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R&P GM 1/4 Ton Disc Conversion

Discussion in 'Builds and Fabricators Forum' started by FinoCJ, Aug 5, 2023.

Page 3 of 4
  1. Aug 30, 2023
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    Yes
     
    colojeepguy, Aug 30, 2023
    #41
    FinoCJ likes this.
  2. Aug 30, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Well...got one side completed....it's been a bit of a fight but hopefully it will all work when finalized. Knuckle studded, new drag link and TREs, new seal, new kingpin bearings, new wheel studs to work with the disc brakes, etc. I will wait to bleed until the other side is done...the driver side should hopefully go a bit easier now that I sorta know what I am trying to do. Then will have to remove the drum RPV from the MC (assuming it has one) for the front circuit.
    [​IMG]
     
    FinoCJ, Aug 30, 2023
    #42
    timsresort, colojeepguy, Steamboat Willys and 4 others like this.
  3. Aug 30, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Even cleaned up and put the spicer joint tag on
    [​IMG]
     
    FinoCJ, Aug 30, 2023
    #43
    3b a runnin, SoCalNickG, timsresort and 5 others like this.
  4. Aug 31, 2023
    wheelie

    wheelie beeg dummy 2024 Sponsor 2023 Sponsor

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    Looks great. Hoping to match your work this winter. Thanks for posting.
     
    wheelie, Aug 31, 2023
    #44
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  5. Aug 31, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Dave.... assuming this all works, I can send you part numbers for the detail items. Let's hope it works.
     
    FinoCJ, Aug 31, 2023
    #45
  6. Aug 31, 2023
    wheelie

    wheelie beeg dummy 2024 Sponsor 2023 Sponsor

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    I'd certainly appreciate it. Thanks. I have confidence in your work.

    I'll be changing master cylinders as I think mine is going south anyway. I'll probably try to source a late 70's cj unit for the disc/drum set up from the factory.
     
    wheelie, Aug 31, 2023
    #46
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  7. Sep 1, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Driver side done ....So, time to figure out the RPV.....
    [​IMG]
     
    FinoCJ, Sep 1, 2023
    #47
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  8. Sep 2, 2023
    wheelie

    wheelie beeg dummy 2024 Sponsor 2023 Sponsor

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    RPV??? Pardone' me ignorAUN'ce.
     
    wheelie, Sep 2, 2023
    #48
  9. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    RPV = residual pressure valve
    Usually a drum brake circuit will use a 10lbs RPV whereas a disc brake circuit would use no RPV or possibly a 2lbs one. When I bought the Wildwood MC from R&P, I ordered it as drum/drum, so I would expect it to have 10lbs RPV for both circuits. Rich said I would remove if I converted a circuit to disc.
     
    FinoCJ, Sep 2, 2023
    #49
  10. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    So I am not sure about the RPV....I assume it would be the larger hex head between the MC and the brake line flare nut. Basically what the flare nut is threading into.....
    [​IMG]

    As this is a Wildwood MC, I searched for Wildwood RPV to see what it looks like.... if there are rpv's in the MC, they sure don't look like this.
    https://www.wilwood.com/MasterCylinders/MasterCylinderValves

    So, I am kind of thinking the RPVs got left out? (The pedal has never felt great with this setup)....so guess I'll try bleeding the system and see what happens. If there is a 10lbs RPV, once the pedal is pressed and caliper piston pushes the pads against the rotor, they shouldn't release even when pedal is released?
     
    FinoCJ, Sep 2, 2023
    #50
  11. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    According to Wildwood diagram, there is only the outlet port.... looking like I have no RPVs? Would that mean I should add a 10lbs one for the rear drum circuit (and where should it be added)?
    upload_2023-9-2_18-5-6.png
     
    FinoCJ, Sep 2, 2023
    #51
  12. Sep 2, 2023
    Jw60

    Jw60 Cool school 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    The residual valves are surprisingly simple. Look for a rubber disk with a hole in the middle or a small spring assembly that allows a free flow out and a slight resistance in.
    I guess it is under the large hex. Remove anything under the large hex that does not actually seal the hex to the housing on the circuit going to the disks (or pull both and use the disks from the local ad)

    i think you just solved how I'm gonna hook up a hydraulic tow bar brake line...
     
    Jw60, Sep 2, 2023
    #52
  13. Sep 2, 2023
    vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

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    vtxtasy, Sep 2, 2023
    #53
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  14. Sep 2, 2023
    Jw60

    Jw60 Cool school 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Jw60, Sep 2, 2023
    #54
  15. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    FinoCJ, Sep 2, 2023
    #55
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  16. Sep 2, 2023
    vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

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    Too bad they can't furnish you with the 2lb duckbill and avoid the extra plumbing.
     
    vtxtasy, Sep 2, 2023
    #56
  17. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    Based on driving and pedal feel, I am not convinced the RPVs are even in there....guess we'll find out when I remove the outlet fitting....
     
    FinoCJ, Sep 2, 2023
    #57
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  18. Sep 2, 2023
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

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    I guess since I am using a frame mount at about the same height at the caliper, I should use a 2lbs RPV.....may not be critical. I can call Willwood and see what they might have.....
     
    FinoCJ, Sep 2, 2023
    #58
  19. Sep 2, 2023
    Jw60

    Jw60 Cool school 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    It's 2lb for disk. 10lb will drag and no valve will take a bit of pumping to work. I had one wilwood brand in-line valves fail so if you can just replace the guts that's the way to go.

    If you go with the in-line valve keep it away from the exhaust or the internal rubber duckbill may get upset. :rolleyes:
     
    Jw60, Sep 2, 2023
    #59
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  20. Sep 2, 2023
    vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

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    I would check for both valves being in there. You could jack up one side now and see if the brakes drag. Like Joe said, do you need to pump the
    brakes to get any action? You could also have someone hold the brakes and check to see if the wheel turns.
     
    vtxtasy, Sep 2, 2023
    #60
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