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Topic Summary

Posted by: OnlyOneDR
« on: June 20, 2020, 05:55:06 PM »

Drum brakes are fun but most people don't think so.  I just think they are misunderstood.

The longer shoe needs to be the self-energizing shoe, meaning that when the vehicle is travelling forward it will be the shoe that wedges against the fixed pin as friction develops.  In the first picture of the thread (front wheel brake) the self-energizing shoe is the rear one (to the left) since the forward motion results in clockwise rotation.  In the later picture (rear wheel brake) the self-energizing shoe is the front one (right side) because it will wedge against the bottom pin in clockwise rotation.  Clearly, this gets mirrored when you move to the other side of the vehicle.

Finally, after 20 years I can regurgitate useful information from my one semester class of automotive engineering!
Posted by: aboyandhisdog
« on: April 02, 2020, 12:57:14 PM »

That is very interesting, Steve!  So I suppose a guy should state just what he has when giving out information. ;D :P  My 11" brakes look like Jorge's photo and when I did a brake job about 8 years ago I got all the parts at Napa and specified that they were for a '71 CJ5.  This might indicate that Jorge and I have the "floating design" as you referenced.  Probably all of the early CJ 5's were like this???  Anyway, when I took my first 4wd trip after replacing the shoes, I broke a shoe on the trail.  I came home scratching my head as to what went wrong.  Well, what went wrong is that I had put the long shoes forward thinking that was correct.  After a bit of research here on the 3A and some valuable input from Bob W., I learned that the short shoe was to go forward on these brakes.  Switched them all around and not an issue since!  Thanks for your research!!!
Posted by: SteveKfl
« on: April 02, 2020, 11:53:11 AM »

Here's what I love about this site.  Learning, and exchanges of experiences and information.  I did some searching on the web, and this is a controversial subject topic.  What I can determine is, it "depends on the system", and "primary" or "leading" shoe 'is' consistently the "front facing shoe".  The "long or short" is where the questions come up.  My Jeep Universal Form SM-1002-R6 for CJ2A, CJ3A, CJ3B, CJ5 CJ6 and DJ3A  has a "Note: On some vehicles, the lining on the forward shoe is longer than the lining on the reverse shoe".  Well, that clears everything up, or not.  No diagrams for 4WD brakes included in manual???  So here is what I 'think' I learned.  The 11" conversion pictured here has gone to a newer style "Floating Design" which indeed does use the primary short shoe up front, as the primary's "floating action" puts the most pressure on the rear shoe, the "longer shoe, by design.  Now on older Willys and Studebaker too, the "fixed pivot design" aka "Simplistic" with a dual pin wheel cylinder, the pressure is said to be "equal" and the thrust of the drum to the shoe up against the pivot makes the "primary" and "longer shoe" needed up front.  There is only a picture of a DJ3A rear wheel system in the SM that clearly displays that, and I found the attached pic of a Studebaker Passenger side rear brake the same as in the SM.  I also found a reference that stated that "cars and light trucks used the forward long shoe design prior to 1962", but not stating "all".  I could not find a picture of a Willys early model 4WD for comparison.  Maybe someone has one and can share that?  Now I know why I thought long shoe up front and primary.  Thanks for stimulating me to learn something new today.
 
Posted by: aboyandhisdog
« on: April 01, 2020, 08:05:07 PM »

Jorge, I have the 11" brakes too and this looks like mine.  You can adjust them 98% before putting the wheel on and then just finish the adjustment when you are all reassembled. 

Steve,  to the best of my knowledge, the primary shoe on these brakes is considered the short shoe and it goes forward.  Either that or the long shoe is the primary shoe and it goes to the rear.  A distinction without a difference, no doubt!  Long story short, the short shoe goes to the forward.
Posted by: SteveKfl
« on: April 01, 2020, 07:40:45 PM »

If the orientation of the pic is with the front to the right, passenger's side, isn't the "primary shoe lining" (longest one) supposed to be on the front?
Posted by: derekredmond
« on: March 31, 2020, 01:36:04 PM »

Here's the photo of Jorge's installation.



Posted by: Jorge Hedges
« on: March 31, 2020, 11:07:48 AM »

Hello All!

I am starting to adjust my upgrade to 11" brakes.  Need to know if I have the drum setup in pic below correct.  I adjusted the shoes to a slight drag, and lines have been bleeded.  Just wish to know if you see anything strange in the drum setup.

Pic is right (passenger) side setup; Jeep front is to the right of this pic.

https://photos.google.com/photo/AF1QipNYuGTRsxREGNp_HtI5vV3UqhaZNVP2LyIDECtT

Thanks!

Jorge

PS:  Not sure why, but can't log in...  system says I am a member, but won't accept my email/user name.