Single master cylinder diagnosis

[jmmj]

Hey guys, hows it going?

My MC is having an issue. The plunger/piston wasn't coming out after being pressed in. So i took it all apart, it was really dirty and i was surprised that the seals are in good condition and that theres no scoring on the walls. Under the reservoir are two holes, one is pretty tiny, that appeared clogged up so i was hopeful that was the issue. I cleaned it all up, gave it a very light hone, cleaned it again, dried it all off with compressed air and put it back together with fluid.

Its much better but its not right. The plunger/piston doesn't always come back out all the way and then, when i went to bench test/bleed it, the first stroke is solid with pressure through out the stroke, then the next will only build pressure at the very bottom of the stroke, regardless if the piston comes all the way out or not. But if i wait 20 seconds, it'll give another full stroke with full pressure.

Anyone got any ideas?? I'd like to understand whats happening before i make a decision about rebuild/replacement.

Cheers.
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New project!! Brazilian Split!!
63 Panel Van Project (Sold)
71 Bay window Devon Camper (Sold)
79 Brazilian Bug / Fusca

[western auto]

adjust your brakes, bleed out the air

[BarryL]

[jmmj]

[jmmj]

[BarryL]

[Stocknazi]

I removed and inspected my 15 year old Varga master cylinder and found a ring of pitting at the very beginning of the bore at the seal (near the push-rod) that seems to be suborn to remove with a hone. Other than this half ring of pitting the bore is really nice. The part of the bore the main seal rides is perfect so I have confidence it will function OK, but may leak, or develop a leak at the end seal. The pitting rust ring MAY be just ahead of the end seal, so it may possible not even come into contact with the seal surface. I'll need to do some careful measuring to confirm.

I know is not standard practice, but is it possible to get a little more aggressive in this one inch of bore where the end seal would ride?

Normally I would replace it, but Varga Brazil parts are not available (or cheap) like they used to be. It's going back onto the bus regardless, and will be using all the original parts, other than the cracked reservoir and dust boot. I refuse to used a new Chinese junk cylinder.

It's getting old (and expensive) replacing all these brake parts simply because they have some minor rust pitting in the bores. This is the last bus I'll be using DOT 3/4 brake fluid. DOT 5 silicone fluid from here on out.

Anyone sleeved any master/wheel cylinders?
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WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).

"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."

Thomas Jefferson

[pondoras box]

ATF messed the cup and seals up. Might be a good time to consider doing a dual circuit conversion. It’s worth the time money and effort especially since you’re halfway there. That’s the second thing I do to any VW I get. The first thing is fix / adjust the emergency brake system. If originality is your primary concern no one can see it and a crinkled nose is not very original looking.
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Looking for anything from Hal Casey Motors out of Hamburg New York, from license plate surrounds to matchbooks.

1961 23 Window (Bobo)
1965 11 Window (Zelda). https://www.thesamba.com/vw/forum/viewtopic.php?t=563183
1965 13 Window (Lucas)
1957 Oval ragtop
1960 hardtop
1964 hardtop
1965 hardtop
1988 Cabriolet VR6 conversion
Plus a lot of other rusty junk

[Stocknazi]

[Eric&Barb]

[BarryL]