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11" Drums Worthwhile Over 10x2 Drums?

Discussion in 'Early CJ5 and CJ6 Tech' started by Broylz, Jul 17, 2016.

  1. Jul 17, 2016
    Broylz

    Broylz Member

    Gallatin, TN
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    I was reading about conversion kits and somehow was under the impression i would have 9" drums all around. Turns out my 70 has 10" x 2" drums all around.

    Im still looki g at the disc brake upgrade up front for better performance when wet or muddy etc but is the rear drum upgrade worthwhile if i have 10x2 over the 9 inch drums already?
     
  2. Jul 17, 2016
    Danefraz

    Danefraz Well-Known Member 2023 Sponsor 2022 Sponsor

    Chico CA
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    a lot of folks have gone to 11" drums,, including fronts, myself included. I haven't had the chance yet to stomp on the brakes and see how much better they work yet (build in progress still).

    I didn't want to mess with disks until I find a D-30 from something in the 70's or early 80's. I missed a chance at one a couple years ago. (Haven't seen one locally on CL in a long while).

    Rock auto and others have the parts.

    I like raybestos (used them a long time), wagner is good too.
    1969 JEEP CJ5 3.7L 225cid V6 Brake Shoe | RockAuto

    It seems that 10" stuff is 2x the cost of 11" stuff...

    good luck.
     
  3. Jul 17, 2016
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The rear wheels don't do much of the braking. When you hit the brakes, weight transfers to the front wheels of the vehicle and the front brakes do most of the braking. In a CJ this weight transfer is so severe that in 1974 Jeep added a proportioning valve for the rear wheels, to keep the rears from locking up on hard braking.

    If you are thinking about converting the fronts to disks, the 10" rears may be sufficient. If you have the fronts locking up and the rears never do, you could consider putting a larger cylinder in the rear drums, to get more stopping force on the rears. Replacing the fronts will also make a small pile of spare parts with which you can service the rears, if needed.

    If you converted, parts for the 11"x2" Bendix brakes are cheaper and much more widely available than parts for the 10"x2" Wagner brakes. If I needed a full rebuild of the 10" brakes, I'd add up the prices and see how much more you'd need to go with the 11" brakes. The 11" brakes also offer a cable operated parking brake, if you'd like to replace your transfer-case-mounted parking brake.
     
  4. Jul 17, 2016
    dnb71R2

    dnb71R2 SuperDave 2023 Sponsor

    Grand Mesa, CO
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    When I upgraded to 11" drums on the rear (from the 10") I noticed definite improvement. I did the front 11" brakes at the same time. It really didn't cost that much either.
    Here's my suggestion: Go ahead with the upgrade, but make sure you get the backing plates that will allow your parking brake to be moved to the rear axle, too. Ditto what Tim said!
    Replacement parts for the driveshaft parking brake are not the best in quality. I've learned this the hard way.
    I'm converting my parking brake now.
     
    Last edited: Jul 17, 2016
  5. Jul 17, 2016
    wheelie

    wheelie beeg dummy 2024 Sponsor 2023 Sponsor

    York, PA
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    Would you do a write up on your parking brake conversion. Part numbers included. Parts sources. Issues. I think it would be useful to many here.

    I would like to think that the 1972-1975 parking brake system would work on an ecj5 that is utilizing the matching 11 brakes but, perhaps the cable lengths are not correct.
     
  6. Jul 17, 2016
    piffey263

    piffey263 Active Member

    Medford, OR
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    I had 10 inch drums all the way around. I got around to swapping the front first, made an improvement. Then 11 inch brakes all the way around made a bigger difference.

    I broke the bleeder on the back brakes. Went down to flaps to price and see if the wheel cylinder was available... if I recall they wanted $36 for one cylinder and it would take a few days to get.

    It was cheaper and faster to get a wheel cylinder for the 11 inch brakes. I all ready had the 11 inch drum parts from a 74 cj5.
     
  7. Jul 17, 2016
    Broylz

    Broylz Member

    Gallatin, TN
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    Oct 9, 2012
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    After pricing everything out and not being able to find a good spring kit for the rebuild, i think it may be the best route to do the 11" upgrade. If i go all round 11" drums now, it will be the same price as the front disc kits only and make parts more available...
     
  8. Jul 18, 2016
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    The biggest benefit to going with front discs is if you do a lot of water crossings where you wheel. Good 11" brakes will stop a small Jeep really well.
     
    colojeepguy likes this.
  9. Jul 18, 2016
    Mcruff

    Mcruff Earlycj5 Machinist

    Albertville, AL
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    I have disk brakes up front (dana 30) and the factory 10" rear brakes, mine will stop good and hard and I have pulled a 2500lb trailer and the brakes would stop it fast if the jeep would not slide on the pavement. For just normal driving the disks alone are an incredible improvement.
     
  10. Jul 20, 2016
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    On the '71, I swapped to 11" drums, and drilled them for better wet performance after deep crossings. Worked great!
    Drilled drums when dry stop as well as disc.
    Should be some stuff in our archives here if you are interested in drilling drums. :)
     
  11. Jul 21, 2016
    Broylz

    Broylz Member

    Gallatin, TN
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    never heard of drilling drums before. Seems like a good compromise.
     
  12. Jul 21, 2016
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Was a Big Thing here a bout 10 years ago or so, a lot of people did it, at one point there was a template someone did up making the rounds. Try a search here on "drilled drums".

    H.
     
  13. Jul 21, 2016
    Broylz

    Broylz Member

    Gallatin, TN
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    i did a lot of looking at it last night. some of the older links were broken but i can easily come up with something. I can come up with a template quickly in auto cad or inventor...
     
  14. Jul 21, 2016
    Focker

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

    WA
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    Blury pic, but you can see the pattern.
    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Jul 21, 2016
  15. Jul 21, 2016
    Broylz

    Broylz Member

    Gallatin, TN
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    Thanks Focker. Thats what i had envisioned. Even spacing around the circumference should be easy enough to lay out.
     
  16. Jul 21, 2016
    Focker

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

    WA
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    From what I've read...Most use a 1/8" bit.
     
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