Rear Brake MC

[DGXSER]

I knew things were going to good. I got the front brakes sorted out. Decided to clean upt he rear Caliper for good measure. Had trouble getting the pad screw out, but finally got it, using brake MC to push the piston out and ran out of fluid. Now the rear MC will not pump fluid for nothing, I pulled the banjo off the caliper and pump the MC you can hear it push and gugrle but no fluid. Tried opening the bleed bolt, pulled the MC apart and put it back to gether everything seems tight, twist and push to get the seals in, and can hear it pumping air and gurgling, but no fluid moving.

Need new seals in the MC? Is there a trick to getting this thing bled??

Any help would be appreciated.

Thanks,

[bikerphil]

Bleeding Rear Brakes

Should be able to clean the seals with fresh brake fluid and re-use them unless there is visable damage. Don't forget to scrape the cr@p out of the seal groove in the caliper body. To bleed, try filling up the MC, then with your thumb and finger over the hose (disconnected from caliper), pump the MC. As a small amount of pressure builds, let let your fingers on and off the banjo to bleed the air out. Kinda like priming a pump. Once you have some positive pressure from the MC, hook the line back up to the caliper and bleed as normal. HTH

[DGXSER]

Thx for the advice Phil. I did tear down the caliper and clean the groove, the seals and the piston up and put it back together.

I just took the MC off for the fourth time tonight and took it apart completely. Made sure every opening is clear and clean. Reassmebled, and Filled the MC with brake fluid through the banjo hole to have the pump primed so to speak. then put it all back on the bike, also prefilled the caliper with fluid through its banjo hole with the bleeder open. Pushe don the pedal and got a psirt fo fluid and air out the bleeder, then nothing after that. Acts liek a pump that lost its prime for sure.

My assumption is the seals are bad and leakin by instead of pumping the fluid out. Anyone have a pic of the seals in the rear MC as they should be, naybe one got turned inside out when it went dry and I do not know it.

Thanks again for any help. Dont mind buying the kit to rebuild but been almost a week waitin for pads and an oil filter from partsnmore.

[XSPastor]

Persistance, Perisistance...

You may have to pump it for a while. Don't give up. Loosen the bleed screw, push and hold the pedal down, tighten the bleed screw, lift the pedal and repeat. You may have to do it quite a few times. This MC doesn't pump a whole lot each time. If the MC runs dry, you'll be starting all over so pause when it's half full and refill it. You'll get it.

[Bigfoot]

I have been having the exact same problem on my MNS. I had given up and thought I needed to purchase a rebuild kit - even though everything looked ok. Maybe I didn't try long enough.

[bikerphil]

Rear MC diagram

Like Pastor said, keep trying. Here's a pic...

[DGXSER]

Success!!

Bigfoot - It is a PITA.

I gave in and bought the MityVac. Even then I had to take the entire system off the bike and put my MC in my shop vise (gently, no real pressure, just holding it in place) retightend the banjo on the back of the MC for good measure, and then with the caliper lower than the MC used the vac on it pumping it up to 15-20"vac and opening the bleeder till it got down to about 5" then closing it back. After about 5-10 minutes of this I got fluid through.

Put it all back on the bike and finished bleeding like normal. Works like brand new again.

Now I think I have discovered I may need the second gear fix. Feels like clutch is slipping on and off when I get on it in second gear. Have not noticed it in first (yet) or any other gear. Knock on something of natural fibers. And thought this was a PITA. Not sure I want to dig into the gears yet, that would definitely be stretching my limits. Only had the thing a week and SWMBO stated no projects.

[XSPastor]

If it's the gears, it won't feel like slipping - more like a machine-gun kind of clunking/grabbing. If it feels smooth like slipping, then it's your clutch.

[XSPastor]

Cheater!

Bigfoot - It is a PITA.

I gave in and bought the MityVac. Even then I had to take the entire system off the bike and put my MC in my shop vise (gently, no real pressure, just holding it in place) retightend the banjo on the back of the MC for good measure, and then with the caliper lower than the MC used the vac on it pumping it up to 15-20"vac and opening the bleeder till it got down to about 5" then closing it back. After about 5-10 minutes of this I got fluid through.

Put it all back on the bike and finished bleeding like normal. Works like brand new again.

Now I think I have discovered I may need the second gear fix. Feels like clutch is slipping on and off when I get on it in second gear. Have not noticed it in first (yet) or any other gear. Knock on something of natural fibers. And thought this was a PITA. Not sure I want to dig into the gears yet, that would definitely be stretching my limits. Only had the thing a week and SWMBO stated no projects.

Glad you got it done - even though you had to cheat and use the mighty-Vac!

[boyat68]

DGXSER:

Even though I have the mity-vac, I find it just as easy to bleed the system using a piece of vinyl hose attached to the bleed nipple with a tie-wrap, and the piece of tubing dropped into a cup of brake fluid to prevent air from being sucked back into the system, then fill the reservoir, open the bleed screw, push the lever down and hold while closing the bleed nipple. If you did this in sequence, then the fluid will course throughout the system . I suspect that you were allowing air back into the system while closing the bleed nipple, where as the mity-vac will eliminate this. The problem with the mity-vac is the tendency for the hose to pop off of the nipple while manipulating the set up. I mainly use the mity-vac to check the vacuum advance operation.

[DGXSER]

Boyat:

I have always bled brakes exactly that way. I did both fronts that way as well and it worked great like always. Just something about the vertical MC along with elevations of the caliper the MC and the lines that even after about half an hour of working the thing, I was just pushin air. I will say that I did get the rear banjo to move ever so slightly when I had it in the vise so I wont swear it was not ever so slightly lose and that would kill everything I know.

Even with the mityvac, I spent over half an hour using it with everything on the bike and still got nothing but air coming out and no feeling in the pedal. It seemed like it needed the caliper lower than the MC for it to work. At least that was when I held my mouth right and it took . After toying with it for at least three to four hours total, I don't consider anything cheating

As to the gears, I will play with it a little next chance I get to take it out wihtout suffering permamnent frost bite. It basically felt like when I got on it in second it would come and go out of gear. Did not hit hard when it came in, but definitely like in and out. Worse case I just go easy on second gear. It does not show up when you just owkr through the gears normally, not going above 3-4000 and does not show up engine braking or downshifting. Besides, its been way to long since I have ridden for gettin that froggy on somehting with this kinda power to often. Almost scares ya. Probably should.

Thanks again to everyone for the help and advice!!

[Axel]

Bleed baby

My bleeder screw broke off so I had to bleed it at both ends of the line . Dont forget the mechanics secret of tying off the lever or pedal (once you have most of the air out)with a bungee cord or something and leave overnight . Somehow the bubbles work their way to the top and you have a hard lever/pedal .