mdrums

Well you have to apply the brakes to get the CL nut off...you can't flush or bleed with the brake pedal depressor on so you have to keep taking it on and off..plus the jacking of the wheel off the going BS. You also have to keep taking the Motive pressure bleeder off too to. Then the other issue is if you change brake pads you have to start the car to build pressure back up after each caliper bleed because the brakes will not grab properly. It's extremely time consuming with many extra steeps if you do not put the car on a lift or jacks.

I just put my car on 4 jack stands to do bleeding and other brake work. 5 lug is so much simpler and safer to deal with.

Bono

medpilot105 and others that have taken the time to reply, it seems we may be talking about the wrong topic in focusing on the centerlock nut. I'm convinced some people have had problems with the nut mechanism, and it doesn't surprise me given the relative complexity. Here's what I think the bad news is and what others are specifically focusing on in other threads I have been seeking out and studying. The main issue seems to be that the entire cl hub mechanism/design might be a bad design and fail under race/track conditions. Text from a thread that I found to be the most enlightening/factual was graciously shared by an individual at brracing. I'll try to post it here, but you can also find it by searching: race shops weigh in on cl issue..basically says their shop will not support/warranty track use of street CL mechanisms..they are converting their tracking custmers to a multi-lug or cup cl option:

Here is the text posted in another thread by brracing... "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"

mdrums

When Izzone, Trakcar, Greek, Erik, M3EvoBr, Milkshake Man, Juan or I lose a wheel...then ya'll should be worried. Trakcar changed cars so frequently so he actually is not a good gauge but Erik has his car with tons of track days and Izzone does countless track days so those 2 guys are who I watch for CL issues.

medpilot105

TRAKCAR

I think the 4.0 has something different in the uprights. Orbit says the wheel bearing are different but can someone verify on PET?

deputydog95

center locks are dumb

deputydog95

Erik has only had 2 days or so on CL's. Izzone on the other hand.....

For $2500 you're crazy not to convert. CL's are dumb.

TRAKCAR

I love 'em

deputydog95

Let's hope I never have to have the "I told you so" conversation.

mooty

slow 911

mooty

guys many of u are missing the pt

CL is fine
BUT there are time u need to
chg wheels in
10 min on trk, u
likely
make mistake on CL. harder to fk up five lugs.
take ur car to jiffy lube. they will fk up. Thales ur five lug there. less lowly fk up. so smaller fk up issue is better. I know how to do it right but there are time I can't do it myself. and many shop
inc dealers will get it wrong.

it's ur car do what u like why argue
I have a CL RS and a five lug RS. I'm faster chg lug wheels.

oh btw it's WAY more than 2000 to chg to five lugs.

senna

Bruce,

1) what wheel was on the car when the fail happen?

2) you implied the hub may or may not be the cause. Do you think outside of all other possibilities, including instalation human error that an aftermarket wheel could be out spec?

Thanks,

SC

911SLOW

Same bearings front and rear with the rest of the GT3s.

Different rear wheel carriers, track rods and wishbones.

mooty

wheel career is called uptight?
so u cannot convert 4.0 to lug

10 GT3

I keep monitoring these threads, but still don't believe the CLs are a curse from personal experience. I have over 22K miles with more than 30 track days in those miles. I am on my 5th set of tires, 4th set of front pads, close to my end of my 2nd set of front rotors (Got 2nd gen PFCs waiting) and 3rd set of rear pads. Probably the longest I've gone without removing the wheels is 2K miles and I've had 4 different shops remove/install those wheels, yet I have NEVER had a problem with my CLs. Keep in mind that all those miles are only with the OEM stock wheels, hence I can't comment about aftermarket wheels.