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Discussion Starter #1
I saw a compatriot lose the left rear wheel off his supercharged Exige today at the new New Jersey Motorsports Park. He's fine, and the car was insured (visible damage: rotor broke in half, rear clam messed up from the lack of a wheel and I think the sling that the tow trucks used). He said that he is meticulous about torquing the bolts, and that earlier in the day one had already broken, before the three broke and ended his day.

What's the opinion out there on the OEM wheel bolts? His is pretty low right now. I'm a little worried.
 

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Very surprising, IMO.
I can only see this happening if the bolts were seriously over-torqued at some point in their history. Maybe they were put on by an impact wrench cranked up to max by a shop or previous owner.
How 'bout the calibration of the torque wrench that's being used? The automatic ones can, and do, go out of calibration.
How 'bout confusion between torque scales--NM vs FtLbs?
 

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I saw a compatriot lose the left rear wheel off his supercharged Exige today at the new New Jersey Motorsports Park. He's fine, and the car was insured (visible damage: rotor broke in half, rear clam messed up from the lack of a wheel and I think the sling that the tow trucks used). He said that he is meticulous about torquing the bolts, and that earlier in the day one had already broken, before the three broke and ended his day.

What's the opinion out there on the OEM wheel bolts? His is pretty low right now. I'm a little worried.
If torqued correctly there is nothing wrong with the OEM wheel bolts. After breaking one of the bolts, I have to ask why did he continue to run on only 3 bolts? :eek: He should have just quit at that point and tried to figure out why the one bolt broke or at the very least replaced the broken bolt before returning to the track. I wouldn't even consider running with 3 bolts on a wheel on the street much less on a track! :panic:
 

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I also don't understand running with 3 bolts.
 

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Discussion Starter #5
If torqued correctly there is nothing wrong with the OEM wheel bolts. After breaking one of the bolts, I have to ask why did he continue to run on only 3 bolts? :eek: He should have just quit at that point and tried to figure out why the one bolt broke or at the very least replaced the broken bolt before returning to the track. I wouldn't even consider running with 3 bolts on a wheel on the street much less on a track! :panic:
Just to clear up any confusion, he had a full set in when the accident happened. He'd replaced the broken one earlier in the day.
 

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One breaks and puts extraneous force on the last 3. Would have been best to replace all 4. Would I have at that point? Not sure, but hindsight is 20/20 :eek:
 

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I saw a compatriot lose the left rear wheel off his supercharged Exige today at the new New Jersey Motorsports Park. He's fine, and the car was insured (visible damage: rotor broke in half, rear clam messed up from the lack of a wheel and I think the sling that the tow trucks used). He said that he is meticulous about torquing the bolts, and that earlier in the day one had already broken, before the three broke and ended his day.

What's the opinion out there on the OEM wheel bolts? His is pretty low right now. I'm a little worried.
Wow. Sorry to read about his trouble but the minute bolt #1 broke, his track day should have ended. I wouldn't even go far on the street with three bolts. The oem bolts are solid, but three bolts wouldn't stand up to hard cornering on the track. Unless he stopped instantly when bolt #1 broke, all of them could be compromised,

Tom
 

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Even if he did stop instantly, the other three could be compromised. Break one? Get a new set! Plus I've heard it recommended that anybody who tracks, and/or R&Rs the wheels with any frequency, replace them every year anyway.

xtn
 

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3 Bolts!

We all know that Lotus has 4 bolts, when most cars have 5.
A few days ago, I noticed that the smart car only has 3 bolts!

 

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I've always gone with if 1 breaks, replace the set. If I broke one on each of two wheels, I'd replace all 16.
+10 on this point. The bolts / torques are calculated to handle a certain level of stress. Once one breaks at the track odds are very high that the remaining three have been overstressed and need to be replaced.

IMHO, I'd rather write off the costs of track day than risk my life and/or car by driving a car that I have any doubts about.
 

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We all know that Lotus has 4 bolts, when most cars have 5.
A few days ago, I noticed that the smart car only has 3 bolts!
Yep, my Smart car (a.k.a. the anti-Exige) has only three bolts. Some older cars (old Jag's, original Cobras, old 'vettes and other vintage sports cars) have only one "bolt" in the form of a knock-off wheel. Some big trucks have over 36 bolts holding the wheels on. The number of bolts alone is irrelavent. It all depends upon the engineering design and requirements.

I have no doubt that the engineers at Daimler did the proper calculations or stress, bolt stretch, shear strength, etc... so that during normal driving the wheels on my Smart car will stay on.
 

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Discussion Starter #14

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Sheared a bolt? That's nothing :) I was in a Viper at Buttonwillow one time that sheared the whole damn wheel right off the center. But at least all the bolts held that center on the hub. :crazyeyes
 

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Did this happen on the banked turn track by any chance?
Yes, and the bolt broke while torqueing them in the paddock, not while driving. I was a witness to both unfortunate events. If he was really running with 4 bolts I have no idea why this happened - I assumed he was risking it by running with 3 and got bit. :(
 

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Yes, and the bolt broke while torqueing them in the paddock, not while driving. I was a witness to both unfortunate events. If he was really running with 4 bolts I have no idea why this happened - I assumed he was risking it by running with 3 and got bit. :(
If the bolt literally broke while he was torquing it in the pits I have to wonder if he was over-torquing them. There is no way they should break under those conditions
 

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Yes, and the bolt broke while torqueing them in the paddock, not while driving. I was a witness to both unfortunate events. If he was really running with 4 bolts I have no idea why this happened - I assumed he was risking it by running with 3 and got bit. :(
Since you were watching him... was he using a torque wrench? Do you think he was using it correctly?

Most people would be surprised how little force it takes reach 105 Nm with a decent lever arm...
 

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Discussion Starter #20
Did this happen on the banked turn track by any chance?
I'm actually not sure. It was out of my line of sight when it happened. I spoke to him afterward, but didn't ask that question.
 
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