Historic Sporting Trials Association









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The popularity of home built specials in trials post 1946 and the extreme nature of some of the cars being built led to the introduction of what became the National Trials Formula. The NTF restricted the wheelbase and engine position, a home built car using a V Twin J.A.P engine mounted rear of the back axle was the main reason that engine position was specified. Knobbly tyres were also banned and an 18" crossply rear tyre was specified, these were specially remoulded and called 'Mudpluggers'. The shortage of suitable worn tyres for remoulding led to the change to 15" radial rear tyres in the 1971 NTF.

Explanation of HSTA Classes:

The primary aim of the HSTA is to recreate period sporting trials for sporting trials cars constructed in accordance with the National Trials Formula between 1953 and the end of 1970 (trials where fiddle brakes are used, not classic trials, not PCTs or car trials).

The Formula defines the specification of the majority of the cars as they ran in the period. Many historic cars have subsequently been developed to compete in other branches of motor sport such as classic trials with the result they no longer meet the requirements of the period NTF. Similar situations have occurred in all forms of historic motor sport and owners have changed their cars back to their original format in order that the car is eligible to compete in current historic events. The HSTA would seek to encourage owners of historic sporting trials cars to restore them to meet the requirement of the proposed Historic Sporting Trials Formula.

All the trials will be run with sections laid out for Historic cars, although the Post Historic cars will generally use the same sections and may have to use higher tyre pressures they are not in any way competing against the Historic cars!

Sporting trials cars constructed in accordance with the National Trials Formula between 1953 and the end of 1970.

These cars generally used 18 " rear wheels with cross ply tyres to a maximum width of 5 " The RAC approved 'Mudplugger' was introduced as a control tyre.

Engines used were: Ford 1172 side valve, BMC A Series to 950cc, Austin 7 and Reliant. Although Ford pre crossflows, crossflows, larger BMC A Series and Hillman Imp engines were available during this time they were generally not used in Sporting Trials cars.

Front axles were generally from Ford Y type/1172 side valve or Austin 7 with transverse leaf spring.


Sporting trials cars constructed in accordance with the National Trials Formula up to 1974.

The principle change made in the 1971 NTF related to the rear wheels and tyre specification Cars were now required to use 15 " rear wheels with radial tyres to a maximum width of 165. If a pre-1970 car, which originally used 18 " rear wheels, was to continue to be eligible to compete in sporting trials the wheels had to be changed to 15 ".

Examples of engines that were starting to be used were: Ford pre-crossflow and crossflow, the larger BMC engines such as 1098 and 1275, Imp and it derivatives, Renault 16,

Front axles had now changed to beam axles with coil over dampers and rack and pinion steering.

Use of Electronic Engine Management or fuel injection is not allowed, neither are motorcycle carburretors

Cars must be 'in the spirit' of the period 1971 to 74

Here is an informative article from 1964 explaining Sporting Trials

reproduced with the kind permission of AUTOSPORT

reproduced with the kind permission of AUTOSPORT

Period clothing is encouraged, here are some styling tips!

reproduced with the kind permission of AUTOSPORT


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