How to service the RX motor in your Scalextric car

Maintain your Scalextric car’s RX motor with these simple hints and tips

Abstract

The earlier Scalextric cars produced in the 1960s were fitted with open frame motors the most common of which is known as the RX motor. This motor was also fitted to many of the Hornby locomotives of the period. This article shows how an RX motor can be serviced in a methodical way by considering the mechanical, electrical and magnetic aspects of the motor.

Introduction

The RX motor was fitted to most Scalextric cars from the 1960s. In order for your Scalextric car’s RX motor to give the best possible performance it has to be in the best possible health. Effectively giving the maximum torque for the electrical power available to it. For any electrical motor to give its best 3 key areas need to be considered; the mechanical condition of the motor, the electrical condition of the motor and the magnetic condition of the motor.

Mechanical

Mechanically the RX motor needs to be in the best condition possible to ensure that no energy is lost and the motor can transfer all of the generated torque to the rear axle. To do this several areas need to be reviewed:

• Firstly check and ensure that all the parts are present and undamaged. All missing or damaged parts must must be replaced.
• Check and ensure the motor armature spins freely with no rubbing or tight spots. This could be caused by missing or damaged bearings or a damaged motor housing.
• Review the motor pinion gear and ensure all the gear teeth are in good condition. Replace the pinion gear if gear teeth damage is found.
• Add a drop of oil to each of the bearing felt pads.
• Ensure the brush spring sleeve is present and in good condition. Replace if necessary.

Electrical

There are many electrical connections and contacts used on the RX motor. Each of these must be in good condition to ensure the best performance of the motor. To do this several areas need to be reviewed:

• Firstly check and ensure that the solder joint between the wire from the pick-up brush and the eyelet that fits over the brush spring sleeve is complete and sound. Replace or remake this joint if any of the wire strands are broken or not making contact.
• Inspect the eyelet for any dirt or metal oxides that may have formed over the years. Clean the brush spring back to clean shiny metal where it contacts the motor brush.
• Inspect the brush spring for any dirt or metal oxides that may have formed over the years. Clean the brush spring back to clean shiny metal where it contacts the motor brush and the screw that secures the magnet.
• Inspect and clean the motor brushes removing any dirt, oil and carbon deposits. Ensure the carbon block is present and securely attached to the brass strip. Clean the motor brushes back to clean shiny metal where they contact the brush spring and eyelet.
• Remove any dirt, oil and carbon deposits from between the commutator segments of the armature.
• Remove any dirt, oil and carbon deposits from the commutator.
• Check the three solder joints that secure the armature windings to the commutator, remake these joints if necessary.
• The electrical connections for a car with an RX motor are:
  • Contact: Track braid to track rail
  • Contact: Braid contact to track braid
  • Solder joint: Wire to braid contact
  • Solder joint: Motor brush sleeve to wire
  • Contact: Motor brush to motor brush sleeve
  • Solder joint: Motor brush carbon block to motor brush
  • Contact: Commutator to motor brush carbon block
  • Solder joint: Armature wire to commutator
  • Solder joint: Armature wire to commutator
  • Contact: Commutator to motor brush carbon block
  • Solder joint: Motor brush carbon block to motor brush
  • Contact: Motor brush to brush spring
  • Contact: Brush spring brass bolt
  • Contact: Brass bolt to eyelet
  • Solder joint: Eyelet to wire
  • Solder joint: Wire to braid contact
  • Contact: Braid contact to track braid
  • Contact: Track braid to track rail

Magnetic

The magnetic field used by the RX motor is provided by a permanent magnet at the rear of the motor. The magnetic field reaches the outside of the armature by the use of steel plates that are also used as the housing for the motor. To ensure the magnetic circuit is maintained the RX motor uses various materials to ensure the magnetic field is not reduced.

• Ensure the magnet is secured by the correct brass screw.
• Ensure both the steel housing plates make good tight contact with the magnet.
• Ensure the aluminum plate adjacent to the magnet is fitted correctly.
• Ensure the brass plate at the commutator end of the motor is fitted correctly.

General

Through experience we have found that some RX motors still do not perform well even with all of these checks completed. This may be caused by a weak magnet or internally damaged armature windings. These faults are outside the scope of this article. There are many other possible faults with the earlier cars with the open frame motors. This is intended as a simple fault finding guide only. If the information above does not resolve the fault then contact us for further information.

About the author:

Gary Harding has been working with Scalextric cars for over 30 years and now operates Scalextric Car Restorations in the UK. Scalextric Car Restorations is a Worldwide internet based business that offers for sale high quality Scalextric cars and Scalextric parts from the 1960s to the present day. All the restoration work is carried out to the highest standards with the highest quality parts available. Only the best cars are selected and the final result is a car that is genuinely like new.
Further help and advice relating to this article or Scalextric cars in general can be found at:
http://www.scalextric-car.co.uk

Scalextric service kit for the vintage Scalextric RX motor

This new service kit can be used on all the vintage Scalextric RX motors used in Scalextric cars including the ‘Race Tuned’ versions with the black coloured frames.

The kit comprises:

• New wiring with motor terminals
• New brush spring with sleeve
• New brushes

We often find that replacing the worn out brushes, the corroded brush spring and the frayed wires along with a good clean can revitalise these great old open framed motors.  It’s also worth checking the motor spins freely with no tight points and adding a drop of oil to the felt pad at each bearing.
Some more great tip from Scalextric Car Restorations

Scalextric pre-wired Johnson 111 motor assembly

The Scalextric cars produced during the 1070’s were generally fitted with the Johnson 111 electric motor.  The long thin, gold can motor has proved reliable enough over the years but can fail due to over lubrication causing overheating and eventually a total burnout.  Repairing a motor that has failed in this way is not really an option due to the difficulty of the repair.
The best option is to replace the failed Scalextric Johnson 111 motor with a refurbished motor.  This Scalextric Johnson 111 motor is refurbished and fitted with new wires, pinion gear and guide.  Which means it can be fitted by anyone with no special electrical skills.

Your classic Scalextric car will be up and running again in minutes giving you all the fun you remember.
Another great Scalextric spare part from Scalextric Car Restorations.

Scalextric cars with too much lubricating oil

Scalextric cars are electro-mechanical devices that need the moving parts to be kept in good condition.  Taking this view from time to time is very helpful especially when we maintain the older Scalextric cars.
The most frequent failure with the old open frame Scalextric RX motor is that of excessive lubrication.  Lubricating oil is good when applied to the right places, oil is bad when applied to the wrong places.  When we service an RX motor we remove oil from the wrong places and put oil in the right places.



The worst place for oil is the commutator of the RX motor as this mixes with the carbon dust from the motor brushes to form a conductive paste which shorts out the commutator segments.  This leads to overheating of the motor and eventually failure of the solder joints that join the armature wires to the commutator.  Once the solder joints fail the motor stops working.

The other place oil is not welcome is on the rubber tyres.  Oil will impregnate the tyre and make it go hard and brittle in just a few weeks.  So, remove all oil that gets onto the tyres immediately, especially if the car is to be placed in storage.

Another great insight from Scalextric Car Restorations

Scalextric slot car motors that smoke

We frequently are presented with older Scalextric cars that emit smoke when power is applied.  Very often the motor runs slow too.  The common interpretation is that the motor is “burned out” which is far from the case.  This mostly affects the Scalextric RX motor, Johnson 111 motor and the Raymond motor.



The smoke is caused by oil burning off which is heated by the electrical current flowing through it.  The oil has become conductive as it has been mixed with carbon dust from the motor brushes.
The answer is very simple.  Dismantle the motor and clean away the oil / carbon material.  With this done and the motor re-assembled, 90% of motors come back to full health.  A small, half drop of light engineering oil should be applied to the motor bearings.

Another great insight from Scalextric Car Restorations