1999 R1100RT Rear Brake Bleeding, no Pedal

[chrisinsc]

So many hours into this with practical work and lots of reading. Lightly used this bike for the last few years as I was riding the 2008 R1200RT.

Anyway, rear brake pedal went soft so been meaning to replace the rear master cylinder and needed to do that this week. But I have a 2nd R1100RT which needs a new battery and a rebuilt front shock and sons dont want to ride so this known good master cylinder with a hard pedal even after sitting for two years I put in the bike and I cannot get a hard pedal. I have used a big syringe to push fluid from the caliper all through the system and filled the reservoir that way. No joy. No pump from the plunger, zero activity. Its like it has no seals in it. Wont even pull from the reservoir. Is it possible the ABS unit is the culprit?

 

[m_stock10506]

If you got fluid to back fill from the caliper to the rear reservoir, then the ABS isn't blocking fluid flow. "Usually" if you back fill the reservoir, you'll get the pedal to start pumping fluid.....but not always.

If you have access to a vacuum bleeder, get a vacuum on the rear caliper bleeder and with the reservoir filled, you should start to get fluid to move. I hate to admit this. When I couldn't get the pedal to move any fluid, I put a length of clear hose on the rear bleeder and sucked on the end of the hose like a straw. I didn't have a mity-vac. The pedal started moving fluid right away, way before any brake fluid started coming out of the rear caliper into the hose. Just saying, I don't recommend anyone else try this.

I have read, but never tried this myself. A length of clear hose from the rear bleeder arched over to a bottle or cup on the floor. Fill the bottom of the cup so that the end of the hose is submerged in brake fluid. This is supposed to work like a check valve. Keep pumping the pedal until you get fluid movement.

 

[chrisinsc]

If you got fluid to back fill from the caliper to the rear reservoir, then the ABS isn't blocking fluid flow. "Usually" if you back fill the reservoir, you'll get the pedal to start pumping fluid.....but not always.

If you have access to a vacuum bleeder, get a vacuum on the rear caliper bleeder and with the reservoir filled, you should start to get fluid to move. I hate to admit this. When I couldn't get the pedal to move any fluid, I put a length of clear hose on the rear bleeder and sucked on the end of the hose like a straw. I didn't have a mity-vac. The pedal started moving fluid right away, way before any brake fluid started coming out of the rear caliper into the hose. Just saying, I don't recommend anyone else try this.

I have read, but never tried this myself. A length of clear hose from the rear bleeder arched over to a bottle or cup on the floor. Fill the bottom of the cup so that the end of the hose is submerged in brake fluid. This is supposed to work like a check valve. Keep pumping the pedal until you get fluid movement.

Thanks for the input, I am putting a speed bleeder on the caliper so I can pull good vacuum from there. Last thing before I get a brand new master cylinder.

 

[chrisinsc]

If you got fluid to back fill from the caliper to the rear reservoir, then the ABS isn't blocking fluid flow. "Usually" if you back fill the reservoir, you'll get the pedal to start pumping fluid.....but not always.

If you have access to a vacuum bleeder, get a vacuum on the rear caliper bleeder and with the reservoir filled, you should start to get fluid to move. I hate to admit this. When I couldn't get the pedal to move any fluid, I put a length of clear hose on the rear bleeder and sucked on the end of the hose like a straw. I didn't have a mity-vac. The pedal started moving fluid right away, way before any brake fluid started coming out of the rear caliper into the hose. Just saying, I don't recommend anyone else try this.

I have read, but never tried this myself. A length of clear hose from the rear bleeder arched over to a bottle or cup on the floor. Fill the bottom of the cup so that the end of the hose is submerged in brake fluid. This is supposed to work like a check valve. Keep pumping the pedal until you get fluid movement.

Thanks for the input, I am putting a speed bleeder on the caliper so I can pull good vacuum from there. Last thing before I get a brand new master cylinder.

 

[m_stock10506]

I am putting a speed bleeder on the caliper so I can pull good vacuum from there.

Be sure to keep the original bleed valve someplace where you can find it. If you ever want to back fill the line from the rear caliper, the speedbleeder will not allow fluid to go in that direction. I have also found that when the lines are air-bound, spped bleeders will not allow enough vacuum to pull the fluid up from the MC. You have to get fluid into the system before the speedbleeder will start doing its thing.

 

[chrisinsc]

Figured why not just put a new rear master cylinder in and then pushed fluid from the caliper all the way around to the reservoir. No joy.

 

[52184]

Figured why not just put a new rear master cylinder in and then pushed fluid from the caliper all the way around to the reservoir. No joy.

Try cracking loose the fitting for the line from master cylinder to rear caliper, at the master cylinder itself, then with the reservoir full work the pedal slowly to bleed air out of the master cylinder, using the fitting in the same way you’d use a bleeder screw. Newer master cylinders on the newer bikes often come with a very small bleeder fitting to accomplish the same task.

Best,
DeVern

 

[chrisinsc]

Try cracking loose the fitting for the line from master cylinder to rear caliper, at the master cylinder itself, then with the reservoir full work the pedal slowly to bleed air out of the master cylinder, using the fitting in the same way you’d use a bleeder screw. Newer master cylinders on the newer bikes often come with a very small bleeder fitting to accomplish the same task.

Best,
DeVern

Thanks DeVern, I did that when I pushed fluid from the caliper but did not think to then bleed the MC. Will try it.

 

[Omega Man]

Never worked on a motorcycle master cylinder but have done many vehicle master cylinders. I wouldn’t occur to not bleed the master ahead of mounting. In simple times, I would make bent brake line from the exit port to sit submerged in the brake fluid and watch for a bubble free stroke.
Nowadays there are universal kits-

https://www.oreillyauto.com/detail/c/dorman-help/tools---equipment/mechanics-tools/brake-tools/brake-bleeder-tools/058eaccfa9b5/dorman-help-plastic-master-cylinder-bleeder-kit/mtm0/13911

OM

 

[chrisinsc]

Thanks OM

 

[chrisinsc]

I have a piece of hard pipe I used to bypass the ABS unit last weekend to no avail. I will use that. Last weekend I bypassed the ABS unit with the original MC and could not get a hard pedal so I replaced the MC. Original MC was 25 years old so it was an easy decision to just do that. I would be happy but red faced for sure if I bleed the MC and it works, its the only thing I did not do. But that's the amateur mechanics lament I guess.

 

[chrisinsc]

Is there a bleeder on top of the ABS unit under the tank on this bike? I forget.

 

[pglaves]

Is there a bleeder on top of the ABS unit under the tank on this bike? I forget.

yes

 

[chrisinsc]

yes

thanks paul