NJ-GT

Some people have mentioned the splines being unlocked upon inspection, with no apparent cause, despite of being previously locked.

If the locking mechanism is not at work, under heavy braking, there are enough forces on the right side to invoke rotation of the CL big lug ( because it isn't a nut) counter clockwise.

With just a 45 degrees rotation CCW, the CL lug would be way outside the recommended tightening torque of 440 ft-lbs. It would be a matter of testing what 45 degrees of rotation CCW means for actual torque holding the lug to the hub, but I bet the number is below 300 ft-lbs, and somewhere you wrote that there is need to replace the hubs if the car is driven with the CL system tightened under a threshold torque value.

I don't think the soft aluminum red caps can stop forces in the hundreds of ft-lbs of torque, especially when a loose CL lug will cause the wheel to rub the hub CW and CCW (depending on acceleration and deceleration), causing material loses (aluminum), more play, knock on the five red soft caps. Once the CL lug is loose (not tighten to specs), it is a matter of time before that wheel destroys the CL hub at the edge where the lug bolts to the hub (weakest section based on material thickness), and that wheel to detach nicely from the car.

My suspicions would be invalid if the locking spring loaded splines stay locked, but some people have mentioned them coming unlock from the Porsche dealers service, or seen unlocked at track days. If these things are unlocking for no apparent reason (moisture on the springs, softening under hot metal on track conditions, or any other reason), then the loose CL caused by heavy braking on the right side is feasible, the consequences are already known.

Rob S

Nah, I'm not much into homework or class presentations today. But I will make a class announcement and proclamation, which is little more than a restatement of the obvious: if it's true that these wheels are "coming loose" or "losing torque" in some fashion after a period of usage, it's clear that there are some forces (whether they be from rotational torque, bending, tension, compression, shear, or some combination) that are not being adequately resisted by the structure and assembly. It could be that in the majority of these cases, misinstallation is the cause. But if the failure rate is signficantly greater than that of a five-lug wheel, then the robustness of the design -- which includes the installation process -- is questionable.

I know that the old British knock-offs were not particulary similar. I think Porsche even used Rudge knock-offs on the 356. But I thought it was worth a nostalgic look at the past, given that even after all this time, the fundamental concern still exists. Especially amusing in that forum was mention of wheels falling off when cars were towed backwards.

mdrums

I googled Porsche Center Lock....lots of links to failures came up linking to various website forums and car news websites.

I then googled Porsche 5 lug failure....nothing came up except center lock failures.

I bet anyone that typical of Porsche company attitude that Porsche will never acknowledge or fix this issue with it's street car center locks even though this is a major safety hazard in my eyes.

I personally don't have the $9-11k do change over to 5 lug hubs. I follow the center lock procedures by the book and triple check my work. Nobody touches my center locks but me. If something happens and I have center lock failure I will make sure every news agency, car website known to man knows what happened. I'm surprised that by now that no one has put an onslaught of bad media press on Porsche for the center lock failures.

85Gold

6GT3 and 7.1GT3 have cooling hose fitting issues and see how much good lots of Interwebz chatter has done. :roll eyes: Newer 7.2 CL cars are having issues and see how much good Interwebz chatter has done.

Known fix for 6GT3 and 7.1GT3 is remove engine and weld/pin fittings at a cost of $2500 and up. Mine with an as long as you are in there new hoses, water pump, front and rear seals, new lightweight flywheel, clutch and RS front pulley was around $6500.

Known fix for CL issues has been posted at around $3000 plus a set of wheels. Are you going to risk a potential failure that could cost you a $100k plus car for that amount of money. :roll eyes: At least you may be able to recoup some of your expense by selling your CL track wheels to some unbelieving drover and maybe sell the whole CL system to the Cars and Coffee crowd.

Just saying there is a sticky about fix your fittings or else, so maybe we need a sticky about replace your CL's or else.

Peter

DJN

Mike,

When doing the calc's for the 5 lug conversion, it makes you sleep better at night if you only "worry" about the net cost of the conversion:

Mike's Net Cost = Labor/alignment + 5 lug Parts + 5 lug wheels - (minus) the proceeds from selling your CL wheels

You can also save money having new 5 lug centers made for your existing CL 3-piece wheels (I think you still have your Forgelines? Correct?).

Anyway, this makes for "nicer" numbers.

Cheers!
Doug N.

deputydog95

Shouldn't have let your wife pick the wheels. So what if the center locks are pretty

mdrums

Guys, I've listed my CL's and wheels for sale...1 guy only wants the hubs only...I call him back, leave message, no response...other guy whats to swap me his 5 lugs from his 2010 Targa for my CL's, he live 30 minutes from me, local Porsche dealer will do the swap but learns that he can't use his spacers and loses interest.....trust me I'm trying....

DJN, The 3pc Forgelines had issues and where sent back. I sold my 19" OZ track CL's...ready for 18" wheels and would get Forgelines again....for now I've stopped doing DE's until I or we learn more about CL's or someone wants to swap me there 5 lugs for my CL's. If that doesn't happen I'm done with DE's for a long time or until I can sell my GTS and get something way less expensive with 5 lugs. I'm serious considering taking out the RSS roll bar, custom adjustable sways, selling GT2 seats, selling lower control arms and all and possibly selling the GTS. This is a pretty depressing time for me right now...sales at work sucks, CL track issues I keep reading about has scared the daylights out of me and track events have been THE only enjoyable thing I've found to do where I totally forget about work.

Izzone

If u do not apply a generous amount of grease to the nut mating surface there will be a false torque on the nut from friction.

If you do not disassemble the nut and clean / regrease it the inner part of the nut will give false torque, the mating surface on the nut is meant to spin independent of the outside

My bet is most people screw up the above steps, or do not understand how to correctly do them. They are just as important as the actual torque setting

I have removed many other people's wheels to find the splines locked and almost no grease on the nut.....common mistake

If the splines are locked it is impossible for the nut to lose torque once the splines are engaged to their safety position, and I have also seen many many cars at the track with them disengaged

Izzone

You are too paranoid

mdrums

Don't get me started...you want to see a knock down drag out fight at my house? I also shouldn't have listened to Trakcar and Izzone either...they made me feel good about ordering the car with CL's. Back in the spring of 2011 no one really new about the weakness with CL's...only thing was the pain in swapping out wheels for track events...so I though what the heck they really are not that bad to take on and off so I'll get them, may wifey happy...no big deal...well now these things are freakin falling off cars at the track for some reason.

I've found a new hobby...guns....and I'm going back to playing my drums in weekend bands, something I can get paid to do....done with DE's for now....plus in my so called "wanna be aero beetle" it's not fun running by yourself.

savyboy

OMG Thank you Randy. Any wheel movement is not transferred to the CL shell (which has the threads).

That mating surface of the conical assembly to the CL nut shell is the same as a thrust washer or thrust bearing. Hence my comment asking for someone to show their understanding of how the system actually works.

The miniscule rotational movement about the drive pins cannot exert a loosening force upon the CL nut shell in a properly maintain system. There is no path.

Pics posted here of a disassembled CL after I finish my lunch and glass of wine.

You guys know Mr. Jesse set his raped-ape lap time at LS on CL's right? And I had approx 100 track days on my blue car with no problems at all. Drive pins looked perfect.

Izzone

You crack me up, my technical brain cannot populate big words like u

But we are on the same page

I have 8,000 track miles on my centerlock wheels

I still stand that most do it incorrect, setting torque is one of many steps

I have seen cars leave shops that some brag as first rate with improper centerlock installation....I've corrected the techs before, most have no idea how to do it correct

Targa Tim

Not really...

For those who have a lot of track miles and have no incident, good for you. But that is not enough proof that the system is safe. I have more than a few patients with incurable diseases, but they are still surviving.

There are too many incidents lately, and I do not believe that all these people will go out without inspectiing their cars.

I have a track day this coming Sunday. After that, I probably will stop for a while as well. When I have to go out to have fun and my mind is not at ease, that has already spoiled all the fun factor.

CRex

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).

I speculate the following: the "flanges" as pictured are about the width of the narrow ridges and about 1/3 the width of the wider ones. There is theoretically no rotational play if the lock happens to engage the flanges in the narrower ridges but there is definitely room for rotation if the flanges "land" inside the wider ridges.



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?

The locking mechanism has TWO set of splines--the first, tens of fine, daisy-type sawtooth that mates with the CL nut assembly such that there's no rotation there once engaged. These we all religiously check before after (LOL during) our runs. But the rotation seen here takes place between the second set of splines--the inner ones--and the wheel hub. No amount of checking will change how they seat inside the conical housing on the hub. Your picture appears to evidence exactly that. Those scuff marks on your pictured lock are caused by "flanges" coming into contact with the whole bloody lock and not force being applied while in contact...

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...

911rox

I think you guys are spot on... and knowing how much track work you have both done is proof that the system works! For the moment, my system looks pristine but I too have followed these procedures religiously... And whilst nerve-racking, I have complete confidence in the CL system for now.

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 weeknesses 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!!!