I know what your feeling about the brakes failing where your at right now. This happened last year too didn't it? Too say the least, it can be down right scary up there. Going up, not so much, coming down.....well, yeah, pretty frigging scary. 1st gear & 4 Low is your friend at this point.
A couple things come to mind about the brakes failing...
It could be the master bypassed on you. I dealt with that for a few years with numerous masters. It's caused from doing a hard brake, too much pressure builds, and the fluids bypass back thru the seals in the master. It takes a few seconds for the pedal to firm back up. If it happens again, just release the pedal, leave it alone for a few seconds, and figure out other ways to slow down (besides a boulder) like down shifting, emergency brake, anything to buy you a few seconds. When you have firm pedal again, do not stomp on it. Slowly apply pressure to it until you stop.
Why does this happen? Sometimes it is just a bad master. (I got 2 bad masters right out of the box). Other times it is because there is too much pressure in either the front or rear system. Example: When you press on the peddle, it increases fluid pressure to both systems. If the pressure is too great, and a back pressure happens, the fluid is forced back into the master as the seals just give way and open up. The rear system is almost always the culprit.
What to look for? I think yours is pre-front abs, but might have rear abs. There is a box inline that controls the fluid pressure allowed to the rear. Too much pressure can be caused by contaminated fluids, and blocked the lines partially. The other can be a bad rear caliper, and or soft lines to the calipers. Lines can be old and softer than they should be causing swelling. Have someone step on the brake peddle as you watch the soft lines. If you can see them bulge/swell/grow in size, they need replaced. Do this for all 4 soft lines to the calipers. Replace as needed.
What color is your brake fluids? Black/dirty fluids will result in poor braking, even failure to work at all. Should be clear at all times, even if you have to flush the system with DOT3 4 times a year. This is the most overlooked brake maintenance item that I know of.
I'm sure you know some of this, but just for the heck of it, it doesn't hurt to say it anyways, just in case.
Oh, & big bushes are stronger than you think. They can stop you like a tree can, but do not cause as much damage. LOL!
I'm sure the spirit of Dr. Jack Lobdell was with you the whole way...
