8" Rotor = Less heating?

[shift]

Im currently running hope M4's.

the back break gives me a bit of grief on a track that requires breaking.

i dont believe there are air bubbles in the cables as ive had the breaks re-bled.

Whats happening is the leaver is getting to the point where it expands so much i cant get enough strength to pull on the leaver hard enough as its extended out so far so im losing about 50% of my breaking power. (have to swap to 2 fingers to be able to lock up the back wheel!)
Then after about a min or 2 of no riding, its back to normal

Ive adjusted the leavers so that at the start of the run, the leaver almost hits the grips at full lock to counter for this, but its not working all that well.

ive currently got a 6" rotor on the back

im wondering whether upgrading to an 8" would reduce the amount of heat that is generated which would reduce the problem im having

or should i get the breaks bled again?

thanks

[Squidly Didly]

Make sure the brakes are bled with Dot 5.1 fluid. Most shops including auto places only stock Dot 4, but you can get 5.1 from a motorbike shop.

Otherwise yes, larger rotors will not only provide more braking power, but distribute heat better too.

[dhd]

I may be clueless here but.....If it's a closed system can you take a bit of fluid out to stop them pumping up so much when they heat up? :?:

[Squidly Didly]

hmmm it's an open system brake, but that's not a bad idea there dhd.
What he said...

[shift]

I may be clueless here but.....If it's a closed system can you take a bit of fluid out to stop them pumping up so much when they heat up? :?:

Yeah, they're open.

also, ive adjusted the leaver so that it is almost touching the grip at full compression when the breaks are cold, they when they're hot, the leaver only comes in a cm or so... so if i was to drain any fluid out, i wouldnt be able to break at all unless the breaks were hot...

[Squidly Didly]

Did you bleed the brakes yourself or a shop? Find out what brake fluid is in there as it's pretty damn hard to heat up M4's.

If all fails get a 20mm adaptor and run a 185mm rotor.

[wombat]

How big a run are you doing, I mean these things must be getting pretty damn hot. They are an open system though, so it sounds to me as though there's something wrong with the expansion resovoir, it's restricting flow or something effectively creating a closed system.
Of course, my experience with the brakes is pretty much bugger all, so it's probably best to consult the resident Hope whore: come on squid, we want a better answer!

[Squidly Didly]

best to consult the resident Hope whore: come on squid, we want a better answer!
Unfortuantely Hope don't have as many consistant issues as Hayes so it's very hard to decipher problems via text on a screen :!:

[wombat]

Touche. It would probably suprise you though to hear that my Hayes are running pretty well for once!

Back on topic though, how exactly does the "open" system work? Does anyone have a schematic for them? (or care to draw a simple one?)

[Squidly Didly]

cue S.

[shift]

they're not terribly long runs... and its mainly happening on a fast track with lots of corners, or when im stuck behind someone and have to keep breaking to avoid hitting them.

not sure what kind of fluid is in there as the bike store did it...
i might go buy some of this dot 5.1 oil and see if it makes a difference.

cheers!

[hozewell]

hydros are so annoying like that, i can never figure out what keeps stuffing up my hayez brakes either.