Lost Rear Brake

Twice I have been up at a higher Altitude 8000 + feet and had no rear brake, pedal goes to the floor. Has anyone had this happen ? It must have something to do with thinner air and the brake fluid ?? 05 Electa-glide

Air has to be in the system somewhere. Either a loose line or bleeder or seal in master cylinder or caliper. Get it checked out... Somehow there is air in the system. It's a closed system so altitude cannot cause it... B.O.L.

This is usually air in the system, but it also seems to happen when the brake fluiold and has absorbed a bit of water. The water breaks down and with the reduced air pressure the oxygen expands and you lose the grakes until you get to lower altitude. Don't just bleed your brakes, change out the fluid. I do this on every 10,000 mile service I perform.

My cross country trip from the rear brake point of view:

Had issues in NH, they said the brakes needed to be bled. They bled them, the brakes worked well.

Got to South Dakota and suddenly lost about half of the pedal. Took it to the dealership; they said there was nothing wrong.

Got up to above 10,000' on the Million Dollar Highway in CO and lost my rear brakes completely.

Went to the next dealership and they said my brakes needed to be bled, any amount of air in the line will be amplified at altitude. Bled the brakes and went on.

Got back to NH. Brakes were OK but not great. Winter time, no more riding.

Moved to Colorado and sent the bike to another dealership for a ton of performance and cosmetic work. When it was done, took the bike for a ride and no rear brake. :gah: Went back to the dealership and was told that the mechanic had noted that there was something wrong with the rear brakes when he took it for a test ride. Turns out the rotor was warped, which would be ok for a little, but then if you try to brake in a bad spot, you lose your brakes.

So, maybe the altitude isn't helping, but have someone (or measure it yourself) check the rotor.

PS - this was all within about three weeks, except for the move to Colorado.

Nice How They Let You Know That The Mech. Noted Your Bad Brakes After You Came Back Complaining About Them.

I was thinking the same thing.....especially considering they just hopped up the motor too. Nothing like having extra horsepower that you're not used to and having no brakes to go along with it. :gah: Good thing you're an experienced rider Hot01.

in the hyd. theory fluid doesnot compress (1%) is the factor. so if you lost brakes 1. were you headed down hill before or during? so were your pads hot or glazed over? 2. did you have brake work done right before you went to a high alt. (then decend) air / contamination in the system. 3 leaks /heat causing brake fade......fluid under pressure will not change to the extreme with out having an outside influence. basicly a 1 ton jack will be a 1 ton jack (with in a fraction) at sea level, and 10000 feet as long as it is intact and not contaminated

Can you pump it and get them back??

Thanks for all the good info !! I think heat may ge a factor, although I don't use the brakes that hard or much that I thought I would over heat them. I think I will change the fluid and bleed the line.
I recently talked to a buddy with the same Yr and model and he had it happen to him at high Alt.
He has talked to the stealership twice and they have no Idea.
Thanks again for all the good info.

They will come back, but it takes awhile

Sounds like a heat thing... Mic out the rotor... Might just find some warpage...Hyd fluid isn't compressible, therefore if you push, the system will apply... Unless air is in there...

what

this thing with the dealerships is enough to drive most folks nuts,,,, example,,,new 2002 ultra,,, traveling thru n.m.,,, stop for gas,,, oil drip out of intake,,, call dealer closest,,,explain to him oil...says where you from,,, oregon coast,,,, OH he says,,all that is wrong is you are now riding well above sea leval,,, sounds fishy to me so i call my dealer in portland ,,,, he says dont worry about it,,, if it blows up it is under warrenty,,, well i am in new orleans dealership few days later ,,, ask him about it,,, still dripping oil,,, OH he says,,, you are BELOW sea level here ,,,so will do that till you get out of town,,, couple days later in savannah georgia,,,oil change ...new tire,,, reading bike magizine while i wait... article says dripping oil is from oil pump out of time... guy who wrote it is in atlanta,,, so i am going there anyway,,, called him two days later,,, ya ,,come on in ,,, now this guy is NOT in a dealership,,, he says give me half an hour,,, i stayed and watched him,,, the pump WAS out of time ,,, rode bike for another 50000,,, never dripped again,,,, after reading the article ..i called my dealer and a couple others ,,,including savannah i am sitting at,,,they ALL told me the guy does not know what he is talking about,,,, but it worked and it does ,,,so good luck with dealers...pops