The MGA front suspension is an independent double-wishbone design carried over from the earlier TD and TF models, with coil springs and Armstrong lever arm shock absorbers whose arms form the upper wishbones. The lower wishbones pivot on inner mountings and carry the coil spring in its spring pan; the steering knuckle is attached to the wishbones via a kingpin (the factory term for the vertical pivot through which the stub axle rotates when steered). Several production-change breakpoints during MGA manufacture affect the front coil springs, spring spigots, steering knuckles, anti-roll bar provision, and track rod end hardware, and the correct part for a car of known chassis number depends on these breakpoints being confirmed.
Wishbones, spring pan and kingpin
The double-wishbone layout uses the Armstrong lever-arm damper arms as the effective upper wishbone, pivoting with the suspension movement as the damper operates. The lower wishbones are separate items pivoting at the chassis; they mount to the spring pan which carries the base of the coil spring. The stub axle rotates on a kingpin that passes vertically through the steering knuckle, and the factory specification gives a kingpin inclination of 9 to 10½ degrees.
Replacement wishbones, spring pans, kingpins, and the associated bushings and retaining hardware are available as service items.
Coil springs
On the 1500, new front coil springs were introduced from car/chassis 15152. They were made from thicker-gauge wire and had a reduced free length to stiffen the front suspension, and are only interchangeable in pairs.
Cars built pre-15152 therefore use the earlier specification; cars built from 15152 onwards use the later stiffer specification. Twin Cam cars received the revised specification from the start of Twin Cam production. Coil springs must always be replaced in pairs to maintain equal ride height and spring rate left-to-right. From car/chassis 58996 on the pushrod 1500 (November 1958), and from Twin Cam car/chassis 842 (November 1958), the front spring spigots were increased in diameter to eliminate a spring-noise issue identified in service.
Cars built before these breakpoints use the original smaller spring spigots; cars built after use the revised diameter. When ordering replacement springs and spigots, the chassis number determines which specification applies.
Steering knuckles
The steering knuckles and their retaining nuts were modified from car/chassis 54247 on the 1500, with washers being added at the same point. Different steering knuckle specifications were also used across MGA variants to accommodate the three different front brake types, Lockheed drums on the 1500, Dunlop discs on the Twin Cam / De Luxe, and Lockheed discs on the 1600 / 1600 Mk II. Wire-wheeled cars and disc-wheeled cars also use different hub specifications within each variant. The correct steering knuckle for a car of known chassis number therefore depends on variant, wheel type, and (for 1500 cars) the chassis-54247 breakpoint.
Anti-roll bar
From car/chassis 66574 (April 1959), the spring pans were modified to permit installation of an optional anti-roll bar, with corresponding changes to the lower wishbones. The same modifications were introduced on all Twin Cam cars from car/chassis 2275 (June 1959), with the anti-roll bar fitted as standard on the Twin Cam from that point. The anti-roll bar was also standard on all De Luxe variants, and remained optional on the 1600 and 1600 Mk II.
Cars without the anti-roll bar use the earlier spring pans and unmodified lower wishbones; cars with the anti-roll bar use the later hardware. Andrex friction-type TE.1 competition shock absorbers are not compatible with the anti-roll bar and should not be fitted in conjunction with it.
Front shock absorbers
The same Armstrong double-acting lever arm piston-type shock absorber is fitted to every MGA variant at the front. The damper bodies are in natural aluminium with the arms painted black. Andrex friction-type TE.1 competition shock absorbers could be fitted alongside the standard Armstrong items on all models except the 1600 Mk II, with special mounting brackets available for this installation. Twin Cam cars could additionally be fitted with higher-setting hydraulic valves to the front (and rear) shock absorbers, recommended for circuit racing; this option is believed to have become available from approximately January 1959.
Track rod ends
Track rod ends received cup and fibre washers below the grease nipples, together with a grease escape drilled in the steering ball socket cap. This modification was introduced on left-hand drive cars from car/chassis 53875 (July 1958), and on right-hand drive cars from car/chassis 55545 (August 1958).