There's a report on NSXprime here about this topic. Right now, NSXprime is upgrading servers, so this link may not work for the rest of today or so, for which I apologize.

This fellow tracks his NSX. He makes sure his lug nuts are properly torqued to 80 lb-ft at the start of each track session. In a track session, his right rear wheel came off. It turns out that all five studs snapped. The photo in that topic shows two adjacent studs snapped at the lug end, and the other three snapped flush with the face of the rotor. Presumably the two snapped first, and the added, non-symmetrical stress on the other three caused them to fail after that. (There's also a 10 Mb vid taken from the cockpit, for those who are interested.)

Folks are speculating about the possible causes and preventive measures. It was noted that there is stress on the studs every time they are torqued, which means every time a wheel is removed; the suggestion was made that the studs should be replaced every two years as a preventive measure on a car that is heavily tracked.

My questions for this group:

1. Have you ever heard of this happening before? Not on lugs that are loose and were never tightened, but on lugs that were properly torqued?

2. Do you agree with the recommendation to replace studs every two years? Is this overkill, or is this good general practice?

3. Any other suggestions, recommendations, or comments anyone would like to add?

Thanks in advance...

 

Was there any ant-sieze or grease on the studs when torqued?

 

Were his wheels hubcentric?

If you're not using hubcentric wheels, I would consider the studs a wear item.

 

A possibilty is that the guy checked and re-torqued his lug nuts after every session --- when the wheel is still hot. This would build up a much higher torque into the studs (which translate into tension by the pitch of the threads) but the torque wrench would still read the same.

 

Out of curiosity, what proportion of stock wheels are hubcentric, and what percentage of aftermarket wheels are? Generally speaking (most and few are good enough for me for now..)

 

All and Few

 

I believe the wheels were stock NSX wheels.

He said he torqued the wheels right before each session, and each time they had had two hours or more to cool down since the previous session.

I don't know about the anti-seize (good) or grease (bad). I'll ask him to take a look at this topic.

 

I used to have trouble with studs on my ITR, but I attributed it to 5mm spacers up front I was using. I snapped 4 front studs over a 1 year period. Once I stopped using the spacers I quit snapping studs. I continued racing without the spacers on non-hubcentric wheels with no issues for an additional year. Doesn't appear to be the same issue as the NSX, but it was a PITA to continue breaking/replacing studs.