A modern trials special

A description of T. C. “Cuth” Harrison’s Harford

The “mud-plug” type of trial has suffered a rather chequered career since the end of World War II when it first became popular. At first, production cars were used, quickly followed by “specials” fitted with large capacity American engines. In the 1949 and 1950 seasons the Ford Ten-engined special showed a definite superiority and its use in this type of trial and indeed in many other competition spheres has become almost universal.

One of the most rabid enthusiasts for trials is the current R.A.C.trials champion, T. C. “Cuth” Harrison. His career has been almost as varied as that of the late Ken Wharton, embracing all types of racing and rallying, from Grand Prix racing in E.R.A.s to a Coupe des Alpes in the Alpine Rally. But  “Cuth” thinks that more skill is needed to pilot a trials car to the top of a muddy hill than in any other form of motoring competition. Given enough money anyone can overcome the problems of a racing car but the R.A.C. trials formula is framed in such a way that money cannot buy success. This is “Cuth’s” reason why one or two drivers and cars are not on top all the time. For example Eric Jackson had a good season in 1958 but on the day of the Trials Championship he could do nothing right in spite of the car being exactly the same as on the occasions of his previous successes. If the driver is off form the car cannot help him.

To find out what constitutes a good trials car W.B. journeyed to Sheffield where Mr. Harrison is the main Ford dealer. He has built several trials specials of his own design, usually known as Harfords.  These have mainly used Ford components but one did use a majority of Morris Minor components. This was a particularly roadworthy car doing well in hill-climbs and sprints as well as in its normal duties of mud-plugging. This car was capable of over 75 m.p.h.and “Cuth” scoffs at the idea that trials cars are unsafe on the road.

The R.A.C. trials formula is fairly simple, the main idea being to stop competitors putting too much weight on the back wheels. Maiin points of the formula are as follows : Four-wheel drive, twin driving wheels and chains are not permitted; tyres must be of a type listed by the R.A.C. (which excludes Grip tyres); the engine shall be so located that the centre of the foremost sparking plug orifice is not more than one-fifth of the actual wheelbase aft of a line connecting the centre of the front wheel hubs; tyre sizes and minimum wheelbase are laid down according to engine.size; overhang at the rear shall not exceed one-third of the wheelbase.

“Cuth’s” present car is based mainly on a Cannon chassis because he just does not have time to devote to special building these days and anyway it’s cheaper!  The chassis is based on two large diameter tubes with a network of smaller tubes for bodywork support. A Ford front axle beam is utilised but it is mated to Austin Seven brakes and wire wheels! The axle beam has been flattened  so that the centre piece does not dig into any mud or rocks which may be in the centre of the hill. The axle is located by shortened versions of the normal Ford radius arms. Brakes are not needed much on a trials car so the use of Austin brakes is an opportunity to get rid of some weight at the front. The transverse spring is also of Ford manufacture. A novel feature to a casual observer is the single, vertically mounted Woodhead  telescopic damper in the centre of the axle beam. “Cuth’s” reason for using this is to allow more vertical movement for the wheels so that they lift easier when tree stumps or rocks are encountered. But, as he says, ” those with two shock-absorbers do just as well as me.”

The power unit is naturally the faithful Ford Ten engine, which surprisingly has had very little tuning attention. “Cuth” feels that many people go in for too much tuning so sacrificing the bottom end torque which is so necessary for trickling round tight corners. His car is fitted with an Aquaplane manifold, twin S.U. carburetters and a four-branch exhaust manifold. The cylinder head is perfectly standard. No dynamo is fitted but two 12-volt batteries are situated in the rear of the car to put more weight on the rear wheels.

A shortened version of the Ford radiator is used by most competitors, and since any car would boil in the conditions of a slow climb of a trials hill not a great deal of attention is paid to cooling. Most trials enthusiasts will have seen the hot-water bottle with which many competitors replenish their radiators.

The normal Ford steering is retained by Mr. Harrison as precise steering is not the main requisite of a trials car. The only instrument in the car is a revolution counter which is driven from an Aquaplane timing chest cover which replaces the standard timing cover. The drive is taken from the camshaft. To comply with the law the rev.-counter is marked off in miles per hour.

The rear axle is taken from an Austin Eight. purely for obtaining a rear axle ratio of 5.4 to 1 which is used in conjunction with the normal Ford bottom gear ratio of 18.72 to 1. Springing medium for the axle is supplied by two vertical coil springs near the ends of the axle. Two inclined Woodhead shock-absorbers are mounted in between these coil springs. Theoretically the inclination of the dampers should help sideways location but, as “Cuth” says, people with vertical dampers do just as well. A short Panhard rod is mounted on the left of the chassis and is coupled to a bracket on the differential casing. Wide base Austin wheels are used at the rear and tyres are always bolted on as with pressures of only 3 or 4 lb. they would quickly leave the rims.

Although a wide choice of tyre is available nearly all competitors use the Goodyear Allweather (which means it will probably be banned !). This tyre has fairly large lugs which give a certain amount of grip in muddy conditions. The petrol tank is taken from a Ford 5-cwt. van and has a capacity of about 3-1/2- gallons. The specification of the latest Harford is completed by an outside handbrake which operates on the rear wheels and is mainly used for stopping the car from sliding back down hills. Front brakes are rarely used as they hamper steering on muddy sections.

Thus it can be seen that for a not-too-large bag of gold one can purchase or build an interesting trials and driving test special which offers a great deal of fun for a small layout. In the words of “Cuth” Harrison  “Trials require a great amount of skill and offer at the same time a day out in the open doing something I like.”—M. L. T.