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| C Type Profile |
The early competition success of the M type was the spur for MG to produce something better. One problem was the capacity of the M engine, which at 847cc did not do itself any favours when entered in the 751 to 1100cc class of competition cars. H. N. Charles had been working on a small car capable of exceeding 100 mph, in direct competition to the Austin 7. A new, slightly longer, chassis of ladder frame design was produced which had cross tubes brazed into mounting plates, bolted to the chassis side rails. The chassis passed underneath the rear axle and incorporated sliding bronze trunnion bushes for the rear of each leaf spring, thereby dispensing with the spring shackles of the M type. Trunnions were also incorporated into the front springs and the overall effect of all these changes was to greatly stiffen the chassis as well as lower its centre of gravity and improve the car’s general stability on the road or track. The experimental car, designated EX120, utilised an engine with a bore reduced to 54mm and a stroke reduced to 81mm, giving a capacity under the 750cc limit. Great care was given to reducing friction losses within the engine this included not only a great deal of component polishing but, for example, fitting needle roller bearings in place of the plain white metal bushes on the camshaft. The car was finished with a very simple lightweight body and once a small supercharger was fitted to the engine, the experimental car was taken to Montlhéry, just outside Paris in January 1931 where speeds in excess of 100 mph were achieved, the first time for a car of under 750cc. There was further success for the car later in the year when it completed over 100 miles in the hour, another first for this capacity. The MG Car Company, capitalised on the publicity of this success by ‘productionising’ EX120 and the result was the C type, which was also known as the ‘Montlhéry Midget’. Some of the extra work that went into the production C type was to revert to a 57mm bore and reduce the stroke to 73mm, still keeping the capacity under 750cc but allowed room to increase the crank pins to 1 5/8" diameter. The immediate effect of this change was to make the two-bearing crankshaft much stiffer. H. N. Charles made further changes to the valve timing creating greater valve overlap and this proved to be so successful that, with two exceptions, remained the design for all future cars up to 1936, whether in a standard production or racing car. Early C types retained the M type cylinder head design with inlet and exhaust on the same side but part way through its production run a new ‘cross flow’ cylinder head was developed and this design feature was to remain with MG production until the demise of the OHC engine. Transmission was through a four-speed manual ENV gearbox as there was no equivalent Morris component in production at the time. The gearbox incorporated a cross tube in is case through which the unit was bolted to the chassis side rails. This arrangement was able to dispense with the rear engine mounting, inherited from the M type, and allow the engine and gearbox assembly to be supported at three points on the chassis, thus removing some of the stresses inherent in the earlier design.
C type bodies retained the open two-seat configuration of the M type complete with an opening rear boot which now contained the rear mounted petrol tank. The body was doorless and featured two large ‘humps’ on the scuttle, designed to deflect air over the driver and passenger. Just like the “12/12” M type the year before, the C types first racing success was in May 1931 at the JCC Double Twelve race at Brooklands where it won the race outright and the three car, Team Award.
C type specification
Wheelbase
Track
Steering
Brakes
Wheels
Tyres
Weight of complete car |
6' 9" (2.06m)
3' 6" (1.06m)
Adamant
8", later 12" drums, cable operated
2.50" x 19" side laced wire, Rudge type
4.00" x 19"
12 cwt 28 lbs (622.3 kg)
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Bore
Stroke
Capacity
Power output
Super-charged |
57mm
73mm
746cc
37.4 to 44.1 bhp,
44.9 to 52.5 bhp |
| 2nd May 1931 |
to 8th June 1932 |
C type pictures:
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