Trials Technical Regulations 2018


These regulations apply to vehicles taking part in all trials. Modified vehicles taking part in events held wholly on private property need not be registered, taxed or be fitted with a speedometer..

All vehicles should be presented for scrutineering in a clean condition.

(a)    have a protective bulkhead of non-flammable material between the engine and the driver/passenger compartment capable of preventing the passage of fluid or flame in the case of fire. Gaps must be sealed with GRP or intumescent putty. Magnesium is prohibited for bulkheads
(b)    have a complete floor of adequate strength rigidly supported within the driver and passenger compartment. No gaps or holes should be visible.
(c)    have a minimum permitted wheelbase of 1270mm.

6.2. BODY (including aerodynamic fitments)
(a)    be fitted with bodywork that includes a crew compartment effectively isolated from the engine, batteries, gearbox, transmission shafts, brakes, road wheels, operating linkages and attachments, petrol tanks, oil tanks, water header tanks, brake reservoirs, catch tanks and radiators (and be fitted with doors or bodywork giving side protection to the driver and passenger). Be aware of the waistline requirement on side bodywork as described in section 6.3(a).

(b) have a bonnet or casing of metal or solid non-flammable material covering and surrounding the main engine structure that is secured by fasteners of adequate strength and have a positive locking action. All moving parts must be covered.

(c)    be fitted with bodywork of sufficient internal size to Sections 6. 2(e) and 6.3(a) below.
(d)    not have the space normally occupied by passengers encroached upon, but may have the passenger seats removed.
(e)    have bodywork providing a minimum transverse cockpit opening width of 810mm. This width may not be interrupted

(f). Be equipped on all wheels with mudguards which present no sharp edges and cover the complete wheel (flange+rim+tyre) around an arc of 120
degrees. This minimum coverage must:a) be achieved with a continuous surface of rigid material within which ventilation louvres may be fitted. The tyre must not be visible when viewed from above.b) extend forward ahead of the axle line.c) extend downward behind the wheel MS/UK reg 56.2.3

(a)    have a normal adequate seat within the driver/passenger compartment. The seat must be rigidly located within the compartment and for modified vehicles must not tilt, hinge or fold, it must retain the driver within the vehicle. The rear-most part of any seat must not be more than 380mm behind the rear wheel axis. The seat cushion (i.e. the part on which the occupant sits) when uncompressed, must not be less than 150mm below the top edge of the adjacent body side or door. Other seats fitted must similarly comply
(b)    If a single seat vehicle the maximum time for the driver to get out of the vehicle must not exceed five secondsc(  The vehicle occupant(s) seated in their normal position,wearing normal equipment,with seat belts fastened and steering wheel in place.must be able to evacuate the cockpit in of 7 seconds.MOTORSPORT UK  Reg (J)5.19.2.  

(d)All classes should have head restraints fitted to stop drivers and passengers heads going backwards on impact.

(a)    be equipped with a positive method of throttle linkage closing in the event of linkage failure by means of an additional external spring to each throttle spindle.
(b)    No trials vehicle may draw induction air from within the driver and passenger compartment. Air intakes must either be forward of the front bulkhead/windscreen or piped through to the rear of the vehicle to draw outside air from behind the rear bulkhead. The air pipe is to be of non-flammable or flame retardant and fuel resistant material and must be securely located.
(c)    The choice of size and make of engine is free in all trials classes.
(d)    Engines that produce excessive smoke may result in exclusion from further competition. This will be a decision based on fact, a observed by the scrutineer and Clerk of Course.

(a)    be fitted with sprung suspension between the wheels and the chassis unless originally manufactured otherwise. The choice of spring and damper supplier is free, in standard  vehicle trials (SVT), lifted springs may be fitted,  but they must use their original mounting points. Suspension and steering movement must be controlled to avoid fouling of wheels and tyres on chassis or bodywork.

(a)    be fitted with brakes that are operative and capable of stopping and holding the vehicle as required. A foot operated single pedal brake system should be used to achieve this.
(b)    independently operated front or rear brakes are permitted in modified class one and AVT class A trials vehicles to act as fiddle brakes. They are not permitted in modified class Two, AVT classes B. & C or SVT trials vehicles.
(c)    A separate hand brake system must be fitted to all vehicles.

(a)    have a full circumference full diameter steering wheel unless originally manufactured otherwise.
(b)    have steering movement controlled to avoid fouling of wheels and tyres on chassis or bodywork.
(c)    have steering lock assemblies removed on all modified trials vehicles.
(d)    SVT and AVT classes B, & C vehicles must have the steering wheel and the steered wheels directly connected by a mechanical link.
(e)    the fitment of  a power assisted steering system is permitted in all trials classes. Lock stops on front axles must be in place in SVT Class. In AVT and Modified classes they may be removed.
(f)    it is permitted to extend the steering drop arm in Modified class, however this is a component which is under tremendous stress whilst in use therefore it is essential to carry out this conversion to the best engineering standards.

6.8. WHEELS  
(Except in the case of vehicles originally manufactured without wheels.)
(a)    have not less than four road wheels and tyres (excluding the spare).
(b)   May be fitted with   TUV Approved hub adaptors /wheel spacers up to 30mm in depth. 
(c)    not be fitted with duplicated driving wheels unless originally manufactured otherwise or unless permitted by supplementary regulations. Reversing of standard un altered road wheels within the standard SVT classes is prohibited.

6.9. TYRES
(a)    be fitted with wheels and tyres that are compatible and also acceptable to the organiser. A particular type and size of tyre may be prohibited by the ASRs. The use of dumper style, open-centered or very aggressive tread pattern tyres is prohibited in SVT and AVT Classes C for all trials.  At certain venues (for example Military venues) dumper style, open-cantered or very aggressive tread pattern tyres is be prohibited for every vehicle regardless of class. Hand cutting of tyres is strictly forbidden in all classes apart from Modified
(b)    a spare wheel need not be carried.
(c)    Cross Country Vehicles may have more than four wheels and tyres.
(d)    all tyres used on any event must comply with the minimum DOT requirements on depth of tread.
(e)    the use of tyre chains and studded tyres by competitors is prohibited.
(f)    tyres should  be covered  by the mudguards or body work for the full width of the treaded area.(see reg 6.2f)and MS/UK Blue Book (P) page    ..  261  reg 56.2.3


(a)    any fluid lines, tubes or internally/externally metal braided hydraulic pressure hoses carrying coolants through the driver and passenger compartment must be enclosed in a solid metal cover and insulated and isolated to prevent the occupants of the vehicle touching the hot surfaces. Such lines or tubes or coverings must be painted red.
(b)    all open radiators, expansion bottles whether  front or rear mounted, must be covered in such a manner that nobody can burn themselves on the hot open/unprotected areas of the radiator.  Special attention should be made to protect occupants from hot water from an exploding radiator.

(a)    have the transmission outside the driver and passenger compartment, beneath the floor or secured in casings or covering of solid material.
(b)    be equipped with an operable reverse gear.
(c)    the use of limited slip, torque biasing, or locking differentials is permitted in Modified class 1,2 and AVT Classes A,B. Modified vehicles may have their diffs welded or pegged permanently locked. STV may only have diff locks or limited slip diffs if it was a production fitment for that particular vehicle.
(d)    vehicles may have traction from tracks only if the vehicle was originally manufactured in that manner.
(e)    vehicles with automatic transmissions must have a starter inhibiting switch allowing it to start in park and/or neutral only.

(a)    have any oil lines passing through the driver/passenger compartment protected, and if non-metallic enclosed in internally/ externally metal braided hydraulic pressure hose.
(b)    oil coolers, filters and cooling water expansion tanks must not be fitted in a position where, if burst, the hot fluid can come into contact with the occupants of the vehicle.

(a)    have any fuel lines passing through the driver/ passenger compartment protected, and if non-metallic or pressure lines, enclosed in internally/externally metal braided hydraulic pressure hose.
(b)    if fitted with fuel fillers in the boot, or under closure, have collector/ spill trays incorporated to enable spillage to drain outside the vehicle.
(c)    use normally available pump fuel. The use of fuel additives, octane boosters, or AVGAS (aviation fuel) is prohibited.
(d)    if using LPG, conform with the Construction and Use Regulations, and also the LPG Industry Technical Association Code of Practice No.11 and have a 75mm diameter 'day-glow' orange disc affixed immediately adjacent to the competition number on both sides.
(e)    have tank fillers and caps which do not protrude beyond the bodywork, nor are situated within the driver/passenger compartment. The caps must have an efficient locking action to reduce the risk of accidental opening during an accident and ensure closing after refuelling. Air vents(fuel tank breather pipe) must be at least 250mm to the rear of the cockpit. All fuel caps should be of the sealed type to prevent spillage.
(f)    It is strongly recommended that the fuel tank is covered  with an outer steel container which acts as a second line of defence in the event of a roll over.
(g)    Vehicles that have modified fuel systems which vent straight to atmosphere are required to have a one way valve that is manufactured for use in fuel systems fitted in the breather to stop fuel spillage.
(h) Spill Kit See MSA blue book section  (P)57.5.3.All vehicles to carry a small spill kit complying to J5.20.13(to soak up 1.25ltr of vehicle fluids and plastic bag to environmently dispose of it

(a)    have any batteries in driver/passenger compartment enclosed in a leak proof container and securely located. Such batteries must be duly protected to prevent leakage of acid and spillage onto the occupants of the vehicle in the event of a rollover.
(b)    have battery terminals which are protected from any metal contact which could result in a short circuit.
(c)    be equipped with battery,horn, generator and self-starter.
(d)    headlights on all  vehicles will be required in all night events.
(e)    have the battery earth lead, if not readily distinguishable, identified by a yellow marker.
(f)    be fitted with suppressors as required by the Wireless Telegraphy Regulations.
(g)    Modified vehicles and AVT vehicle must be equipped with a circuit breaker. This must isolate the battery from all electrical circuits and must cut the engine at the same time. The switch location is optional,  For modified vehicles the operation must be possible from both inside and outside the vehicle. The circuit breaker control(s) must be identified by a red spark on a white edged blue triangle. If a diesel engine is fitted with an electric stop it must be connected to the circuit breaker. If it is a pull cable stop system a second cable must be fitted next to the isolator switch and marked clearly “pull to stop engine” on a plate 75mm x 50mm white background with red lettering. Not necessary in SVT

(a)    All vehicles must be fitted front and rear with substantial tow points comprising of a tow ball or similar bolted in place with sufficient strength to with stand a snatch recovery of a vehicle when fully bogged down. Towpoints must be painted a contrasting colour.
(b)    be equipped with a nylon rope of a minimum 25mm diameter. This rope must have a closed loop at each end and be of at least 4.5 metres in length. The use of chain or wire bond is prohibited. Polypropylene or hemp ropes are not advisable. N.B. Marshals may use any equipment approved by the Clerk of the Course.
(c)    the use of a kinetic type rope is prohibited.

(a)    have the exhaust system isolated from the driver/passenger compartment (e.g. beneath the floor or secured in casings of solid material).
(b)    trials vehicles may have front mounted exhaust. Hot surfaces must be covered or shielded with suitable material.
(c)    have no part of the exhaust system protruding laterally beyond a plane through the outer track of the front and rear wheels, or to the rear of the bodywork more than 150 mm (5.9 in.).
(d)    if all enveloping body is fitted, have supplementary protection for exhaust systems that protrude outside the bodywork. 

(a)    in all AWDC events, conform to a maximum permitted noise level as laid down in the current MS/UK ‘Blue book’. The current requirement as listed in the MS/UK blue book is a Max of 100dB at 0.5m with the engine at 2/3 maximum revs.  Continuous noise testing will take place during events and competitors will be advised of excessive noise. WARNING: Temporary silencers, bypass pipes and the inclusion of temporary parts to achieve silencing requirements are prohibited. Officials may refuse to carry out noise checks on vehicles utilising temporary parts in exhaust systems. Please refer to section E of the current MSA Yearbook. Measurements to be taken at 4500 rpm max  (or two thirds throttle opening if no tachometer fitted or diesel engine) with engine at normal working temperature.

(a)    If fitted, to have windscreens of either laminated glass or plastic, of a minimum thickness of 4mm (except STV or where the standard equipment is used). plastic sidescreens, where fitted, should also have a minimum thickness of 4mm unless fitted otherwise by the original manufacturer.
(b)    The use of mesh or net hinged sidescreens on open vehicles to retain the limbs of driver and passenger in the event of a roll-over is advised. The use of a sun roof with glass is not permitted in Modified vehicles it has to be replaced with a metal panel.

Aluminium alloy roll over bars and roll cages are banned in all forms of motorsport where a roll cage is required to be fitted. The use of  roll cages is strongly advised for all events.

(a) General Considerations
i.    The basic purpose of the roll over bar is to protect the driver/passenger if the vehicle turns over or is involved in a serious accident. This purpose should not be forgotten, and in consideration of this, all roll bars and roll cages should be built to the following MOTORSPORT UK specification detailed in Section (K) or (P) an approved Cross Country Vehicle and Four Wheel Drive design which should in any case incorporate many of the provisions detailed therein.
ii.    The roll over bar/cage must be designed to withstand compression forces resulting from the weight of the vehicle coming down on the roll bar/cage structure, and to take fore and aft loads resulting from the vehicle skidding along the ground on its roll structure.
iii.    Modified classes  Full roll cages as per drawing MOTORSPORT UK Blue Book section (K) page 178 Drawing No 5 or 6 (min spec)  are mandatory . 

iv.    The minimum in the AVT classes is a screen or roof frame which extends past the height of driver and passenger and fitted by the manufacturer, it is recommended to fit a central roll hoop with rear bracing bars and central diagonal for any open topped vehicle competing in the AVT classes MS/UK Blue Book section (K) page 179 as illustration 1   this is not mandatory only advisable.

(b) Fabrication
i.    The main hoops and rear braces must connect direct to the chassis by either welding or bolting. One continuous length of tubing must be used for the hoop member with smooth continuous bends and no evidence of crimping or wall failureMain, Front and Lateral Rollbars. These frames or hoops must be made in one piece without joints.Their construction must be smooth and even, without ripples or cracks. The vertical part of the main rollbar must be as straight as possible and as close as possible to the interior contour of the bodyshell. The front leg of the front rollbar or a lateral rollbar must be straight, or if it is not possible, must follow the windscreen pillars and have only one bend unless a windscreen pillar reinforcement (K) page 160  [1.3.5(e)] drawing No 62 page 195 is fitted.The mounting foot must not be rearward of the foremost point of the rollbar.Where the main rollbar forms the rear legs of a lateral rollbar (see drawing K6), the connection to the lateral rollbar must be at roof level. To achieve an efficient mounting to the bodyshell, the original interior trim maybe modified around the safety cage and its mountingsby cutting it away or by distortion. However, this modification does not permit the removal of the complete parts of upholstery or trim. Where necessary,the fusebox may be relocated to enable a rollcage to be fitted.MSA Reg (K) 1.3.1 page 158
ii.    All welding must be of the highest quality with full penetration. Wherever possible gas shielded arc welding should be used.
iii.    For space frame vehicles it is important that the roll bar structure is attached in such a way as to spread the load over a wide area. The roll bar should be designed as an extension of the frame.
iv.    For monocoque chassis, consideration should be given to using a 360 degree hoop completely around the inside of the vehicle, thus substituting for a frame.
v.    Braces should be of the same size tubing as used for the main structure, their fixing should be located as near as possible to the (top of the roll bar, in any case at a minimum of three quarters of the height of the roll bar.
vi.    The mounting plates of the roll bar braces to the chassis must be of steel plate of minimum thickness 3mm, welded, riveted or bolted onto the chassis. The total surface area of each plate should be not less than 120sq cm of which at least one third connects with a chassis vertical member. The chassis outrigger to carry the roll bar mounting must be a minimum of 75mm x 50mm x 3mm box section.
vii.    The mounting of the main roll bar hoop(s) must be secured with at least three steel bolts and nuts (hexagonal headed bolts of minimum diameter 8 mm [0.315 in.]), or by at least three high tensile Allen head cap screws and nuts of at least 8 mm diameter. The attachment plate to the roll bar braces must be of the same thickness as the wall of the tube. When the roll bar rests on a box member of the latter, it must be locally reinforced by a structure constituted of either welded bolt heads or welded tubing ends.
viii.    Removable connections used in roll bar design should conform to the recommendations within the MS/UK blue book.
ix.    Bolts and nuts used should be of highest quality steel (preferably aircraft standards) and be of sufficient minimum diameter according to the number used. Square head bolts and nuts are prohibited.
(c) Closed Vehicles
As a general rule, the safety roll over bar structure must be made of two hoops, one behind the front seats and the other following the windscreen pillars (Refer to current MS/UK yearbook for full details of all drawings). The structure must be constructed in such a way as not to obstruct access to the front seats and not encroach upon the driver/passenger space. It may encroach upon the rear passenger space and pass through the rear upholstery. The main hoops must be placed as near as possible to the roof. It is permissible to mount a longitudinal support at door level providing it forms part of the structure and is of similar tube dimensions. It may be welded in or located with approved couplings, it must not be higher than one third of the door height above the sill and angled at more than 5 degrees with the horizontal.
(d) Open Vehicles
To the same specifications as Closed Vehicles, except the main hoop must be symmetrical about the longitudinal centre line of the car and complying with current MOTORSPORT UK drawings.
(e) Other Considerations
i.    An effective rollover bar must be fitted of a height no less than 50mm at its top edge above the helmet of the normally seated driver. It must be wider than the driver’s shoulders at that height. It must be constructed of steel tubing (for specification see section (g) materials. It should have a hole of 6mm drilled in the underside for checking the tube thickness. It should have the top bar straight or curved, but not tubes meeting in an inverted ‘V’. It must be effectively braced to a structural member.
ii.    Closed vehicles the main roll over bar hoop must be placed as near to the roof as possible.
iii.    Non-standard vehicles are advised to fit a safety roll over bar to the following minimum requirements: minimum height 710mm from the rear of the uncompressed seat cushion, of minimum flat width 380mm running into radius corners and affording driver and passenger equal protection. It must be mounted to a structural member with front mountings not less than the cockpit width and braced rearward.
(f) Diagonal Struts
These should be fitted such that the upper forward joint is on the driver’s side of the vehicle to add further support in the area of the driver’s head.

(g) Materials
(All dimensions represent minimum requirements.)
Tube Specification: Cold drawn seamless carbon steel or medium weight blue band, For full material spec see  MS/UK Blue Book  section (K) page 160 reg 1.4.1 to 1.4.3 and section (P) page 263 reg 57.1 to 57.1.2  

In all groups recognized manufacturers may utilize a roll over bar of free conception as regards material and tube thickness providing it is able to withstand three simultaneously applied loads:1.5 w lateral 5.5 w fore and aft 7.5 w vertical w = weight of vehicle plus 75 kg. Roll over bars of this type must be supported by a duly signed and completed Safety Roll Bar Certificate. The roll bar manufacturer must be registered with the MS/UK Ltd. Titanium is prohibited.
(h) Roof
All vehicles in AVT and Modified classes should be fitted with a roof panel unless the driver chooses to use a MS UK approved helmet. Specification for a roof is:
A panel which is sufficiently strong enough to protect the occupants in the event of a rollover, the panel must cover both occupants adequately.
An MS/UK scrutineer has the final decision as to what is sufficient.  When fitted to the rollcage it should not be riveted into the tubing.

Overalls are not compulsory but advisable. Oil soaked clothing should not be worn whilst competing.

Crash helmets in Modified classes are to be used if a solid roof is not fitted. A helmet is compulsory in timed trials and team recovery competitions.

The helmet must conform to the current MS UK regulations listed in the ‘Blue Book’ [K(10.3.1].  Snell SA2010,to SA2015 these are the  most common standards for motor sports crash helmets. The full list is in the MS/UK Blue Book, do not accept any other.
Helmets should have an MS/UK compliance sticker affixed to the right hand side by an MS/UK National  scrutineer.
Please protect your helmet from external damage by using a helmet bag or similar, chips within the outer laminate of the helmet may make it unsafe and unusable. For Timed Trials, Team Recoveries  all Competitors must wear approved Crash Helmets (K.10) clothing which covers the arms, legs and torso up to the neck, and unless a windscreen to fitted goggles or visors to protect the eyes.

All Safety Belts must be made out of approved materials and anchored securely in the vehicle. No modification may be made to the seat belt or seat buckles, unless it is carried out by the belt manufacturer. The minimum requirement for SVT trials are one diagonal shoulder strap and one abdominal strap, with fixing points on the body or chassis of the vehicle on either side and to the rear of the driver’s seat. The seat integral safety belt design of the Range Rover is acceptable.
AVT class that don’t use the original manufactured mounting points and seat belts must have a harness of 4 or more point mounting fitted, with each belt strap mounted to a separate anchorage point.

Modified vehicles must have a harness of 4 or more point mounting, each belt strap must be mounted to a separate anchorage point  .It is compulsory for all occupants to wear seat belts while competing. The only exceptions to this rule are HGV vehicles competing in Heavy Vehicle trials and any vehicle competing in a SVT that is not legally required to have seat belts fitted.

Products permitted for use within AWDC events are listed in section [(P 58.1.2) also see (K 3.1.2) page164 and list  Table 3 page 176 of the current MS/UK Yearbook. All vehicles must have a handheld extinguisher in the driver/passenger compartment, The minimum requirement for this is as follows:  AFFF (manufactured to a standard of 34b) minimum Capacity 2.4 litres (from 2022)  ,2019 to 2022 1.74 Ltr, Zero 2000 Minimum capacity 2.4 litres, ViRO3 Minimum capacity 2kg, Dry Powder 2 kg. Fire Extinguishers must be serviced every 2 years.

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