The Allard Sprint Car and the 1172 Terrier
Sydney Allard’s Steyr-engined “specials” have been a feature of sprints and hill climbs since the war, but the latest in the series promises to be the most exciting of all. It is a twin-engined four-wheel-drive sprint car using two of the well-known Steyr engines.
Back in 1946 Sydney Allard was using a sprint car fitted with a Ford V8 engine, which was not really satisfactory, and his attention was drawn to a German engine originally intended to power lorries. It was a V8 of similar capacity to the Ford but being 100 lb. lighter and giving more power — about 90 b.h.p. at a modest 3,600 r.p.rn. It was also air-cooled, thus saving the weight and complication of a cooling system.
Mr. Allard managed to obtain four of these engines together with a spare crankcase and a few spares which have gradually dwindled over the years until his spares situation is now virtually nil, so that any major damage to an engine will put it completely out of action. One engine is fitted in his sports hill climb car, two in the new car and one as a standby. These interesting engines are 60 deg. V8s having a cast-iron crankcase, with each cylinder being a separate well-finned barrel upon which is fitted the light alloy cylinder head casting carrying two push-rod operated, inclined overhead valves. The crankshaft runs in five plain bearings using the quick-change thin shell type. Above the crankshaft runs the chain-driven camshaft which operates the valves through relatively short push-rods. Ignition is by Scintilla Vertex magneto driven from the nose of the camshaft, while each cylinder is fitted with an Amal carburetter.
The engines have been bored out once since 1947, giving bore and stroke dimensions of 80 by 92 mm. and a capacity of 3.7 litres. Modifications to compression-ratio and carburation have put the maximum power up from its original 91 b.h.p. at 3,600 r.p.m. to over 180 b.h.p. at 5,000 r.p.m. In order to obtain a very low build for the new sprint car two engines have been converted to dry sump lubrication which has meant the fabrication of new sumps only two inches deep. The oil pumps have been adapted to run from the timing gear in front of the engine and the oil tank is situated right at the front of the car.
Turning to the chassis, this is a fairly simple structure being of the ladder type and made from 14-gauge butt-welded channel section mild steel. This chassis virtually forms a base plate because, as can be seen from our photograph, the chassis rails rest on the wooden bench and all mechanical components are above this level. There are three tubular “hoops” welded to the chassis, one in front of the engines, one behind and a half hoop in front of the driver which will serve as a bulkhead and to hold the steering wheel and instruments.
Front suspension is by very large fabricated wishbones, the lower arms pivoting on the chassis side members and the upper arms being pivoted on a tube which runs from the first “hoop” to the housing which locates the rack and pinion steering gear. A transverse leaf spring will be attached to the lower arms of the wishbones and will run through the chassis side members. Damping will be by large telescopic shock-absorber units, but in practice the suspension will be virtually solid. The front differential is a Ford commercial unit as modified for Allard de Dion axles which will drive universally-jointed half-shafts to special Allard-manufactured hubs. A Girling disc brake is mounted sideways behind the differential, a la B.R.M.
The rear suspension is simple to describe because there is none. The well-known Allard chassis mounting differential is bolted to the three central chassis tubes with inboard mounted 12 in. by 1¾ in. Lockheed drum brakes. Behind the differential is the housing for the quick-change spur gears to effect rapid alteration of the final-drive ratio. On each outer chassis member a housing has been fabricated which will hold the fully-floating hubs. The driver will sit just in front of the differential to the right, while on the left a petrol tank holding about three gallons of fuel will be fitted. To keep up air pressure a hand pump will be fitted for the driver to operate.
The engines will be mounted side by side, each one driving through a Ford V8 three-speed gearbox. The right-hand engine will use a gearbox with higher ratios in which the first gear ratio is the same as second gear on the standard left-hand box. These two gearboxes will each drive through short shafts to a housing which holds a series of sprockets. The final drive will then be taken by chain to the propeller shaft. A freewheel will be fitted between the front and rear propeller shafts, allowing the front-wheel drive to be overridden by the rear.
The use of two engines and gearboxes means the use of two clutch pedals and two gear levers with all its attendant problems, but Mr. Allard has evolved a cockpit drill which he hopes will prove satisfactory. The two gear levers will be mounted side by side to the left of the driver (two Ford Consul column levers used vertically) and on the starting line he will engage both gearboxes in first speed and as soon as possible after he has started he will change the left-hand box into second gear, which has the some ratio as first gear in the right-hand box. The propeller shaft has eight sprockets, each engine driving four chains to these sprockets. Thus when the gearboxes are in the same ratio the power from both engines will be transmitted to the wheels, but when one gearbox is in a higher ratio that engine will he doing most of the work, therefore Mr. Allard hopes to do most of the acceleration in the gears with equal ratios. His next change will be from second to top in the left-hand box and from first to second in the right-hand box. At maximum revs. in these gears the road speed should be about 120 m.p.h. and with the present tyre sizes of 6.00 by 16 at the front and 7.00 by 16 at the rear he calculates that the maximum speed should be 165 m.p.h. at 5,500 r.p.m. using the present 2.8 to 1 top gear ratio.
The car will stand only 2 ft. 6 in. high when completed and no bodywork will be fitted for the time being except for a nosepiece. When bodywork is eventually added the wheels will be exposed. He also hopes to obtain a set of American “slicker” tyres which are used on all the best “dragsters” in the States.
Mr. Allard is going to be a busy man during his runs but his car is certainly something different in the true sprint “special” tradition, and the public are obviously going to appreciate his efforts. We look forward to his first appearance at Brighton on September 5th. — M.L.T.
When a brand new car wins nine out of its first ten races, only losing the odd one because of a spin then it is time to take notice. Either we have a brilliant driver or a sensational car — or both!
The car in question is the Terrier 1,172 Formula Special driven by Brian Hart and designed by Len Terry, which has consistently beaten some very potent opposition. So one evening recently we went to see driver and designer at Brian’s home in Winchmore Hill where the car was built and is garaged.
Len Terry, the designer is no novice when it comes to automobile design having worked in the drawing offices of such firms as E.R.A., Aston Martin, Vauxhall and more recently Lotus. Brian Hart is a student at the de Havilland aircraft works at Hatfield and took up motor racing last season when he drove a Lotus 7 in 1,172 Formula races without a vast amount of success.
Driver and designer met only last Christmas at a 750 Motor Club function when Brian confessed his desire to build a special which would be capable of beating the powerful opposition he had encountered the previous season. The idea appealed to Len and they began work together to such effect that by March of this year the car was completed and ready for testing.
Since tuning is fairly restricted by the 1,172 Formula the obvious points to aim at were lightness and superior roadholding and to this end a space frame chassis was designed utilising 20 gauge mild steel tube and weighing only 54 lb. Stressed skin construction was dispensed with as the lower frame members were triangulated, thus allowing a lighter gauge undertray to be fitted. The only part that is stressed is the scuttle which is made of sheet steel. Front suspension is Lotus 7 with the lower wishbones reversed to ease braking stresses while at the rear a Nash Metropolitan axle is used. This is suspended on vertical coil spring/damper units and rigidly located by an unequal length “A” bracket which also serves as a Panhard rod and two channel section upper trailing arms — actually a piece of box section mild steel cut in half.
As far as the engine is concerned it has been tuned to the limit allowed by the Formula and in addition has been tilted 25 degrees to the offside and offset to the nearside so that the propeller shaft runs at seven degrees from the centre line of the car. Mr. Terry reckons this is about the maximum for offsetting the propeller shaft before power losses result. The cooling system of the Aquaplane cylinder head has been modified slightly to cope with the tilt of the engine but it has been perfectly reliable throughout the season. At the time of our visit the two S.U.s were about to be replaced by two even bigger S.U.s.
The bodywork was made by Len and Brian except for the nose cowling and is beautifully made although they readily admit that the flared rear wings are pinched from the original Lola while separate mudguards are used at the front to save expense. The cockpit is well upholstered in green with a pleasant wood rimmed steering wheel. The remote control gear lever falls nicely to hand and the high propeller shaft tunnel holds the driver firmly in position, With Dunlop R5 racing tyres the car has neutral steering characteristics which Brian finds most suitable for the relatively low power of the Ford engine.
The success of the car has aroused great interest amongst enthusiasts and many enquiries have been made regarding the availability of replicas of the Terrier. Although they originally had no intention of marketing the car a small company has been formed called “The Terrier Car and Engineering Co.” with premises at High Road, Thornwood, Essex, where kits of parts will be assembled for the enthusaist who wants to get into 1,172 racing, although the car could be made into a desirable road car as Brian Hart has proved over many miles of driving to and from race meetings.
A complete car can be made for around the £500 mark, according to the specification and judging from Brian Hart’s record this should give a competent driver a chance of getting among the awards. With Len Terry’s fertile brain on the design side there are bound to be improvements in the layout of the Terrier and if things go according to plan there may even be a Formula Junior car on the way. If it does as well as the 1,172 car the Italians may be in for a surprise. — M.L.T.