just got a new rear brake set after i snapped the foot peg off mine. i got the new set today ( the whole rear brake assembly ) but it will not bleed and build pressure.
i looked for hours today and only found a few help articles, none of them helped.

i switched the master cylinder and caliper set with the old one since i only needed a new mounting bracket, and it still wont build pressure. everything is together tight and correctly, i been pumping it slow and doing everything i can think of. pressure just wont build. i have two brake kits now, one of them has to work. im obviously doing something wrong?

 

I use a tube, never had a problem that way. Buy a piece of clear tubing that fits over the bleeder Run it up for a few inches and then down into a container. Take the top off the reservoir and just barely crack the bleeder. Pump the brake. Don’t let the reservoir get low. Watch the clear line, it should fill with fluid and any air should go to the top of the fluid. You don’t have to close the bleeder each time you pump the brake because if it does suck anything back in, its just fluid in the clear line. This lets you pump thru a bunch of fluid pretty quickly and thus force out air. Close the bleeder when you think you've done enough and no air comes into the clear line. Check for firmness, if good, you’re done, if not, repeat.....

 

thanks ill give this a try. i did alot of different variations of bleeder valve adjustments and hoses, obviously none of it worked. i also never had the top off the resivoir tho. does that make a difference? i was told to keep it on in every thread.
i also read that if none of this works you might need to rebuild the master cylinder. if it comes down to that where can i get a build kit? if its cheap would the dealer have it that i can just get the same day. or do i need do get it online.

when i take the hose and bold OFF the caliper completely and pump the break. fluid pumps out but its not a large amount. it gives a little fluid and then a small puff of air. how much should they be pushing out?

thanks

 

If you mean that the brake system won't initially suck in the fluid so that you can bleed it, then you need to suck it in manually.

You need to hook up a hose to the bleed valve, crack it open, start pressing the lever down and then start sucking through the hose as hard as you can until the fluid appears. The system works on compression, so it won't suck unless there is already fluid throughout the entire brake system first.

 

Just open the bleeder on the caliper and fill the reservoir up and let it gravity bleed. Keep filling up the reservoir when it gets low, then pressure bleed it.

 

Also try to bleed by loosening the bolt that holds brake line right by master cylinder. Thats where most of the air accumulates. Rear brakes are tough to bleed but it should help. Loosening bleeding valve is not gonna make any difference if you have air in the line by master cylinder. Not a big problem.

 

sorry guys but i tried all of this today, it seemed to help a little. i got a bit more pressure to the point where when i cracked the bleed valve it would come out a little on its own, but the brake still wont lock, and the pedal goes straight down.

i dont mind to keep trying with it, but how much should i be getting out when i pump the pedal? some people like i said think the master cylinder seals are warn which doesnt allow it to build enough pressure to force through the lines and into the caliper. fluid comes out but its not like its squirting everywhere. it is a very small hole but if there is SOMETHING,,, coming out then its still working?

 

it depends. If the cylinder was over extended, it could have ruined the seals inside the cylinder. What will happen then is the pressure bleeds back past the seals into the master cylinder. So there won't be an external leak. It can still push fluid out of the bleeder, but as soon as pressure is built up a little, it will take the path of least resistance, and if your seals are shot, the path of least resistance is back into the master cylinder instead of to your caliper. If you pump up the pedal and then bleed the caliper, there should be a quick burst of fluid. It won't shoot out far, but it should come out with a little force. It also won't be much, but should be some. If you pump up the pedal and it doesnt get harder to press, or build up pressure, you might have an issue with your master cylinder.

Are the master cylinder and break caliper matched? meaning from the same year bike? A lot of times, manufacturers will change the cylinder size of the master cylinder internally from year to year, and only a caliper from the same year bike may match up correctly. This doesnt happen all the time, but it is a possibility.

having said that. I would remove the caliper from the swing arm, raise it much higher than the master cylinder and try it again. This will help aid the air to move to the top of the caliper. Also, find a piece of steel about the same width as your rotor and place it between the pads. This way, it give the pads something to come in contact with and you won't have to push them back into place. This is of course as long as you have fluid already coming out of the caliper.

just keep in mind the cylinder only pushes a tiny amount of fluid. Its going to take some time.

But im very suprised Rod38um's suggestion didnt work. Did you have the bleeder only slightly cracked? it won't work if you loosen the bleeder too much as air will be sucked in around the bleeder threads.

 

Another option, which is really quite similar to Rod's suggestion, is to go to Autozone and get a $20 vacuum pump which comes with hoses/reservoirs and use that on the bleeder end just like Rod was saying. It's really still the same process.... like justasquid said, you still need to just crack the bleeder a little so you don't let air bubbles in and you still need to be wary of the fluid level in the reservoir. The vacuum hose is not necessary, but its what I use and I makes the job a bit easier/quicker.

The main thing is just to get comfortable with bleeding the brakes, its just one of those things that takes time even when you do it right. You'll get it with a little practice.