Overview

Datsun 1200 used three basic brake master cylinders:

11/16 diameter safety split circuit (tandem), used with disc-brake models
11/16" safety split circuit (tandem), used with deluxe drum-brake models
11/16" single reservoir, used with economy drum-brake models

In Japan, STD trim 1200s used the single, DX used tandem drum, and GL,GX used tandem disc.

All North American 1200s used tandem master and came with disc brakes.

Compatibility

Datsun 1200 with drums uses same cylinders as Datsun 1000
Datsun 120Y w/o booster uses same as Datsun 1200

B10 11/16" single 46010-18001 <> 46010-H1010
B10 11/16" tandem 46010-H0100 <> 46010-H1000 Deluxe
B110 11/16" single
B110 11/16" tandem drum
B110 11/16" tandem disc/drum 46010-H1005 <> 46010-H1006
B120 11/16" (until Oct 1989)
B210 11/16" tandem drum 46010-B5000 < 46010-B5003
B210 11/16" tandem drum 46010-H7400 < 46010-H7401
B210 11/16" tandem disc/drum 46010-H5100 < 46010-H5101
B210 11/16" tandem disc/drum 46010-H7500 < 46010-H7501
B210 3/4" 46010-U0601 < 46010-U0602 without push rod (use with booster)
B310 13/16" without push rod

B120 1990-1994 mounts horizontally see Sunny Truck Disc Brakes

Larger Master Cylinder

Some club members are using a 13/16 master cylinder from the B310. This increases pedal effort, but reduces pedal travel for a "tighter" feel. Discussion: Is anyone running a 13/16 master cyl w/out a booster?

A larger master cylinder will require more leg pressure, but will require less pedal travel. However, even though you press harder on the pedal, it will not create more pressure at the wheels.

The size of the master cylinder does not affect front-to-rear brake proportion. Instead, the relative size of the front brakes to the rear brakes sets the proportion.

A larger master cylinder will generate LESS pressure but the pedal will be STIFFER. Because there is less pressure, you have to push harder on the pedal to make it stop the same. You get more volume (firmer pedal), but less pressure.

The reason Datsun chose 11/16" had to do with how much leg pressure is required. At 11/16" (given the size of the brakes at the wheels), even a small driver can generate enough force to panic-stop the car. The downside is a bit of pedal travel. When they started offering power brakes in the B210, they went to a larger diameter master for decreased pedal travel. That's why when the power booster fails, it is difficult (requires much leg pressure) to stop the car.

Vehicles with a brake booster can have larger master cylinders, so that you get a firmer brake pedal with less travel required. But with the booster even a small driver can operate the brakes to maximum force.

Adjustment

B110 has a non-adjustable master cylinder. When re-installing or after fluid has drained, do the following:

Perform Brake Bleeding, including "bench bleeding" of the master cylinder.
Tighten the master cylinder retaining bolts to 1.5-1.8 kg-m (10.8 to 13.0 ft-lb) torque.
Adjust brake pedal height.

Part Numbers

http://www.rockauto.com

Master Cylinder (disc brakes)
WAGNER F96862 $51.79
A1 CARDONE 111655 (remanufactured) $32.79
TOKICO Master Cylinder PN 46010-H1006 
TOKICO Master Brake Cylinder (rebuild kit) PN 46010-H1027

TOKICO
46020-10611 ASSY-CAP,RESERVOIR
46010-H1000 ASSY-CYLINDER,BRAKE MASTER
46010-H1005
46010-H1006
46010-H0100 ASSY-CYL. B/MASTER TANDEM FOR DRUM

1071-
46010-H3300 ASSY-CYLINDER,BRAKE MASTER
46010-H3100 ASSY-CYLINDER,BRAKE MASTER (TANDEM)
46020-E0300 ASSY-CAP,OIL RESERVOIR (NABCO)
46020-U0512 Newer CAP
46020-U0201 ASSY-CAP,OIL RESERVOIR

Rebuild Kits

Note that Tokico and Nabco internals are different. So while you can interchange the whole Master, a rebuild kit needs the specific kind.

TOKICO REBUILD KIT
* PBR K7859X [for 11/16 cylinders]
** This is a major overhaul kit and supercedes all 11/16 kits.

NABCO REBUILD KIT
* ?

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Brake master cylinder