Sacrificial Master Cylinder Cap for Early 356B

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Jim Keller

Sacrificial Master Cylinder Cap for Early 356B

#1 Post by Jim Keller »

I am about to do a major brake job on my 1961 B (Ch 117190), including all new wheel cylinders and a rebuild on the master. When the mechanical work is done, I plan to use my homemade "universal" pressure bleeder to fill and bleed the system so I can do it alone. This requires modifying a master cyl. cap for the pressure hose. I don't have a spare master cylinder cap for my present situation, and don't necessarily want to drill a hole in a good original one (who would?), but I have heard that an "early" VW bus master cylinder cap will work as a substitute. Anyone have any further info, guidance or suggestions? Like what year(s) constitute an "early" bus?

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Jim Alton
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#2 Post by Jim Alton »

Yes, they should interchange. My Motive Products brake bleeder works on all my old cars (see below). Motive Products sells power bleeder adapters that could save you some fabrication.

A VW Bus master cylinder cap [211611351B] is $6.00 from Wolfsbürg West. Motive Product's 1100 adapter is $21.95, the metal 1109 adapter is $34.95.

That's assuming your 356, like mine, has a plastic master cylinder. If my car's was changed it was before it came into my hands.
 
Jim Alton
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Jim Keller

#3 Post by Jim Keller »

Jim,

Thanks for the info and the links. The Motive bleeder is pretty much what I made, except mine has a connection for my compressor. That way, I can move from corner to corner without coming back to the trunk (or engine compartment for "backwards" autos) to restore the pressure.

There was a big VW parts retailer in Anaheim, but I'm having some trouble locating them. I've found BFYObsoleteParts, but it appears to be a different outfit and they don't list the cap on their website. So maybe I'll do a web order from Wolsberg West.

Thanks again.

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#4 Post by Jim Alton »

I've had my bus for a bit over 20 years and many of the old VW suppliers seem to have shrunk or gone away but Wolfsbürg West is bigger than ever.

I'm not trying to criticize your efforts, but for the sake of other folks reading this, there's not much need to repressurize the Motive Products power bleeder while doing all 4 wheels. Connect it to the master cylinder (don't forget to remove the screen from the master cylinder or you'll just pump clean brake fluid onto the floor), pump it to 10 or 15 psi and you're good to go with maybe once giving the pump some strokes during the whole operation.
 
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Sacrificial Master Cylinder Cap for Early 356B

#5 Post by Dale H Moody »

Some pressure bleeders can introduce air into the system at the master cylinder (especially if the fluid level drops too low in the M/C before it's noticed) and create abiguity at the wheel cylinder by always producing bubbles in the fluid (as well as the system). I use a bleeder that sucks the fluid out of the wheel cylinder with no such problems except for the little bit of air drawn in around the loosened bleeder valve. Don't remember who made it but it was considerably more expensive than the pressure type...........Dale

Jim Keller

#6 Post by Jim Keller »

Dale,

I appreciate your comments about the possibility of introducing air during the bleeding process, but that tends to happen when the bleeder only provides air pressure to the master cylinder reservoir and you must frequently check the status of the fluid level.

My pressure bleeder forces brake fluid, under pressure, to the master cyl. reservoir, so that no air is introduced into the car's braking system.

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Re: Sacrificial Master Cylinder Cap for Early 356B

#7 Post by Mervyn Hyde »

Reviving this old thread. I needed a cap for my Motive Pressure Bleeder, to avoid having my 'assistant' sit in the car for 20 mins complaining. I couldn't find one that fitted locally so made up an adapter using an old shock absorber rubber and few bits with threaded ends and nuts on the bracket. Sealed well on the reservoir at 15psi and did the job. Used the new (?) Bendix Dot 4 fluid that is blue and changes colour as the fluid picks up moisture in time.
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Jim Alton
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Re: Sacrificial Master Cylinder Cap for Early 356B

#8 Post by Jim Alton »

Blue brake fluid is famously illegal in the USA.
 
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Re: Sacrificial Master Cylinder Cap for Early 356B

#9 Post by Mervyn Hyde »

It is useful. I should buy a few more lots then ...
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Re: Sacrificial Master Cylinder Cap for Early 356B

#10 Post by Brian R Adams »

Re-reviving this old thread:

I'm thinking of buying a Motive pressure bleeder. I have 2 Japanese cars, plus my 356 to bleed. May I assume the Motive "European" model's adapter cap will work with my recent replacement (single-circuit from Zims) 356 MC? Or do I need to modify a spare MC cap I happen to have?

https://www.amazon.com/Motive-Products- ... B0002KM5L0

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Re: Sacrificial Master Cylinder Cap for Early 356B

#11 Post by WilliamVaughan »

Humph! Poke the brake pedal through the open door with a (borrowed) rake handle. Who needs aerosolized brake fluid near a nice paint job.

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Re: Sacrificial Master Cylinder Cap for Early 356B

#12 Post by David Jones »

I put a schrader valve in a remote reservoir cap. This was from a T6 body car and fits my "A" car reservoir as well. I just attach the clip on tire tire chuck and turn the pressure regulator down on my compressor to 5 psi and then beed the brakes. At that pressure I get enough flow that the fluid moves slowly enough that it bleeds the brakes adequately but if the hose should slip of the nipple I do not get much spill even if I am not really quick to shut the bleed nipple off. I maybe have to refill the reservoir once in a normal bleeding operation.
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Re: Sacrificial Master Cylinder Cap for Early 356B

#13 Post by Martin Benade »

I did the totally analog version of that, a Schrader valve and an old bicycle tire pump. I’ve done the rake handle too but the front wheels are quite tricky to bleed that way.
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Re: Sacrificial Master Cylinder Cap for Early 356B

#14 Post by Bruce Smith »

Make it easy - go with the Motive. The cap should be just fine with your MC. If in doubt, give them a call. They've got a web site.
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Re: Sacrificial Master Cylinder Cap for Early 356B

#15 Post by Wil Mittelbach »

Brian R Adams wrote: Fri Feb 07, 2020 4:49 pm I'm thinking of buying a Motive pressure bleeder. I have 2 Japanese cars, plus my 356 to bleed. May I assume the Motive "European" model's adapter cap will work with my recent replacement (single-circuit from Zims) 356 MC? Or do I need to modify a spare MC cap I happen to have?
Brian
For several years, have been using the Motive pressure bleeder with its cap fitting the brake fluid reservoir of my '65C.
Very satisfied with its usage.

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