Whether or not Jim and I bark at each other, you have the same dogs barking up the same tree. That ought to speak volumes.

Proper bleeding will not allow air to go back into the cylinder. Even if the bleeders are sucking air, the volume of brake fluid drawn in from the resivor exceeds the volume of air sucked in by the leaking bleeders, meaning that you can bleed all the air, even if the bleeders are sucking air.

My manual drums gravity bleed like they were attacked with an m-16. Jim claims that his disc brakes won't gravity bleed for anyting. The difference is probabally the differences in the systems.

If you gan get them to gravity bleed, it's the only way to go.

Why would it suddenly fail right at this moment? The answer seems fairly easy with many reasons. First of all, the pump people seem to do so with overkill. That's the reason I pefer to gravity bleed my brakes. When the pumper is in the car, they have, probally, the same grimace on their face when they are sitting on the toilet. They are applying ten times the pressure on the pedal than it would take to lock them up. Often, in accidents, brakes fail. It almost looks as if it was the cause of the accident, when in fact the driver was on the brake so hard that they ruptured the system with overpressure.

Even if the pumper isn't pumping with overkill, the m/c cups are traveling much further in the bores than they would under normal operation. As a reslut, the cups are going past their normal area, which has been kept polished by the cups and the cups have worn themselves into the "normal operating" travel area.

Of course, I'm taking a couple of hit-or-miss stabs, but both reasons are fairly logical explainations as to why the m/c would suddently crap out.