Boiling rear brake fluid

[MrRuss]

Hello

Recently every ride I have, hard or gentle results in the rear brake fluid boiling. The rear brake does apply pressure when I stand on it but I think the pad maybe rubbing on the disk constantly causing the fluid to boil.

Iv only had the bike 3 months and when I checked the rear calliper it is quite dirty and looks unloved and not cleaned very often.

Any ideas, or does seized calliper sound about right?

Thanks

[hardnutdvd]

can you get the rear wheel of the ground? get a mate to lift the back end up and try spinning the wheel. it should freespin fairly easy. if the brakes are binding your disc would be burning burning hot too.
how easy is it to push in neutral? if it was seized solid you wouldn't be pushing it anywhere!

a rear caliper overhaul wouldn't hurt, dont take long and is a peice of piss to do! if i can do it, anyone can. there is a good guide on here somewhere.. i'll try and find it for you.

[MrRuss]

Hmm.. It is easy to push around. The other thing is that it has braided hoses and they maybe resting against the rear cyclinder heads. Maybe the heat is transfering from the engine to the hoses and fluid..?

Ill get my mate to lift the back end and we'll spin the wheel tonight. Cheers.

[porndoguk]

Hmm.. It is easy to push around. The other thing is that it has braided hoses and they maybe resting against the rear cyclinder heads. Maybe the heat is transfering from the engine to the hoses and fluid..?

Ill get my mate to lift the back end and we'll spin the wheel tonight. Cheers.

Do you have the exhaust heatsheild removed? and what brake fluid you using? dot3?

dot 5 has a higher boiling point, but its a bit extreme to be using higher grades of brake fluid for a road bike,

id hazard a guess to say a piston is seized, but next time you ride check the temprature of the rear disc, if its hot then you got a sticky piston.

if it is stuck you wont be able to tell by pushing the bike as the weight of the bike will make it easy to push, but with the wheel in the air is the only way to truely/initially tell

rick

[MrRuss]

Thanks mate. I think the heatshield maybe removed but Ill check when I get home. Not sure what fluid is in there, Im hoping its just seized brake piston but Ill chceck where the hoses are as I guess if they were too long and installed by a chump then they could by resting against exhaust/cylinder.

Thanks Rick

[Delboy]

Also, if it's old brake fluid it would need changing as brake fluid is hydroscopic and if its absorbed moisture this would affect it.

[MrRuss]

It was binding rear calliper. NC30 is getting repaired next week. Cheers for your help everyone.

[Delboy]

Well done on finding the fault, I'd still change the fluid if it 'boiled' at one point, good job MrRuss on getting the 'ol girl sorted!