Rear Brake Help

[Jake.]

Hey all, Just looking for some help with the rear brake on my bike.

A few months ago, I got a 140cc bike from Small Wheel Deals and in the past few days, the rear brake has stopped working.

It first started playing up a few days ago and we bleed the brake and replaced the brake fluid and all was good. We had to do this again but it only lasted a few hours until they stopped working again. This morning the rear brakes won't work at all, have no compression and we have tried to get them working with no luck. There is also no brake fluid in the bike each time this has happened.

Just wanted to get an opinion from someone on here before I start pulling things apart.

Thanks.

 

[DvDRip]

did you try torqueing up the bango bolts on the brake line?
is the bike new? if it's not the bango bolts leaking it's warranty time

 

[rach88]

i dunno if this is the same, but i had similar probs with my front brake. turns out the brake cable had a small leak. Just replaced the cable and bleed again and it was all sorted.

 

[corey58]

on the master, your rod that's pushers up on the the piston is mushroomed out. take the master off and with the bench or a hand file take some metal of it to make it has a smaller circumference allowing it to return freely.. seen it happen to so many bikes

 

[headsmess]

best fix? get a new master cylinder.

then, before putting it in service... strip it(youll need internal circlip pliers..or modified needle nose pliers)

then, check the bore for any burrs where the fluid enters from the resevoir. so far, i havent found one without some sort of burr...

even if there arent any, take the time to get a piece of dowel and some 400grit wet n dry. then very lightly "hone" the cylinder, using metho as a lubricant.

DONT use MINERAL OIL!

wash everything thoroughly in metho, reassemble( if it needs lubing...metho or brakefluid. once again, NO MINERAL OIL! unless you get a dedicated "brake assembly fluid"/rubber grease)...rebleed. hey presto! you now have an almost 100% reliable master cylinder...

pays to check the rubber cups for any cuts and damage...even the slightest nick in the edge? throw away... and dont even bother trying to find new cups. you wont. just replace the whole damn thing again...

best method is to get one from a wrecker, off an old bike that has brakes that still work...its a sure sign theyre fairly reliable...

 

[Jake.]

Cheers mate, will probably just end up buying a new master cylinder as me and my dad have checked everything out and it just doesn't work.

Pulled it all apart and put it back together and still nothing so i'll head down to the shop in the next few days.

Thanks