Draft Cycle Works

Monday, April 27, 2015

Deglazing a drum brake system

So ever since I built this cl450 front, I've never gotten it to function well. I've deglaze and adjusted it several ties, but I can't seem to find the sweet spot. It's a dual leading shoe system which apparently can be finicky. Another reason I'm taking the brake apart is because I've always heard a clicking sound when rolling the wheel backwards. After inspection it turned out one of the cotter pins had been bent out and was making contact with the wheel hub casting.

For deglazing, I sanded the shoes down with 220 grit perpendicular to the length of the shoe. I also chamfered the leading edge and the side a tiny bit. Just enough to remove the shine. For the drum liner I used 120 grit and a 45* cross hatch.

To adjust the shoes, I set the linkage so both cams were in the same position. I rassembled the drum with the punch marks lined up on the shaft/lever. I then tightened the cable until I heard contact. I expect that this is pretty close to the proper adjustment but I continued to make some minor adjustments.

My thought is that the liner is not perfectly round so I should be able to adjust the cable until I can hear one shoe make contact, then rotate the wheel 180* and make the same sound with the other shoe. This would mean that the shoes are adjusted the same distance away from the drum liner. I hope.

I adjusted the linkage until the sound was similar 180* apart. After dropping the bike back down, it seemed to hold better, but I'll need to ride it to really see if there was an improvement. I'm still waiting on the tins to Com back from paint.

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