Transmission Brake

 Transmission Brake

4/18/2023

Because of a rear output shaft seal leak I had to redo the transmission brake.  After cleaning and painting the backing plate I installed a new adjuster unit and a new actuator unit, along with new shoes. The adjuster and actuator units were probably reusable but I had new so I replaced them.  I also replaced the brake shoes as the old ones were oil soaked.  What I found out, however was that the combination of all those new parts made the circumference of the brake shows too large to fit the drum on.  

After multiple times taking off the shoes and putting them back on, the fix was to shave 3/16" off the actuator side of the shoes.  The aftermarket shoes were made different and I assume were a little different size at the points where they fit into the adjuster and actuator.

I did have another set of new shoes from a different manufacturer that might have worked better but I didn't realize that until after I'd finished the job.

A tip: to make sure the shoes and drums will fit, before you fight getting them on with springs (I didn't figure out this hack until too late), just use zip ties to hold them in place and see if the drum fits.

Make sure you have the leading edge of the shoes (the pad furthest from the end) in the direction of rotation (Rotation is counter-clock wise), and the adjuster turned all the way out.  Of course also make sure the internals of actuator and adjuster are properly put together and greased. Not that the actuator only moves the shoes about 2mm so the shoes to drum fit is pretty close.

A couple of other things I learned in the process.  You cannot put the springs on the shoes while they are in place; you have to put them on first then stretch the shoes into place.  If you have the hub on before you do all of this (initially I did not but it was in place by the time I realized the drum wouldn't fit and I did not want to take it back off), and the actuator in place, the spring will not pass between the two.  So my fix was to put the actuator partially in place but held out just enough to pass the spring, using a zip tie to hold it out of the way.  Another problem in getting these shoes on is that the springs tend to fall out, so I used bolts of the correct size, stuck into the spring holes to hold them in place until the shoes are in place; you can also use golf-tees to do the same job.

These shoes are not the right way around.  I took this photo before changing them.  the long (leading) edge should be on the left/down side. Adjuster on the left, actuator on the right side.

Pic shoes the leading edge (left) and trailing edge (right).