RM MK1...4

RM stands for ‘Racing Master’ and is the first family designed by Tamiya for road racing in which the chassis is completely made of FRP, which in turn stands for ‘Fiber Reinforced Polymers’. This material is constructed from fibres impregnated with an organic resin. The combination of resin and fibres combines the properties of the two substances, resulting in a structure that is characterised by excellent mechanical strength and lightness.
The RM family has undergone several evolutions:

Cam An Lola, article number 58021 released for sale in 1980 and available on the market until 1983. RM Mk1,
– Datsun 280ZX, article number 58022 released for sale in 1980 and available on the market until 1984. RM Mk2,
-Tornado, item number 58032 released for sale in 1982 and available on the market until 1984. RM Mk3,
-Ford C100, item number 58033released for sale in 1983 and available on the market until 1984. RM Mk4

The RM Mk1…4 represent Tamiya’s entry into the world of competition for rear 2-wheel drive cars, These are the technical characteristics of this family

– main chassis formed by one or more FRP plates,
– the motor is mounted at the rear,
– the battery (highlighted in red in the image) is mounted longitudinally in the central part of the chassis for Mk1 and MK2; the battery (highlighted in orange in the image) is mounted transversally in the rear central part of the chassis for Mk3 and Mk4,

– two-wheel drive with rear wheel drive,
– geared rear differential with alloy rear shaft,
– suspension-free steering system and
– a front bumper that is the only protection against frontal crashes.

From 1980 to 1984 Tamiya released the Mk1, Mk2, Mk3 and Mk4 chassis investing resources to become the reference for rear-wheel drive cars.
It is possible to divide this family into two groups: the Mk2 chassis is directly related to the Mk1 chassis and the Mk4 chassis is directly related to the Mk3 chassis.

Mk1 Lola Cam An
The Mk1 Cam An Lola chassis model 58021 is released in 1980, Tamiya uses the best available technology and also introduces several new features. The single FRP chassis is available as a spare part under part number SP5140 with the description “RM FRP chassis”.

To improve steering adjustment and control of the mechanical speed controller, all six joints are spherical and adjustable.

The front steering system is calibrated for toe-in; toe-in measures the angle each wheel forms with the longitudinal axis of the model.
Toe-in is closed (highlighted in red) if the wheels are pointing inwards from the direction of travel, toe-in is zero (highlighted in orange) if the wheels are parallel to the direction of travel and toe-in is open (highlighted in green) if the wheels are pointing outwards from the direction of travel.

The toe-in position can be adjusted simply by adjusting the ball joint highlighted in red. The solution for better balance of the car and optimum wear of the front wheels is for the toe-in to be closed, the solution for better traction and optimum wear of the rear wheels is for the toe-in to be zero.

A first for Tamiya, the front steering system is adjustable for camber angle; camber is the formed angle measured between the plane passing through the wheel centreline and the plane vertical to the road surface.
Wheels with positive camber (highlighted in red) offer a smaller footprint concentrated towards the outside of the wheel, neutral wheels (highlighted in orange) offer the largest footprint and wheels with negative camber (highlighted in green) offer a smaller footprint concentrated towards the inside of the wheel.

The camber position can be adjusted simply by adjusting the Allen screw and using the red arrow as a reference. The solution for this model is to have the front wheels with slightly negative camber in order to limit transverse displacement in straight driving.
With positive and negative camber, the elasticity of the foam rubber absorbs the roughness of the road surface by deforming, with the result that during deformation the entire footprint of the wheels is in contact with the road.

A first for Tamiya, the front steering system is adjustable for the Ackerman effect; you can adjust the correct steering angle to curve the model so that the front and rear axle shaft extensions do not intersect. When cornering, the steering angle of the inside wheel is greater than the steering angle of the outside wheel (situation highlighted with the wheels in red) or the steering angle of the inside wheel is less than the steering angle of the outside wheel (situation highlighted with the wheels in orange).

The position of the Ackerman angle can be calibrated simply by adjusting the position of the servo-saver axis using the red-orange arrow in the image as a reference: moving the servo-saver axis towards the front of the model accentuates the curvature angle of the inner wheel, and moving the servo-saver axis towards the rear of the model decreases the curvature angle of the inner wheel.
An inside wheel with a greater steering angle than the outside wheel results in predictable and progressive steering: the model follows the curvature angle precisely, without the four wheels pulling in different directions. An inside wheel with a smaller steering angle than the outside wheel results in less control when entering a bend, the turning radius will not be uniform.

The chassis is designed to allow optimal weight installation: the battery is located centrally along the longitudinal axis of the model, the receiver and servos are installed on the sides of the battery, and there are plastic bumpers at the front and rear. The chassis is made of FRP and is shaped in such a way as to ensure flexing while the model is in motion, flexing which absorbs the roughness of the terrain, partly replacing the lack of suspension.
It is possible to adjust the trim of the chassis via the two joints highlighted in red:

– if the model is under-steered in right-hand turns and over-steered in left-hand turns; tighten the Allen screw on the right-hand side and
– if the model is over steered in right-hand turns and under steered in left-hand turns; tighten the Allen screw on the left side.

The differential is newly developed and has metal gears. The differential is available as an accessory or spare part under the part number SP1147 with the description ‘RM differential gear set’.

The motor speed regulator is newly developed mechanically to better regulate the speed of the machine. The control lever and arm are adjustable: to find the zero point of the motor speed controller, you can choose between speed control precision or speed control acceleration. The mechanical speed controller is available as an accessory or spare part under the part number SP1148 with the description ‘RM speed control switch’.

The rear wing is adjustable to improve the model’s performance:

– the wing must be at a sufficient distance from the body to be able to act on the rear wheels; the further away from the model, the more effective it is,
– the wing must be at a correct height to be able to take in clean air and increase its effect without offering too much resistance; the wing is better affected by the airflow not fouled by the body the higher the wing is and
– the wing must have the correct inclination, if too inclined it loses its effect and only provides aerodynamic drag.

For the Mk1 Can Am Lola there are two more firsts for Tamiya: the Lexan body and 10 ball bearings (2 per left front wheel, 2 per right front wheel, 2 per rear axle of the drive system and 4 for the differential).
The motor is the RS540SD.
All these features make the Mk1 chassis perfect for high-level competition, but this over-engineering leads to a high cost.

Mk2 Datsun 280ZX
To meet the demand for less complex rear-wheel drive models, the Mk2-chassis Datsun 280ZX model 58022 was released at the same time. This model has the same basic features as the Cam An Lola model 58021 but with some modifications that make it less expensive:

– simpler bodywork and no adjustable rear wing,
– the engine is changed from the high-performance RS540SD to the RS540,
– the engine speed controller is the cheaper version developed from the one found on the F2 and F2 CS chassis (highlighted in blue), the shape of the Mk2’s control arm is redesigned (highlighted in red)

– there are no standard ten ball bearings and
– the rear gear is fixed and made of plastic; lighter than the metal differential, less performing and more prone to rapid wear.

– different arrangement of the receiver and the two servos, highlighted in red on the Mk2 model and in blue on the Mk1 model

All these parts can be bought later as accessories:

– accessory SP1136 RS540SD motor in the Black version,
– accessory SP1148 professional motor speed controller for RM Mk1-2 chassis,
– accessory SP1073 ball bearings front wheels,
– accessory SP1149 ball bearings for rear axle and differential

Mk2 retains all the chassis adjustments of the Mk1, but with a more competitive price that allows more people to approach this type of rear-wheel drive road model.

Mk3 Tornado
Tornado model 58031 Mk3 chassis was released in 1982 only two years after the first Mk1 model. The Racing Master family is a typical example of Tamiya’s market strategy. When Tamiya enters a market, it releases a very technologically advanced and over-engineered model that adopts the best available technology.
This strategy is also used a few years later when Tamiya enters the buggy world with the Hot Shot model number 58047, The Hot Shot adopts many highly advanced technical solutions, then is simplified by first releasing the Super Hot model number 58054 and then the Hot Shot II model number 58062.
For the Racing Master family, Tamiya behaves in the same way; the first chassis (model Mk1) is over-engineered at too high a cost, the following versions are first simplifications (model Mk2) and then true redesigns to reduce costs while maintaining or improving performance (model Mk3 and Mk4).
With the Mk3 model, Tamiya introduces a new chassis that is completely different from its predecessor. The Mk3 offers less adjustment, but is lighter than the Mk1, losing approximately 200 g.
The Mk3 chassis consists of two overlapping plates (highlighted in red and blue) while the Mk1 chassis consists of one piece (highlighted in orange).
The blue part houses the battery, receiver, On-Off switch and servo complete with mechanical speed controller. The layout of the parts is taken from previous models such as the Countach chassis, Countach CS, F1, F1 CS and Golf; a first for Tamiya, the plates of the Mk3 are both made of FRP, while in previous models the electronics carrier plate is made of metal.
The chassis in red guarantees the absorption of bumps by replacing the shock absorbers, which are absent.

The system that houses the motor and rear axle of the Mk3 model resume is simplified and lightened; on the left that of the Mk3 model and on the right that of the Mk1 model.
Tornado model number 58032 installs the RS540SD Black Sprint motor.

The front steering system on the Mk3 (left in the photo) is an evolution of the nylon one found on the F1 CS chassis (right in the photo).

The steering control servo is installed between the two front wheels, so the weight of the servo helps the front wheels to grip the road surface. This servo arrangement configuration echoes that of the 934, P34, Countach, Countach CS, F2 and F2 CS chassis.

The mechanical speed controller is developed for the Mk3 and Mk4 chassis, it is only used later on the Super Champ model number 58034.
The mechanical speed regulator is available as an accessory or spare part under part number SP5172 with the description “forward 3 step and reverse 1 step with braking circuit”.

Mk4 Ford C100
Tornado model 58031 chassis Mk4 is released in 1983 only a year after the Mk3 model and is a confirmation of Tamiya’s commercial strategy. The Mk4 model stands to the Mk3 model as the Mk2 model stands to the Mk1 model: the Ford C100 is modified to become the model for those who want to have fun without spending as much as is necessary for the Tornado, which is reserved for those who want to try their hand at track racing.
The Ford C100 has the same general characteristics as the Tornado model 58032 but with some modifications that make it less expensive:

– The body of the Ford C100 is made of styrene: it is richer in detail than that of the Tornado and weighs around 200 g more. Because of the body the Ford C100 is thought of as the Mk1 model and has lower performance than all previous RM chassis,
– the motor changes, it is no longer the high-performance RS540SD Black Sprint, it becomes the RS540,
– the electronics carrier plate of the Mk4 is modified to accommodate the service battery pack to power the servo and receiver. In the Mk3 the service power for the servos and receiver is taken directly from the primary battery to power the motor, no service battery pack is installed.
The main chassis (highlighted in red) is the same on the Mk3 and Mk4, the electronics chassis of the Mk3 (highlighted in blue) is more compact than that of the Mk4 (highlighted in orange).

Evolutions of the RM chassis
Tamiya evolved the RM Mk1…4 chassis into the RM Mk5…7 chassis. These last 3 chassis are essentially the same product decked out in 3 slightly different versions:

– FRP top and bottom plates connected by brackets that form a structure to house the battery and radio,
– the positioning of the servos and receiver is in the centre of the chassis,
– the motor is mounted at the rear and its weight added to that of the battery shifts the car’s centre of gravity towards the rear,
– two-wheel drive with rear-wheel drive,
– geared rear differential with alloy rear shaft,
– integrated steering system with left- and right-side independent suspension (a first),
– rear axle with suspension designed purely for road use and
– the front bumper.

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