Failure at Braid Contact on Scalextric cars from 2016 onwards
For a scalextric car to operate
the electrical current must flow into and out of the car. That's two
discrete electrical connections. To do this the slot rails in the track
are the two conductors. The electric current connects to the car via
the flexible woven braids fitted to the guide blade, then to the braid
contact plates and then through wires to the motor. The rotation of
the guide blade for corners and the like is managed through the use
of the flexible wires.
The wires need to be securely
fixed to the braid contact plate to make the electrical connection and
to withstand the regular rotation of the guide blade.
Recently (we believe sometime
in 2016) Scalextric introduced a change in the way the wire is crimped
to the braid contact plate. This is the silver coloured plate that makes
contact with the braid. There is a very serious problem with this new
design of crimp.
There is insufficient length
to the crimp fingers to fully secure the outer insulation of the wire.
With the action of the guide rotating over time the wire pulls out of
the crimp. This breaks the electrical connection between the wire and
the braid contact plate.
Once the crimp has failed
the Scalextric car stops on the track.
Here is a close-up picture
showing the failed condition. As this is a design based problem the
repair is not as simple as it might appear.
Option 1. Simply re-make
the crimp. This will last for a short while until the crimp fails again.
Option 2. Just crimp onto
the conductor wire strands. This will last for a short while until the
wire strands break through the action of metal fatigue.
Option 3. Solder the wire
to the braid contact plate. This doesn't work as the latest braid contact
plate is plated in a material that doesn't take solder. There'd also
be the strain relief problem.
As shown in this picture
to make the electrical contact the insulation is removed and the end
of the wire strands are tinned with solder and bent back over the insulation.
That's why the electrical contact fails once the crimp fails.
As this is a design based
problem the solution must also be design based. That means a new design
The solution is to use a
new braid contact plate made from a slightly stronger steel that is
plated with a thin layer of brass. This will take solder.
To overcome the lack of strain
relief with this soldered solution a short length of ultra-flexible
silicon wire is used. This wire consists of 128 strands of 0.05mm diameter
copper and a silicon insulating layer.
This is flexible enough to
easily withstand all the movement of the guide blade.
Here is the repair complete
in the Scalextric car. The original green and yellow wires are shortened
to make the room for the silicon wire tails. The joints are soldered
and a length of insulating tape covers the exposed joint.
We freely admit this isn't
pretty but it does use the right materials in the correct Engineering
Stronger brass plated steel
braid contact plates. Solder joints. Ultra-flexible wire where the wires
are needed to move regularly.
About the author:
Gary Harding has been working
with Scalextric cars for over 35 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: