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Thread: Wheel hub and stud inspection / preventative maintenance questions

  1. #1
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    Default Wheel hub and stud inspection / preventative maintenance questions

    So on my way home from WSIR yesterday, i hear a loud POP followed very rapidly by a few others in rapid succession at which point the left rear wheel completely separated from my S2000 on the highway. Fortunately the fender captivated it and i was able to get to the shoulder with minimal additional damage.

    The cause? All 5 wheel studs on my drivers rear wheel failed in rapid succession. This was operationally, almost immediately (car sat for a few hours at the cantina) after I had completed Red4.

    So while I am of course rebuilding both rear corners now out of paranoia, it opens up questions. I spent several hours the previous weekend with the car in the air inspecting things, and i couldn't spot any fatigue or issues on the studs, so I considered it good, I also spend time on brakes, major suspension and steering and essentially anything that could cause my day to end upside down or on fire.

    My questions to everyone here are:

    1: Is there a good way to spot this kind of fatigue before it becomes catastrophic like this? The hub was perhaps 18mo old. It was old by track car standards but the bearing was still good which is the typical failure mode on the S2000.

    2: Is there anything i should add to my practice to help mitigate this kind of failure in the future?

    3: The wheel was a 17x10 949 6UL (pretty much destroyed by the incident). I had not been using hub-centric rings for a while as most had advised they are not needed. I am re-thinking that now.

    Also considering how lucky i was to not have this failure in T8 i think I'm going to go buy a lottery ticket today


    2018-03-31 19.16.39.jpg2018-03-31 19.18.29.jpg2018-03-31 19.40.43.jpg
    Last edited by anorexicpoodle; 04-01-2018 at 12:33 PM.

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    Chest hair required Olitho's Avatar
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    Wow! That is serious and you are very lucky it did not happen in Turn 8 or 9.

    How it waited to happen on the freeway is a mystery. Perhaps the heat rates happen differently on track vs. off in a way that the rate of metal expansion relieves some stress on the lugs. That is pure conjecture.

    With that said, the cure is ARP studs. With all my new Corvette hubs I can't wait to get away from OEM wheel studs. They are brittle in comparison to ARPs. I have never seen an ARP stud break or even wear out threads. The OEM studs will sometimes gall.

    Lastly, because I constantly take wheels on an off, I only torque to 90 foot pounds vs. Corvette recommended 100 ft pounds. I have never had a problem doing that, never had lug nuts come loose, but I figure it helps save the lug nuts from pre-mature stressing and a tragic outcome such as yours.

    Your mileage may vary, but that is what I do.
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    Are you using factory torque? Torque wrench or guess? Click or beam torque wrench? After that I echo oli. Also some of us use these cheap ebay aluminum lugnuts. They wear while the stud doesnot. They yield while the lug does not. We throw them away annually and replace them. We want the lugnut to be the weak link.
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    JJ1
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    My first thought is do you re torque lug nuts when they are hot or warm at the track? I’ve seen this lead to sudden failures like that. They could have gone from warm and over torqued to cold and under stress on the freeway....

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    I don't know what visual cues you'd find on stressed OEM wheel studs. Galling can be hard to detect. It might be that you begin treating them as a wear item.

    I tend to agree with what Oil said. Consistent torque values that are high enough to get the job done, but no no higher, and ARP studs should keep you out of trouble. Every time I buy a new set of ARP studs, I make note of their price, which isn't cheap. When I see posts like this, I feel like they're worth the expense.

    Glad you're OK and that the car didn't get dinged up too badly.

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    No never re-torqued hot.

    If i re-torque i back off then re-torque to ensure it doesnt keep tightening (ive seen guys re-torque without loosening before every session and then wonder why they have 120lbs of torque on the wheel when they get home)

    Torque wrench is a 2 year old craftsman click-type. Always torqued to 90lbs. I also have an older proto i use at home. both come up about the same, i.e. 90 on one is 90 on the other.

    Lug nuts were Gorilla, purchased < 6mo ago. I rotate lug nuts every year or so because corroded threads can lead to lower than optimal torque.


    FYI Hubs were OEM honda not aftermarket. I never used secondary market hubs explicitly to stave off this kind of failure.
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    Chest hair required Olitho's Avatar
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    Ryan, all that you type above sounds prudent, but yet they still broke.

    The only other observation I can speculate on is that one or two were slightly loose. It has been my experience that compromise all of them. And as soon as one goes they all snap like a zipper.

    Is that possible? I know on a few occasions in the past 10 years I have managed to go out with one or two not fully tightened as I thought they were.

    Were the wheels new?
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    Wheels were maybe 1 year old.

    I cant deny the result, which is why im looking for what I missed or what I should add to my regimen.


    WSIR is particularly punishing on the left rear of the car for sure since im WOT through all the big right handers. Ive been reading a lot on fasteners recently and i think the lack of hub rings might have been a contributing factor since without them the lug is forced into 3 axis of load.


    For sure doing ARP studs this time around, on OEM hubs and adding hub rings to my kit. Also replacing the entire left knuckle out of paranoia, not sure what other stresses this failure introduced into it, however this is surely a case where an ounce of prevention would have been better, im just not yet sure what i could do to spot it.

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    Chest hair required Olitho's Avatar
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    How many lugs on an S2000 hub?
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    Actually, i just had a realization, that in February at CVR i dropped that corner off of the T2 exit going CW and bent that wheel. Now this is common enough at CVR for T2 to claim a wheel when it comes back up onto the track, i replaced the wheel (different set than the one i was on this weekend) and didnt think much more about it. I now wonder if there was fatigue introduced there. Nothing jumped out during visual inspection, and in fact i replaced the wheel and raced the rest of that weekend at CVR. Spurious correlation or possible traumatic cause? not sure.

    Has anyone ever used penetrant testing on hubs to spot stress fractures between events?

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    Quote Originally Posted by Olitho View Post
    How many lugs on an S2000 hub?
    5 lugs

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    Senior Member bellwilliam's Avatar
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    if you are fast and on sticky tires, it happens with Miata. at T8.
    This is Andrew (he is here on Trackhq) with Trackspeed Engineering.

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    I will echo what Oli and Fatbilly said.

    1. go with aluminum lug nuts. you want it to be weakest link, and treat them as a consumable. You don't want fancy super strong lug nuts that might destroy lugs when you say over-torque or others.
    2. once you have 1 lug fail, the other will fail within minutes..... This happened with a fellow SuperMiata racer at CVR a month ago. He broke one of the lug, and still went out. ALL other lugs broke off within a lap.
    3. I think more likely was you had a loose lug nut, or a bad bearing.
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    Quote Originally Posted by bellwilliam View Post
    if you are fast and on sticky tires, it happens with Miata. at T8.
    This is Andrew (he is here on Trackhq) with Trackspeed Engineering.

    That is like the scariest video I've ever seen. I'm switching to aluminum lug nuts.
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    Quote Originally Posted by SDSUsnowboards View Post
    That is like the scariest video I've ever seen. I'm switching to aluminum lug nuts.
    this is a known issue for higher hp Miata, nothing to do with lug nuts though. Vettes have same issue..... We now recommend rear hub change every 50-100 hours (depending on grip level). here is another video for your enjoyment.
    S1 Supermiata - 220whp
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    A few random thoughts that effect keeping a wheel on the car:

    you can have 1 nut loose and that sets up a chain reaction and you can shear lugs.

    Make sure if you use aluminum nuts to tap them on the ground and make sure no aluminum shards are stuck there. Also when mounting aluminum wheel on steel studs do not cheesegrater the wheel on studs. Sometimes a shard of aluminum will fake out the torque wrench.

    Be careful with hub rings. I got these lame non-hubcentric wheels and was very skeptical of using them. But years of racing they are still great wheels. I ran hub rings. In MY CASE it was possible for a ring that was glued into the wheel to stick on the hub. Then I could put another wheel on and conceivably an idiot helper could place wheel with stacked hub ring and fake out a torque wrench. So I now run without the hubrings but certainly would love to have hubcentric wheels.

    progressively tighten a wheel. I still see guys rattle gun on 1 lug then add the rest. When you don't have a hub centric wheel it is even more important because you are depending on the nut cone to center your wheel concentrically.

    ARP may be able to tell you or you can calculate the yield point of the stud. In theory if you stay under the elastic point you can cycle that fastener forever. It is like rodbolts some are torque to yield. Those are a one time use fastener.

    having 2 wrenchs to check against is good. Consider beam torque wrenchs because they are the most reliable.

  17. #17
    Administrator ucfbrett's Avatar
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    Quote Originally Posted by bellwilliam View Post
    if you are fast and on sticky tires, it happens with Miata. at T8.
    This is Andrew (he is here on Trackhq) with Trackspeed Engineering.

    This video still wigs me out. Worst place for a failure, then sitting on the outside in harms way. Eeesh.

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