artomotive

Classic cars, defined by the human hand

Miniature Autoworld March 1965 | Drawn and described by Malcolm T. Firth

ERA Type B

AFTER Raymond Mays and Peter Berthon had raced a modified 6 cylinder Riley in the 1933 season with much success, they were approached by Humphrey Cook with the suggestion of forming a company to build racing cars. The new firm of English Racing Automobiles was formed with premises in the grounds of Mays' own home in Bourne, Lincolnshire, the same buildings now being the present day B.R.M. headquarters.

With the aid of Reid Railton on chassis design, and T. Murray-Jamieson on superchargers, the first E.R.A. appeared in the spring of 1934. Four examples of this first A type E.R.A. were built, principally to partake in sprint and hill climbs as well as Voiturette races, and engine sizes of 1100c.c., 1500c.c. and 2 litres were produced. In each case the engine was a 6-cylinder derived from a Riley design and blown with a Murray-Jamieson designed Roots type supercharger.

In 1935 the 1½ litre version was built for sale to private entrants, differing slightly from the earlier A type. These B types had softer rear springs and additional chassis bracing under the rear seat, and the first of these, chassis No. R.I.B., was sold to Dick Seaman who competed with this car in British and Continental events until he joined the famous pre-war Mercedes team, and it is this B type car which is depicted in the plan as it is raced today.

The B type 1½ litre engine was, as previously mentioned, derived from the Riley 6 cylinder engine with a very sturdy cylinder block in which the crankcase extends far below the crankshaft centre line. The three bearing crankshaft is very heavily counterweighted and although of very long stroke the engine revs easily up to 7500 r.p.m. The fuel mixture is fed to the engine from a single S.U. carburettor through a two lobe Roots type super charger bolted on the nose of the engine. The hemispherical cylinder head has two valves per cylinder operated by short push rods and rockers from twin camshafts mounted high in the crankcase as on the Riley design. The drive is taken direct to a Wilson preselector gear box mounted in unit with the engine, giving road speeds of 125, 98.70 and 42 m.p.h. in the gears.

Drive is taken from this by a torque tube propeller shaft to the rigid back axle. The rear suspension has short half elliptic springs shackled at both ends to outriggers from the frame. The front suspension has a rigid beam front axle mounted against on short semi elliptic springs.

The main chassis frame is of channel side members with scanty cross members, being very prone to flexing. The B type had Girling mechanical brakes but many of these were converted privately to a Lockheed hydraulic system before the war. The friction type shock absorbers originally fitted were also often discarded in preference to hydraulic piston dampers.

Being primarily designed for sprint and hill climb work, not much attempt was made to produce wind cheating bodywork, and although the car is very slim, the high central driving position does not help in this respect although it does give a first class view of the road.

Miniature Autoworld

ERA B Type

ERA Type B technical drawings
Miniature Autoworld

ERA C Type

ERA Type C blueprints

Miniature Autoworld March 1965 | Drawn and described by Malcolm T. Firth

ERA C Type

In 1937 three B type E.R.A.'s were converted into C types at the works, and one of these was R.8B, the car of Earl Howe which became R.8C and is depicted in its present guise in the plan, having had special bodywork fitted soon after the war.

The C type E.R.A. differed from the B type in that the chassis was heavily stiffened and the channel section side members replaced by a box section frame. The beam front axle was replaced with a fully independent suspension using Porsche trailing arms with torsion bars running side by side in a tubular chassis cross member. The rear axle also incorporated a Z.F. limited slip differential to help transmit the increased engine power to the road.

This power increase came about from the use of a Zoller vane type compressor in place of the previous Roots type supercharger, but as these required very skilful maintenance, beyond the scope of most private owners, they were only successful on the works cars. With the Zoller blower, the speeds in the gears rose to 140, 117, 97 and 74 m.p.h. Lockheed two leading shoe brakes became standard on the C type to cope with the increased performance. As it is raced today, R.8C sports a semi streamlined monoposto body, built for T. C. Harrison when he raced the car after the war. The body is not authentic but bears some resemblance to the 159 Alfa Romeo and the later E type E.R.A. It is today raced in Vintage events by Bertie Brown and is the only E.R.A. in existence with the independent C type front suspension.

Harrison has always been an E.R.A. fan and after the war he acquired this C type and also the previously described R.1B. It was his intention to cannibalize R.1B as a source of spares for R.8C and the car was completely dismantled to this end. When he eventually sold R.8C, Harrison had R.1B rebuilt and completely restored to include hydraulic brakes and shock absorbers, otherwise the car is completely authentic. Now the property of A. S. Cottam, it is probably the best preserved example in existence and is regularly raced in Vintage events.

Essential Prototype dimensions : -

B typeC type
Chassis No.R.1BR.8C
Wheelbase7ft. 10in8ft. 0in.
Front Track4ft. 3in.4ft. 4½ in.
Rear Track4ft. 3in.4ft. 2 in.
Front Tyre Size550 x 17in.550 x 18in.
Rear Tyre Size650 x 16in.650 x 16in.
Overall Length11ft. 2½in.11ft. 5½in.
Overall Width (Body)lft. 10in3ft. 3in.
Overall Height (to Screen)3ft. 10in.3ft. 10in.
Body ColourDark BlueDark Green