Avoiding hydraulic brake system overfill when bleeding with worn pads I have limited experience with bleeding Avid Elixir 5, Shimano SLX and cheaper Shimano and Tektro brakes. I usually time the bleed just before brake pad replacement, in order to avoid the risk of contaminating the pads (because a rotor can be cleaned, but pads cannot).

The problem is, when I replace the pads with new ones, the disk rubs. This necessitates shedding brake fluid until the caliper pistons are allowed to move far enough back. The problems with this are:


risks introducing air to the system, because I use the lever bolt, instead of the caliper bolt
risks shedding too much liquid and voiding the bleed
it is tedious


Is there a trick to bleed the system just correctly, while mounted on the bike, with fully worn brake pads?
The problem you are encountering is likely because the pressure during the bleed process forces the pistons out slightly - this means that in effect you overfill the system.

You are best to push the pistons back fully with the old pads in place, then remove the old pads and replace with a bleed block.

You can buy specially designed bleed blocks, or you can see how to make your own here:http://www.epicbleedsolutions.com/blog/how-to-make-a-bleed-block/