Race Shops: Weigh in on CL Reliability?
08-15-2012, 01:49 AM
#1
Rennlist Member
Thread Starter
Race Shops: Weigh in on CL Reliability?
There are a bunch of great shops that maintain a presence on this board and on Rennlist in general (Sharkwerks, RSS, GMG, BRRacing, Orbit to name a few). Given the several highly visible catastrophic CL failures of late, there seems to be a wide range of opinions on whether the CL mechanism should be trusted. Some say they're fine and the failures are due to error; others say go 5 lug or don't track at all.
To the shops that support and maintain these vehicles, what is your take on the issue? All insight greatly appreciated.
To the shops that support and maintain these vehicles, what is your take on the issue? All insight greatly appreciated.
08-15-2012, 03:55 PM
#2
Rennlist Member
:crickets:
08-15-2012, 04:28 PM
#4
Rennlist Member
08-15-2012, 04:33 PM
#5
Rennlist Member
Thread Starter
Yep. Wondering if it's out of liability concerns. Sad if it is.
08-15-2012, 07:18 PM
#7
Basic Sponsor
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OK, we'll weigh in (BRracing). And, then will post the standard disclaimer. This is not a judgement, determination, ruling, etc, but an opinion based on our and our customers experience, and we do not have actual data or analytics to either support or contradict our opinion or the viability or non-viability of the CL for track use.
There are a lot of views about the 997 CL and ability or suitability for track use. There are a lot of opinions about the possible causes to the known failures. We have had a customer who has had one of these failures (right rear). I was driving in one of our other 997.2 GT3's, right behind our customers car, when the failure occurred. I had been behind the car the whole session (failure was at Buttonwillow in May 2012). The car had not been over the curbs, had not had an off, had not encountered any abuse. We have also managed this car for most of the last year, and can again attest to the car being very well driven and not subjected to curb hopping or driving abuse. We also have many other 997.2 cars w CL, and are very well versed in the CL procedure (we have printed out the procedure, and made sure all our guys have read, reviewed, and adhere to the procedure).
We have talked w Porsche and many others on this. What has caused the biggest issue for us is that no one can provide any feedback or guidance on how to determine if there is an issue. How are we to know that a hub is in good shape, great shape, or starting to have an issue, or worse, has an issue? We have inspected all our cars, and have looked for all possible signs. We can not find any evidence or telltale signs. We can not see any difference between the failed hub and the other good hubs. We can not find or determine any abnormal stress, stretch, elongation, thread stretch, hub weakness, drive pin galling due to any issue, etc. We have asked for documentation or information on this, and have not been able to find any. The car that had the failure also had the recall processed on the CL.
Therefore, we have taken the position that since we don't know the health and status of a CL hub, can't determine the health of the CL, that the safe position is that the CL are not safe for track use. We will disclaim all responsibility for any CL car that will be taken to the track that we work on. As a result of that position and the discussion w some of our customers, we have converted some of the CL cars to a different solution. The viable solutions to us being either the Cup Car center lock or the 5 lug design. Both are good solutions in our view. We have tested at several track days since, and have had no issues. This is our view. And....if someone wants a kit for the Cup Car version, we now know the fitment, offset, and issues to make this kit work on either a narrow body or a wide body car. We can sell this kit. The CL option we like more, but it is more expensive (about 2x the cost of the 5 lug for the hub conversion itself....the wheels are the same cost, labor for either the 5 lug or the Cup CL option is about the same).
Now....what was interesting and ironic to us, was while in the midst of this investigation of the issue and solutions, Porsche all of a sudden made a change in the Cup Car CL design. We have, and had, other Porsche Cup Cars that we support. There is both the 997.1 version, and the 997.2 version. The change that occurred right at the end of June 2012, was a change to the 997.2 Cup Car hub. The new design is about 3 times as heavy, is much thicker....in every way a much more robust item. This is the version we have installed on 997.2 street cars w CL and now we even converted some of our 997.2 Cup Cars to this design. We are not provided info from Porsche as to why this design change was implemented. But, they recalled all the old versions. Odd timing to us, but nonetheless, seems to have significance in that the hub design needs to be very robust.
That's our view. Until someone has documentation to help us know when an issue is occurring, or what has given rise to the failure, we don't know, and therefore we can not accept or have the confidence in the CL for track use.
That's our view. Bring on the questions.
We are NOT material engineers. We are NOT design engineers (I may have an engr degree from UCLA, but that doesn't make me a design engineer for this application).
Bruce
BRracing
There are a lot of views about the 997 CL and ability or suitability for track use. There are a lot of opinions about the possible causes to the known failures. We have had a customer who has had one of these failures (right rear). I was driving in one of our other 997.2 GT3's, right behind our customers car, when the failure occurred. I had been behind the car the whole session (failure was at Buttonwillow in May 2012). The car had not been over the curbs, had not had an off, had not encountered any abuse. We have also managed this car for most of the last year, and can again attest to the car being very well driven and not subjected to curb hopping or driving abuse. We also have many other 997.2 cars w CL, and are very well versed in the CL procedure (we have printed out the procedure, and made sure all our guys have read, reviewed, and adhere to the procedure).
We have talked w Porsche and many others on this. What has caused the biggest issue for us is that no one can provide any feedback or guidance on how to determine if there is an issue. How are we to know that a hub is in good shape, great shape, or starting to have an issue, or worse, has an issue? We have inspected all our cars, and have looked for all possible signs. We can not find any evidence or telltale signs. We can not see any difference between the failed hub and the other good hubs. We can not find or determine any abnormal stress, stretch, elongation, thread stretch, hub weakness, drive pin galling due to any issue, etc. We have asked for documentation or information on this, and have not been able to find any. The car that had the failure also had the recall processed on the CL.
Therefore, we have taken the position that since we don't know the health and status of a CL hub, can't determine the health of the CL, that the safe position is that the CL are not safe for track use. We will disclaim all responsibility for any CL car that will be taken to the track that we work on. As a result of that position and the discussion w some of our customers, we have converted some of the CL cars to a different solution. The viable solutions to us being either the Cup Car center lock or the 5 lug design. Both are good solutions in our view. We have tested at several track days since, and have had no issues. This is our view. And....if someone wants a kit for the Cup Car version, we now know the fitment, offset, and issues to make this kit work on either a narrow body or a wide body car. We can sell this kit. The CL option we like more, but it is more expensive (about 2x the cost of the 5 lug for the hub conversion itself....the wheels are the same cost, labor for either the 5 lug or the Cup CL option is about the same).
Now....what was interesting and ironic to us, was while in the midst of this investigation of the issue and solutions, Porsche all of a sudden made a change in the Cup Car CL design. We have, and had, other Porsche Cup Cars that we support. There is both the 997.1 version, and the 997.2 version. The change that occurred right at the end of June 2012, was a change to the 997.2 Cup Car hub. The new design is about 3 times as heavy, is much thicker....in every way a much more robust item. This is the version we have installed on 997.2 street cars w CL and now we even converted some of our 997.2 Cup Cars to this design. We are not provided info from Porsche as to why this design change was implemented. But, they recalled all the old versions. Odd timing to us, but nonetheless, seems to have significance in that the hub design needs to be very robust.
That's our view. Until someone has documentation to help us know when an issue is occurring, or what has given rise to the failure, we don't know, and therefore we can not accept or have the confidence in the CL for track use.
That's our view. Bring on the questions.
We are NOT material engineers. We are NOT design engineers (I may have an engr degree from UCLA, but that doesn't make me a design engineer for this application).
Bruce
BRracing
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08-15-2012, 07:53 PM
#8
Rennlist Member
Thread Starter
Thank you for posting Bruce. Greatly appreciated.
08-15-2012, 11:03 PM
#10
Addict
Rennlist Member
Rennlist Member
08-15-2012, 11:32 PM
#11
Rennlist Member
Bruce, thanks for the great feedback. From purely a standpoint of due caution, which was/were the failed part(s) in the May Buttonwillow incident?
p.s. Think I'll nominate post #7 as "post of the month". Finally, a nugget of solid facts on the subject!!
p.s. Think I'll nominate post #7 as "post of the month". Finally, a nugget of solid facts on the subject!!
08-16-2012, 01:54 AM
#14
Rennlist Member
Thread Starter
Ok, GMG, Sharkwerks, RSS, etc - care to step in? Motive here is purely an informed discussion so that owners can get a broad range of facts and opinions from those who work on these cars the most.
08-16-2012, 01:59 AM
#15
Race Director
