Even More JR History...
/We’ve been going through our archives and found few new interesting documents. First up is a description of the new Allard JR that appeared in the May 1953 Allard Owners Club Monthly Bulletin. Next up is a new car announcement for the JR that appeared in the July 1953 issue of Road and Track.
The JR Allard
The new JR Allard, designed specifically for sports car races, continues that same successful theme which has characterized the marque in the past. In one important respect it has broken away from previous principles in that it is designed to take one engine only – the Cadillac V8 – instead of being adaptable for Chrysler, Mercury, etc. The Cadillac has been chosen in preference to the Chrysler unit because it is more compact and 130 lb lighter. The output can be increased from 210 bhp in standard form to approximately 300 bhp by employing certain parts produced by Detroit Racing Equipment. Amongst the modifications used are two, four-choke Rochester carburetors; only two chokes on each are operating on small throttle openings, the other two coming in progressively as the throttle is opened further.
A single dry-plate clutch takes the drive via a Cadillac 3-speed gear box with right-hand change, and a short open propellor shaft to a quick-change final drive unit produced in collaboration with H.W.M. The drive passes under the differential to a pair of spur gears and forward again to the crown wheel and pinion. A quick change of these spur gears is easily carried out and there are also four crown wheel and pinion ratios so that the car can be suitably geared for any circuit.
Continuing the J2X practice, a de Dion axle is used at the rear utilizing coil springs as the suspension medium. The fore and aft location of the axle beam is taken care of by twin radius arms on each side, but the method of sideways location is completely new. Two A-brackets are used, the base of the top-most being carried on the rear cross-member of the chassis frame above the axle beam, and that of the lower is pivoted on the axle beam itself. The two apexes meet in a universal joint behind the axle and Silentbloc bushes are used in the pivots. Fully-floating rear hubs are used, carried on twin taper roller bearings, so that wheel location is not affected by drive shaft breakage. The rear brakes are carried inboard on either side of the final drive housing and Alfin drums are used here as well as on the front.
Front suspension is by the well-known Allard system of split axle with coil springs and forward projecting parallel axis radius arms. Two leading shoes are carried in the front brakes and hydraulic telescopic dampers are used all around.
The chassis frame bears a strong resemblance to the Palm Beach model, and in fact the track and wheel-base are the same. Twin tubular side members are used liberally braced together by welded steel plates. The cross-bracing of box and tubular members serves to give an immensely rigid structure. Tubular hoops are welded to this frame and support the body immediately fore and aft of the cockpit, affording some protection to the occupants in the event of an inversion. The complete frame turns the scales at only 180 lb.
The aluminium body has the complete forward section hinged at the front, giving access to engine, steering, suspension, and brakes.
The main fuel tank holds 25 gals. But a removable auxiliary tank alongside the passenger seat gives a further 25 gals. With a load of and driver the weight distribution is roughly 50/50 front and back, but unladen this changes to 57% front and 43% rear. The engine is placed farther forward than has been Allard practice in the past, giving the greater preponderance of weight on the front axle. I.J.AB.
