1976 Bus - Brakes Mysteriously Faded, Then Came Back -

[Abscate]

[wagohn]

[SGKent]

Good Job
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[wagohn]

Thanks all. We had a father/daughter brake bleeding day and the brakes came back fully. Daughter got to experience both scenarios, pumping the brakes and bleeding the calipers. She's also a dab hand now at removing/fitting heavy bus wheels.
We did not have to bench bleed the master cylinder, but took out a lot of air when bleeding. Thankfully the bleed screws came undone easily after soaking all night in PB Blaster.
Test drive and the bus stopped true and straight, no heat generated on the wheels from sticking brakes, etc. We're back in business.
Thanks!
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1976 VW Transporter, 2.0 FI Engine

[SGKent]

Be sure to check the length the front of the piston extends at rest to the old master.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[wagohn]

This is the MC I used. The switch positions were the same as the one I took off. Even came with new bottle mount seals and rubber o-ring. AND it came with a bench bleed kit. Pretty good for $50.

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1976 VW Transporter, 2.0 FI Engine

[Whaanga]

[wagohn]

I decided to go with the frayed black grommet in the pic. Other than the shoulder it was complete. I've ordered a new one and will fit when it arrives.

New MC is now on and holding fluid. Next step, bleed the brakes.
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1976 VW Transporter, 2.0 FI Engine

[wagohn]

So I got the old MC off and everything came off fairly easily. The only possible issue was removing the filler tube. There appears to be a "shouldered, black rubber, inner insert at the inlet and the shoulder area is torn up or deteriorated. How crucial is this, can I reasonably use as pictured, and in the pic do I have it the right way around?

Inner booster was dry.

Thanks for your attention.

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1976 VW Transporter, 2.0 FI Engine

[wagohn]

[airschooled]

It's been mentioned here before, but some new cylinders have the rear brake light switch mounted planar with the front switch, and that can get in the way of the handbrake cable. Good cylinders mount the switch at an angle. It's up to you if you want to try to return/exchange it, or make a chafe-guard for the cable; just look out for it!

Robbie
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[vwwestyman]

[kreemoweet]

[Abscate]

Start those brake line unions before you bolt up the MC, that lets you manipulate both to line them up. I find I can feel the threads engage when I have both in hand, vs one being bolted up.
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[wagohn]

Thanks all, New MC should be here tomorrow. I just soaked the brake pipe nuts in PB Blaster for the night in prep.

On a side note, I'm using newly purchased Harbor Freight 6" ramps, should have bought them years ago. Drive right on, rock solid, and lots of work room. Great deal for $45 and rated for 13000 lbs.
I'm getting older and need a little more room.

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1976 VW Transporter, 2.0 FI Engine

[oscarsnapkin]

[Whaanga]

I had a similar issue a couple of years ago. I had redone the front and rear brakes and felt I had a good system. I then had a workday with Colin (Itinerant Air-cooled) and when he drove my bus, he quickly identified that I had a bad master cylinder. What was strange to me is that when I applied the brakes, I felt I had good control - but I had learned to compensate by pushing the pedal down with a quick, last-minute foot move. Colin used a slower physical approach. So - I tried changing how I applied the brake and suddenly realized that I indeed had a problem. (see the write up from Colin's website: http://www.itinerant-air-cooled.com/viewtopic.php?...d1248fd48)

I was able to source a quality master cylinder and when Colin came for his next visit, we replaced it. It was a pretty do-able job and then not soon after, the servo failed. AND - so I had it rebuilt and now - I have much more confidence in my brake system.

From my experience and what others have written, it make sense to replace your Master Cylinder.
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Late 1973 Bay w/a transplanted 914 Engine

[ToolBox]

[kreemoweet]

I might add to suggestions that some very experienced air-cooled vehicle buffs recommend taking apart
brand-new brake cylinders to clean out factory debris. I've never done so, and not been stung. Yet.
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'67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities

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[wagohn]