Thanks to Reliant World forum members "Hidunc" and "Halfamix" for the following info .
EARLY SINGLE BRAKE LINE KITTENS used the following ;
BRAKE ; WHEEL CYLINDER ; FRONT ; PASSENGER SIDE
POSITION ................... QUANTITY .... PART NUMBER ..... SIZE ...
N/S [ Passenger side } ......... 2 ...................... GWC127 ..................... 15/16" { 0.9375" } {23.8mm} bore
SUPPLIERS { A few of many }
The following is the description given by Minisport
Replacement front left side wheel cylinder.... GWC127 - 15/16" (23.8mm) bore.
850/998 Minis built between 1969-1984 with twin front brake shoes.
The following is the description given by Minispares
Genuine original AP lockheed L/H front wheel cylinder for twin leading shoe drum brakes for MK2 cars from 1967.
Bleed nipple included but requires 37H3833 gasket when not supplied.
These are 0.9375" bore size which is larger than the MK1 type and the repair kit is GRK2002.
BORG & BECK PART NUMBER ; BBW1351
.............
BRAKE ; WHEEL CYLINDER ; FRONT ; DRIVERS SIDE
POSITION .............. QUANTITY .. PART NUMBER .... SIZE ...
O/S [ Driver side } .............. 2 ......................... GWC126 ..................... 15/16" { 0.9375" } {23.8mm} bore
SUPPLIERS { A few of many }
The following is the description given by Minisport
Replacement front right side wheel cylinder.... GWC126 - 15/16" (23.8mm) bore.
850/998 Minis built between 1969-1984 with twin front brake shoes.
The following is the description given by Minispares
R/H front wheel cylinder for twin leading shoe drum brakes.
MK2 1967 on with bleed nipple.
REQUIRES 37H3833 GASKET x1 when not supplied.
These are 0.9375" bore size which is larger than the MK1 type and use GRK2002 repair kit.
BORG & BECK PART NUMBER ; BBW1541
.............
LATER DUAL BRAKE LINE KITTENS / FOX used the following
BRAKE ; WHEEL CYLINDER ; FRONT ; PASSENGER SIDE
POSITION ................... QUANTITY .... PART NUMBER ..... SIZE ...
N/S [ Passenger side } ......... 2 ...................... GWC103 ..................... 13/16" {0.8125" } {20.6mm} bore
SUPPLIERS { A few of many }
The following is the description given by Minisport
Replacement front left side wheel cylinder.... GWC103 - 13/16" (20.6mm) bore.
Early 850/998 Minis built between 1964-1967 with twin front brake shoes.
The following is the description given by Minispares
First twin leading shoe types from Sept 1964 up to 1967 pre MK2 with 0.8125" bore size.
2 of these per L/H hub.
Repair kits for these are 8G8816.
Later cars used 0.9375" bore size GWC126.
If using on 37H2013 back plates you will need to slightly elongate bolt holes for wheel cylinders as the bolts will not quite fit in.
BORG & BECK PART NUMBER ; BBW1281
...........
BRAKE ; WHEEL CYLINDER ; FRONT ; DRIVERS SIDE
POSITION .............. QUANTITY .. PART NUMBER .... SIZE ...
O/S [ Driver side } .............. 2 ......................... GWC102 ..................... 13/16" {0.8125" } {20.6mm} bore
SUPPLIERS { A few of many }
The following is the description given by Minisport
Replacement front right side wheel cylinder.... GWC102 - 13/16" (20.6mm) bore.
Early 850/998 Minis built between 1964-1967 with twin front brake shoes.
The following is the description given by Minispares
First twin leading shoe types from Sept 1964 up to 1967 pre MK2 with 0.8125" bore size.
2 of these per R/H hub.
Repair kits for these are 8G8816.
Later cars used 0.9375" bore size GWC127.
The GWC102/3 cylinders are for twin leading shoe MK1 variants 1.5" wide shoes from Sept 1964 to 1967.
If using on 37H2014 back plates you will need to slightly elongate bolt holes for wheel cylinders as the bolts will not quite fit in.
BORG & BECK PART NUMBER ; BBW1280