A shaft-drive "500"

Photo feature

The accompanying photograph shows a 500-c.c.racing car now nearing completion. The specification is somewhat different from usual trends, in particular forward mounting of engine, rear-wheel drive and complete absence of chains.

The car is not in anyway considered to be a superior form of “500” , rather is it an experimental shape of things to come.  I feel that with the terrific urge of the modern 500-c.c. power-unit, conventional chain-drive will be hard pressed to stand long-distance racing. If one has to lift the foot to save the chains one may just as well accept the slightly lower mechanical efficiency of gears and shaft and press on.

Brief specification is as follows:

Name:  P.R.A. (Preston Racing Automobile).

Chassis: B.R.M.-type frame.

Suspension: (Front): Double wishbone of unequal length and coil spring. (Rear): de Dion with concealed transverse coil spring and articulated dead axle.

Dampers: Friction.

Brakes:  Hydraulic twin master cylinders, drums at all wheels.

Engine:  Norton s.c. front mounted with crankshaft fore and aft.

Transmission: Shaft to gearbox and final drive unit mounted at rear, and incorporated guide slot for dead axle.

Fuel System: Pesco-type pump from side tanks.

The car has been driven and appears to be very satisfactory in all ways. It is hoped to be able to get some indication of how practice compares with theory during the coming season.