Monday 15 June 2020

Rear brake cylinder sizes

Comparison of wheel cylinder sizes.


Lockheed rear wheel brake cylinder, twin piston comparison as found on BMC rear axles [Midget, Sprite, Austin A40] and Mini rear. Fixed cylinder, one per side.

Cylinder bore
Unipart
part number
AP Caparo
part number
Old Lockheed
part number
Notes on original applications (not an exhaustive list; approx years)
1/2" (0.5)
GWC1126


Mini 1275GT rear - 1975 to 1976.
5/8 (0.625)
GWC1101
4241-075P
LW11075
Mini Mk1 Cooper S with servo; rear.
Mini MkI (not Cooper or Cooper S) rear - 1962 to 1967
9/16" (0.563)
GWC1131


Mini MkI rear - 1959 to 1967
9/16" (0.563)
GWC1134


Mini MkIII rear - 1974 to 1978
11/16" (0.689)
GWC1129
4241-193P
LW11193
MG Midget [1500] rear - 1975 to 1979.
Mini 1275GT rear - 1964 to 1975.
3/4" (0.75)
GWC1102
4241-396P
LW11396
Austin Healey Sprite & MG Midget (1098 & 1275 engines) rear, 1964 to 1975.
Austin A40 Mk2, rear - 1962 to 1968.
Mini MkI (not Cooper or Cooper S) rear - 1959 to 1962.
Mini MkII (not Cooper or Cooper S) rear - 1967 to 1975
plus other Minis
7/8" (0.875)
GWC1115
4241-933P
LW10104
1962 MG Midget Mk1 & Austin Healey Sprite MkII rear (with front drum brakes and twin piston fixed single rear wheel brake cylinders). NB earlier cars have sliding single piston wheel cylinder of 7/8" bore in a different back-plate.

NB position of locating pin and matching hole in original rear brake back-plate may vary, so might need to drill different locating pin hole in rear brake back-plate if considering changing sizes of wheel cylinder outside original application.

Note early Austin Healey Sprite and MG Midgets (until approx late 1962) as well as Morris Minors had a different style wheel cylinder (single piston, sliding), rather than the above fixed cylinders with dual pistons..

Would MGB wheel cylinders GWC1103 (7/8" [0.875]) - MGB GT and MGB Roadster GWC1122 (13/16"? 31/64? [0.8?]) fit any of the above rear back-plates?

No comments:

Post a Comment