Rear Brake

[TimO]

I wonder if someone could offer some advice. A short while ago my rear brake over heated, must have been binding I guess. Over the last few weeks I've replaced everything. Master cylinder £24 from www.gprdirect.com, Hel brake line £29 from www.h-e-l.co.uk and a new caliper from www.motomeccaspares.co.uk £70. (Not the hideous prices quoted from 3X!)
Even after all of this I can't get any pressure in the system, the caliper has made a slight difference in that I can now get the pads to touch the disk! But theres so much travel in the pedal.
The only bits I haven't replaced are the reservoir and the pipe that links the reservoir to the master cylinder, surely they wouldn't make any difference, would they?
I thought it might be my bleeding technique, but to check I changed the fluid in the front, no problems there.
Any suggestions, I've tried riding round with only the front brake for a while but the novelty has now worn off and the rear disk is going rusty. I'm now getting quite unhappy
Ta
TimO

[RaptorMan]

Hi TimO,I too had a problem with my back brake overheating a while ago,binding on.Took the caliper off and cleaned all the road crap out,copper greased the pad backs and edges(very lightly)and re-assembled it and it has been fine since.
Have you tried using the suction bleeding technique
Keep reservoir topped up,open bleed nipple and use a light vacuum like a syringe or similar to suck the fluid through.
I take it the pads are freely moving in the caliper

[Shlockengronk]

99 per cent of bikes have their bleed nipple above the brake pistons however the rear brake on the raptor is the lowest point of the system so it can be a pain to get air out (so ive been told)..........vacumm is the go.......... i havent tried with the bike upside down theres not enough brake line to swing the caliper on the top, bleed then bolt it up

[ozzy]

you cannot affectively bleed rear caliper from having new brakelines and new caliper fitted in fitted position.the bleed nipple is too low.remove from bike,place old disc between pads to stop them closing too far.with a friend hold disc in a higher position that master cylinder and bleed.if you can get a rearly big syringe even better.attach to bleed pipe and suck fluid though.took me a while when i fitted hell lines but now have a rearly effective brake.also check ajustment on clevis that enters master cylinder to compress fluid.be sure to get all the air out b4 using brake.alot of problems with brakes binding or sticking on, in general, is that air left in your brake system expands when hot causing the brakes to come on.good luck.

[TimO]

Thanks Ozzy.
I've actually been doing most of this, well apart from the bit that involved the friend, it's not easy with only two hands you know!! Also unbolted the caliper and left if tied up in a higher position overnight
I just couldn't believe how long it took to get all the air out. There's still some free play on the pedal, maybe thats down to the adjustment on the clevis pin.
TimO

[louisbastow]

Thanks Ozzy.
I've actually been doing most of this, well apart from the bit that involved the friend, it's not easy with only two hands you know!! Also unbolted the caliper and left if tied up in a higher position overnight
I just couldn't believe how long it took to get all the air out. There's still some free play on the pedal, maybe thats down to the adjustment on the clevis pin.
TimO

I had the exact same problem. I decided to replace the fluid and let it run all the way out. Big mistake.

Not only the caliper with the bleed nipple on the bottom, There was air in the line that loops up and then down to the brake caliper.
I ended up loosening the line at the piston and moving it so it went straight down, then i took the caliper off, jammed an allen key in between the pads and made sure the bleeder nipple was at the top so any air would come out.

It did work but it took a long time and probably half a bottle of brake fluid, but it's ok now. It still has a bit of play but i think it not getting any better than that.