[danK]

Rear hayes mag disc just let go! Before the ride I noticed the lever had to be pulled more to activate, but when I grabbed both brakes in an emergency "don't let me fall off the mountain" grab while rolling backward with the front wheel in the air (don't ask how I got myself into that position), and the rear brake just disappeared! The lever went straight to the grip. After gathering myself, I noticed I had maybe 5% of braking power but only if I pulled the lever all the way in.

Do I have a big air bubble? I don't see any DOT leaking. Rotor is straight. Pads are still in.
Help, please.

 

[skywaybuzz]

Sounds like you are losing fluid and probably air aswell. Did you pull back the rubber cover on the lever where the hose attaches to the lever master cylinder? Sometimes the hose splits under there .I would check for leaks and bleed again.

 

[BalleRacing]

Rear hayes mag disc just let go! Before the ride I noticed the lever had to be pulled more to activate, but when I grabbed both brakes in an emergency "don't let me fall off the mountain" grab while rolling backward with the front wheel in the air (don't ask how I got myself into that position), and the rear brake just disappeared! The lever went straight to the grip. After gathering myself, I noticed I had maybe 5% of braking power but only if I pulled the lever all the way in.

Do I have a big air bubble? I don't see any DOT leaking. Rotor is straight. Pads are still in.
Help, please.

You may have a air in the system or a leak. Check the hose where it pivots, if you have the silver Hayes line it can fatigue crack after awhile. I have had this problem on my Hayes brakes with the silver brake lines and my lever suddenly went to the grip when I braked. I checked for leaks and I had a small crack in the break line where the hose comes from the handlebars and attaches to the front of the frame. I went to the Goodridge brake lines after that happened, they are much more flexible and stronger than the stock Hayes lines.
Erik,
Balle Racing
www.balleracing.com

 

[danK]

Found the culprit, at least one of them

You may have a air in the system or a leak. Check the hose where it pivots, if you have the silver Hayes line it can fatigue crack after awhile. I have had this problem on my Hayes brakes with the silver brake lines and my lever suddenly went to the grip when I braked. I checked for leaks and I had a small crack in the break line where the hose comes from the handlebars and attaches to the front of the frame. I went to the Goodridge brake lines after that happened, they are much more flexible and stronger than the stock Hayes lines.
Erik,
Balle Racing
www.balleracing.com

After checking the hoses for splits and making sure the connections were tight, I decided to bleed my brakes. That's when I found a rear brake pad's retainer clip broke in half. I bled it anyway, and have good feeling at the lever but when the bike is upright the pad drops in the caliper and rubs. So that's an easy fix since I need new pads; just make sure to get Hayes replacement pads since some aftermarkets don't come with the clips.
Thanks to all for the help.