ID of Early Type 3 Front Wheel Cylinders?

[jadney]

I have a bunch of Type 3 front wheel brake cylinders here to rebuild. There's no problem rebuilding these, but I'd like to know which ones these are. The difficulty is in the fact that the parts book lists 3 different versions of 22.2 mm (7/8") front cylinders but I've only ever seen 2 different style bodies.

Here are 2 photos of early and late left 22.2 mm bodies, showing front and back views, plus 2 different styles of 22.2 mm pistons.

The cylinders in the photos are both lefts. Note that the piston on the left has a narrower slot than the one on the right. Everything in both photos is 22.2 mm (7/8".)

The parts book lists 4 different Type 3 left front wheel cylinders:

311 611 061 20.61 mm (13/16") Notch & Ghia to 27,849 [I don't have any of these cyls.]

311 611 061 A 22.2 mm (7/8") Square to 27,849 plus all from 27,850 to 221,974. I believe the cyl on the right is that version.

311 611 061 B 22.2 mm (7/8") All from 221,975 to 483,592 (MY 1964.)

311 611 061 C 22.2 mm (7/8") All from 315 000 001 to 315 220 883 (MY 1965)

It looks to me like the cylinder on the left in my photos must be either the B or C version, or possibly both.

I have 2 questions:

What is the difference between the B & C versions?

Which versions got the pistons with the narrow slots?

(Is it simply that the A & B versions came with the narrow slot pistons and the C version, introduced for 1965, was the first to get the wide slots?) I'm pretty sure the wide slot pistons are the late version, as that's what came with all the later rear wheel cylinders that I'm very familiar with.

Complicating this is the fact that the parts book calls out 5 different pistons for these cylinders. 3 were supplied on cars and 2 are called out only as replacements (X in the usage column, and "see Workshop Manual B-8".) I have 2 clearly different pistons, but not 3. Anyone know what the 3rd one would have been? Anyone know what the X versions are/were?

Bonus question: If the only difference is the piston slot width, it appears to me that the wide slot piston would be the preferred replacement for all earlier cylinders. Is there any reason, other than originality, not to do this?

There's a hint in the parts book, where it says "see Workshop Manual B-8", but that section covers the tandem master cylinder. In fact, there's no coverage of the drum front brakes at all in my copy of the B Workshop Manual. Seems odd. There is one comment in the troubleshooting section about correcting brake shoes that are tight in the slots, which leads me to believe that the wider slot pistons were introduced to eliminate that possibility.

thanks for your comments,
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Jim Adney
50+ years of VW Type 3 experience
Specializing in VW Type 3 parts and service

[Zwitterkafer]

Old post, I know, but I checked in PR and concluded the following:

A = bore increased to 22.2 mm
B = body changed, and bottom of piston slot angled to match brake shoes
C = like B, but piston slot widened

Another possible variable to check would be the piston diameter where the rubber boot attaches.

To be retrofitted, piston C would have to be the same overall length, have the same angle of slot cut to the same depth, etc.
_________________
"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC