Centerlock failure
08-17-2011, 02:56 PM
#63
Rennlist Member
Kind of annoyed by the CL Blind lovers rhetoric....
I havent seen one person say "CL's are amazing! Screw lugs, Porsche is God". All we CL people ever say is it isnt as bad as people perceive it to be. This thread is meant to get to the bottom of the problem, and help other enthusiasts out. Plain and simple....
Now back to the topic, I wonder if the lack of applied grease had any effects on the issue. Totally agree DE organizers need to take pre-spec more seriously with CL owners. If anything, it will educate non-informed drivers of the issue.
I havent seen one person say "CL's are amazing! Screw lugs, Porsche is God". All we CL people ever say is it isnt as bad as people perceive it to be. This thread is meant to get to the bottom of the problem, and help other enthusiasts out. Plain and simple....
Now back to the topic, I wonder if the lack of applied grease had any effects on the issue. Totally agree DE organizers need to take pre-spec more seriously with CL owners. If anything, it will educate non-informed drivers of the issue.
08-17-2011, 02:58 PM
#64
Rennlist Member
Perhaps he has been "bagged" and "gagged" by Porsche AG? Maybe they promised that if they fix his car completely under warranty and he says nothing further on the subject, then he will "kept" in CL wheels and hardware for life.
In a thick German accent, "If you don't you vill be shot!"
Doug N.
In a thick German accent, "If you don't you vill be shot!"
Doug N.
08-17-2011, 03:03 PM
#65
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Join Date: Feb 2006
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Kind of annoyed by the CL Blind lovers rhetoric....
I havent seen one person say "CL's are amazing! Screw lugs, Porsche is God". All we CL people ever say is it isnt as bad as people perceive it to be. This thread is meant to get to the bottom of the problem, and help other enthusiasts out. Plain and simple....
Now back to the topic, I wonder if the lack of applied grease had any effects on the issue. Totally agree DE organizers need to take pre-spec more seriously with CL owners. If anything, it will educate non-informed drivers of the issue.
I havent seen one person say "CL's are amazing! Screw lugs, Porsche is God". All we CL people ever say is it isnt as bad as people perceive it to be. This thread is meant to get to the bottom of the problem, and help other enthusiasts out. Plain and simple....
Now back to the topic, I wonder if the lack of applied grease had any effects on the issue. Totally agree DE organizers need to take pre-spec more seriously with CL owners. If anything, it will educate non-informed drivers of the issue.
08-17-2011, 03:06 PM
#66
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08-17-2011, 03:53 PM
#68
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This is terrifying with the speeds we carry and other cars on the track...I'm really glad the OP is ok.
Just to make sure I'm not missing something important, is this the proper procedure for the wheels?
1. unweight the wheel (car off the ground)
2. break CL nut free and remove wheel
3. grease the CL nut as described in the TSB
4. replace wheel on hub
5. check the spline (lock) is not stuck in the inner most position and can move freely (this is fuzzy to me, please confirm)
6. tighten CL nut by hand or hand tool until tight
7. with the car still off the ground, torque the car to the appropriate spec (444 ft/lbs)
8. back off the CL nut by roughly 1/4 turn
9. re-torque the CL nut to the appropriate spec (444 ft/lbs)
10. re-weight the wheel by bringing the car back to the ground
Did I miss anything?
Just to make sure I'm not missing something important, is this the proper procedure for the wheels?
1. unweight the wheel (car off the ground)
2. break CL nut free and remove wheel
3. grease the CL nut as described in the TSB
4. replace wheel on hub
5. check the spline (lock) is not stuck in the inner most position and can move freely (this is fuzzy to me, please confirm)
6. tighten CL nut by hand or hand tool until tight
7. with the car still off the ground, torque the car to the appropriate spec (444 ft/lbs)
8. back off the CL nut by roughly 1/4 turn
9. re-torque the CL nut to the appropriate spec (444 ft/lbs)
10. re-weight the wheel by bringing the car back to the ground
Did I miss anything?
08-17-2011, 04:33 PM
#69
Rennlist Member
Hi Brim,
Clarification on #5: You should be able to poke the locking mechanism with your finger, it should freely move with its spring loaded action in and out (in the axle orientation). Also, you can reach in and just slide it out, it just sits perfectly in the hub.
Also, add #11: Put the locking pin in the "lock" position, this is, flush with the inner toothing of the CL nut - see step 15 in the new supplement for CL wheels.
Cheers and good luck all!
Doug N.
Clarification on #5: You should be able to poke the locking mechanism with your finger, it should freely move with its spring loaded action in and out (in the axle orientation). Also, you can reach in and just slide it out, it just sits perfectly in the hub.
Also, add #11: Put the locking pin in the "lock" position, this is, flush with the inner toothing of the CL nut - see step 15 in the new supplement for CL wheels.
Cheers and good luck all!
Doug N.
08-17-2011, 04:43 PM
#70
Here's the link to the GT3 Owners Manual.
http://www.porsche.com/all/media/pdf...l_GT3_PCNA.pdf
You can find this text on page 4
"Your vehicle warranty does not cover use in competition, racing or track use or other events. Components and/or parts that fail during racing or driving events (including Porsche sponsored events) will not be covered by the manufacturer new car limited warranty or the pre-owned vehicle warranty."
http://www.porsche.com/all/media/pdf...l_GT3_PCNA.pdf
You can find this text on page 4
"Your vehicle warranty does not cover use in competition, racing or track use or other events. Components and/or parts that fail during racing or driving events (including Porsche sponsored events) will not be covered by the manufacturer new car limited warranty or the pre-owned vehicle warranty."
08-17-2011, 06:37 PM
#71
Rennlist Member
Same BBS here, no issues.
Anything leading up to faillure? Vibration? You sure it was "locked"? My left rear has become hard to "lock" get the lock to pop out, the other 3 are easy.
I hope that it is OK that I shared this on a couple of other forums to see if you are indeed the first to have the displeasure of losing one..
Anything leading up to faillure? Vibration? You sure it was "locked"? My left rear has become hard to "lock" get the lock to pop out, the other 3 are easy.
I hope that it is OK that I shared this on a couple of other forums to see if you are indeed the first to have the displeasure of losing one..
I am sick looking at this picture. Warranty from PNA? For a tracked car? Ha! Never happen.
Funny how all the product literature shows the car on a track, but the warranty specifically excludes track use of any kind.
I still stick by my assertion that the C/L on this car are poorly executed and should never have been put on a street car.
Please report this to the NHTSA, I will be suprised if we don't see many more failures as these cars start to rack up miles. Basically, we are all beta testers for this poorly thought out bit of marketing fluff.
AP, are you still reading these forums????????
Funny how all the product literature shows the car on a track, but the warranty specifically excludes track use of any kind.
I still stick by my assertion that the C/L on this car are poorly executed and should never have been put on a street car.
Please report this to the NHTSA, I will be suprised if we don't see many more failures as these cars start to rack up miles. Basically, we are all beta testers for this poorly thought out bit of marketing fluff.
AP, are you still reading these forums????????
I must say that they fix everything that does not have to do with track abuse, like overrevs, suspension, tires, brakes and maybe give you a hard time with things that you could concider consumables like clutches and pressure plates.
But you must leave the car stock. It does depend on the dealer, but still after 3 years and 80 track days, I have been treaded fairly by Porsche.
I am not liking this one bit, however I am happy to hear you are ok and the car did not have any other damage after the incident.
Hmmmm......looks like metal fatigue in the hub thread area (as they are gone!!!).......this can't be good.......overtorquing?.......Or more likely the aluminum CL hubs may not be standing up to the new (significantly higher!) torque spec of 444ft.lb (600 N.m). GT3DE: Did you find the CL nut?
I'm sure PCNA will dig into it, they don't have much choice on this one.
Keep us informed.
Best Regards,
Doug N.
Hmmmm......looks like metal fatigue in the hub thread area (as they are gone!!!).......this can't be good.......overtorquing?.......Or more likely the aluminum CL hubs may not be standing up to the new (significantly higher!) torque spec of 444ft.lb (600 N.m). GT3DE: Did you find the CL nut?
I'm sure PCNA will dig into it, they don't have much choice on this one.
Keep us informed.
Best Regards,
Doug N.
Good eye! It sure did. Yowsers. Super curious to hear how this turns out.
**I have no idea what happened here nor cast any aspersions on the OP** however I have seen some dreadful centerlock remove/install practices, the system requires specific procedures and most folks don't have a clue or could give a crap to learn.
At Laguna in the garages last year I saw a supposedly reputable tech removing and installing these with an air wrench, no torque wrench after, and the splines not engaged when done
I tried gently to explain the procedure to a blank hostile stare and walked away in disgust.
**I have no idea what happened here nor cast any aspersions on the OP** however I have seen some dreadful centerlock remove/install practices, the system requires specific procedures and most folks don't have a clue or could give a crap to learn.
At Laguna in the garages last year I saw a supposedly reputable tech removing and installing these with an air wrench, no torque wrench after, and the splines not engaged when done
I tried gently to explain the procedure to a blank hostile stare and walked away in disgust.I have never checked/re-torqued after initial install of the CL. And have never had a problem across 80 track days now. Not necessary in my experience. As hard as these can be to break loose after a track weekend, I would be terrified of torqueing them even more when hot at the track for fear I would never get them loose again.
From a common sense standpoint I'm going to throw a few topics, and I expect yelling and crying from the CL-blind-lovers.
1) Aluminum flexes with changes on temperature and even more if there is a mass of 50+ lbs tighten to 500 ft-lbs or whatever the magical 6ft long torque wrench put on those CL wheels, and such mass generating up to 2g of lateral force.
2) if the locks are not properly placed, chances for the nut to start rotating are there.
3) It's truth the GT3 generates less than 300 ft-lbs of torque at the rear axle, but that's on acceleration, during braking it generates much more than 500 ft-lbs of torque in opposite direction. If these CL nuts all get tighten clock-wise, that means that during braking the driver's side nuts would tend to get loose as they are getting a force from the wheel/nut combined working counter-clockwise against the hub and rotor. I hope the are tighten clockwise on the right and counter-clockwise on the left side.
By looking at the picture I would say the CL nut got loose, and the red pin (they avoid complete 360 turn of the wheel over the hubs) took care of destroying the wheel and the 5mm thick PCCB center bells.
That's my theory and I'm sticking to it.
1) Aluminum flexes with changes on temperature and even more if there is a mass of 50+ lbs tighten to 500 ft-lbs or whatever the magical 6ft long torque wrench put on those CL wheels, and such mass generating up to 2g of lateral force.
2) if the locks are not properly placed, chances for the nut to start rotating are there.
3) It's truth the GT3 generates less than 300 ft-lbs of torque at the rear axle, but that's on acceleration, during braking it generates much more than 500 ft-lbs of torque in opposite direction. If these CL nuts all get tighten clock-wise, that means that during braking the driver's side nuts would tend to get loose as they are getting a force from the wheel/nut combined working counter-clockwise against the hub and rotor. I hope the are tighten clockwise on the right and counter-clockwise on the left side.
By looking at the picture I would say the CL nut got loose, and the red pin (they avoid complete 360 turn of the wheel over the hubs) took care of destroying the wheel and the 5mm thick PCCB center bells.
That's my theory and I'm sticking to it.
I think you have the answer. I do check spine engagement and torque before and after each session and the left rear has consistently required more degrees of turn to target torque than right rear. Also degree is greater with R6s v R888 which also supports your theory. Marring of nipples on the left rear also greater than right. The fronts do no loosen at all.
GT3DE, just a couple questions if I may...
Had you had the CL recall done? Did they identify any issues with the hubs at all?
Also, with swapping over wheels, did you follow the whole car off the ground, grease, torque and retorque procedure?
Just trying to understand what contributing factors there may be. We know that the setup is less than ideal but if the metalurgy and components aren't up to the task, we all in deep ****... I'll be making sure to be shown the wear on my rear hubs when it goes in next week so I know what to look for moving fwd...
Sorry this happened to you and I hope they at least step up and sort out the car if not the wheel... One BBS centre aint going to cost all that much in any case....
Ps. If they try to deny on the basis of aftermarket wheels, remind them what wheels their RS used last year in the 24 hr NBG enduro...
Had you had the CL recall done? Did they identify any issues with the hubs at all?
Also, with swapping over wheels, did you follow the whole car off the ground, grease, torque and retorque procedure?
Just trying to understand what contributing factors there may be. We know that the setup is less than ideal but if the metalurgy and components aren't up to the task, we all in deep ****... I'll be making sure to be shown the wear on my rear hubs when it goes in next week so I know what to look for moving fwd...
Sorry this happened to you and I hope they at least step up and sort out the car if not the wheel... One BBS centre aint going to cost all that much in any case....
Ps. If they try to deny on the basis of aftermarket wheels, remind them what wheels their RS used last year in the 24 hr NBG enduro...
This may very well be operator error, but the procedure is overly complex and prone to problems as many will fail to execute it properly. We've all seen CL failures in racing, including F1. The question is - what's wrong with five bolts, properly torqued? something anyone can do in their sleep. Why fix what's not broken?
I think there is a lot of aggression directed towards Porsche for not paying up for the repairs before they even responded to this issue (talking about lawyers and the such ...) . I propose we refrain from Porsche bashing until they make a statement about this.
The problem is we have a lot of unknowns on our hands here. The wheel might have been torqued correctly and the entire thing just broke. In that case we do have a problem. Or there was a problem with one of the parts, or the torque-ing wasn't properly done and the entire thing came loose. The damage we see could be caused by the wheel falling of and breaking things on its way out. It does not mean that it broke loose and then fell off.
I guess we need to wait on the results of the investigation.
The problem is we have a lot of unknowns on our hands here. The wheel might have been torqued correctly and the entire thing just broke. In that case we do have a problem. Or there was a problem with one of the parts, or the torque-ing wasn't properly done and the entire thing came loose. The damage we see could be caused by the wheel falling of and breaking things on its way out. It does not mean that it broke loose and then fell off.
I guess we need to wait on the results of the investigation.
Let's give it some time. In the meanwhile I will get my nuts replaced, hubs, nubbies and locks checked by the dealer, but with my "eyes only" inspection, all looks fine. This happened to 2 cars now that I know of (6speed poser claims the same). If there are more they will come forward, but I think we would have known of it already. Let's wait for PNA and OP responses.Well, you just answered my question. The nuts get tighten clockwise at all corners, and that is a problem.
Rear tires and wheels are much heavier than front ones, keep in mind that it is the rotor and hub wanting to stop, while the wheel/tire want to keep running (inertia), hence the torque in deceleration that exceeds the torque in acceleration. If this torque value gets high enough, it would be the same as getting the Incredible Hulk and ask him to rotate you driver's side rear wheel while the car is on the air and the handbrake fully applied, wheel and CL nut will come off.
However, Porsche has a lock for the CL system. But I wonder, if a torque value high enough just breaks that lock, and then it is just a matter of time for that right side wheel to come off.
Testing is easy, but some parts need to be sacrificed:
1) How much torque has to be applied to actually break the lock mechanism (damage it)
2) Calculate the torque the car is generating on deceleration. Using the braking distance and times, and the car's weight with driver this can be calculated.
If 1 and 2 are close in value, that's your answer.
During acceleration the passenger's side would be the problem, but the car barely makes 270 ft-lbs of torque to the wheels, not even close to the torque that has been applied to the CL nut when tightened.
During braking the driver's side would experience massive deceleration torque, and the more grip the tires have, the worse the problem would be.
The driver's side should be tighten counter-clockwise.
However, there are too many CL-blind-lovers so I rest my case. I'm a happy 5 Titanium lug bolts guy, so as long as these lovers don't wreck me at a track day, things would be just fine.
Rear tires and wheels are much heavier than front ones, keep in mind that it is the rotor and hub wanting to stop, while the wheel/tire want to keep running (inertia), hence the torque in deceleration that exceeds the torque in acceleration. If this torque value gets high enough, it would be the same as getting the Incredible Hulk and ask him to rotate you driver's side rear wheel while the car is on the air and the handbrake fully applied, wheel and CL nut will come off.
However, Porsche has a lock for the CL system. But I wonder, if a torque value high enough just breaks that lock, and then it is just a matter of time for that right side wheel to come off.
Testing is easy, but some parts need to be sacrificed:
1) How much torque has to be applied to actually break the lock mechanism (damage it)
2) Calculate the torque the car is generating on deceleration. Using the braking distance and times, and the car's weight with driver this can be calculated.
If 1 and 2 are close in value, that's your answer.
During acceleration the passenger's side would be the problem, but the car barely makes 270 ft-lbs of torque to the wheels, not even close to the torque that has been applied to the CL nut when tightened.
During braking the driver's side would experience massive deceleration torque, and the more grip the tires have, the worse the problem would be.
The driver's side should be tighten counter-clockwise.
However, there are too many CL-blind-lovers so I rest my case. I'm a happy 5 Titanium lug bolts guy, so as long as these lovers don't wreck me at a track day, things would be just fine.
I am looking at that photo again and see one side of the splines are sheared off while the other side is not. The only way I can imagine this happening is to speculate the threaded portion of the hub failed (broke away from hub) and rotated the CL nut on the splines as the wheel angled away (off vertical) from the hat.
The chunk of metal missing from the top side of the center of the hub would be from when the outer threaded part let go, and the wheel cocked on the internal CL spline mechanism, breaking off the chunk, which supports my theory. All the other damage would have been subsequent to that happening (progression of events).
Finding the threaded part of hub and CL would be key to conducting a metallurgical analysis of the shear point of the hub to see if that is what happened.
The chunk of metal missing from the top side of the center of the hub would be from when the outer threaded part let go, and the wheel cocked on the internal CL spline mechanism, breaking off the chunk, which supports my theory. All the other damage would have been subsequent to that happening (progression of events).
Finding the threaded part of hub and CL would be key to conducting a metallurgical analysis of the shear point of the hub to see if that is what happened.
Why are the splines sheared off while the other side is not?? I agree that the only way I can imagine this happening is to speculate the threaded portion of the hub failed (broke away from hub) and rotated the CL nut on the splines as the wheel angled away (off vertical) from the hat. And that to me is the big questions. Why did that fail?
08-17-2011, 06:44 PM
#72
After looking at the pictures I'm not so sure that the failure came initially from the CL nut assembly, but rather was an initial failure of one, then more of the 5 red anodized pins held in by 10 mm bolts because the splines of the hub assembly seem to be intact. If even one of the pins failed due to improper tightening or failure to fully release and engage the locking mechanism, then it would create additional shear to the remaining pins and manifest itself in further destruction of the hub housing and wheel as evidenced in the pictures. The 5 red anodized pins would seem to keep the wheel from spinning on the hub rather than simply being there for alignment purposes. It could be the weak link that led to catastrophic failure. The wheel is mangled so it took a hit on the 5 pins. I never had a problem with my CL's on my GT3 but admit to a bit of a warm fuzzy with the tried and true 5 lugs on my new GTS. Wouldn't keep me from another CL wheel though.
08-17-2011, 08:22 PM
#74
Addict
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I would like to see the pictures from "Carrera GT" back side of the wheels from his GT3 RS 3.8.
08-17-2011, 08:48 PM
#75
After looking at the pictures I'm not so sure that the failure came initially from the CL nut assembly, but rather was an initial failure of one, then more of the 5 red anodized pins held in by 10 mm bolts because the splines of the hub assembly seem to be intact. If even one of the pins failed due to improper tightening or failure to fully release and engage the locking mechanism, then it would create additional shear to the remaining pins and manifest itself in further destruction of the hub housing and wheel as evidenced in the pictures.
If the pins sheared first the wheel would simply freely rotate on the hat/hub, it would not have broken the outer part of the hub off. Think about it.
No offense and appreciate the post, but above explanation doesn't seem possible
