HELP! Brakes-NO BRAKES!-Brakes again

[Quart Meg Miles]

I had your symptoms on a +2 S130, which had a single cylinder plus servo, and it turned out to be crystals formed in the bottom of the master cylinder reservoir despite it having been recently cleaned and filled with brand new fluid. I deduced that one had popped up into the working cylinder and held open the one-way valve. It failed on me twice, just as you describe, before I got to the bottom of it. There was no chance of water getting in the reservoir which might have caused crystal formation over a long period, which there wasn't.

The supplier, I don't recall whether it was Girling or Lockheed, had never heard of such a thing and it didn't happen again after cleaning out hundreds of 2 mm crystal spheres and refilling the system.

[RedS4]

I used to have an interesting problem with brakes, but sort of backwards to the one described, in that when I applied the brakes, the pedal would push back and the brake force would feel to double (very disconcerting to the following car...) - this was put down to the servo as it was replaced and the problem went away....

[Tahoe]

It took a little longer than I thought but last night I finished the conversion from the dual Datsun to a single Tilton. The Tilton fit perfectly, the only thing I needed to do was shorten the push rod and extend the threads further. I replaced 2 brake lines to bring it back to a single circuit and then pressure bled the system. The brakes are better and the pedal not as hard when stopping. Not dramatically different, but it is different and for the better. Although the pads have plenty of meat on them I'm not sure how old they are so will replace those next Winter. While doing the work I replaced the one rear disk I was having issues with and my clicking sound disappeared for now. Turns out I had 2 spare rear discs I didn't even now I had. I was digging through boxes and found them. Probably left over from the 1980's sometime.

As for the Datsun master, well it was trash. Looked good from the outside but years of the car sitting etc. had caused pitting in the bore and of course the seals were no good. I'm happy with the Tilton choice and the remote reservoir.

[billwill]

So your symptoms were probably caused by seepage past the master cylinder seals in one of those pits?

[Quart Meg Miles]

So your symptoms were probably caused by seepage past the master cylinder seals in one of those pits?

Unlikely Bill, going from solid pedal to absolutely nothing won't be caused by a seepage past pits. It sounds like my experience (top of this page), something intermittently holding open the little flap. He doesn't seem to have located the exact cause but has, hopefully, solved the problem by changing the whole system.

[Tahoe]

You're right, I haven't pinpointed the exact reason, but I'll continue to dissect the master when I have time. It just feels so good to be driving it again! Next project is MX5 headlight lifts. My vacuum switch and pods are toast.