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74 Cj5 Front Drum To Disk Conversion

Discussion in 'Intermediate CJ-5/6/7/8' started by 304, Feb 21, 2017.

  1. Feb 21, 2017
    304

    304 New Member

    Pico Rivera
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    Gathered GM Caliper Bracket, GMCalipers, 87 jeep rotors, replaced open knuckle studs with Dorman pn 610601. Previous discussions stated that 1/8 would need to be removed from brake pads and 1/8 removed from hub. I am not sure what side of hub needs grinding and also does each pad need 1/8 removed. Please advise, because at this time I am not clear since the rotor binds against the caliper bracket when tightening the spindle nut..
     
  2. Feb 21, 2017
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Moved to correct forum.

    Welcome :)

    H.
     
  3. Feb 21, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    I can't help with the hub grinding, I didn't have that issue.

    Put the pads on last and grind just enough to install them.

    From my '71 disc conversion experience, I'm not sure if it applies to a' 74?
     
  4. Feb 21, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    Are you sure you don't need a 1/8" spacer vs grinding?
     
  5. Feb 21, 2017
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Naches, WA
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    I am not sure where you read the hub needs to be ground 1/8". There is the possibility that if the back side of the hub is not flat where the rotor mounts to the hub, the hub will need to be machined flat. In Folkers case if I remember correctly, he did not need to do that. In my case where the hub would not allow the rotor to fit tight to the back side of the hub, put the hub in a lathe and machined the flat.
     
  6. Feb 21, 2017
    304

    304 New Member

    Pico Rivera
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    I may have been clear. The rotor rubs against the caliper bracket, when I tried to to install the hub and rotor. Is a part number available for the 1/8 spacer? Does this spacer go on the spindle? Thanks for your help.
     
  7. Feb 21, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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  8. Feb 22, 2017
    jeepermc

    jeepermc Active Member

    Western WA
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    The first thing that jumps out at me is the rotors. 87 Jeep rotors?? Did you mean the 1 1/18" rotors from a 77 CJ? That's what is commonly used with the GM calipers in my experience with this conversion. I've had the backs of the hubs machined just enough that the pad fits in the caliper and the rotor still spins. No mods to the pads, just machine the back of the hub. This also give you a flat surface for the rotor face to mate with and to press the studs through the rotor into the hub to make your assembly.
     
  9. Feb 22, 2017
    304

    304 New Member

    Pico Rivera
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    Thanks for all the guidance. Just to make sure what are my options. First the Rotors are for a 87 Jeep Rotor 1 1/8. Just so I understand my options per "nickmil" I can replace race using Timken LM501311 and replacing seal with National 84308. Or machine hub. For clarification, the hub can be machined on the back side. How much is machined off? Also, based on my uploaded pictures, which side is machined. Please advise. Thanks for the help.

    IMG_1419.JPG IMG_1424.JPG IMG_1426.JPG
     
  10. Feb 23, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    Machine where the hub meets the rotor.

    Question...
    Have you secured the hub to the rotor with the studs yet? When you do, the hub may suck down to the rotor more. It might just be the space you need.
     
  11. Feb 23, 2017
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    When I upgrade my DANA 30 from drums to disc I used the GM caliper brackets. It was necessary for me to machine the back side of the hub for the rotor to set flat to the hub. The reason is clearly seen in your first photo. Note the wear mark on your hub where the two come into contact. I removed enough material so that when viewed as in your second photo, the two were flat and tight to one another. I can not tell you exactly how material was removed but I did test fit during machining.

    When assembling everything on the jeep, I found I needed a wider bearing race for clearance. I tried the race nick had noted but found an issue. If you look at Folker's thread, post #36, you can see the problem and how it was resolved. I also had a couple of other issues with wheel studs and caliper banjo bolts. Look at posts #33 & 36.
     
  12. Feb 23, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Do you have a picture of the machined surface?
     
  13. Feb 23, 2017
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Sadly, no.
     
  14. Feb 23, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    I just googled and found this...This should help everyone.
    [​IMG]
     
    Daryl likes this.
  15. Feb 24, 2017
    304

    304 New Member

    Pico Rivera
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    Thank You all. This is very helpful.
     
  16. Mar 2, 2017
    Posimoto

    Posimoto Hopeless JEEP Addict

    Minden, Nevada
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    FWIW, unless you have the capability to machine the hubs yourself it's cheaper to just buy new hubs already machined for discs. I believe I bought mine from 4 Wheel Parts. As I recall all of the newer production hubs for the Early and Intermediate CJ's are already machined for discs.
     
  17. Mar 2, 2017
    Posimoto

    Posimoto Hopeless JEEP Addict

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    They have gone up in price a little since I bought my hubs, but here they are.

    Crown Automotive Front Wheel Hub - 5358568H

    You might have yours machined for less than that, but I couldn't find a machine shop around here that would do it for less than $75 ea.
     
  18. Jul 4, 2017
    bh10

    bh10 New Member

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    Wouldnt be easier to source a dana 30 with disc and convert it over?
     
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