D21 brakes

Yes. Install so the drums splines are closest to the end of the bull pinion shaft.

I just went in for a look and tried grinding and sanding and blew it out. Splins and drum look servicable. Didn't seem to help with stopping.About decided to send to Rick to reline everything.

To your question as to how the balls work, and I am assuming you mean the balls in the brake assy, it is like this. The balls are inside two sockets that have ramps in each direction radially. Springs hold them two brake halves together. When one depresses the brake pedal, the outer bang closes around the drum half that is not splined to the pinion and tries to stop it. As it now moves slower than the splined half, it rotates slightly and the balls in question start to ride up the ramps. This forces the two halves apart slightly and causes the inner and outer brake linings to contact the outer and inner steel housings. The more pressure applied to the bands vial brake pedal the more self energizing the side pressure becomes as now the non- splined half is assisted by the braking action and forces the balls up the ramps even more. This is the reason when the two springs that hold the two halves together break or the ramps break, the brake continues to self energize and locks the wheel down and can only be released by backing up - unless it explodes and pieces either make for no brake or a complete lock up. Scuffing up the metal should not be excessive, the issue is the brake material glazes over - scuffing them up is more beneficial if there is enough pad left.   

DrAllis wrote: Just know that even when the brakes are working great on a D-21, you may sometimes feel like Fred Flintstone trying to stop his car. They are just borderline OK (at best) and even worse with duals, and the heavier the tractor is the less effective they are. I always lightly grease the ball pockets so they don't rust and the balls can freely roll. I also lightly grease the splines and install the drum on/off in several different locations to spread the grease film around. Wipe off any excess grease. For those who are so damn sure you shouldn't grease/lube anything because of a dirt environment, keep it to yourself. I oil gathering chains on a corn head and they are in dirt all the time too.

I have worked alot figuring out what is the best type of antisize/lube that really works. I cringe when I see the silver stuff, it should be called sure to sieze. Hear me out or flame me doesn't matter whether on king pins,tie rods any where or just about everywhere I have had remarkable results using CRC DIELECTRIC, the stuff for coating electrical connections, dont use it there, cuases resistance.

DrAllis wrote: The original brake band and disc linings from 35+ years ago were made out of asbestos of some kind.