Rear Master Cylinder? Completely lossed rear Brake!!!

[cadarst]

Anyone ever change the Piston Cups or Piston gaskets, whatever they are called, in the rear master cylinder? I have totally lost my rear brake on my 02 CRF450R, and have a new brake line coming. Read an article that said 02-03 crf450's have problems with brake fluid boiling and pretty much roasting the seals on the piston in the rear master cylinder, and also brake line expansion, causing complete loss of rear brake. Any suggestions, or anyone have this happen to them? ?

[aremean_troy]

happened to me before. Just change the cups on the pistons in the rear master cylinder and everything will be fine. Honda sells the rebuild kit (the 2 cups, the seals and the piston)

[cadarst]

did you replace the brake line too?

[aremean_troy]

nope... In fact the only thing that I replaced, is the one of the cups. If I remembered correctly, its the top cup (primary cup?)

[cadarst]

one more, sorry. did you completely lose your rear brake, or just spongy? Mine went from spongy , to completly gone, even with pressure bleeding, no brake! ?

[aremean_troy]

It was completely gone... almost killed myself on one of the turn when it failed...

But now its ok... just get the rebuild kit first and see how it goes. I think it only cost about 25 bucks!

[skip #7]

My 02 lost the first one at 6 months then lost another about 2 years later,the brake just is there then the next corner it's gone.

[feetup&sliding]

It was completely gone... almost killed myself on one of the turn when it failed...

But now its ok... just get the rebuild kit first and see how it goes. I think it only cost about 25 bucks!

.

WAIT! STOP!! DON'T PUT IT IN YET. The internals were changed in later years to prevent this. It happened on my o2 and I replaced it with the 03 (or maybe it was 04) part, which is different- updated to prevent that failure. Also refill the system with Motul HiTemp brake fluid, youll never have another problem.

[HondaDirtRider5]

It would probably take me 3 laps to relaize i had lost my rear brake ?...i come into corners kinda hard and when i hit the front brake the front end dives and the rear end just kinda floats skipping across the ground.....understand that 70% of your braking power is up front so if it goes out your going to be able to stop fine ?

[mvlcorona]

My rear brake went flat too on my '03. I bought the rebuild kit and installed it in about 15 minutes. Very easy to do. When I bought the kit, my dealer said that 02's had problems with the rear master and the new rebuild kits fix their problems too.