Unbelievable brake master cylinder rebuild

[angrydicky]

I heard about some woods not far away from me that had some old cars quietly rotting away, so I went for a look.
Found the remains of a Tweed Grey Austin A35 van. Heaven knows how long it’s been sitting here. Most of it was there but in a fairly desperate condition as you can see. The rib case gearbox and lack of chrome trim on the door point towards it being a very rare 1962 AV6 van, basically a stop gap model between the AV5 and AV8. Poor old thing.

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In the centre of the above picture, you can just about make out what I spotted which is the brake pedal sticking up out of the ground. Hmm, I wondered, does it still have its master cylinder?
The A30/35 master cylinder has never been remade (to my knowledge) so it’s a matter of having old ones stainless steel sleeved. There are people doing them on exchange basis or you can have your own done. But I didn’t have any spares…
I grabbed hold of the brake pedal and lifted the entire master cylinder, reservoir and pedal assembly, complete with the remains of the floor, out of the ground.
Well, it was all there! But surely it would never work again? Stay tuned for part 2.

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[mercrocker]

Post 62 would be right with those doors I think? What a bloody find! Good luck with the master, I take it you know Mr Prinn down this way?

[angrydicky]

Post 62 would be right with those doors I think? What a bloody find! Good luck with the master, I take it you know Mr Prinn down this way?

Yes indeed I’ve bought spares from him before, not for a few years though. I’ve been off the A30/35 scene for years after becoming disillusioned with the club and getting more interested in the older ‘counties’ cars.

Yes, pressed doors ended with the end of AV5 production in 1961. It was part of the switchover to 1098 and ribcase box with the AV6.

[mercrocker]

Yeah, I left the local club (think I joined up when I bought mine in 1978!) as it just degenerated into a chess club - lots of intently inward-looking folk sat in pairs on the same tables poo-pooing almost everything suggested. Never mind. Robert is still a good egg and very helpful - let me know if you want anything picked up locally.

[angrydicky]

Thanks for that, much appreciated!
Yes he’s a good bloke. I could have gone to him and bought a used master cylinder had I needed one, but it was more a challenge for myself to showcase my amazing* skills and see if such a rusty relic could be resurrected.

[angrydicky]

Part 2.

The first job was to strip the rotten pedal assembly, floor and reservoir top off the master cylinder. Normally, this would only take a few minutes but due to being in the ground for 40+ years nothing was coming quietly and I had to break out the big guns.
Started with the oxyacetylene to try to heat up the clevis pin enough to drift it out. It didn’t play ball and I ended up having to cut the pedal off.
The oxyacetylene did manage to shift the four studs which with nuts hold the reservoir top to the master cylinder and the floor.

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[angrydicky]

Part 3.

With all that crap out of the way, I removed the old reservoir gasket and just look at all the crud packed into the reservoir! I dug all that out and found the little baffle inside was still present, although very rusty, which was unsurprising. I had a new one ready to go in so wasn’t too bothered about that.

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Now it was time to turn my attention to actually stripping the bloody thing. I took it in the sandblaster and cleaned up the front end to give me half a chance and I managed to get the old circlip out intact. I didn’t want to risk reusing it so popped a new one in, but it would have gone again.
Got the old pushrod out and it was so corroded around the middle it wasn’t reusable. Now I could see the piston for the first time. At least it wasn’t wedged halfway down the bore like the usually are but I tried the usual tricks and it wouldn’t budge.

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I cleaned up the old rusty tube nuts in the two ports in the back of the master, knowing that I would need to get them out to pump the piston out via one of these ports, and blank the other one off to build up pressure. Oxyacetylene to the rescue again. Once heated up they both came out nicely with molegrips. Threads and seats were excellent.

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[Asimo]

This has me more excited than most of those “will it run?” Videos. Will it stop?

[angrydicky]

Part 4.

The pump.

This is a hydraulic oil pump with a 3/8” x 24 UNF adaptor in it, with the other port blanked off using an old bleed nipple with a T-handle brazed to it to make a little tool for quick easy port blanking. Without blanking this port the oil would shoot straight out of there and would never build up enough pressure to push the piston out. If you’re not careful when doing this, the piston can let go with a bang and become a mini-missile - best to do slow strokes when pumping or have something soft for it to land in!

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Surprisingly the innards were actually very good - I’ve seen far worse pistons in road going cars, and the spring and valve were like new. Well, as close to new as is possible. Just goes to show, even the bore wasn’t anywhere near as bad as I expected. Neither were the seals! They were genuine Lockheed of course.
I laid the bits out so you can see what I stripped off, although some of this is scrap.

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The innards cleaned up well in the sandblaster.

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With it finally stripped fully, I gave the body a quick shotblast. Yes, it’s a rough casting due to all those decades in the ground but it’s definitely salvageable. Bore looks better in this picture than it was, it was pitted but was far better than it had any right to be.

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[brandersnatch]

Bloody marvellous.