Metro brake problem
Turbo Mini Forums

Actually Midas problem, but they're standard Metro brakes, with servo. Recently I had to change a rear wheel cylinder and couldn't bleed the brakes although I'ne never had trouble before. Tried a new m/c, no improvement. Took it to my local garage after which it was OK but since then the pedal has been getting lower and lower before the brakes bite. It doesn't pump up as you'd expect if there was air in the system, and there were no signs of a leak when it was MoT'd. I've got no idea what's going on, any suggestions please?

Geoff

Servo or master cylinder are shot I would expect.

I took both of a metro on Saturday...

EDIT: I wish I could type...

Edited by apbellamy on 7th Feb, 2011.

Andy, the servo is only a couple of years old, but as it isn't part of the hydraulic system I can't see why it would make the pedal subside over a period of months. The old one was certainly shot, but it didn't cause these symptoms. The m/c is brand new, changed out of desperation really (with your reservoir!) but when I took the old one apart it looked in perfect order, as it should have done as it was only the same age as the servo.

Geoff

We had a similar problem with our van. Ended up with 2 pumps befoer it would stop. A new master cylinder cured it.

Do you have the compensator thing fitted to the m/c for the rear breaks? Looks like a cylinder that bolts into the master cylinder before the rear circuit bolts in.

ballooning flexy hoses?

If something is worth doing, it's worth doing half of.

I've got the thing screwed into the m/c, called a pressure reducing valve in the manual. Presumably it just limits the maximum pressure? No idea how it works or if it can go wrong.
I don't think hoses are the problem as the pedal is reasonably firm when it bites, it's just that it's been getting progressively lower before anything happens.

Geoff

Im kindve having the same problem at the minute, except ive recently refurbed my braking system with stainless pistons and new seals, braided hoses.

Standard 8.4 mini discs, i keep bleeding the system but it makes a marginal improvement for a very short while and goes back to how it did before.
No leaks to my knowledge.

Even if the servo is new it could be at fault.

Have you checked all the vacuum connections to the servo, and also the one way valve?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

If the servo has failed wouldn't it just mean the brakes get heavier? It's doing something because you can feel the pedal go down when the engine starts. Tickover is OK so I don't think there's an air leak

Geoff