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Safety Warning! Wheel nuts!

Neil Haughey

New member
I had one hell of a shock after returning from the Haynes test track last week. The track has a lot of low speed left hand turns which puts a lot of stress on the drivers side front wheel (RHD). Anyway I always check a car over thoroughly before taking to the track starting with the tyres and working inboard.

Imagine my horror when checking and cleaning the wheels to find that on the front drivers side wheel I have one wheel nut missing and one finger loose. All other nuts on the car are tight enough to hold the wheels on, hence the car drove fine back from Haynes with a wheel held on by only 3 nuts.

I checked the car after each session on the track except the last session because we drove home shortly afterwards, so the failure must have happened near to the end, if I had of gone for more laps I am sure I would have had a wheel come off. Each session was only 6 laps or so (very short tight track maybe 30 secs per lap) and ISTR I did about 6 sessions total so maybe 15 min to 20 min total track time.

This has got me seriously spooked now because the nuts are fairly new (maybe 15K miles although they have been off a fair few times) and I don't recall any threads about using non stock nuts for track days although I recal reading something about Ruf not using the stock alloy nuts.

Maybe the mega tight turns at that track create a special set of circumstances we don't see on most tracks however I thought I better share this experience with you guys.

Testament though to the grip of these Hankook RS2 tyres.
 
I posted a thread on this very topic a few years ago before my first track session as I was concerned about the stock nuts and no-one came back to say that the stock nut were anything other than adequte - even for people running semi-slick tyres. I always make sure the nuts are tight before any track session (as i'm sure you did) and so far have had no probs. I have recently fitted a 7mm shim though and have been thinking about fitting longer studs, but on the basis 4mm of that is the difference between my old and new offset i'm only 3mm net short which in theory isn't a problem, but i'd like to be sure.

Is it possible to fit the wheel bolts off a later model Porsche in lieu of studa and nuts? Just thinking that you are halving the amount of thread engagement area and therefore halving the opportunity for any threads to work loose?
 
You can fit steel nuts rather than alloy. I believe you have to to be allowed to compete in a 944.

Was it part of the activity days that you were there for, Neil?
 
Hi All,

All competition cars (in Porsche Club GB championships) have to use steel wheel nuts and solid tyre valves too. I have used alloy OEM nuts with slicks for many, many years with no breakage - but it is important to use a torque wrench on each nut to ensure they are supporting the load evenly. Too tight and they can break (I use 130Nm for alloy nuts on solid wheels and 100Nm for steel nuts against billet alloy hubs).

Good job you spotted it Neil. Could have been nasty.

Regards,
Andrew
 
I predict a nationwide shortage of alloy wheel nuts at all theusual parts suppliers [;)]

Thanks for the heads up Neil, I know my own alloy wheel nuts are a fair few years old and have been off and on the car more times than I can count up to (always torqued to 130Nm though)
 
No it was an R26 organised day, have a look on the R26 section and there is a picture of me under the caption about turning left. Very good laugh with the guys / gals and I got really into that little track. Strange because I wasn't expecting to like it so much but I turned up my front shocks after the first time out and got really hooked into the corners from then on (to much oversteer otherwise).
 
Forgot to add that the wheels are 7j and 8j 16" cup 1 (thin spokes) from a 968 i.e. original Porsche wheels. The tyres are 225 front and 245 rear.

ISTR always using 95 lb/ft as per the owners manual but I am always concerned about tyre fitters over torqueing the nuts and then stretching them out such that 95 lb/ft doesn't work any more, any metalurgists out there know if this could be an issue?
 

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