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Wheel Stud Length Question

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  • Wheel Stud Length Question

    My car originally came with the 14" steelies which weren't terrible, but swapped to the 15" 8 spoke alloys from the parts car. I saw the offset was greater on the alloys and used those lugs. The alloys are also likely thicker. However, the stud lacks about one thread from coming flush with the outside of the lug nut. I worry the lugs will loosen without longer studs.

    Does anyone know if the stud length was longer on cars equipped with alloys? Or the length? The thread is the same. Are the lug studs pressed in? Any experiences to share?

    I've checked them periodically with a torque wrench and they stayed tight. However, last week after I rotated the tires I had a local shop re-balance the (new) fronts as I had a noticeable shimmy. The re-balancing didn't help much, btw. I just pulled the fronts to replace the front end links and had to use a long breaker bar to remove the lugs. I actually sheared a 1/2 to 3/8 adapter in the process. Dunno what he torqued them to, but any more would've surely sheared the damned studs. I was lucky I didn't shear them removing the lugs.

    Anyway, I hadn't thought much about the stud length until this. Although the shop never mentioned any concerns about stud length and/or possible loosening, I'm guessing the tech over-tightened to try to compensate? They've worked on the car several times for tires, alignment, balancing etc.

    Finally, if you're running the original steel wheels and want to see just how good your suspension can be, try to find a set of used OEM 15" alloys. The wider stance from the increased offset, and to a lesser degree the larger diameter, really open the suspension and allow it to work as designed. I think the cheapie steelies keep the suspension in a state of bind, mainly due to the narrow offseet. If you don't use OEM's, I'd stay with that offset. My car didn't just feel better, it felt like a different car.

    If anyone knows the offset of each, that'd be great information.

    All input appreciated.
    1998 Contour GL V6
    2002 Cougar XR

  • #2
    The bolted joint engineering rule of thumb is that thread engagement for a nut must be at least equal to the bolt major diameter for the joint to develop and maintain full strength, so for an M12 stud, you want at least 12mm of engaged nut threads, tho most lug nuts will engage more than that as safety factor.

    This ^^^ is a good (old) post about longer lug studs, and it seems that Contours could get lug studs from 42mm to 48mm, and longer than stock is considered 52mm.

    If you're using closed end lug nuts, make damn sure that longer studs don't bottom in the nut.

    And to answer, lugs studs are pressed in from the back of the wheel hub.

    IIRC, Contour lug torque is 90 ft-lbs, go buy thee a good 1/2" drive click type torque wrench. If the wheel balance tech grossly over-torqued the wheel nuts, the studs may be damaged, and I'd replace them all.

    Oh, and apply a small amount of grease or anti-seize to the lug studs, it keeps them from corroding and freezing.
    2019 Corvette Grand Sport, 1LT, just stupid-fast.
    1985 SVO Mustang (turbocharged track rat)
    1989 Taurus SHO (supercharged track rat)
    1999 SVT Contour (Sedanus-Grocerygetter-Rapidus)
    2008 Mercury Milan Premier (Comfy boat)


    • #3
      Happy to see the link still works!
      30 Contour / Mystiques and counting......


      • #4

        Here's a pic of a car originally equipped with the same alloys. Hard to see, but note the stud is roughly even with the last thread of the nut. I used the same nuts as above. So, it appears these studs are longer by about a full thread.
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        This gallery has 1 photos.
        1998 Contour GL V6
        2002 Cougar XR


        • #5
          It looks like you have enough threads from what I can see.
          30 Contour / Mystiques and counting......