Brake Fluid

Permeation is the problem

http://en.wikipedia.org/wiki/Permeation

The greater the humidity, the faster the transmission.

Mositure will get in through any material that is not metal.

 

Also quick tip:
DONT OVER FILL YOUR BRAKE RESERVOIRS!
Keep it near the low mark once youve flushed the system(s)

 

I bleed my master after every track session, to remove the air.

Air enters the system very fast from hard on-track braking. I start the race with great brakes, but after 8 laps, I can pull the lever to the bars on the GSXR stock brakes. Tokico calipars suck. Nissan much better. Same with R6 calipers.. thats why everyone uses them.

A one way brake fluid bleeding valve makes it easy, and tapping the calipers, lines, and master cylinder to move the air up, as you bleed from master works best.

 

I agree not to overfill, but why wouldn't you keep it in middle or near the high mark? I figured as the pads wear I want some additional fluid as to not run low.

 

maybe for a streetbike... Ive never cavitated a brake reservoir but Im sure you'd get some warning if you create that much pad wear! :up:

 

I agree on it being a "brain thing", so change brake fluid every time it makes you feel better and change your brain fluid 12 ounces at a time every now and then too!

 

So what does everyone use for brake fuild? Motul, Castrol any others ? Just want to see what people have had the best luck with.

 

Any reputable fluid works. Key is changing often. "Dry" fresh brake fluid boils at 500-650 F, older "wet" brake fluid boils at 230 F or so just a little higher than water. Many of the bottles call this out. I just use the valvoline synthetic. Dot 3/4. You should do the same in a car as well most call it out every 2-3 years.

Chrysler got sued a few years ago because a moron rode his brakes down a mountain and the brake fluid boiled. It was very old fluid and the manual did not say to change it. So they sued because theoretically if the fluid was fresh and had the very high boiling point the brakes would not have failed.

In terms of changing after rain - a little could get is if the piston gets wet and a little gets in as they cycle from in and out but this is very slight. More come from the seals having permiability to water vapor 24/7 and the brake fluid being hydroscopic.