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Technical 57 Chevy rear disc brake conversion issue- Wrong axle shaft length?

Discussion in 'The Hokey Ass Message Board' started by oneratfink57, Nov 14, 2020.

  1. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Hey all,

    I’ve got a speedway rear disc brake conversion, and when installed, the drivers side outer pad was rubbing on the rotor (suggesting the axle was sticking too far out of the housing.)

    I disassembled everything and reinstalled the axles verifying they were both fully engaged.

    When I measured the distance between the axle housing and the axle flange I saw a 1/4” difference as seen in the pictures.


    Am I crazy, or did this housing come with the wrong drivers side axle shaft? More incriminating evidence is when I I installed new wheel studs, the passenger side was a smaller knurl diameter than the drivers side.

    Passenger side (no interference)

    [​IMG]

    Drivers side (interference)

    [​IMG]

    You can see where the pad was rubbing on the face of the rotor

    [​IMG]



    Sent from my iPhone using H.A.M.B.
     
  2. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 1,324

    Pete Eastwood
    Member
    from california

    Maybe you have one 1955 axle , 1955 axles are slightly different .
     
  3. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,795

    jimmy six
    ALLIANCE MEMBER

    Every conversion I’ve ever seen had 2 or 3 thicknesses of washers included to center the disc in the caliper. They were normally for the mounting bracket. Yours may have had one replaced at some time in its life.
    Can you tighten the flange without it bowing? Remember your backing plate is no longer there. I would loosen the passenger side and pull out the axle slightly and then try the driver side.
     
    Elcohaulic and oneratfink57 like this.
  4. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,770

    olscrounger
    ALLIANCE MEMBER

    also posi axles are different as I recall-length is a bit shorter on a posi axle I think--been a while.
     
    oneratfink57 likes this.

  5. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin


    Hey Pete, that’s a good point, I actually have a 56 Chevy rear diff kicking around. I could pull that axle and compare it. The 55 and 56 axles are different than the 57, but are interchangeable with one another
    Hey Jimmy,

    the kit came with a spacer (about the thickness of the backing plate) to go between the housing and the bearing retainer. Unfortunately more washers would only make the problem worse because the axle is positioned too far away from the caliper already. So adding washers to the bracket or to the retainer plate would magnify the problem.
     
    jimmy six likes this.
  6. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Hey scrounger,

    I’ll try to look up info on posi axles, thanks for the lead!
     
  7. Budget36
    Joined: Nov 29, 2014
    Posts: 13,173

    Budget36
    Member

    Can you just space the bracket/mount over?
     
    oneratfink57 likes this.
  8. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    No unfortunately I can’t space the bracket

    In the picture below the green vertical line shows where the bracket is, and it would have to move 0.25” to the left (indicated by the arrow) that could be accomplished by machining the bracket, but that’s not a great option considering I think it’s only 3/8” thick lol

    [​IMG]


    Sent from my iPhone using H.A.M.B.
     
  9. badshifter
    Joined: Apr 28, 2006
    Posts: 3,535

    badshifter
    Member

    Have you checked to see if the axle bearing is actually pressed all the way on to the axle?
    On a drum brake setup you would never have noticed but the disc brake setup its important.
    That's the first thing I'd check.
     
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  10. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    Considering that rear end is over 60 years old... you think someone in the past may have stuck an axle in that their uncle said would fit and they just slid it and and drove it for who knows how long before you discovered it?
     
    oneratfink57 likes this.
  11. Any chance its a 1958 -64 bearing on a 57 axle? They are .120 wider. It can be done .It requires a spacer behind the backing plate if done correctly.The warped retainer looks like a poor attempt to make it work.A 57 shoe is 1-3/4 in inside a 2 inch drum so it works for drums. Converting to discs is a different matter. The later bearing has 2 o ring seals ,the 57 just 1.
     
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  12. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    hey irishsteve,

    I think you hit the nail on the head, both axle bearings have two oring seals. I also noticed that both bearings stick out about 1/16 to 1/8” past the exile housing when full seated, so the newer bearings likely explain that. Although I still think there’s something funky going on with the drivers axle to get it 1/4” off.
     
    Last edited: Nov 14, 2020
  13. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    My hope is that dudes Uncle reads this thread and let’s me know what the axle was out of! Only on the H.A.M.B. would I be able to get the answer
     
  14. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Yes I did take a look at that, unfortunately it wasn’t quite that easy this time lol. I did notice that the land the bearing presses up against is longer on the axle I’m having issues with, which is where the extra 1/4” is coming up.

    What it’s coming down to, is I’m likely going to have to weld new perches on the 55/56 Chevy rear I have kicking around and put the disc conversion on that instead. And I’ll have to hope and pray the axle shafts are untouched on that one. It’s never easy!
     
  15. brigrat
    Joined: Nov 9, 2007
    Posts: 5,615

    brigrat
    Member
    from Wa.St.

    I thought the bearing was supposed to stick out a little, that's what centers your backing plate on drum brakes.
     
    gimpyshotrods likes this.
  16. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Maybe it’s supposed to stick out a little, but the backing plate is centered by the axle housing that sticks past the flange on this diff housing. But on a ford 9” and other diffs, I know what you’re saying. You can see what I’m talking about in the pictures
     
  17. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    Just so you're aware, the 55-56 rear ends (third members) are a little weaker than the 57 to 64 rear ends, and do not have a drain plug. They also take "smaller' axles and therefore, a different axle bearing; those bearings are getting harder to find, from off-shore when you do find them, cost more, and the off-shore stuff is no way as good. Are you certain your rear end and housing are a 57? 57's were the only Tri-Five with a drain plug, so they're easy to ID. I'm probably wrong here (by the looks of things), but I thought the caliper bracket in the swap kit, was also used as the axle bearing retainer (???). Is the a groove or a recess on the "back" side of the bracket? It would seem, that would space the caliper outward, like it needs to be in your photos, but the caliper also "floats" somewhat does't it? Maybe try to space the caliper out temporarily with some washers, just to see if that takes care of your issues?
    I was just looking at these kits on E-Bay, and they all seem to have a spacer of some sort that would space the caliper outwards.
    I am Butch/56sedandelivery.
     
  18. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Hey Butch,

    Yes the axle I’m having issues with is a 57. Has the drain plug on the bottom and the flat bearing retainers. I do have a 55/56 Chevy rear also (no drain plug with the weird stepped retainers/ shorter housing.)

    That’s good info on the bearing availability thanks for sharing! So I’ll have to put some thought into it prior to giving up on the 57 rear.

    The pictures below (I can take better pictures later, this is just what I had) shows how it’s currently installed. I believe it is the way it was intended to be. If I put the caliper bracket on the outside of the housing, the bracket would be nearly rubbing on the rotor and pushing the caliper outwards would definitely result in the caliper rubbing on the wheel badly.

    If I simply spaced the caliper, it would just make the current problem worse by pushing the caliper further away from the rotor.


    [​IMG]

    IMG_7579.JPG

    IMG_7577.JPG

    IMG_7801.JPG




    Sent from my iPhone using H.A.M.B.
     
  19. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    So I just went on speedway to provide a picture of the kit I have, and I may need to give them a quick call. My caliper brackets are not machined, but the ones in the image are where the caliper mounts to the brackets (as seen in the image.) Technically if the caliper brackets were machined about 1/8” it might do the trick.

    I never considered the kit was off because the passenger side fits perfect. But we shall see

    https://content.speedwaymotors.com/...600_e04002f4-9f6b-4601-8c9f-0599a1926add.webp


    Sent from my iPhone using H.A.M.B.
     
  20. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Called speedway today, they said the brackets are no longer machined, so it looks like I’m back to wrong drivers side axle.
     
    Last edited: Nov 16, 2020
  21. brigrat
    Joined: Nov 9, 2007
    Posts: 5,615

    brigrat
    Member
    from Wa.St.

    I have several '57 axles, if you can't find any closer to you...................................
    $50 plus shipping! At this price you might want 2!
     
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  22. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Thanks bigrat, I will keep that in mind!
     
  23. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Hey all, for those who are interested, this is how far off the caliper to axle flange distance is. The image is a little disorienting because it looks like the rotor is parallel to the caliper bracket, but it’s not. Note angle of the rotor front to back due to the axle being too long. You can see it best if you look at the length of the wheel studs that are visible

    [​IMG]


    Sent from my iPhone using H.A.M.B.
     
  24. brading
    Joined: Sep 9, 2019
    Posts: 704

    brading
    Member

    Definitely the wrong the wrong half shaft you have got in there. You can see the difference in the distance between the bearing area and the flange of the red and the blue. Get the right shaft and solve the problem.
     

    Attached Files:

  25. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    ^^^^Is the bearing driven on all the way?^^^^ There's a "gap" that's visible. But then again, which axle is which? Tear it all down, re-seat everything, and try again? I am Butch/56sedandelivery;.
     
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  26. oneratfink57
    Joined: Feb 12, 2006
    Posts: 737

    oneratfink57
    Member
    from Wisconsin

    Figured I would circle back to the conversation.

    So as it turns out, my original thought was correct, and the drivers side axle shaft was the wrong length. Still have no idea what car it was out of, but it’s not a 55/56 or 57 Chevy axle.

    what I ended up doing is taking my 55/56 rear end and welded perches on it to run that. It came out of an Arizona car with 60,000 miles so I knew it was un molested and I was getting sick of messing around lol.

    In the process I learned that 55/56 Chevy axle shafts are identical to 57 BUT, they have different bearings. 57 Chevy bearings are larger diameter with two rubber o ring seals. Where the 56 only has one seal.

    For those who are interested, to sum it up all 55/56 rear end parts parts are interchangeable with 57 EXCEPT the housing and axle bearings.

    Bigrat, I’ll probably end up grabbing a drivers axle from you after I assess the damage from Christmas for the kids did on my wallet lol
     

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