MZ/MuZ Riders

This thread concerns the same bike that I had resuscitated in September (http://goo.gl/JAxZJd), after a 10-year storage.

I was on the exit ramp of a highway last week when the rear brake stopped working. Luckily I was only 2 miles away from home, and the front brake still worked. The rubber hose that connects the brake fluid reservoir to the brake pedal had corroded. The brake fluid had completely leaked out.

After installing a new hose today, bleeding out air bubbles from inside the rear brake system, and filling up the reservoir, surprisingly, the rear brake still does not work -- pressing the pedal gives no resistance at all.

What could possibly be wrong? I doubt it is the brake caliper. And I believe I had bled the brake properly. Could it be the brake pedal mechanism itself? While bleeding the brake today, the interface of the rubber housing to the rear brake master cylinder (?) appeared to be very slightly leaking brake fluid with every press of the lever. The cylinder also makes a shushing sound. Please see this MP4 video on my Google Drive share folder: https://goo.gl/KUY93e

What do you think? If it is the master cylinder, is it something that I fix or replace? If it is the latter, does anyone know the make and part number for it? Thanks again for the help with my bike.

these are a beast to bleed

and the push rod from the lever to the pump piston can shut off new fluid from entering the pump if its pushing the piston in to far at the start of stroke
the piston must retract all the way
pressure does not happen till inlet is closed and it must open for new fluid to enter
CLUCK ON PIC TO SEE IT BIGGER

dave

DAVID THOMPSON wrote:these are a beast to bleed

and the push rod from the lever to the pump piston can shut off new fluid from entering the pump if its pushing the piston in to far at the start of stroke
the piston must retract all the way
pressure does not happen till inlet is closed and it must open for new fluid to enter
CLUCK ON PIC TO SEE IT BIGGER

dave

David... I guess what you're saying is, we don't have enough info to determine whether any part is defective yet, and that the "slight oil leak" and shushing noise could be normal, and that I should check the bleeding procedure. Am I right?

the bleeding after checking if the pedal has no free travel

pedal may be to tight at rest and not letting fluid enter master cylinder


see comment in the picture

its a bit hard to see
CLICK ON PIC TO MAKE BIGGER

A novice's question: I don't suppose the banjo bolt pressure switch has anything to do with the braking function, does it? I am asking because I had fiddled with it for preparation of switching it out for a new one.

Not unless you didn't tighten it back down. It is the bolt that holds the brake line in place after all.

edfmaniac wrote:Not unless you didn't tighten it back down. It is the bolt that holds the brake line in place after all.

That was it! I tightened the banjo pressure switch bolt and [duh...] now the rear brake works. That was so stupid of me... But thanks all, for the tips and patience.

One more question: Other than (I suppose...) changing the brake caliper, is there a way to increase the rear brake's stopping power?

i am finding some bikes weak in the rear brake from new..
if its wet getting on the back brake to hard can cause the back end to slide out

i think there making them this way to keep people from spinning them out on wet roads

as most people seem to not use the front enough and the rear way tooo much

dave

where i live it so wet most of the time that careful planning as to speed is needed to keep it up right at any speed..

and your always going up hill even if its only climbing out of a POT HOLE