Rear brake bleeding 94 R1100rs

[jelarner]

Replacing rear master cylinder on 94 r1100rs. Can it be vacuum bled?  If not curious as to why not. Also can I reverse bled the system?  Reverse bled is my plan.

[dirtrider]

32 minutes ago, jelarner said:

Replacing rear master cylinder on 94 r1100rs. Can it be vacuum bled?  If not curious as to why not. Also can I reverse bled the system?  Reverse bled is my plan.

Afternoon jelarner

 

Does your 94 RS have ABS brakes? 

[jelarner]

yes it does

 

[Michaelr11]

Per DR’s question, if your bike has ABS, the module is located higher than the rear caliper and higher than the rear master cylinder. With air in the hoses it becomes really difficult to pull fluid up from the master cylinder to the module. It can probably be done with a vacuum bleeder, but it will probably still be a challenge. Just fill up a syringe or a bleeder bag and push the fluid into the rear caliper bleed screw. It will flow up to the module and then fill up the rear master cylinder. Once the lines are filled with brake fluid, regular brake bleeding is easily done.

[dirtrider]

1 hour ago, jelarner said:

yes it does

 

Afternoon jelarner

 

Then you will probably have also bleed the ABS module rear hydraulic circuit.(bleeder screw on the ABS module)

 

Of your mentioned methods then reverse bleeding is probably the best at getting the most air out the quickest. (that is how the factory initially fills them) 

 

Vacuum bleeding is probably the worst as that doesn't move much fluid very fast so it allows air to stay in the high spots in the system. It will eventually work but is cumbersome. Usually vacuum bleeding to get fluid in the system then conventional pump & bleed is better than just vacuum bleeding.

 

Just be VERY CAREFUL of your paint & dash plastic as brake fluid can easily ruin both.  

 

    

[Jim Moore]

If I was doing this I'd pull the caliper and pump gently until the pads were closed. If I had a thin piece of metal I'd put that between the pads. Then I'd change the master cylinder as fast as I could. Then I'd re-open the pads as far as I could. I'm hoping the fluid pushes any air through the master cylinder and up into the reservoir.

[jelarner]

ok thank you !!!