Austin A90

Longbridge · 1954–1956 · 25,532 built

The Westminster that introduced the C-series six — the engine that went on to power the Austin-Healey.

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About the Austin A90

A late surprise at the 1954 London Motor Show, the A90 Westminster replaced the four-cylinder A70 Hereford and brought an entirely new engine with it: the 2,639cc BMC C-series six, 85bhp at 4,000rpm and 124lb ft at 2,000. It is the same engine, in higher tune, that went into the Austin-Healey 100-Six, and the step up from the A70 is a complete break — 2.2-litre four to 2.6-litre six, with no engine parts in common at all. 25,532 were built before the A95 took over in the autumn of 1956. Do not confuse it with the A90 Atlantic of 1948 to 1952, which shares nothing but the designation.

The A90 is a saloon only — the Countryman estate arrived with the A95 — and where the A90 ends and the A95 begins matters a great deal when ordering body parts. In autumn 1956 the wheelbase was stretched two inches, from 8ft 7¾in to 8ft 9¾in, by redesigning the rear springs and moving the axle; the tail was lengthened, the rear window went wrap-around, the boot sill came down and the grille changed. The A105 muddies it further, because the earliest short-boot A105s of May to October 1956 use the original A90 body and are very rare, while A105s from October 1956 use the longer A95 shell. Brakes are Girling, 11in drums, two leading shoes at the front.

Austin A90 — specification & changes within the model

Built: October 1954 – autumn 1956, Longbridge. 25,532 built. Four-door saloon only.
Engine: 2639cc BMC C-series overhead-valve six (79.4 × 88.9mm), five main bearings, 85bhp @ 4000rpm, 124lb ft @ 2000rpm, single downdraught Zenith with an oil-bath air cleaner.
Gearbox: Four-speed, column change, no synchromesh on first. Borg-Warner overdrive optional from early 1956, working on top, third and second. 9in clutch, 3.91:1 axle.
Brakes: Girling hydraulic, 11in drums, two leading shoes at the front, 2½in linings.
Suspension: Independent coil and wishbone front; live axle on half-elliptic leaves with an anti-roll bar. Cam-and-peg steering, 16:1.
Dimensions: 8ft 7¾in wheelbase, 15ft 2¼in long. 6.40-15 tubeless tyres. 12 volt, 51 amp/hr battery.
Chassis prefixes: BS4 and BS6.
A90 or A95?: From autumn 1956 the A95 is two inches longer in the wheelbase, with a lengthened tail, wrap-around rear screen, lower boot sill and a new grille, and it adds the Countryman estate and a Borg-Warner automatic.
The A105: May to October 1956 cars use the A90 short-boot body and are rare; from October 1956 the A105 uses the A95 shell and sits an inch lower.
Not the Atlantic: The A90 Atlantic of 1948–52 is a completely different car that happens to share the designation.