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Backing Plate Help- 11inch

Discussion in 'Early CJ5 and CJ6 Tech' started by Wilesbd, Jul 31, 2022.

  1. Jul 31, 2022
    Wilesbd

    Wilesbd New Member

    Pa
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    I thought I find found a 2nd set of backing plates to do my 11" brake swap on my 59, but comparing them to the first set, these plates are alot thicker. Did I mess up or can I still use these.

    First set is off a 74 cj5. Second set is off a mid 70's f100 dana 44.

    20220731_000659.jpg 20220731_000706.jpg 20220731_000717.jpg 20220731_000713.jpg
     
  2. Jul 31, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

    Medford Mass USA
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    Welcome from eastern Massachusetts.

    WHich is which? F-100 is not a bolt-on option for a Jeep. They can be made to work, but I'm not sure what's involved. Looking at them, either the center holes are different, or the bolt circle is different. They might have a different 'deck height' (for lack of a better term) too. I would be surprised if the Jeep plates were thicker than for the F-100, but maybe. The CJ GVWR is lower than the pickup.
     
    Last edited: Jul 31, 2022
  3. Jul 31, 2022
    Wilesbd

    Wilesbd New Member

    Pa
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    The f100 plates are the thicker of the two, it's the right one in the first picture.

    Aside from the overall thickness of everything, the bolt holes are in the same locations and the center hole is the same diameter.
     
  4. Jul 31, 2022
    duffer

    duffer Rodent Power

    Bozeman, MT
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    I think those will likely work. The mounting looks the same. It should not be too big a task just to mock one up and see if everything fits properly.
     
  5. Jul 31, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

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    If one will bolt on, the other will not. Measure the bolt circle. I put my ruler on the screen, and the left bolt circle is 45 mm and the center hole 30, while the right is 42-43 and 32 resp. Not the same. Maybe the OP understands that; they are not bolt-on compatible.

    Inspection is sufficient; look at the web thickness between the bolt circle and the center. Different.
     
    Last edited: Jul 31, 2022
  6. Jul 31, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

    East Tennessee
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    I don't know whether an accurate measurement can be made with a ruler against a digital picture on a computer screen.

    I think they would work fine. Ford used the DANA 44 in some of the trucks, and if they fit a DANA 44 they will fit your Jeep axle. As already said it is easy to find out by mocking one up. If you are going to use them on the rear axle I suggest bolting your bearing retainer to the plate to use as a template to drill the extra drain hole at the bottom of the plates.

    I found a similar thick backing plates in my pile a couple of days ago when I was looking for a set for another forum member. It is thicker material and has a brace around the wheel cylinder. I think it came off a F250 4X4 and it will fit a Jeep axle. I have came across some backing plates that would not work on the front of a Jeep without enlarging the center hole, but would work on the rear. I do not know what they came off of.
     
  7. Jul 31, 2022
    Wilesbd

    Wilesbd New Member

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    Thanks for the input guys. I just checked again, the bolt holes are identical on both plates, but the center hole is indeed 2.5mm larger on the f100 plate, will this be a problem?

    It'll be a couple days until I can get the chance to try to mock this up.
     
  8. Jul 31, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

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    Of course you can measure relative distances off the screen. Two objects at the same distance will be proportionally the same. Not a difficult concept. And you can compare by inspection, as I suggested.

    Novak used to sell instructions for how to modify F-100 backing plates to work on a Jeep. People paid money for instructions. Not worth much if they simply bolt on.
     
    dnb5853 likes this.
  9. Jul 31, 2022
    CHUGALUG

    CHUGALUG Member

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    I have a Jeep plate on one side and a ford plate on the other with exactly the same orientation and exactly the same parts and cylinders. I can put you through the windshield in a 60mph panic stop. If the holes match up the few thousands one plate is thicker then the other will make absolutely no difference in anything.
     
  10. Jul 31, 2022
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

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    True, sort of. But parallax raises it's ugly head if the camera isn't exactly centered over what it is you're trying to measure. To add to the problem the distance you take the picture from & the lens can accentuate the effect. :(

    As the OP is now reporting the mounting holes are indeed the same spacing I'd say this is what happened to you measurements.
     
  11. Jul 31, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    I have used Ford backing plates like that, they will work fine. The center hole on those is actually bigger than the Jeep plates, but that isn't a problem. Do need to drill the drain hole if used on the rear.
     
  12. Jul 31, 2022
    Wilesbd

    Wilesbd New Member

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    Thank you very much, I think these will probably be the rear set, hoping to get them mocked up this coming weekend.

    Thanks for everyone that helped.
     
  13. Aug 1, 2022
    Twin2

    Twin2 not him 2022 Sponsor 2021 Sponsor

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    not that I have anything to do with a rear brake change But
    if I was to go through the trouble to put larger brakes on rear
    I would think the rear backing plates with the emergency cable holes would be my choice
     
  14. Aug 1, 2022
    Wilesbd

    Wilesbd New Member

    Pa
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    My intention was to keep the jeep 100% factory/dealer correct. I decided to compromise a bit with upgrading to 11" drums and a dual master cylinder, since unless someone looks close they aren't noticeable. But I didn't want to deviate any further from original so I decided to keep the original style parking brake.

    Honestly it's going to be a street queen, so I'm not to worried about the e-brake holding anywhere but a parking lot, and I'll probably thru some wheel chocks under the pass sear just incase.
     
  15. Aug 1, 2022
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

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    This is hoe I did it.
     
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