Single to Dual Master Upgrade

[pantone149]

If I convert my 65 bug from single to dual master brake cylinder, I expect to possibly have to change the adjustment of the brake pedal pushrod. Should I expect to have to lengthen or shorten the adjustment? About how much?

[KTPhil]

I don't know specifically, but with so much hardware changed out over the years I wouldn't worry about a numerical measurement.

Follow the right sequence:
1. Set pedal stop to obtain correct pedal tip-to-bulkhead distance (a little under 8" typically).
2. Set pushrod length to obtain 1/4" play at the pedal tip.
3. Lock down locknut and NEVER CHANGE IT AGAIN. Any later change in pedal play should be handled by the pedal stop, not the pushrod length.
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[pantone149]

Ok, thanks a bunch. If pedal tip-to-bulkhead distance should be a little under 8" typically is that measured from the braking surface (the rubber cover) to the carpet, or to the metal bulkhead?

[KTPhil]

Measure from the carpet covering the bulkhead to the nearest pedal part (typically the back of the metal pad, or the rubber cover).
Between 7-3/4 and 8" will do it.
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[pantone149]

I measured several times and got from 7.75-8.0 inches from carpet (no additional padding or insulation) to the back of the brake pedal. In spite of that my pushrod is almost maxed out before touching the cylinder piston. Not sure if that's OK or not.

[KTPhil]

[daveblank]

What's a good brand of master cylinder for this upgrade?

[OldSchoolVW's]

This one from NAPA:

https://www.napaonline.com/en/p/NMCM2110

Lifetime warranty. New manufacture, not rebuilt or reconditioned.
_________________
Tom

"Following distance is proportional to IQ."

"It's okay to think."

"If you don't do it this year, you'll be one year older when you do." Warren Miller

'63 Beetle Sedan
'69 Beetle Sunroof
'70 Beetle Sedan
'73 Type 3 Fastback

[daveblank]

[OldSchoolVW's]

[daveblank]

[56Cabrio]

This is what I did on my oval, kept my original in place for looks though.
Here is a good thread on upgrading
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
Pic from gallery

_________________
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1956 Rag Top owned since 1988
1956 Convertible owned since 2000
1963 Hard Top

RIP Dad 4/20/1951 - 2/4/2023

[Bobs67vwagen]

I did the above reservoir on top of the master for a 74 pan that I put together recently. It is simple, no lines to leak or worry about, and the reservoir is cheap and available. I do not think it's location will be a problem with weather.

[slave1pilot]

I did the same thing on OL' Herb

_________________
Currently:
1959 pan with a 64 body and a 63 ragtop grafted in Herbie replica
Previously:
1967 Beetle
1968 Beetle
1970 Beetle

[pantone149]

OK, so I have all new everything. Master Cylinder (Brazilian, Dual for 1967), steel lines, rubber lines, brake cylinders, and brake shoes (drums all around, 1965 bug). Pushrod is adjusted to allow about .25" pedal travel. All shoes are adjusted "snug" to the drum (drum can be turned manually with moderate effort). Reservoir filled with new fluid, DOT3. If I press the brake pedal nothing happens, no fluid movement. I've had the front bleeders open overnight (rears are closed) and expected some fluid to move by gravity to the MC but nothing happened. I also tried gravity bleeding (a few days ago) only the right front by opening that bleeder but plugging off all the other exit ports of the MC and nothing happened, no fluid flow. Shouldn't the MC get filled with fluid solely by gravity from the reservoir? What am I missing?

[Cusser]

[Bobs67vwagen]

Hi did you bench bleed the master before installing it? Do you have one of those hand held pistol grip vacuum bleeders such as the mitey-vac? You should have at least a little flow of fluid by gravity.

[Cusser]

[pantone149]

Bobs67vwagen: Yes, I have a mity-vac and virtually nothing (little dribbles) gets sucked out into the device. The vacuum gauge on the mity-vac show increasing vacuum as I hand pump and the vacuum sticks around pretty well if I don't loosen the bleeder valve. When I do loosen the bleeder valve a little tiny dribble of fluid just might come through, but don't bet the farm on it.

I tested to make sure that fluid is moving from the reservoir (mounted by spare tire) into the MC and when I got a bunch of slippery fluid on my hands I determined that there is flow into the MC.

No I did not bench bleed. Reading a thousand posts on the Samba tells me about 50% of folks bother, the other 50% say it's a moot point. The shop that sells me VW parts told me the same (Wolfgang Int).

This is Brazil MC #2. The first one did OK for a while but gave up after a few thousand pedal strokes (I'm not kidding) and a few thousand mity-vac pumps (not kidding again).

My wife tested the pedal stroke last night and told me the number is not .25" but more like .5". This is something I plan to correct today.

[Apostle_]

I am using a 67 master and reservoir. Had to drill an extra hole so I can keep the washer bottle. I used 1 meter of hydraulic hose and it was enough for both lines. I'm also using the fuel injection style clamps on the lines to the master. All new hard and rubber hoses.