RM MK5...7

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; first the four Mk1..4 models were developed closely related to each other, then these Mk5…7 models were developed:

Porsche 956 Rothmans, article number 58042 released to sale in 1984 and available on the market until 1992. RM Mk5
– Toyota Toms 84C, article number 58049 released to sale in 1985 and available on the market until 1992. RM Mk6
– Porsche 956 Newman, item number 58052 released to sale in 1985 and available on the market until 1986. RM Mk7

For the Porsche 956 body there are three sets of accessory sticker set number 5222:

Porsche 956 Canon
Porsche 956 ISEKI
Porsche Newman released for sale as complete model number 58052

The RM Mk5…7 represent a step change in the RM chassis series; they are very popular because they are easy to assemble and have few components. Many sets have been lost over time because they are relatively inexpensive and represent a basic model with which many people begin to approach the world of radio-controlled models.
These are the specifications of this family:

– FRP upper and lower plates connected by supports 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. This rear imbalance makes the car understeer,
– two-wheel drive with rear-wheel drive,
– geared rear differential with alloy rear shaft,
– integrated steering system with independent suspension on the left and right side (a first), The front suspension system is a very short spring; with this solution, ease of calibration and lightness is preferred to efficiency in absorbing bumps and
– rear axle with suspension designed purely for road use. The rear suspension system is designed to absorb bumps with a spring that changed according to the model; but the main task of damping bumps is borne by the FRP lower frame
–┬áthe front bumper is the only protection against frontal crashes; but it is small and in the event of a frontal crash it is highly likely that the front suspension will break and/or the energy of the impact is absorbed by the body, which deforms or breaks.

The main difference between the MR Mk5…7 Porsche 956 Rothmans, Toyota Toms 84C and Porsche 956 Newman chassis models is in the shape of the body; the body is lexan for all three models, but the Porsche 956 Rothmans and Newman have different body to the Toyota Toms 84C. The Porsche 956 Rothmans and Newman have a fixed rear wing, while the Toyota Toms 84C has an adjustable rear wing attached to the body supports.
Pictured from left to right are the Porsche 956 Rothmans, Toyota 84C Toms and Porsche 956 Newman. Starting at the front and moving towards the rear of the chassis, these are the differences for:

Front mounts
Porsche 956 Rothmans has 2 alloy front supports, highlighted in blue.
Porsche 956 Newman and Toyota Toms 84C have 2 plastic front supports, highlighted in red.

Front suspension
Porsche 956 Rothmans and Toyota Toms 84C have conical springs in the front suspension.
Porsche 956 Newman has cylindrical springs in the front suspension.

Mounting screws that fasten the two FRP frames together
Porsche 956 Rothmans has two black rear hexagonal screws for the uprights.
Toyota Toms 84C and Porsche 956 Newman have four screws for the uprights.

Rear shock absorber spring
Porsche 956 Rothmans has a long rear shock absorber spring.
Porsche 956 Newman and Toyota Toms 84C have a shot rear shock absorber spring.

Pillars
Porsche 956 Rothmans have two aluminium pillars, highlighted in blue
Porsche 956 Newman and Toyota Toms 84C have four plastic pillars, highlighted in red.

Carbon Fibre Bottom Plate Holes
Porsche 956 Rothmans have four large holes in the carbon fibre bottom plate, highlighted in blue.
Toyota Toms 84C and Porsche 956 Newman have four small holes in the carbon fibre bottom plate, highlighted in red.
The holes have different shapes between the two plates.

Rear plate
Porsche 956 Rothmans has an FRP rear plate and two black hexagonal screws.
Porsche 956 Newman and Toyota Toms 84C have an aluminium alloy back plate and are secured with two Allen-headed threaded pins + nut.

Rear body supports
Porsche 956 Rothmans and Porsche 956 Newmans have black plastic rear supports. The black supports are cylindrical, highlighted in blue.
Toyota Toms 84C has white rear supports. The white supports have a special shape to fix the body and the rear wing, highlighted in red.

Motor
Porsche 956 Rothmans have black 540 motor and black rear shaft.
Toyota Toms 84C and Porsche 956 Newman have grey 540 motor and metal-coloured rear shaft.

Evolutions of the RM chassis
Tamiya has evolved the RM Mk5…7 chassis into the RM01 chassis, which went on sale in 2011 and again features the same body, the improvements being
– a single re-engineered FRP bottom plate
– resin gearbox
– ball differential
– 380 motor; to improve performance, the model manual shows how to install the 540 motor, an accessory to be bought separately

There is a special version marked RM01x with reinforced aluminium and carbon parts, designed to enhance the racing characteristics of the frame, released in 2013.
Three models have the RM01 chassis:
– Toyota Toms 84C, article number 58509, put on sale since 2011 and available on the market until 2019.
– Porsche 956 Newman Joest racing Porsche, article number 58521 put on sale since 2012 and available on the market until 2018.
– Mazda 787B No. 18 24 Hours of Le Mans 1991, article number 58555 put on sale since 2012 and available on the market until 2018.

The RM-01x chassis have in common with the Mk5…7 chassis some parts that are useful for possible restorations:

– the set that includes all the parts listed below is available with three different part numbers: 51481, OP1461 or 54461 issued for the RM-01X chassis without body model number 84335. Starting from the front and going to the rear, this set includes the front bumper (highlighted in orange), the right steering arm (highlighted in blue), the left steering arm (highlighted in blue), the two systems for attaching the plastic battery clamp (highlighted in red), the two rear body support towers for the Porsche 956 (highlighted in purple) and the ring nut for adjusting the rear suspension (highlighted in green).

Code number 50216 and 50217 are respectively the two front wheels complete with white rims and the two rear wheels complete with white rims, which are now unavailable; however, they can be purchased:

– The two front sponge wheels are available as an accessory to be bought separately code number 51483 or in the high-grip version code number 54334
– The two rear sponge wheels are available as an accessory to be bought separately, code number 51484 or in the high-grip version code number 54335
– the complete set of two front rims and two rear rims is available in different colours; white set number 51482, in the special version for Toyota Tom’s (however, they are also suitable for installation on the Porsche 956) fluorescent pink set number 84285 and yellow set number 84286.

– Body complete with stickers and driver for the Porsche 956 Newman (stickers have some slight differences to the original 1980s version) code number 51491
– Joining the wheel and rim is a relatively simple operation; the wheel must fit on the rim. Tamiya has released an accessory to make this operation even easier; sponge wheel cone part number 54482

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