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Dana 30 Drum Brakes To Discs

Discussion in 'Early CJ5 and CJ6 Tech' started by gibson-d@sbcglobal.net, Jul 30, 2020 at 7:36 PM.

  1. Jul 30, 2020 at 7:36 PM
    gibson-d@sbcglobal.net

    gibson-d@sbcglobal.net Member

    Houston, TX
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    My '71 has a D 30 with 11 X 2 drum brakes. I have a '77 D 30 with factory discs. The '71 axle is 3:73 while the '77 is 3:54, don't want to switch whole axle. What parts other than backing plates, rotors and calipers do I need to remove?
     
  2. Jul 30, 2020 at 7:46 PM
    Lockman

    Lockman My " Rosie" 2020 Sponsor 2019 Sponsor

    White City, NY 14617
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    The Brake systems don't have any common parts with the gears in the differentials. AFAIK,
    as long as both spindles are 27 spline, you should be good to go. I would install new bearings, races & seals , however.
     
  3. Jul 30, 2020 at 10:25 PM
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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  4. Jul 30, 2020 at 11:34 PM
    73 cj5

    73 cj5 Not ready for the junkyard yet 2020 Sponsor

    Mississippi
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    Knuckles to hubs.
     
  5. Jul 31, 2020 at 10:07 AM
    gibson-d@sbcglobal.net

    gibson-d@sbcglobal.net Member

    Houston, TX
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    Knuckles, meaning ball joint removal or just spindles?
     
  6. Jul 31, 2020 at 11:18 AM
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    meaning knuckle and ball joint removal.
     
  7. Jul 31, 2020 at 12:52 PM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    My understanding was that you swap everything from the ball joints out. I thought the outer axle shafts were different too, but I presume you could use the whole shaft from the disk brake axle.
     
  8. Jul 31, 2020 at 1:02 PM
    47v6

    47v6 junk wrecker! 2020 Sponsor

    Washington DC.
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    There are some slight differences in the axle assembly as in dust covers.. But not much.

    The spindles are different between the D30 disk and drum. The hubs are different in that they are machined flat for the disk. If the disk axle you have is complete, swapping the knuckles over is no big deal. Replace the ball joints while you're at it along with the hub seals.

    The 11x2 drums are pretty good though.
     
  9. Aug 1, 2020 at 9:32 AM
    Framer Mike P

    Framer Mike P Member

    Hopkinton, NH
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    I think you need to determine which brakes your 77 axle has to know if you need to swap the knuckles. The 76-? had disc brakes with a caliper mounting plate that bolted to the knuckle with the spindle sharing the six bolts - rotors should be about 1 1/8 inches thick. If you have these brakes I see no reason why you would need to swap the knuckles. Somewhere around 77-78 they changed to a caliper which used a c shaped caliper mount which bolted to two ears cast onto the back of the knuckle - rotors should be about 7/8 inches thick. If you have this set up I would agree you would need to switch the knuckles over.

    It might be worth considering selling the 77 axle intact and using the 1/2 ton chevy truck caliper brackets to covert to discs. These would bolt on using the six spindle bolts like the earlier jeep brackets.
     
  10. Aug 1, 2020 at 12:39 PM
    73 cj5

    73 cj5 Not ready for the junkyard yet 2020 Sponsor

    Mississippi
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    I took a d30 drum and an 80’s wt d30 and swapped the steering knuckles, spindles, and wheel hubs. I didn’t swap axle shafts, you don’t have to remove the ball joints. Just unbolted everything and swapped it over.
     
  11. Aug 1, 2020 at 5:47 PM
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    The disc brake knuckles have a relief cast In them to clear the caliper without grinding. Iirc the clocking of the spindle studs is different as well. Just much easier since he has all the stuff needed to swap everything. Or do the Chev conversion as you suggest.
     
  12. Aug 3, 2020 at 1:27 PM
    gibson-d@sbcglobal.net

    gibson-d@sbcglobal.net Member

    Houston, TX
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    My '77 has the 6 bolts and thick calipers. Another question, will my original D 27 axle bolt on to the '77 so I have a roller. This way I can remove the disc brake axle, put it next to my CJ while I switch parts. The '77 is my parts source.
     

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