Brake fluid

[rmc_olderthandirt]

My club (enduro club) and I spent a week in Utah, riding the Paiute trail system. What a blast!

I was out on one of the group rides and managed to overheat my front brake! I have never done that before, but then I never dropped 4000 feet in one non-stop run before. So all these guys in the club are much better riders than I am and we are on a 100 mile ride and I am just determined to NOT be the one lagging so I am really working it hard.

So we get to a spot where the leader stops and waits for everyone. We are on a slope so I am holding myself in place with the front brake. It felt mushy so I was playing with it some, squeezing and releasing. After about the 4th squeeze it just completely went away!

I reason that once I stopped the heat from the brake caused the fluid to boil next to the caliper and then the resulting gas bubble just absorbed everything that the master cylinder would put out.

I was told that the hardest part of the downhill was still to come so I was worried. Once we started going again I got a little bit of braking action back but it was still really mushy so I avoided the front brake completely, saving it for this really hard section to come. I get all the way down to the valley without using the front brake, never did see this hard section they were talking about!

Anyway, now I am considering my options for brake fluid. I had been using just some DOT-4 fluid I bought at the auto parts store but now I figure I should use something a little more "high performance".

So what does everyone else use?

Rod

 

[dirt bike dave]

I am a big fan of Motul 600, aka Motul RBF 600.

http://www.apexperformance.net/cartgenie/prod-1493.htm

Bought a few used bikes that I was able to boil the OEM fluid on. After replacing with Motul 600, no problems.

 

[Patman]

Bigger rotor, braided stainless line, GOOD pads and something like Motul fluid should cover you as much as possible from brake system weaknesses.

I've boiled the fluid on a bike and a car before, it's a pretty scary feeling when the lever / pedal just blows through the travel with almost no effect. Engine braking becomes a good friend at that point.

 

[dirt bike dave]

Another thing to consider is some guards can restrict airflow around the brakes.

FWIW, I drag my rear brake a lot, and will absolutely boil the rear fluid with cheapo brake fluid, even if its fresh. Boiled a front once or twice, too, and that is NO FUN in the mountains.

Same bikes, same everything except a change to Motul 600 = no boil for me.

 

[Patman]

Excellent point on the "guards". A waste of money in most instances and if it shields the brake from rocks it also blocks airflow.