Sporting Trials Car Construction Regulations


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.
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750 Motor Club Sporting Trials Championship – Regulations


(1)        Only fully paid up members of the 750 Motor Club are eligible for this championship.  Competitors will not be required to register for this championship. Production of a valid 750 Motor Club membership card when entering an event in this championship will automatically entitle the competitor to score points.


(2)        All sporting car trials organized by the 750 Motor Club and listed on the 750 sporting trials calendar or published in the 750 Motor Club bulletin prior to January 1st of the current year will be eligible for inclusion in the current years championship.  Inclusion of any trial in the championship is subject to approval by the Sporting Trials Committee.


(3)        The Championship will run from the 1st of January to the 31st December annually and consist of 15 rounds, of which the best nine results will count for the championship. The winner will be the driver with the most points scored from nine events.


(4)        Points will be awarded as follows

15 points for finishing 1st

14 points for finishing 2nd

13 points for finishing 3rd

12 points for finishing 4th and decreasing by 1 point for each subsequent position down to 3 points for finishing 13th

All the remaining finishers receive 2 points

Starters of the event will receive 1 point

The points scored from the best nine events will count towards the championship


(5)        All cars must comply with either the National Trials Car Formula as set out in the Motorsport UK Year Book, or the 750 Motor Club Sporting Trials car formula, further details being available from 750 Motor Club headquarters or the Sporting Trials committee.


(6)        All competitors will be graded into one of three classes based upon their event results of the previous season’s Championship events.


Class A           Experts


Class B           Semi-Experts


Class C           Novice Drivers who have not entered at least ten events. If the drivers tenth event is part way though a season, he/she will complete the season in Class C


Driver classification will be confirmed at the start of each season. Drivers in B.T.R.D.A. Red or Blue classes will be classed as Class A, while BTRDA Rookie class Drivers will be in the B class on all 750 Championship events.
The Committee reserves the right to change the class of a driver at their discretion based on their knowledge of a driver’s experience.


(7) Any driver irrespective of class may become overall champion.


(8) Awards:

Best overall     Championship Trophy

1st Class A     Everyman Shield

1st Class B     Bill Butler Shield

1st Class C     Novice Cup


No competitor may win more than one award. The driver who is second to the overall winner will take the class award. All the above awards to be returned to the trials committee by the December of each year.


(9)        Registered contenders, who act as Clerk of Course or Secretary of Meeting will receive twenty points for the maximum of one trial only. His or her name must appear in the supplementary regulations for the event.


Please note, per Blue Book G.1.3 named officials are not allowed to compete on an event.


(10)      In the event of a tie at the end of the season’s championship events, the winner shall be the contender with the greater number of wins. If there is still a tie then the greater number of 2nd places shall be counted and so on until a winner is confirmed.


(11)      All cars competing in the Championship must display 750 Motor Club and relevant sponsors stickers on both sides of the car.


(12)      Club membership cards WILL be checked at each event


(13)      Any car not complying with either the National Trials Car Formula or the 750 Motor Club Sporting Trials Car Formula may be excluded from the event and the Championship. The Board of the 750 Motor Club reserves the right to withhold eligibility of any car, which it considers an attempt to go against the 750 Motor Club regulations, and points gained by the driver of such a vehicle will be forfeit


(14)      The interpretation and arbitration of the rules of the Championship is the prerogative of the 750 Motor Club Board, its decision is final


(15)      There is a 3 second allowance for the competitor to regain forward motion, the marshal to count, “and 1 and 2 and 3.” However, should a competitor’s engine stall on a section these counts as a stop with no time allowance? The exception to this is should the engine stall whilst the car is going downhill, and the driver can continue forward motion and restart the engine there is no penalty


(16)      TYRES:-Any tyre on the Sporting Car Trials tyre list(List 3) in the current Motorsport UK Year Book is acceptable for this championship.