Rear brake question

[Drewski]

Having an issue with the wife's '99R6. Changed rear pads and bled the system, all was working fine for a day or two. Now there is no pressure on the rear pedal. If I try and bleed the system again, there is no air coming out the bleeder valve so I'm thinking the master cylinder is working fine. Frozen caliper? I know there isn't much to the rear system that can go wrong. Any help is appreciated as I might be missing something.

[jasnmar]

Frozen caliper won't make there be no pressure on the pedal. Frozen caliper will make it so the pedal is hard to push.

Air or malfunctioning master is where I would look.

[TTD]

On some bikes (like my KTM dirt bike), there is a high spot in the brake hose that sometimes gets a bubble after a period of sitting.

If nothing mechanical is the issue, see if the brake hose has a clear hump in it where air might sit... usually far from either end so when you bleed it is virtually impossible to get it out.

With my KTM, it's the front brake. I have to physically bend the hose so the master cylinder is the high point, then I lightly touch the brake lever about50 times (less than 1/4 inch movement). Enough to open the hole, but not enough to force fluid down. Eventually, the air bubble moves into the reservoir and my pressure is back.

[ZX-12R]

If nothing mechanical is the issue, see if the brake hose has a clear hump in it where air might sit...

From checking out photos of '99 R6's on the internet, there is a big hump in the rear brake hose routing.

[TTD]

It's worth checking out before you work too hard on other stuff.

[Eric Baker]

Take the caliper off and hold it above the master and the hump in the line while you bleed. Make sure to put a block of wood or something between the pads so the pistons don't over extend.

[Paul_E_D]

Tony's got it. Air bubble for sure

[Drewski]

Thanks all. I appreciate it.

[Drewski]

Thanks again guys. I finally had time today and after dropping the hump in the brake line lower than the caliper and bleeding the line again, it was perfect in 10 minutes. Thanks for the great advice on what to look for!!

[TTD]

Cool... glad it helped.

[Rambunctous]

Take the caliper off and hold it above the master and the hump in the line while you bleed. Make sure to put a block of wood or something between the pads so the pistons don't over extend.

This just worked on a ducati with a higher than everything else hose. Pulled the caliper off and the hold down clamps and bleed it while holding the caliper near the tail light. Finally got some good pedal.