Originally Posted by
DeathBySnuSnu
Typically disc calipers do not require as much volume to engage. The pads retract very little from the disc, especially with a residual valve. Drums must retract a lot farther to disengage fully.
You are usually looking for pressure instead of volume with disc. A lot depends on your mechanical linkage to the master.
I run a 22mm on mine, but I have a large mechanical ratio on my lever.
An early 19mm master should be fine.
Check your brackets for the calipers.
Make sure the caliper centers well on the disc. If it is not near centered it could make it have to retract farther than normal.
Another big problem with the kit brackets is the thickness of the bracket itself. Most if not all of the caliper brackets are way thicker that the drum backing plate by at least .100" When you put these on the bearing/axle/disc and all can float in and out spreading open the caliper. Then next time you hit the pedal it is way down there, one pump and it I'd back where it should be. I lathe cut my caps down. You could use ring shaped spacers between the cap and bearing.
Very few of the kits go over setting them up. I was suprised with mine also. Some of the better kits (expensive) have instructions and a bearing spacer.
Did yours? Was the bracket thicker than the backing plate?
Again... i cut .100 off the bearing cap. End play good. Then put it together and the caliper was not centered. Threw the cut bearing caps in the trash and started over. Spacer under the bearing to get the caliper centered and then cut the remainder off the next set of caps.
Dang long winded today I guess.