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Last Post 04 Aug 2011 08:24 PM by  cmamich
Busted Studs
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BlackCavalier52
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21 Jun 2011 01:21 PM

    For the past few auto-x seasons, I've been using a set of 'dedicated' wheels and tires for racing - primarily just so my DD tires won't get corded. Over the course of the last three events that I changed wheels, I've collectively broken 6 studs. Mind you only one was while tightening, the other 5 broke while trying to loosen them.

    I asked the fellow at the auto parts store what I'm doing wrong. He pointed to the fact that the car is now 11 years old. Every tire rotation of wheel swap stretched those studs and possibly its just metal fatigue. I've also recently started to disregard my torque wrench. I believe its out of calibration so when I think I'm cranking it to 80 ft lbs, its actually much higher... possibly compounding the problem.

    What should I do? Just go to the parts store and get enough hardware to replace them all? Or are wheel studs supposed to last longer than 10-11 years?

    ...waiting for the wisecracker who says "get a new car"

    The Nebulizer
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    21 Jun 2011 01:50 PM
    • Accepted Answer
    REPLACE THEM ALL - QUICKLY!

    You have been lucky. They are definitely not supposed to last 10-11 years under those kind of conditions and they are now dangerous. They are indeed stretched as the parts guys said and as you have seen just waiting to fail from metal fatigue. Don't let one fail while you are taking a turn at 40+ mph.

    The recommendations I have heard for performance studs is they be replaced every season. This might be overly cautious with high quality performance studs, but certainly 10-11 years and many torques on Chevrolet studs is well passed pushing your luck. Torquing (especially over-torquing) and autocross are very hard on studs and will lead to failure even with well machined studs of the highest quality after a few years.

    No question about it. Replace them all immediately and consider yourself lucky they broke while wrenching and not driving.

    JBrettHowell
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    21 Jun 2011 02:21 PM
    • Accepted Answer

    dupe

    JBrettHowell
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    21 Jun 2011 02:21 PM
    • Accepted Answer
    And use some anti-seize on them to try to prevent the lug nut from seizing on the stud which is part of the reason the studs are breaking when you are trying to take the lug nut off.
    BlackCavalier52
    Basic Member
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    Posts:155


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    22 Jun 2011 12:34 PM
    • Accepted Answer
    I don't ever use air wrenches myself, but obviously I can't speak for what tire shops are doing. I've only been replacing the studs with parts from Autozone, but would you have anything specific you'd recommend?
    cmamich
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    23 Jul 2011 10:47 PM
    • Accepted Answer
    Verify what the recommended torque is for your specified thread diameter/pitch. In reusable bolted connections such as a wheel stud application, the maximum torque value should be such that the material is loaded to 90% of its yield. I'm guessing 80 ft-lbs, or possibly higher due to faulty torque wrench, is too much causing plastic deformation of the stud leading to early fatigue failure. A typical 7/16 stud only requires 65 ft-lbs max, assuming normal OEM stud material. Aftermarket studs will use different materials allowing higher torque values, giving higher clamp loads, while not plastically deforming the material.
    snaponbob
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    Posts:2862


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    24 Jul 2011 07:20 AM
    • Accepted Answer
    cmamich wrote:
    Verify what the recommended torque is for your specified thread diameter/pitch. In reusable bolted connections such as a wheel stud application, the maximum torque value should be such that the material is loaded to 90% of its yield. I'm guessing 80 ft-lbs, or possibly higher due to faulty torque wrench, is too much causing plastic deformation of the stud leading to early fatigue failure. A typical 7/16 stud only requires 65 ft-lbs max, assuming normal OEM stud material. Aftermarket studs will use different materials allowing higher torque values, giving higher clamp loads, while not plastically deforming the material.

    1) As stated, the existing torque wrench is out of cal. GET A NEW ONE !!!! Oh, and USE it.

    2) The statement "Aftermarket studs will use different materials allowing higher torque values" is not accurate. I switched from OEM studs (factory spec 100 lbs/ft) to ARP. Very quickly I broke studs. In speaking with ARP, they stated that the studs I installed should be torqued to 75-80. Problem solved.

    cmamich
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    04 Aug 2011 08:24 PM
    • Accepted Answer
    Well perhaps I should have qualifed my statement. Be cautious of what specific material your aftermarket stud material is made of it does matter in defining what the torque value should be.

    http://arp-bolts.com/pages/technica...e_us.shtml

    See link.
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