Jump to content

rear brake bleeding help


springer

Recommended Posts

so i just put my new swinger on and changed the brake line. now i cant get my brake to build any pressure. after hours of trying without a vacuum pump, i searched on here and found that it is much easier with one. so, i bought one but its not helping. i pumped half a giant bottle of brake fluid with no bubbles coming out of the bleeder valve, but still no pressure. is there something obvious i am missing?/ something maybe not so obvious? i have no clue what to do but this is very frustrating. bangheadbanghead

 

 

someone PLEASEEEE help me.

Link to comment
Share on other sites

The rear brake can be a real bastard to bleed off. I messed with mine quite a bit and what worked for me was taking the rear caliper off the bike and setting it on the ground. The lower you can get the caliper from the master the better. Then crack the bleeder and keep the master full. I just kept filling mine for an hour while I was working on something else. Obviously try to catch your fluid so that you don't waste it.

Link to comment
Share on other sites

I have had good luck with this method: unbolt the caliper from the axle carrier and put a piece of flat bar metal between the pads in the caliper. Then hold it above the rear master cylinder reservoir with the bleed screwe at the highest point. Open the bleed screw and gently step on the brake pedal, but don't let it bottom out. Before the pedal gets to the bottom of its travel, close the bleed screw and then release the pedal, wait a couple of seconds and repeat. This seems to work because air likes to rise and by making the bleeder the highest point, it gives the air someplace to go and get out of the system. You want to only stroke the pedal 1 time for each time you open the bleeder screw to prevent aerating the fluid. This method will probably require a helper, but isn't that what wives and GFs are for. Sometimes the open bleeder screw and keep the reservoir full method will work because it will gently wash the bubbles out with the fluid, The main thing is you don't want to induce a bunch of air into the fluid at the master cylinder by pumping the pedal violently.

Link to comment
Share on other sites

x3 on the unbolting it. you can get some air trapped in the line anywhere there is a high point in the line and the fluid will just keep going past the air as you bleed it and never purge....kinda like a p-trap. you can gravity bleed or conventional bleed, or even install an auto-bleeder with a check valve, and hook a hose to it and run back to the rezivoir and just pump it fast untill all the air comes out, but don't let the piston over-extend in the caliper....

Link to comment
Share on other sites

The rear brake can be a real bastard to bleed off. I messed with mine quite a bit and what worked for me was taking the rear caliper off the bike and setting it on the ground. The lower you can get the caliper from the master the better. Then crack the bleeder and keep the master full. I just kept filling mine for an hour while I was working on something else. Obviously try to catch your fluid so that you don't waste it.

 

 

I have had good luck with this method: unbolt the caliper from the axle carrier and put a piece of flat bar metal between the pads in the caliper. Then hold it above the rear master cylinder reservoir with the bleed screwe at the highest point. Open the bleed screw and gently step on the brake pedal, but don't let it bottom out. Before the pedal gets to the bottom of its travel, close the bleed screw and then release the pedal, wait a couple of seconds and repeat. This seems to work because air likes to rise and by making the bleeder the highest point, it gives the air someplace to go and get out of the system. You want to only stroke the pedal 1 time for each time you open the bleeder screw to prevent aerating the fluid. This method will probably require a helper, but isn't that what wives and GFs are for. Sometimes the open bleeder screw and keep the reservoir full method will work because it will gently wash the bubbles out with the fluid, The main thing is you don't want to induce a bunch of air into the fluid at the master cylinder by pumping the pedal violently.

 

 

x3 on the unbolting it. you can get some air trapped in the line anywhere there is a high point in the line and the fluid will just keep going past the air as you bleed it and never purge....kinda like a p-trap. you can gravity bleed or conventional bleed, or even install an auto-bleeder with a check valve, and hook a hose to it and run back to the rezivoir and just pump it fast untill all the air comes out, but don't let the piston over-extend in the caliper....

 

 

What I have also done was, lift the rear of the bike as high as you can basically get it. Hell tie it to the rafters with a tie down!! Pump the peddle then tie it down with something then crack the bleeder. And let it sit over night and hopefully the air bubble will work itself out overnight.

Link to comment
Share on other sites

Alright heres your problem. I believe your doing everything right and no matter what you do its not gonna work and heres why. where the master cylinder is pumping out the brake fluid pull that off and stick your finger over it and pump your brake and bleed that first. If the master cylinder is still good it should blow your finger off like nothing. I bet you take apart that master cylinder and one of the orings on the pump shaft is worn to the point of replacement. Just ordered that rebuild kit myself was doing the same exact thing.

Link to comment
Share on other sites

well, i almost set fire to my shee last night. i have tried just about every method mentioned so far except checking the master cyl. caliper removed, hold up high, down low, gravity bleeding for 2 hours constantly refilling res. nothing is working. i didnt figure my master was bad because it was working fine one minute, changed swinger and brake line, and put it back together in just a few hours. i will check it like you said and may just order the rebuild kit so there is no question. anyways, thanks for all the input, hopefuly i can get this figured out before the dune trip in a couple weeks. if not, some other members offered to help.

Link to comment
Share on other sites

i usually takes me about 15 minutes to bleed brake lines and calipers. here is what i do. i bleed at each point. first i unbolt at the line at the master cylinder. cover bolt hole with finger and pump the brakes. you will feel air preasure build behind your finger. let out air on the down stroke. when you have fluid rebolt the line at this point.

next unbolt the brake line at the caliper and hold the end of the line between two fingers. pump the brakes. you will feel air preasure at the end of the line. let the air out on the down stroke and the squeeze tight on the up stroke so you dont let air back in. once you have fluid at this point rebolt the line to the caliper. then bleed caliper as normal. i know it sounds like a lot and a pain in the but but it works. the last time i did my brake system it was from a full rebuild so there was no fluid in the entire system. with this method it took me about a half hour to do both front calipers and about 10 to 15 minutes to do the rear. just the way i do it so good luck.

Link to comment
Share on other sites

so i just put my new swinger on and changed the brake line. now i cant get my brake to build any pressure. after hours of trying without a vacuum pump, i searched on here and found that it is much easier with one. so, i bought one but its not helping. i pumped half a giant bottle of brake fluid with no bubbles coming out of the bleeder valve, but still no pressure. is there something obvious i am missing?/ something maybe not so obvious? i have no clue what to do but this is very frustrating. bangheadbanghead

 

 

someone PLEASEEEE help me.

 

 

my process.

 

pump the brake for a while, hold it down crack the nipple open, wait for the air and fluid to come out, then close it, then pump and start all over again.

 

is there a leak in the system? did you put the copper washers back on? the line on the mastercylinder that goes to the rear caliper has to go the right way. the metal part of the line has to go threw those 2 things to make it sit right.

Link to comment
Share on other sites

  • 3 months later...

Hey man. this is seriously the best way to do it hands down. i just put new lines on the front and did it this way.

 

take a tube that will fit snuggly over the brake bleed tube (not loose, you want a tight fit so no air gets in). make sure you have a good bit of that tubing. next fill a cup or something that will stand on its own and the brake line can run down into. fill that cup jug whatever with brake fluid making sure that it the tube will not come out of the fluid. now crack the bleeder and leave it open and pump your brake lever. you dont have to do this real fast just do it at a steady pace until you no longer see bubble coming out of the tubing that is inside the brake fluid. once you see no more bubbles close your bleeder and pump away. should feel it starting to get firm. make sure you dont run out of fluid in your resevoir while doing this or you will just suck air back in the line. just repeat the step, it should only take 2 times of doing this until your brake pedal feels really firm. any questions just ask ill try to get back with ya.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...