Anyone have an issue with the rear master?

I was going down a ridiculously steep canyon road in 120F weather when my rear master just gave up. It went from normal on one corner to nothing on the next. Straight to the floor. I managed to get down to the next valley on the front brake (no straight parts) and rested my heart and the bike. After an hour or so it came back enough to get back to civilization (the bike). Then rested it a while longer and it is back to normal. But I still don't trust it.

Is this an annomaly or is there an upgrade I should consider?

I admit that I rode the rear a little too much, ok way too much, but I was expecting it to get soft before it went to the floor. Did I mention that it was ludicrously steep? Did I mention that it went from normal to complete failure in 2 sec?

Any thoughts welcomed as I am about to spend money on a new master just for fun.

cheers

D-Day

Probably nothing wrong with the master cylinder. I would think the fluid probably boiled from heat. Over time the fluid will accumulate moisture which lowers the boiling point. Suggest flushing the system with fresh fluid.

When fluid boils it does happen suddenly without warning. As long as there is pressure on the line it probably won't boil but when you let up and pressure is released it can boil immediately so the next time the pedal is pressed it's working against air.

Awe man, I'm afraid to answer this post with you only having 4 previous posts to your name....been burnt twice this week already....however, glad your OK if it actually happened

glad to hear youre ok change your brake fluid like right now, it can go bad ya know. once it boils im pretty sure its not any good anymore

Agree the fluid is done for and needs to be changed. Brake fluid is hydroscopic and over time absorbs water. When you heat it up the water boils and creates gas in the fluid, and gas can be compressed. When you compress the gas the pedal gets spongy!!! Brake fluid should be flushed every couple of years to make sure it is dry and up to the task.

Hygroscopic

D_Day wrote:
Anyone have an issue with the rear master?

I was going down a ridiculously steep canyon road in 120F weather when my rear master just gave up. It went from normal on one corner to nothing on the next. Straight to the floor. I managed to get down to the next valley on the front brake (no straight parts) and rested my heart and the bike. After an hour or so it came back enough to get back to civilization (the bike). Then rested it a while longer and it is back to normal. But I still don't trust it.

Is this an annomaly or is there an upgrade I should consider?

I admit that I rode the rear a little too much, ok way too much, but I was expecting it to get soft before it went to the floor. Did I mention that it was ludicrously steep? Did I mention that it went from normal to complete failure in 2 sec?

Any thoughts welcomed as I am about to spend money on a new master just for fun.

cheers D-Day

1.First off why are you having to ride the brakes that hard? When going down hill if your in the right gear the motor will help hold you back.
2.If you change your brake fluid and still find your having trouble and want to change the master contact me before you buy new. If you find your master is bad I have one sitting in my parts bin.
And I tend to let things go for a good price to members.
Danny

Is this another post pulled from the past? When was the last time it was 120º last summer in California?

Best I can tell, this one is legit Dave..but you sure nailed the last one.........

I am legit guys, but I do understand the healthy sceptism

Thanks for the input. That explains it. Helping me regain confidence in the rear brake.

I did change the fluid ASAP. But I was still not sure why it happened.

I was last August and I was going down a canyon road (goat trail) not meant for non-locals. But that is what I do. I guessed on the 120 degrees but it was much hotter in the canyon than the town we left which was measured at 100, maybe it was 110 or 115? Yep, we were two up at the time and loaded for travel. The passenger was unaware until we stopped and

I rode the rear more than I normally do because I was really concerned about overheating the engine. We were only doing 15-20 miles an hour. The gears were slowing us but it was getting pretty hot. It was really hot.

BTW went through death vally on a different trip at an advertised 130F while I was there and had no problems with overheating but I was moving at 50-70 almost the whole time. Great trip.

Thanks for the replies. Appreciate the help.

D-Day