Using Existing Disks w/ larger Birfs

Discussion in '40- & 55-Series Tech' started by dburnum, Oct 25, 2005.

  1. dburnum

    dburnum

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    I have a '74 FJ-40, that back in March I converted to 4 wheel disks. I used the MAF kits to do so, and really like the Wilwood calipers, and DBA discs on the front. Lack of future planning though has created a possible problem. I wish to change my tires in the next year from the 31"x 10.5 that I have now to a 34"x10.5" LTB. I think I'll probably need to upgrade the birfs to a newer style since my wheeling is mostly mild to moderate......not sure about that though. I do get some body damage sometimes.....not sure if that's moderate. Anyway, heres the ?:
    If I upgrade the birfs w/ larger knuckles, can I still use the adapter plate I got with the MAF kit, so that I can keep the calipers and DBA discs?

    TIA,
    Doug

    Sept '74 FJ-40
    '86 FJ-60 2F
    4 Wheel Discs
    Everything else- stock
     
  2. bandy rooster

    bandy rooster

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    you should probably do what mace is gonna say...
     
    Last edited: Oct 25, 2005
  3. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    The spindle size is the issue.

    I do not believe you can go to longs..

    You can however have your coarse splined birfs sent out to longfield. But that is a bit of a waste IMHO

    If you do not lock the front you will probably be okay with the drum stuff even with the 34's
     
  4. dburnum

    dburnum

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    I do eventually maybe mid next year, change both front and rear 3rds to an ARB locker.
     
  5. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    ARB is the same for a 74 no matter what Birfs you have in it.
     
  6. mrgadget

    mrgadget

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    I have a '74 and many years ago I went to disc brakes, but I made a bracket and used the '74 knuckles, later I wanted to go to the truck birfs, so I checked the truck and '74 knuckles and they are the same except for the ears for the calipers and the spindle bolt hoes are larger, I drilled mine out and tapped them for the truck spindle and did a little grinding to allow the truck birf to go in and all wrks great for years.
     
  7. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    So what hub, NOT LOCKOUT, are you using then...disc brake?


    What rotor?
     
  8. dburnum

    dburnum

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    This is all good information. I suppose, I should have included a long term plan for this vehicle in my first post. As my tires get larger, and I do wish to lock the front-end eventually. I thought I would need to install longfields, or newfields. I think I've read elsewhere though, that to install those you need a newer style knuckle and hub. I also wish to do a SOA conversion this spring with an OME Susp (no spring lift). While doing a cut -n- turn, I figure I can replace to the newer style knuckles to accept the longfields or newfields.
    OK...That is the plan......Now

    1. What can I do to keep the Wilwood calipers from the MAF kit?
    2. Since there is a newer hub(splines), can I use the same DBA disc?
    2a. If not. Is there another DBA disc that will work on the newer hub?
    3. Previous post mention truck(mini truck) knukles. Will those knuckles allow for newfields or longfields
     
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