of a better term) inside the hub (arrow in photo below).
By my potato math, there appears to be 5 "flanges" on the hub (I need to see the actual thing to confirm). The gap in between the flanges is about 3x the width of the flange itself. That's some 12-14 degrees of rotation allowed between the lock splines and hub flanges in a worst-case scenario (i.e. flange landing at the extreme end of one ridge), no?
I was remiss to not notice the state of my RR CL spline when I started untorquing that wheel. Will have to wait until wheel disassembly to show the state of those inner splines...
Notice in your picture how there are two types of "ridges" between those inner splines? It is the the wider ones that are showing scuff marks from rotational contact with the "flanges" (for lack of a better term) inside the hub (arrow in photo below).
By my potato math, there appears to be 5 "flanges" on the hub (I need to see the actual thing to confirm). The gap in between the flanges is about 3x the width of the flange itself. That's some 12-14 degrees of rotation allowed between the lock splines and hub flanges in a worst-case scenario (i.e. flange landing at the extreme end of one ridge), no?
I was remiss to not notice the state of my RR CL spline when I started untorquing that wheel. Will have to wait until wheel disassembly to show the state of those inner splines...
Understood now. You are correct in this observation. Thank you for the carefully explained and deliciously technical post...haha!Plausible explanation--false torque from dried grease INSIDE the CL mechanism. I last broke out and greased the conical ring in March, whereas the outer conical surface I grease every event. That said, it's only been three months...
Pete much as I truly appreciate all your invaluable input I think you're missing one thing--it's not the wheel moving relative to the hub. It's the whole lock--bound to the nut in the engaged position--moving relative to the hub. Your own picture tells that very same story!! I won't know this for sure until I get to see the innards of my RR lock. But one thing is clear--at multiple points in the past I've torqued it to 450lbft, fully engaged the splines, and afterwards discovered it took less than that amount of torque to undo the CL. I'm not a newbie to the complications of the CL system thanks to you and others, do regularly inspect the disassembled CL parts myself, and do not have issues with any other wheel other than the RR.
Pete much as I truly appreciate all your invaluable input I think you're missing one thing--it's not the wheel moving relative to the hub. It's the whole lock--bound to the nut in the engaged position--moving relative to the hub. Your own picture tells that very same story!! I won't know this for sure until I get to see the innards of my RR lock. But one thing is clear--at multiple points in the past I've torqued it to 450lbft, fully engaged the splines, and afterwards discovered it took less than that amount of torque to undo the CL. I'm not a newbie to the complications of the CL system thanks to you and others, do regularly inspect the disassembled CL parts myself, and do not have issues with any other wheel other than the RR.
Porsche's main failure other than going to CL is their negligence in failing to be fully transparent with the details of the correct use of these CLs and going beyond dealerships with this information. Every owner should have received a manual supplement with the full procedure, why it needs to be done and the 18 page document of warning signs so they, their local mechanic or tyre shop all have the opportunity to be informed. Whilst its great to be able to jump onto an amazing forum like this and be informed by Savy, Izzone and 911slow, this shouldn't be how such critical information should circulate!
Porsche should have been smart enough to identify the weaknesses in a seemingly more complicated system for the average consumer but should also have been smart enough to realise that going to the dealer for a wheel swap (as they'd prefer) is ridiculous... Wheels don't fit in the car and we don't all live 5 minutes away from one...
If ever there was a time to follow the "KISS- keep it simple stupid" principle, this would be it Porsche!!!
ps. As for the suggestion that the secondary locks spring back in the hubs, I have never seen this and realistically doubt this is even possible! I'd have to say if the secondaries aren't engaged, its human error! When I did my 1st wheel swap two months after delivery, two were not engaged from the factory and on at least two occasions in the first 6 months of ownership, I received the car back from the dealer with one or two not engaged right! I now check them after every visit to the dealer!!!
Porsche should have been smart enough to identify the weaknesses in a seemingly more complicated system for the average consumer but should also have been smart enough to realise that going to the dealer for a wheel swap (as they'd prefer) is ridiculous... Wheels don't fit in the car and we don't all live 5 minutes away from one...
If ever there was a time to follow the "KISS- keep it simple stupid" principle, this would be it Porsche!!!
ps. As for the suggestion that the secondary locks spring back in the hubs, I have never seen this and realistically doubt this is even possible! I'd have to say if the secondaries aren't engaged, its human error! When I did my 1st wheel swap two months after delivery, two were not engaged from the factory and on at least two occasions in the first 6 months of ownership, I received the car back from the dealer with one or two not engaged right! I now check them after every visit to the dealer!!!
For those who have not seen the inside of a dissembled CL, here you go. The shell with the threads and outer teeth is separate from the conical assembly that transmits tightening torque to the hold force against the wheel. This is why the system does not need l/r threads for different sides of the car, any movement of the wheel is insulated from the shell by that flat thrust surface. (But CRex is correct that the locking spline assembly can allow for some small movement in the shell to occur). In th epictures below the surface is wiped clean of OptiMoly.
07-04-2012, 10:36 AM
#62
Rennlist Member
Lewis...just drink more....seems to work for Trakcar and Izzone.....I bet those cats have more wheels changes and DE laps than anyone on rennlist and with CL's too.
Porsche should hire Izzone with his engineering background to rewrite the CL section of the owners manual and they could use Trakcar as the demo model...LOL....Porsche should include a rewards card for World of Beer with every CL car sold. Seems to work for these guys...right?
Porsche should hire Izzone with his engineering background to rewrite the CL section of the owners manual and they could use Trakcar as the demo model...LOL....Porsche should include a rewards card for World of Beer with every CL car sold. Seems to work for these guys...right?
07-04-2012, 10:41 AM
#63
Is this still the most current procedure? https://rennlist.com/forums/997-gt2-...read-this.html
I understand the spline issue and torque/loosen/torque requirement, but I'm not 100% on the greasing procedure. I've swapped my wheels once and I'm about to swap again.
I understand the spline issue and torque/loosen/torque requirement, but I'm not 100% on the greasing procedure. I've swapped my wheels once and I'm about to swap again.
07-04-2012, 11:04 AM
#64
Nordschleife Master
07-04-2012, 11:08 AM
#65
Rennlist Member
Is this still the most current procedure? https://rennlist.com/forums/997-gt2-...read-this.html
I understand the spline issue and torque/loosen/torque requirement, but I'm not 100% on the greasing procedure. I've swapped my wheels once and I'm about to swap again.
I understand the spline issue and torque/loosen/torque requirement, but I'm not 100% on the greasing procedure. I've swapped my wheels once and I'm about to swap again.
Ps. The easiest way to seperate the centrelocks is to hold them from the outer section and to bang them firmly on a piece of timber ( the thread side) and they fall apart.
07-04-2012, 11:36 AM
#66
Rennlist Member
OK- One thing I haven't seen mentioned (might have missed in this long thread) is the mating surface between the wheel and the the hub. Imagine if there is dirt or debris between the wheel and the hub when you torque the wheel to 450 lbs- it gets crushed but none the less stays inbetween and under the forces you have with tracking the car maybe abrade the surface of the wheel or the hub and minutely remove material enough to loosen the torque. I don't think it would take much to do that not microns, but not much. Now imagine if the wheel itself is not milled perfectly to mate up with the hub, over time the high spots will wear, and bingo, you loose torque.
I am loath to throw any manufacturer under the bus, but I think I have this exact issue with my new track wheels- manufacturer name deleted for the moment. I just removed my wheels from Monday's track day and 3 out of 4 were definitely under 450 lbs torque- way under. When I look at the wheel hub mating surface it looks suspicious to me. I will post pics sometime later. Now I took apart and greased the CL very carefully per the procedure, everytime I put on and remove my wheels. I also inspected every aspect of the system before and after- everything is nominal, just a loss of torque.
What else could it be? I'm sure this is it.
I am loath to throw any manufacturer under the bus, but I think I have this exact issue with my new track wheels- manufacturer name deleted for the moment. I just removed my wheels from Monday's track day and 3 out of 4 were definitely under 450 lbs torque- way under. When I look at the wheel hub mating surface it looks suspicious to me. I will post pics sometime later. Now I took apart and greased the CL very carefully per the procedure, everytime I put on and remove my wheels. I also inspected every aspect of the system before and after- everything is nominal, just a loss of torque.
What else could it be? I'm sure this is it.
07-04-2012, 11:46 AM
#67
Race Director
Montoya, what wheels do you have? This could be crucial info....any pics too. Porsche does talk about the wheel and hub mating surface with pics in the CL TSB info I have.
07-04-2012, 11:51 AM
#68
Rennlist Member
Here is the pic of the hub. Doesn't look right does it?
MDrums- sorry let's not name manufacturers until they have a chance to respond. The crap that went on with the GMG wheels was not right, and everything here is speculation at this point.
MDrums- sorry let's not name manufacturers until they have a chance to respond. The crap that went on with the GMG wheels was not right, and everything here is speculation at this point.
07-04-2012, 12:08 PM
#69
Rennlist Member
Thread Starter
Here is the pic of the hub. Doesn't look right does it?
MDrums- sorry let's not name manufacturers until they have a chance to respond. The crap that went on with the GMG wheels was not right, and everything here is speculation at this point.
Attachment 645704
MDrums- sorry let's not name manufacturers until they have a chance to respond. The crap that went on with the GMG wheels was not right, and everything here is speculation at this point.
Attachment 645704
FWIW I think we have different problems--my 2 sets of wheels still look pristine on their mating surfaces (for now).
07-04-2012, 12:11 PM
#70
OK- One thing I haven't seen mentioned (might have missed in this long thread) is the mating surface between the wheel and the the hub. Imagine if there is dirt or debris between the wheel and the hub when you torque the wheel to 450 lbs- it gets crushed but none the less stays inbetween and under the forces you have with tracking the car maybe abrade the surface of the wheel or the hub and minutely remove material enough to loosen the torque. I don't think it would take much to do that not microns, but not much. Now imagine if the wheel itself is not milled perfectly to mate up with the hub, over time the high spots will wear, and bingo, you loose torque.
I am loath to throw any manufacturer under the bus, but I think I have this exact issue with my new track wheels- manufacturer name deleted for the moment. I just removed my wheels from Monday's track day and 3 out of 4 were definitely under 450 lbs torque- way under. When I look at the wheel hub mating surface it looks suspicious to me. I will post pics sometime later. Now I took apart and greased the CL very carefully per the procedure, everytime I put on and remove my wheels. I also inspected every aspect of the system before and after- everything is nominal, just a loss of torque.
I am loath to throw any manufacturer under the bus, but I think I have this exact issue with my new track wheels- manufacturer name deleted for the moment. I just removed my wheels from Monday's track day and 3 out of 4 were definitely under 450 lbs torque- way under. When I look at the wheel hub mating surface it looks suspicious to me. I will post pics sometime later. Now I took apart and greased the CL very carefully per the procedure, everytime I put on and remove my wheels. I also inspected every aspect of the system before and after- everything is nominal, just a loss of torque.
That does not look good. Kindly post up some pictures of your hub, flange and drive pins and I can offer some additional comments.
07-04-2012, 12:12 PM
#71
Rennlist Member
Mate this doesn't look right at all. With all this galling on the wheel I'm guessing you've seen wear on the rotor bell as well? The wheels' got to be real loose to create that kind of damage...
FWIW I think we have different problems--my 2 sets of wheels still look pristine on their mating surfaces (for now).
FWIW I think we have different problems--my 2 sets of wheels still look pristine on their mating surfaces (for now).
07-04-2012, 12:15 PM
#72
Rennlist Member
Sorry, but I have to get ready for a 4th celebration at my house. Stock wheels are on the car now. I inspected everthing- trust me it is nominal, no sign of unusual wear on the drive pins (tight), flange (smooth wide band, no galling). The only place might have some wear is the hub surface, but nothing unusual.
07-04-2012, 12:36 PM
#73
Rennlist Member
OK- Quick off of one wheel with pics. You can definitely see where the mating surfaces of the aftermarket wheel has worn on the hub. Everything else looks OK.
07-04-2012, 12:47 PM
#74
The wheel flange to brake hat flange mating area is critical to locking the wheel in place (rotationally) on the hub. Would be an interesting experiment to get a known straightedge on that wheel hub and see how flat the seating area is. If it is flat, then the weird wear might be caused by deformation of the wheel under load (not good either).
Let us know what you find?
07-04-2012, 12:52 PM
#75
Rennlist Member
Looks to me like you dodged the bullet, if that were my car I would personally be ok with the way that looks in regards to the car and the hub, but not be ok with how that wheel hub looks.
The wheel flange to brake hat flange mating area is critical to locking the wheel in place on the hub. Would be an interesting experiment to get a known straightedge on that wheel hub and see how flat the seating are is. If it is flat, then the weird wear might be caused by deformation of the wheel under load (not good either).
Let us know what you find?
The wheel flange to brake hat flange mating area is critical to locking the wheel in place on the hub. Would be an interesting experiment to get a known straightedge on that wheel hub and see how flat the seating are is. If it is flat, then the weird wear might be caused by deformation of the wheel under load (not good either).
Let us know what you find?