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10 inch vs. 11 inch drums

Discussion in 'Early CJ5 and CJ6 Tech' started by EricM, Mar 3, 2009.

  1. Mar 3, 2009
    EricM

    EricM Active Member

    Southern California
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    Is there much difference in stopping power?

    They are both self adjusting. I'm pretty sure parts for the 11 inch are more common and cheaper.

    If you were upgrading from 9 inch drums, and you had a choice, 11 inch would be preferred.

    If you had 10 inch drums already, would there be much advantage to upgrading to 11 inch drums?
     
  2. Mar 3, 2009
    1970CJ6

    1970CJ6 new mexico air

    rio rancho, new...
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    I had 10" on my 1970 CJ6 with hard top and had no problems with them, I could eavn lock them up.

    I now have 11" because I changed the axles and a larger engine., still have MC under the floor'
    Andrew
     
  3. Mar 3, 2009
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    I went from 9" on my 2A to 10"; the 10s were freebies as the guy was upgrading to 11s.
    it was a noticable improvement.
    I then went 11's and it was noticable improvement as well..
    Keep in mind, this was back when 11" brake kits were only $295 for all 4 wheels.
    Nowadays, because of the cost, I wouldn't do it unless I ran across a deal somewhere or the 10s were shot.
    So I guess Eric, start looking.
    complete drum D30s might be a good source for 11" brakes; everyone says the D30 is junk (ha ha); the axle can usually be picked up for under $100; everyone wants disc set-ups; that would be 2 brake set-ups; if you weren't gonna run parking brake cables to the rear, then you could use the front backing plates on the rear as well; find a bent or broken drum D30 and use those parts as well. I recently found a narrow D30 complete, locking hub to locking hub, with 11" brakes for $50; I found another for $100. Keep your eyes open.
     
  4. Mar 3, 2009
    EricM

    EricM Active Member

    Southern California
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    That's a great tip, I'll keep my eyes open for drum D30s.
     
  5. Mar 4, 2009
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    11" drums all the way around are good... but drilled 11" drums are better... as good as disc in their wet/dry stopping power...
    search drilled drums. :)

    I had a buddy advertise his front early Bronco 11" drums and backing plates in our classifieds late last year... a good swap to an ECJ5... he didn't even get a bite... :?
     
  6. Mar 4, 2009
    termin8ed

    termin8ed I didn't do it Staff Member

    Mason, MI
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    depends on what you want to spend. 9" to 10" is a huge improvement. 10 to 11 is good, but not as much as the 9 to 10.
    Posted via Mobile Device
     
  7. Mar 5, 2009
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    Don't you also have to change to 16 inch wheels when you change to 11" drums?
    Or is that just the disc brake set-up?
     
  8. Mar 5, 2009
    Don X

    Don X The Prodigal Moderator Staff Member 2023 Sponsor

    San Diego,...
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    I have 11" drums with 15" wheels so it must just be discs?
     
  9. Mar 5, 2009
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    You can run most 15" wheels with 11" drums. And you can run 15" wheels with disc brakes too... but you have to run modern 15" wheels. Early 15 inchers, like the 8" KH (circa 1971)ones I had on the '71 when I got it would not clear discs, because of a 'hump" on the inside of the wheel. Later 15" wheels, circa late 70s CJ, or modern AR767s or Rockcrawlers don't have this hump and will clear discs.
     
  10. Mar 5, 2009
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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  11. Mar 5, 2009
    anthony

    anthony Member

    redding ca.
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    I agree with Lynn. I drilled my 11" drums and I really notice a big difference when the brakes get wet. I always have good brakes wet & dry. A little weak when they are real wet but dry really quick now. I am happy with the stopping power, running 31-9.5-15 tires. The only draw back would be that I haven't found anyone yet that will turn my my drums after drilling them, but to me its worth it to have better brakes. If I can't find anyone to turn the drums when the time comes I will buy new ones and drill them.
     
  12. Mar 6, 2009
    EricM

    EricM Active Member

    Southern California
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    Would a rear AMC 20 be a good candidate for 11" brakes?


    EDIT: Never mind, I just saw a picture, the backing plates are different.
     
    Last edited: Mar 6, 2009
  13. Mar 6, 2009
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    correct
    offset and bolt pattern all wrong
     
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