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Hot Rods What size knurl

Discussion in 'The Hokey Ass Message Board' started by oj, Apr 8, 2019.

  1. oj
    Joined: Jul 27, 2008
    Posts: 6,037

    oj
    ALLIANCE MEMBER

    I have a Wide5 hub that measures .545 and I need to press new studs into it. I tried .585 knurl but thye wouldn't hold. I have a set of smooth shank studs that measure .620 - anybody care to guess what my hole should be to press them in? I think my hubs are '37ish, all 4.
    I am joining buick drums to the wide 5 hubs, the aluminum drum is thin and I am afraid I'll break the casting when I cram that .620 shoulder thru a .545 hole.
    I kinda think the original Ford spec was .620. Ford only shows the two sizes for passenger wheels, the more common .560 and the .620. Information on the Wide 5 is vague, even in the 'Green Book'. I thought it has to be the .620 and they showed up today and after messing with one I have doubts.
     
  2. '51 Norm
    Joined: Dec 6, 2010
    Posts: 636

    '51 Norm
    Member
    from colorado

    My guess; about .0005 interference fit. I base that on the 1-2 thou. interference fit on connecting rod wrist pins that are about an inch in diameter so about half of that I would think be about right.
    Disclaimer: I've never measured a wheel stud/hub so this is conjecture. Hopefully someone who has actually been there will share their experience with us..
     
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  3. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 7,205

    mgtstumpy
    Member

    I read that the allowance for a forced fit is from .001 to .0025 per inch however Summit indicates that if material is cast iron or steel, your drill size will be 0.005" smaller than the knurl diameter, aluminum is 007". The knurled part of the stud will work into a smaller hole than a round stud, as the grooves give the extra material some place to go.
    Don't forget to check the length and width of the knurled area, if for example the hub is 1/2" thick the knurl needs to be 1/2" long so it doesn't protrude beyond the mating surface. Measure this before you press any studs into axle or the hub so you don't have to reverse the process and press them out again.
    upload_2019-4-9_14-3-51.png
     
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  4. RichFox
    Joined: Dec 3, 2006
    Posts: 9,536

    RichFox
    ALLIANCE MEMBER

    I strongly urge you to consider turning the studs to fit the existing hole rather that opening up the hole to fit the studs. I believe you will need to grind a antirotation flat on the head of the stud, I would guess .002 interferance fit would be good and freeze the studs before instalation
     
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  5. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,352

    DDDenny
    Member
    from oregon

    Good advise here, much easier to control the stud turning dimension than it is the dimension of the drilling operation. If it was done on a mill with an accurate reamer such as from a plus/minus set the outcome is much more predictable.
    Another thing, when pressing the studs in, make sure the hub/axle flange is fully and well supported under stud location, the time spent getting this right is equally as important as getting an adequate press fit, it is easy to distort the flange and/or getting the studs crooked.
     
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  6. oj
    Joined: Jul 27, 2008
    Posts: 6,037

    oj
    ALLIANCE MEMBER

    I'm having a time of it to be sure. I'm scared silly with the suggested interferance fits. Maybe I am getting a poor read on the .545 hub, paint and all. I took the .620 shank and turned it down to .600 and chanphered a leading edge. The pics show the fixture I made to press them in with. 010.JPG 011.JPG
    I start the stud by hand and then assemble everything into the press with a large rod I machined to extend from the press die to the stud head.
    012.JPG
    Somehow it won't go straight. I run the press down unitl it stops, take the wheel out and smack the stud around so its' straight pull it tight as possible with 1/2" nut & Breaker bar then put it back into the press to completely drive the stud in place.
    I've tried several techique improvements to let is press straight and then I saw the plate I am pressing against:
    014.JPG
    I can't believe I did that.
    What do you guys suggest?
    The studs I have are supposed to be for my hubs, they say it take 30-40tons pressure. I machined .020 off and managed to press them on with 20tons but cannot keep them straight.
    Can I remove more metal off the shank to ease the pressing? Remember, this is a bare shank, no knurl. And this is what holds my wheels on.
    Thanks, Oj
    edited: the bent plate is what i pressed against, the pics show the other plate as an illustration.
     
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  8. gatz
    Joined: Jun 2, 2011
    Posts: 1,347

    gatz
    Member

    Turn the good plate edgewise to press against, and use the other bent plate as a support at the hub center, if it's reasonably straight. A bit of a balancing act, but if there's no other heavy steel available.
    We're talking at least 1" thick.

    When you say "paint and all" , there should NOT be any paint in the .545 hub hole.

    By the dimensions given; .055 is way too much interference ! no wonder you're bending stuff.

    Get that down to ~ .005 to .oo3.
    Turn a land for a lead-in for about 1/8" and .0005 / .001 under the Ø.545
    That will let the stud start in straight, but you still have to observe what's going on.
    Put a few drops of Loctite 609 on the shank and press them home.
     
  9. dave lewis
    Joined: Dec 12, 2006
    Posts: 1,343

    dave lewis
    Member

    Something to keep in mind..
    For a very long time Ford used a swedge tool to lock wheel studs in place.
    This swedge process expanded the end and rolled it over into the wheel side of the drum , locking the hub and drum together.
    Also kept the stud from spinning....
    I'm not sure if this applies to the wide 5 hubs but I have experienced this issue in the past.
    There is a process to follow when removing swedged studs..
    If you do not remove the swedged portion of the stud BEFORE pressing out the stud you create an oversized hole..
    Often times this ruins the hub so No stud properly fits...
    Old school auto parts / machine shop guy here..
    Kind of like the farmers insurance ads..
    I know a thing or 2 cuz I've seen a thing or 2...
    Good luck with this..
    My memory is that the correct size replacement stud was pretty loose in the hub until it was swedged into place.
    Dave

    Sent from my SAMSUNG-SM-G891A using The H.A.M.B. mobile app
     
  10. RichFox
    Joined: Dec 3, 2006
    Posts: 9,536

    RichFox
    ALLIANCE MEMBER

    In my experience, a .055 interference fit is insane. Maybe ,005, My Ford hubs have a step machined in them and corresponding flats on the stud that acts as an anti rotation device. I run a .002 press with a smooth shank and they work fine. I don't know what the inside of your hubs looks like.
     
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  11. 270ci
    Joined: May 17, 2010
    Posts: 339

    270ci
    Member

    If you really managed a .055" interference fit on that stud, please do yourself a favor and check for cracks in the hub. Have it magged. Check for distortion of the hub around the stud as well. A lot metal had to move and go somewhere.
     
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  12. RichFox
    Joined: Dec 3, 2006
    Posts: 9,536

    RichFox
    ALLIANCE MEMBER

    What you are trying to do is the same as saying " This hole is tapped for a 9/16 bolt. But I think I can use a 5/8 if I just have a big enough hammer. No you can't. Take your hub to a good machine shop. Or race car builder. Not an assembler, a builder. And let them do it. You are trying your best to ruin your hub. Maybe you already have.
     
  13. oj
    Joined: Jul 27, 2008
    Posts: 6,037

    oj
    ALLIANCE MEMBER

    Well, 'paint and all' includes crap left from removing the original studs from imperfect holes that I'm not inclined to redrill to a 'perfect' hole. I measure with digital caliper and it says .545; I pressed in knurled studs with a .585 shoulder and they wouldn't hold when you really went to 'wheel tight' with a breaker bar. So the .055 intereferance isn't a good number. If you can guarantee that an .005 interferance is good enough that after years of use an impact can safely be used to install & remove a wheel I can make that happen. That would require I ream the holes perfectly straight in the mill and resize the hole, then turn the stud shoulder in the lathe.
    Again, is the .005 enough? I have visions of 30yrs from now a dufuss taking an impact and hammering away to change the tire, just like they do on a new car.
     
  14. RichFox
    Joined: Dec 3, 2006
    Posts: 9,536

    RichFox
    ALLIANCE MEMBER

    I doubt .005 will work without a shoulder as made into 5.5 diameter bolt circle hubs. The flat side on the stud head butting up against the shoulder prevents the stud from turning. On properly sized and installed spline knurled stud, the splines broach female splines in the hole that act as an anti rotation device. The chart posted by mgtstumpy would be my guide if I were you. I would still like to see the other side of the hub.
     
  15. gatz
    Joined: Jun 2, 2011
    Posts: 1,347

    gatz
    Member

    OP said the studs he had were straight....no knurl; so mgtstumpy's chart wouldn't apply.

    I'd like to see the other side as well.
     
  16. All the smooth shank Ford studs I've come across were swedged to hold them tight and the clipped head kept them from rotating. Maybe fit the holes in your hub with a heli-coils or thread-serts and use cap screws and hardened washers from the inside out to hold the drum and act as studs. Similar to putting the Buick drums on '48 style outside flange hubs.
     

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