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  1. #1

    Default New Wheel Studs--Now What?

    So, i bought these 1/2" longer ARP wheel studs to go with my 1/2" wheel spacers on the rear of car. I got them from LMR and they did not come with instructions. I was having some trouble getting them in so i thought i'd look and see what other people have experienced. I also measured the splined area on the new ones and old ones, and found that the new ones are .01" larger. WTF? When I sat and thought about it, I remembered people mentioning having to open up the holes. I found a thread with this post from Jack Hidley.

    Don't install studs without drilling the axle or hub to the correct diameter. If you don't, you will ruin the hub or axle.

    If you force the studs into the axle flange without drilling, they will end up on a 4.55" circle instead of a 4.50" circle. The metal in the flange of the axle is much less stiff on the outside of the stud hole due to the lack of material on the outside of the hole. When the stud is forced into the hole, the metal on the outside is going to move outwards due to its lack of stiffness. This allows the stud to move outwards also. This makes the bolt circle larger. If you carefully look at the axle flange from the hub face, you will see five bulges around the perimeter, one where each stud is located.

    This may not seem like much of a problem, but when the lug nuts are tightened, each stud is now bent to allow the lug nut to contact the bottom of the counterbore in the wheel. If you try to install drag racing wheels with shouldered lug nuts, the lug nuts will bind up massively on the sides of the bore.


    The thing is, I've got 3 completely installed, and 1 about half way before I stopped. Is my #$%& axle ruined?! What do i do now?! Obviously I'll open up the holes for the others, but what do i do about the ones that are already in?
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  2. #2

    Default

    Okay, so no wonder I just dove in. This is a quote from the product page on LMR.

    Studs feature a 0.625" knurl, making them a direct fit into 1979-2004 rear axles and 1979-1993 front rotors. 1994-2004 front hubs must be slightly enlarged with a 39/64" drill bit. This can be done easily with a hand drill.

    So, they SHOULD be right for my rear axles. But what's the deal with that size difference in the knurled area?
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  3. #3

    Default

    Took a measurement of a hole and it's .59, so it could HELP things to drill them with a 39/64 drill bit (now i just have to find one ). That comes out to .609. Also, I'm pretty sure my axle is not ruined because I did a test fit and my rotor and wheel spacer slide right on.

    Don't mind me, I'm just talking to myself.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  4. #4

    Default

    You're fine man. Knock the studs back out and drill if necessary. If you have already installed a couple of studs you might want to trash them and just replace with new ones for your own piece of mind. Maybe they're ok but once the splines have been squished why chance it? What's a few$$ at this point?
    1984.5 G.T.350 had since 16y/o
    95 Cobra, Crystal White

  5. #5

    Default

    The lug nuts do nothing other then keep the wheel straight. The stud is always undersized and is press fit. The knurled edges are designed to cut into the hole that is too small to prevent them from backing out. They are supposed to be hard to get in and out. Im sure there is a calculation of how much bigger the stud should be. They are designed the shear off, and obviously too much force will do so.

    The weight of the car is on the center hub, the lug nuts just keep it from falling off. I had a freind with a civic, he bought some cheap ebay rims. Two days later a wheel falls off. We put in new studs and it happened again, sheared the studs off with the rim first time he hit a pot hole. We put hub adapters on to "center" the rim and actually fit the rim to the hub and never had another problem.

    My 2 cents, if the wheel fits and the studs are in, you are done. I seriously doubt most rims are even machined to a .05" specification. Watch eric the car guys video on steel wheels on his Fairmount build. y were probably 1/2" out of round. When i saw this i started doing some googling, and found this is pretty normal.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  6. #6

    Default

    Thanks guys. I wasn't able to find a 39/64 drill bit, but I'm sick to death of waiting to work on this car (like i would if i ordered it online). I'll try a few more places today, but then it's full speed ahead.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  7. #7
    FEP Super Member erratic50's Avatar
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    Default

    What a pain! Sure hope my new axles and studs don't give me grief like this!

  8. #8

    Default

    Well... a 39/64 drill bit doesn't exist in the wild. I guess I'll skip it considering it may or may not be beneficial to even use one.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  9. #9

  10. #10

    Default

    Quote Originally Posted by 4-barrel Mike View Post
    Thanks. I figured they do actually exist, but i couldn't find one locally and was annoyed. I ended up not having as much car time as i thought i would yesterday, so i went ahead and ordered one 2-day. I won't have any car time again until next weekend.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  11. #11
    FEP Super Member erratic50's Avatar
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    Last time Summit sent me the wrong crap, I got stuck in the middle of my project also.

    I called them up and the service rep said she can express ship it out two day. I said that's great, because I need it "two day". Guess which one of us was amused.

  12. #12

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    Quote Originally Posted by erratic50 View Post
    Last time Summit sent me the wrong crap, I got stuck in the middle of my project also.

    I called them up and the service rep said she can express ship it out two day. I said that's great, because I need it "two day". Guess which one of us was amused.
    Haha nice.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  13. #13
    FEP Senior Member Patrick Olsen's Avatar
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    Quote Originally Posted by Haystack View Post
    The lug nuts do nothing other then keep the wheel straight. ... The weight of the car is on the center hub, the lug nuts just keep it from falling off.
    That is not correct. Unless your wheels are a press fit onto the center hub, how could the hub carry the weight? There's an air gap there - a small one, obviously, but if there wasn't some clearance, you wouldn't be able to install a wheel by hand.

    The wheel/hub interface is a bolted joint - https://en.wikipedia.org/wiki/Bolted_joint. What carries the weight of the car is the massive friction between the wheel and the hub, and that friction is created by the clamping load of the properly torqued lug nuts.

    As for your friend with the Civic, my guess is his "cheap ebay rims" had a conical seat, and he used normal Honda ball seat lug nuts. You can't have properly torqued lug nuts if the seat and lug nut don't match; that mismatch would've allowed some movement between the wheel and the wheel studs, leading to their failure. Adding hubcentric spacers (which, again, don't carry any load) probably minimized the movement of the wheel enough to prevent the problem from reoccurring.

  14. #14
    FEP Super Member 84StangSVT's Avatar
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    Quote Originally Posted by ZephyrEFI View Post
    Well... a 39/64 drill bit doesn't exist in the wild. I guess I'll skip it considering it may or may not be beneficial to even use one.

    Sent from my XT1650 using Tapatalk
    The local Grainger and Fastenal here carry them in stock. Got a good laugh at their faces when I inquired about a 39/64 bit though.....neither of them had even heard of one before. They asked what I needed such an odd size for, to which I simply replied "Working on an 80's Ford". No further discussion ensued after some laughter.
    Last edited by 84StangSVT; 07-05-2017 at 12:53 PM.
    Brock
    1984 Mustang LX Convertible 3.8L V-6/Auto (SOLD)
    1984 Mustang GT Hatchback 5.0 V-8/5 Speed

    I'm an FEP Supporter and proud of it. Are you?

  15. #15

    Default

    Quote Originally Posted by 84StangSVT View Post
    The local Grainger and Fastenal here carry them in stock. Got a good laugh at their faces when I inquired about a 39/64 bit though.....neither of them had even heard of one before. They asked what I needed such an odd size for, to which I simply replied "Working on an 80's Ford". No further discussion ensued after some laughter.
    nice. I guess we do have a Grainger, but it's not easy to get to, so it's risky to just show up there. And am i wrong, but it seems to me a LOT of stores are very vague or just plain don't tell you if they have something at the local location. I'm looking at YOU Home Depot! "Yes you can buy this online, please do... oh you want to know if I have it in stock... here let me show you how many locations i have... "
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  16. #16

    Default

    Quote Originally Posted by Patrick Olsen View Post
    That is not correct. Unless your wheels are a press fit onto the center hub, how could the hub carry the weight? There's an air gap there - a small one, obviously, but if there wasn't some clearance, you wouldn't be able to install a wheel by hand.

    The wheel/hub interface is a bolted joint - https://en.wikipedia.org/wiki/Bolted_joint. What carries the weight of the car is the massive friction between the wheel and the hub, and that friction is created by the clamping load of the properly torqued lug nuts.

    As for your friend with the Civic, my guess is his "cheap ebay rims" had a conical seat, and he used normal Honda ball seat lug nuts. You can't have properly torqued lug nuts if the seat and lug nut don't match; that mismatch would've allowed some movement between the wheel and the wheel studs, leading to their failure. Adding hubcentric spacers (which, again, don't carry any load) probably minimized the movement of the wheel enough to prevent the problem from reoccurring.
    And fords use a hub eccentric rim design, as do pretty much all cars outside of super heavy duty trucks.


    Hubeccentric rims usually have no gap and use a conical shaped mating suface where the rim and hub are held together by the friction of the lug nuts. Unless the studs are designed specifically for a "friction fit" (which is rarely done due to vibrations and wheel ballancing plus the cost of oversized lugs and bolts to handle the additional load) it will wear either on the stud or rims until one breaks.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  17. #17

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    Finished this today. Drilling the holes first definitely sped things up. Wheels are torqued and in place with no problems!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

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