Brake pipes corroded - split / dual braking?

Me too, for cars post 70s.

No - only the (diagonal) circuit that suffered the leak, at least AIUI. Something pretty catastrophic has happened elsewhere?

If the master cylinder is in good condition then you should still have some braking, but the pedal will go a much longer way down. If the M/c has wirn out internal seals then it is quite feasible to have no braking upon fluid loss.

Brake pipes are notoriously hard to assess accurately as to whether the corrosion is excessive. In your case they were right!

Why did you have it mot-ed three months early?

Well, actually, it didnt quite hit the floor, and there was a little resistance, but I presumed I was just pumping out fluid from the hole.

I'm selling it, so it'd be better with 12 months ticket.

Fright can set in when the pedal goes a long way down, probably it will be ok once the leak is corrected and the system bled.

Normally, you get a low fluid light when the reservoir is still about

1/3 full. This should give you braking on the unfailed circuit but you may have to pump the pedal: it is easy to "freeze" with your foot on the floor. Those of us bought up with old wrecks in the 1960's and 70's know all about pumping the brakes if this happens!

I have only had one failure like this, revealed by a puddle under one corner. You would not otherwise know you had a problem if you drive normally. In that case, by filling up the reservoir and ensuring air never got into the system, and driving cautiously, I kept the car on the road for a few days until I could arrange to get the failed pipe replaced. Perhaps not a recommended strategy, but it worked for me.

Trying to remember when dual circuit brakes became mandatory. My '74 Rover P6 didn't have them - the next model, the SD1, has.

On my SD1, the split is to the front calipers. They are four piston types. Two on each side are on the second circuit.

Metros often got the twin circuit calipers, front / rear split always seemed a bit pathetic especially on something with a very light rear end, but better than nothing. Even worse were diagonal split, which I am told were on old vauxhalls.

With diagonal split you would certainly know there was a problem. Not so much so with front/rear split.

[...]

With a front wheel drive car, and front/rear split, loss of the front brakes would be more than 'noticeable'! That's the primary reason diagonal split is near-universal.

Rear brakes on a modern front wheel drive car do next to nothing. That's why the shoes can often last longer than the rest of the vehicle, whilst front pads will have been replaced multiple times.

Chris

ISTR that my Renault 11 was a so-called diagonal split and I was slightly surprised to observe no difference when one circuit failed. However it might have been drums at the front, with one slave cylinder fed off each circuit.

That's probably why the Metro had the split front calipers. Despite being a cheap car, they for some reason gave it quite good brakes. Unlike my SD1.

Never really thought about it - my BMW has single piston slide caliper brakes. Has that a front back split?