Wednesday 19th December 2012

Update: Porsche centre-locks - Porsche GB comments

455 cars called back in the USA for wheel hub issues, Porsche GB clarifies situation here too

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Following on from earlier recalls this side of the pond Porsche has issued a recall on some of its 911 GT3s over in the USA. The recall aims to cure a fault with the centre-lock rear wheel hubs, which Porsche admit may be prone to failure under certain conditions. Porsche has also said that the maintenance intervals originally suggested for these hubs might not be enough to prevent wheel hub failure.

It comes after much speculation of problems with the centre-lock hubs. In summer, Jalopnik posted a video of a GT3 RS shedding a rear wheel at the ‘ring.  What’s more, anecdotal evidence suggests many GT3 owners have already had the recall modifications applied to their cars at dealerships. The full nature of the tweaks involved hasn’t been specified, but Chris Harris’s chat with Wolfgang Hatz a couple of weeks back suggests that new hub nuts rated at 600Nm will be the crux. In the same interview, Hatz stood by the centre lock hubs, adding that if you use them properly, the system still works.

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Update: We've now had official word from Porsche on this subject, and you can find it reproduced below:

"Current market observation shows that the race track usage profile of many vehicles in the 911 model line now comes close to that of pure GT3 racing vehicles (e.g. GT3 Cup).

The component stresses associated with race track use and competitive driving are much higher than for a sporty driving style on public roads.

The revision intervals for race track use must therefore be observed, particularly for highly stressed chassis components, in the same way as is required for GT3 racing vehicles.

If these revision intervals are not observed, the failure of highly stressed components and breakage of the hubs on the rear axle, for example, cannot be ruled out, particularly in the case of components in advanced stages of wear.

In order to standardise revision intervals, Porsche has decided to replace the wheel hubs on the rear axle of the GT3 with standard wheel hubs.

Customers have received a letter from Porsche GB asking them to contact their preferred Porsche Service Department, so that we can arrange to have the necessary work completed as soon as possible. This work will of course be carried out free of charge."

[adzpz]

I must confess I don't know the in's and out's of this issue but if I bought a car of this value and couldn't be certain the wheels might not come if driven hard I would be very disappointed espeically being a track focused version

[EDLT]

Perhaps they should stick to ordinary wheelnuts in the future.

[nxi20]

79 UK GT3s are affected by the recall according to the post by rt911 here http://www.pistonheads.com/gassing/topic.asp?h=0&a...

The big question is does this fix the problem permanently or are the centrelocks / hubs now a lifed component?

[PPPPPP]

[Tango13]

Do the wheel nuts have L/H and R/H threads depending on which side of the car they're fitted and do they have locking springs?

Also 600NM torque? What pitch is the thread FFS? The M46x1.25 that holds the rear wheel on my bike only needs about a quarter of that!

[monthefish]

Can anyone else get that Jalopnik video to work?

I get the message "this video is private"

[SuperchargedVR6]

EDLT said:

Perhaps they should stick to ordinary wheelnuts in the future.

I was thinking the same. What are the advantages of a centre lock wheel, other than speed of removal / refitting?

[Great Pretender]

SuperchargedVR6 said:

EDLT said:

Perhaps they should stick to ordinary wheelnuts in the future.

I was thinking the same. What are the advantages of a centre lock wheel, other than speed of removal / refitting?

Lighter weight and approx. eleventy cool points.

[kambites]

Great Pretender said:

Lighter weight and approx. eleventy cool points.

Really? How much lighter? I'd be astonished if it's more than a 50g difference per corner.

IMO, it's a gimmick for people to brag about in the pub; no more.

[uncle tez]

monthefish said:

Can anyone else get that Jalopnik video to work?

I get the message "this video is private"

No, i get the same message.

[EDLT]

kambites said:

Great Pretender said:

Lighter weight and approx. eleventy cool points.

Really? How much lighter? I'd be astonished if it's more than a 50g difference per corner.

IMO, it's a gimmick for people to brag about in the pub; no more.

About 10kg lighter - after the wheel has fallen off.

[Captain Muppet]

Don't loads of classic (e-types and stuff) use single wheel nuts (which are fitted and removed with a hammer)?

Also how did McLaren do it on the F1, and Ferrari do it on the F40, without them falling to bits every few thousand miles?

[kambites]

EDLT said:

kambites said:

Great Pretender said:

Lighter weight and approx. eleventy cool points.

Really? How much lighter? I'd be astonished if it's more than a 50g difference per corner.

IMO, it's a gimmick for people to brag about in the pub; no more.

About 10kg lighter - after the wheel has fallen off.

True.

[Greg_D]

if i read that letter correctly, they are going to put normal wheel nuts on the rear and leave the front centre lock!!

Surely not?

[Crusoe]

so 333 laps of the ring and you need new rear hubs and bolts, doesn't seem to bad if the milage is just for the track usage (would need several sets of brakes and tyres in that time) though not great if you use the car hard on the road and that distance counts.

[kambites]

Crusoe said:

so 333 laps of the ring and you need new rear hubs and bolts, doesn't seem to bad if the milage is just for the track usage (would need several sets of brakes and tyres in that time) though not great if you use the car hard on the road and that distance counts.

I think the problem is more that they aren't service items and they fail catastrophically.

Replacing the hubs every few thousand track miles is perhaps acceptable; replacing the car because a wheel falls off and throws you into a field, probably isn't.

[Mr2Mike]

Tango13 said:

Also 600NM torque? What pitch is the thread FFS? The M46x1.25 that holds the rear wheel on my bike only needs about a quarter of that!

Does your bike weigh nearly 1400kg, develop almost 400bhp and is able to put over 1G of cornering force laterally into the wheel?

[Crusoe]

Not going to know how many miles a previous owner has done on track so guess all porsche approved cars will have to have the parts replaced if they have gone over the 7/14/28 thousand km limits and can't prove they were done previously.

[clarkey]

Greg_D said:

if i read that letter correctly, they are going to put normal wheel nuts on the rear and leave the front centre lock!!

Surely not?

That's how I read it too, but it can't be right.

[Gorbyrev]

Surely from an engineering point of view there is lots to go wrong. The hub nuts on Metro were 150nm but were notorious for sticking on the collar washer and then working loose. My mate who rallied them made up a special washer to torque the hub on without the collar washer in place just to make sure the hub was tensioning properly. 600nm is fine and well but it has to be 600nm (IIRC the old centre nuts were printed with 500nm) of force applied in the right way. The room for error on standard wheels nuts is much greater due to the less catastrophic nature of a catastrophic component failure. Perhaps the introduction of track style maintenance schedules is a good idea for a road/track vehicle. Track stresses are so much greater than road ones. Over torquing is an much of a problem and led to the loss of another Metro wheel but that is another story!