Sporting Trials Car Formula Regulations 2017

The National Trials Car Formula involves four wheel vehicles complying with all (MSA Blue Book) Technical Regulations except J.5.2.2, J.5.2.3, J.5.2.4, J.5.2.6, J.5.20.4, J.5.20.6, J.5.20.7, J.5.20.8, J.5.20.9, 9.1 and 9.8 and Period Vehicle Waivers. Vehicles can be divided into two classes, up to 850cc and over 850cc up to 1650cc.

Safety Criteria K.8 is mandatory. An electrical cut-out switch must be located on the off side rear of the car and be rearward facing.

It is strongly recommended that all competing vehicles have a roll bar fitted to the following specification:
It should be constructed from steel tube of 38mm. diameter with a wall thickness of 3mm. with forward facing angle supports. The minimum height of the roll bar should be 68.6 cm.(27”). This to be the vertical measurement from the upper surface of the uncompressed seat cushion.

Should an effective roll bar not be fitted then the car must have:
(A) The spare wheel securely mounted at the base and by at least one bolt (minimum M12 HIGH TENSILE STEEL, marked 8.8 by the manufacturer) through the centre flange to the chassis, with a minimum of 5 threads engaged in the nut.

(B) The upper most part of the rim must have a minimum vertical height of 68.6cm. (27”) measured from the uppermost surface of the uncompressed seat cushion.

(C) The roll bar or spare wheel must be able to support the vehicle in the event of the vehicle turning over.

Chassis construction is free, but permitted wheelbase and width dimensions are shown in the drawing below.
Vehicle engines must be located with the centre of the foremost original manufacturer’s sparking plug orifice not more than one-fifth of the wheelbase behind the centre line of the front wheel hubs where the only operative water radiator is mounted in front of the engine, or one-eighth if no radiator is fitted in front of the engine (tolerance 1cm).

The bodywork must be of adequate strength and proper construction to provide a compartment for Driver and Passenger. It must meet the following criteria:

The front and rear overhangs must be as specified in the drawing below.

It must be equipped with fixed seats for a Driver and one adult Passenger, and have seat backs not less than 30.5cm measured from the uncompressed base seat cushions along the angle of the seat back.

The rearmost portion of the seats (without cushions) at this 30.5cm height must not be behind a line through the vertical axis of the rear hubs.

All Passenger handles must be of rigid construction, securely anchored and neither flexible nor adjustable.

No handle must be capable of touching the ground in the event of a rollover and all handles must be sited so that in the event of the car hitting a solid object, handles are protected from contact with the object by the chassis.

Any handle forward of the centre line of the rear axle must be fixed in accordance to dimension E as detailed in the drawing below.

Rear mudguards must be of adequate strength to protect Driver and Passenger from wheels and tyres.

Rear mudguards must cover the full length of the tyre in plan view at the top of the wheel and must extend outwards to within 5cm of the outside edge of the tyre wall.

Front mudguards must cover the full width of the tyre over an arc of 90° and extend rearward to not more than 10° above the horizontal line through the front hub.

Vehicles must use a single four-stroke production car engine not exceeding 1650cc
Must have the cylinder block and cylinder head originating from a series production engine of the same manufacture.
Must have the camshaft and valves in the original manufactured position.
No forced induction.
Must have an effective silencer fitted to the exhaust system.
Vehicles can have a starter motor mounted on either engine block or clutch cover.

Vehicles must be equipped with a differential gear which divides torque equally between the driving wheels.
Vehicles should not use any locked or lockable torque biasing or limited slip differentials, or any other automatic device which is designed to achieve the same result.
Any clutch/torque converter attached to the engine flywheel must be bolted directly to the engine crankshaft.

Any form of suspension can be used. For minimum track front and rear details, see drawing below.

Any form of connection from steering wheel to the front wheels is permitted.
The position of the two swivel axes must not vary whilst steering.
Four-wheel steering is not permitted.

Vehicles must be fitted with operative and effective front and rear brakes.

Independent rear braking is permitted, but no self-compensating controls are permitted on the rear brakes, which must be single leading-shoe drum brakes or disc brakes.

Wheels and Tyres
Wheel rims must not exceed a width of 11.43cm (4.5in) measured between the bead flanges, nor a diameter of 15in for driven wheels.
Tyre security devices are permitted in the rims.
Wheels should not carry any chains, spikes or non-skid attachments.
Tyres must be of a maximum size 165×15 on driving wheels and must be selected from:


Vehicles must carry one spare only, which must be a driving wheel as fitted on the car, fitted with any listed tyre. It is not permitted to add ballast to the spare wheel.
Motorcycle tyres on non-driving wheels are permitted.
Minimum tyre pressure 2psi.


All measurements must be in accordance with these regulations when the car is unladen on a level horizontal surface.
untitled - 333_346_Specific_Regulations_for_Trials_(T)Championship Scoring

1st………….12 pts

2nd…………11 pts

3rd………….10 pts

4th…………..9  pts

5th…………..8 pts

6th…………..7 pts

7th…………..6 pts

8th…………..5 pts

9th…………..4 pts

10th…………3 pts

All other Drivers receive 1pt. for starting the event and 1pt. for finishing the event.

The C. of C. ; Secretary of the Meeting and Club Steward shall receive 12 pts. for one event only providing they are named as such on the Supplementary Regulations for that event.

NOTE:-  Only the nine best results will count for the Championship.