How to make a slot car chassis

Make your own slot car chassis with this simple design process

Abstract

There are many slot car body kits available today providing the slot car enthusiast with many options to make their own functioning slot car (Scalextric car). Some of the body kits are finely modeled while some are more basic but all of them need a chassis in order to be completed and run on the slot car track. This article explains the making of just such a chassis.

Introduction

There are a myriad of small and large scale suppliers of 1:32 scale slot car body kits out there all making resin based slot car kits, most include the windows and the interior. The very best include all the trim parts in metal too, laser cut this and metal cast that. So, the whole range is out there somewhere. The problem has always been about the modeling skills to assemble these kits and then to track down a 1:32 scale slot car chassis, wheels and tyres so you can race your wonderful model. So here you are, all the information needed to make your own slot car chassis.

Making the basic form

The important aspects of a slot car chassis are:

• Mounting of the rear axle
• Mounting of the front axle
• Mounting of the motor
• Mounting of the guide blade
• Fitting to the slot car body
• Mounting of a Neodymium magnet for Magnatraction (if needed)

So, not too much to take into account then… It must be remembered that the gears have to be accurately aligned and the axles have to provide the right ride height for the selected wheels, tyres and slot car model. To produce our chassis we selected 2mm plasticard as a starting point. This will give good thick and strong sections, is workable and can be joined easily with superglue.
We also decided to use all Scalextric parts and standards. That’s the following parts and standards:

• Axle diameter
• Motor (Mabuchi S can with brush end drive)
• Motor pinion gear
• Rear axle contrate gear
• Guide blade, pins and wires
• Wheels
• Tyres

This was done simply to minimise design effort and to allow the slot car modeler to use parts that are in plentiful supply. Therefore, someone with an existing Scalextric car could use all the parts they had to make the chassis functional. The next problem to overcome was the risk of the rear axle coming lose from the chassis.
This chassis is to use plain holes for both the front and rear axles to give the chassis good strength. Scalextric and other slot cars use an open clip arrangement for the rear axle bearings which can “unclip” in use. Scalextric get round this by adding extensions to the interior of the car which hold the rear axle bearings into place.
With resin slot car kits these extensions are not present so the standard Scalextric solution is not robust. As a result we took the solution to use plain holes which cannot fail in this way. This was especially important as we were adding a Neodymium magnet for magnatraction to our slot car chassis.

The image above shows the basic form of the chassis taking place. We started with the motor mounting and the related rear axle position. Here you can see the start of the motor mounts the rear axle bearings and the cut out for the contrate gear as well as the chassis side supports.

At his point we’ve added a little more detailing to the rear of the slot car chassis and the motor fixing solution. We’ve added the basics of the front end too. The guide blade mounting is in position as are the front axle bearings. In this image you can also see the motor in position and the body mounting solution is in place and being tuned.

This image shows the chassis with the first trail of the selected wheels and tyres. In the first instance there will be two wheel options, one road type and one Minilight type (the road wheel is on the rear and the Minilight wheel is on the front). The wheels have the same form factor and so can use the same range of Max Grip tyres. The picture above shows the largest and smallest tyres suitable for these wheels.

This picture shows the chassis fully assembled and a little more refined. The guide mount has been tidied up as has the side sections. You can clearly see the motor is mounted at a slight downward angle too. This allows the rear axle to be mounted lower which, in turn, allows smaller diameter wheels and tyres to be used. The original concept was to allow the Scalextric small Superslix wheels and tyres to be used if desired.

Above you can see the underside of the fully assembled chassis. This image shows the motor and rear axle arrangement as well as the guide and body fixing solution. This chassis will be secured to the slot car body by means of 3 self taping screws, 2 at the rear and one at the front. As this chassis is intended to run close to the track surface the screw heads are sunk into the chassis surface.

Making the chassis adjustable

At this stage we have the basic form of the slot car chassis with a fixed wheelbase of 75mm. This is of little use unless your slot car body has the same wheelbase. So, there’s only one solution, make the slot car chassis wheelbase adjustable.

And now the scary bit. Clearly, all cars as well as their slot car clones have different wheelbases. That’s the distance between the front and rear wheels. So, any universal slot car chassis must be adjustable for wheelbase. This means cutting the chassis into two pieces and providing a means to allow the wheelbase to be adjusted and set. This image shows the front and rear chassis pieces as well as the start of the sliding mechanism.

In order to manufacture this slot car chassis in volume we needed to provide it with a consistent surface finish. Some parts were glossy plasticard surface, some parts were superglue finish and much was a sanded or filed finish. Also, there were minor surface imperfections due to the amount of machining carried out to make these master parts. To remove the minor surface imperfections we spray painted the slot car chassis in primer and sanded it back. We repeated this process until the surface imperfection were cleared away. Here you can see the two master chassis pieces prepared and ready to the make the mould as well as the master wheel models and the selected fixing screws, washers and Nyloc nuts.

Into production

Making one chassis is good but the plan is to make lot’s of chassis kits for the slot car makers out there. Therefore, the master two slot car chassis pieces have to be copied many times over. We use a low volume moulding method make copies of the original parts to go into the slot car chassis kits.

Above is the complete slot car chassis kit. This plastic moulded slot car chassis kit is ideal for many of the 1:32 scale resin and plastic slot car body kits available. The kit comes complete with:

• Rear chassis piece
• Front chassis piece
• 2 off stainless steel screws
• 2 off stainless steel plain washers
• 2 of stainless steel Nyloc nuts
• 2 off front axle spacers
• Neodymium magnet (optional)

Dimensions:

• Overall width 33mm
• Height (without motor, axle and guide) 12mm
• Overall length (minimum) 92mm
• Overall length (maximum) 112mm
• Minimum wheelbase 64mm
• Maximum wheelbase 84mm
• Recommended minimum tyre outside diameter 16mm (small superslix tyres)

This chassis is designed to use the following standard Scalextric parts:

• Mabuchi S can motor
• Rear axle (black or yellow contrate gear) 3/32″ diameter
• 9z motor pinion gear
• Front axle 3/32″ diameter
• Guide blade, pins and wires
• Wheels
• Tyres

The slot car body is secured to this slot car chassis with 2 fixing points at the rear behind the rear axle and by 1 fixing point behind the front axle. This is the standard form factor for the resin and plastic body kits readily available.

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:
http://www.scalextric-car.co.uk