Cars up to approximately chassis number 1153 (not USA/Canada) use an early Girling Mark 2B servo with a specific repair kit and air valve repair kit. This early servo is available on a reconditioned exchange basis. An air filter and seal kit, filter cover, and non-return valve with banjo bolt and sealing washers service the vacuum connection.
Single-Circuit Servo, Later Cars
From chassis number 1154 onwards, and on all USA and Canadian cars from the start of production, a revised Girling servo was fitted. This later servo is also available as a reconditioned exchange unit. An alternative Lockheed servo is available as a direct replacement for owners who prefer a more readily serviceable unit, it fits in the same location using the same mounting points. Each servo type (original Girling and alternative Lockheed) has its own specific repair kit.
Air filter and seal kits, covers, air valve repair kits, and non-return valves with sealing washers are available for the later type. The servo vacuum hose, sold by the metre, connects the servo to the inlet manifold vacuum supply, with original-style or jubilee-type hose clips.
Dual-Circuit Twin Servos, USA/Canada
North American dual-circuit cars use two servo units: one for the front brakes mounted on a bracket on the right-hand side of the engine bay, and one for the rear brakes at the right-hand rear of the engine compartment. The twin-servo arrangement is completely different from the single-circuit system and requires specific servo units, repair kits, and pipe routing.