Testing my rear master cylinder

[Jim]

Hello all,
back brake has gone capput. When i try to bleed the system, hardly any fluid is getting through to the bleed nipple. I have removed the calliper, master and hose and cleaned them all through with the relevant cleaner. When i topped up the master again, nowt is coming through the bleed nipple! No matter how much i pump the pedal. Is my master shot? I was thinking if i put a regular bolt into the master where it attaches to the hose and pumped the pedal, maybe this would show whether or not it was shot. If there was resistance on the pedal it is ok, if there is none as it would seem now, it is shot. Does this seem like a logical thought process? The piston on the calliper seems to be ok and not leaking any fluid. Just another thing, i noticed the calliper only has a piston on one side, there is a pad on both sides, does the calliper only push the one piston onto the disc and forces it onto the one on the other side. The other pad seems to be held on by a short screw. I am used to seeing a piston on both sides when dealing with a car calliper. When i took off the calliper, I could push the pad that has the piston behind back a little with no resistance, i had the bleed nipple off, but surely this proves that there is still ok movement within the calliper. Basically i need to know which bit to replace, I have looked into new replacment masters, calliper and hoses, it costs a fortune. the bloody hose alone was something like ?40! Just don't want to be replacing parts unnecessarily. please advise, Jim

[Rich]

Check the thread "rear brake not working on z" in the help files. Kaput

[Jerry]

Kwack discs can be a bugger to bleed from empty. The only foolproof way I've used is to get a pump-action oil can with a flexi end.Cut the nipple off the end of the oil can hose, and you'll find it will fit over the caliper nipple. Fill the can up with brake fluid, open the bleed nipple, prepare for spillage around the master cyl, and then pump away, thereby reverse bleeding it. You may have something knackered, but usually it's just the master cylinder air-locked.

[Garn 1]

Jerry, I like that idea with the pump-action oil can. I have tried it with a large hypodermic syringe, resulting with the plastic o-ring, on the piston of the syringe, jamming ... not liking the hydraulic fluid. I'll try your way next time. I presume it would be a new can not previously used with ordinary motor oil.
RegardZ

[Jerry]

You'd be alright with a used one, I'd just wash it out with parrafin, then swill it with brake fluid, empty it out, then fill it to use with more brake fluid. It always works for me unless there's a fault in the system.