Rear wheel cylinder manufactured by TRW for Austin Healey BN1 (from chassis 221536), BN2, BN4 and BN6 models fitted with rear drum brakes. This cylinder converts hydraulic pressure from the master cylinder into mechanical movement, applying force to the rear brake shoes.
Fits: BN1 from chassis 221536 (1954 onwards), BN2 (1955–1956), BN4 (1956–1959), BN6 (1958–1959).
Excludes: Early BN1 prior to chassis 221536, and later BN7, BT7, BJ7 and BJ8 models. Not suitable for modified rear brake conversions unless original early rear drum specification is retained.
Always confirm rear drum brake configuration, particularly on cars that may have undergone axle or brake upgrades.
For improved protection against road debris and moisture, fit with the rear wheel cylinder dust cover.
The braking system must be fully bled after installation and checked under pedal pressure. For single-person brake or clutch bleeding, the Gunson’s Eezibleed kit provides controlled pressure bleeding.
Rear wheel cylinders should always be replaced in axle pairs to maintain even braking performance.
TRW is an established hydraulic brake component manufacturer. This cylinder follows the original early Big Healey rear drum specification, making it suitable for restorations that retain factory configuration.
This version is manufactured by TRW. The alternative listing is a reproduction unit. Both fit the same BN1.221536–BN6 applications.
No. Later Big Healey models use a different rear wheel cylinder specification.
Yes. Replacing both sides at the same time helps maintain balanced braking performance.
TRW
