The RM family had several evolutions, but there are three models that are similar to each other and it is difficult to recognize one model from the other: RM Mk.5, RM Mk.6 and RM Mk.7.
RM Mk5 to 7 are step changes in the RM chassis series; they are very popular because are easy to assembly and have few component parts. Many sets have been lost over time because they were relatively cheap and were an entry level model.
These three models have in common one upper and one lower FRP plate connected by “pillars” that assembly a box for the battery and radio gear, rear wheel drive, differential gear, two-wheel steering system with rear axle suspension and independent front suspension for purely on-road use.
The rear suspension system consists of a gear differential system with an alloy rear shaft which is suspended using the FPR plate has the main means of providing flex, only assisted by a spring on the top. This spring changed according to the model. There are no shock absorbers on these models.
The front suspension system consists of uprights suspended in small springs. It's an compact and maintenance friendly system capable of absorbing bumps in typical on-road use.
The servos and receiver is positioned in the middle of the chassis, but the weight of the motor and battery shifts the car's centre of gravity towards the rear. This imbalance at the rear makes the car under-steer.
The front bumper is small and the only protection against frontal accidents. This often leads to the front suspension and bodywork breaking.
Three models have these RM chassis:
- Porsche 956 Rothmans, item number 58042 released for sale in 1984 and available on the market until 1992. RM Mk.5
- Toyota Toms 84C, item number 58049 released for sale in 1985 and available on the market until 1992. RM Mk.6
- Porsche 956 Newman, item number 58052 released for sale in 1985 and available on the market until 1986. RM Mk.7
This is a list of the main differences between the models with MR Mk5…7 chassis: Porsche 956 Rothmans, Toyota Toms 84C and Porsche 956 Newman
- Porsche 956 Rothmans and Newman have different bodywork from Toyota Toms 84C.
- Body material is Lexan. Porsche 956 Rothmans and Newman have a fixed rear wing and Toyota Toms 84C has an adjustable rear wing.
Detailed differences between the three originals, moving from front to rear of the chassis:
(See picture below each section)
1. Front mounts
Porsche 956 Rothmans has 2 x alloy front mounts.
Porsche 956 Newman and Toyota Toms 84C have 2 x plastic front mounts.
2. Front suspension suspension
Porsche 956 Rothmans and Toyota Toms 84C have conical springs in front suspension.
Porsche 956 Newman has cylindrical springs in front suspension.
3. Pillar screws
Porsche 956 Rothmans has two black rear hexagon screws for pillars.
Toyota Toms 84C and Porsche 956 Newman have four screws for pillars.
4. Damper Spring
Porsche 956 Rothmans has long rear damper spring.
Porsche 956 Newman and Toyota Toms 84C have shot rear damper spring.
Porsche 956 Rothmans has two allow pillars. Porsche 956 Newman and Toyota Toms 84C have four plastic pillars.
6. Plate holes
Porsche 956 Rothmans has four big holes in the lower carbon fiber plate.
Toyota Toms 84C and Porsche 956 Newman have four small holes in the lower cardon fiber plate.
7. Rear plate
Porsche 956 Rothmans has carbon fiber rear plate and black hexagon screw.
Porsche 956 Newman and Toyota Toms 84C have alloy rear plate and allen screw.
8. Rear mounts
Porsche 956 Rothmans and Porsche 956 Newman have black plastic rear mounts. The black mounts are cylindric. Toyota Toms 84C has white rear mounts. The white mounts has a special shape to fix the body and the rear wing.
Porsche 956 Rothmans has black 540 motor and black rear shaft.
Toyota Toms 84C and Porsche 956 Newman have grey 540 motor and grey rear shaft.
Later evolutions of the RM chassis
Tamiya has evolved the RM Mk5…7 chassis into the RM01 chassis released for sale in 2011, which again has three models.
Improvements to the chassis are:
- re-engineered one lower FRP plate
- resin gear case
- ball differential gear
- 380 motor
A special version, RM01x, with aluminum and carbon-reinforced parts designed to boost the chassis’ racing features, was released in 2013
Three models have the RM01 chassis:
- Toyota Toms 84C, item number 58509 released for sale in 2011
- Porsche 956 Newman Joest racing Porsche, item number 58521 released for sale in 2012
- Mazda 787B No. 18 Le Mans 24 Hours 1991, item number 58555 released for sale in 2012
Written by Gabriele Andreoni