Scalextric Brabham BT26 conversion to Policar gearbox

This is a how-to for converting a Scalextric Brabham BT26 into a Policar racer.

The Scalextric model I have has a few minor defects that the other Scalextric cars don't have. I'm not sure if this was a batch problem or is a defect of the whole model design. I found that the back of the body is twisted in relation to the front.

I've effectively ignored the issues and believe that when screwed together my conversion chassis will straighten the twisted body.

This makes a really beautiful, smooth and quick handling car.

So this is how I did it and should form a clear guide to anyone wanting to do the same.

Parts you will need:

Although it is possible to build this conversion by buying individual Policar parts:

Complete gearbox (without outrigger screw positions)
Narrow Screws to fix gearbox
Gearbox top and DFV engine parts
Rear wheels
Rear tyres
Rear wheel inserts
Guide, wires, grub screws and pick ups

It is likely to be cheaper to use a donor Policar Lotus 72 and, if you do this all the parts will therefore be painted and decorated. A cheaper option, but requiring decoration, would be a white kit of the same Lotus 72.

The Lotus 72 does not come with the narrow head screws part PCH 07 so these will need to be purchased separately.

B. A donor Scalextric Brabham BT26.

C. A compatible chassis bought from here:

https://www.shapeways.com/shops/arco_chassis

www.shapeways.com/shops/arco_chassis

PLEASE NOTE THIS IS A NON REVERSIBLE PROCEDURE!

Preparation of the Policar parts:Separate the body and remove the chassis from the gearbox by undoing all the screws.

You will need to cut off the soldered plugs that hold the windscreen to the body and also those that hold the driver on.

This will enable you to take the windscreen off and gain access to the top of the main DFV link to the body top.

Cut the bottom off the two soldered plugs that hold the DFV to the main body and separate the two.

DO NOT cut the link piece off the DFV to form a flat back as on this conversion these will fit in the two holes in the rear of the 3d printed chassis.

Remove the Lotus rear wing and water tank from the gearbox top. This has been screwed in with a grub screw so insert an allen key and extract it cleanly.

You now have a complete DFV / gearbox assembly ready for the build.

How to fit the rear wing:

Cut the new Brabham water reservoir off the Shapeways chassis so you have this piece:

Remove any sprue.

Give it a paint in silver (main cylindrical tank), matt white (little rear tank) and matt black (rest of it including the radiator). I have left mine white so it shows clearly in the photos.

Screw that onto the back of the gearbox using the grub screw previously extracted. Keep it well pushed down as you screw it in.

Pull the rear wing up, off the donor Scalextric body. Cut the prongs down so they are equal length like the shorter one.

Once everything is ready the wing should push down into the new water reservoir making a nice solid fixing.

The new rear end is now ready.

3. Preparation of Scalextric Brabham BT26 donor:

Undo the screws and disassemble.

The rear suspension is sometimes glued and may need cutting or prising apart. These are the parts you will need:

For this conversion I have chosen to leave the front wheels and tyres with the stock axle. Mine are relatively circular and correctly fitted. If you need (due to non centred wheels) replace with the front axle assembly from the Policar Lotus using spacers (not supplied):

Cut off (or twist off carefully) the rear engine and gearbox detail from the main body including the backs of the radius arms and separate.

The driver is attached by a tongue to the rear engine and this is likely to come away too. Ensure the driver's hands disengage without breaking the steering wheel.

You will be left with this piece:

The roll over bar must be separated from the DFV assembly. This is quite tricky as it is glued on but with a sharp scalpel should be possible without breaking it.

Roll over bar once cut out:

Driver removal and cutting:

Remove the driver from the engine assembly. He may need to be cut off but I found inserting a knife between him and the tongue and twisting separated him well. Trim him to shape, doing a few test fits to make sure you've cut enough off.

Put the driver back holding the body upside down, ensuring he grips the steering wheel as before.

Your donor body is now complete.

4. Assembly

Screw the motor pod to the Policar DFV and gearbox assembly using the small screws part number PCH 07 and the rear grub screw.

Ensure you insert the rear end of the exhausts before inserting the screw at the rear of the gearbox. I cut off the rear ends of the torsion bars that the Lotus 72 had to approximate to the design of the Brabham BT26 rear end.

Take the 3D printed chassis. Trim off any sprue, screw the gearbox assembly to the 3D printed chassis.

Thread the wires and fit the slot guide. The chassis can be used with the guide from the donor Policar or a wood guide can be fitted.
Screw the body Scalextric body on top using two of the Scalextric donor screws.

Glue on the roll over bar once the body is in place and try to only glue it to the 3 d printed chassis in the locating holes to allow future disassembly of the main body for guide maintenance etc.

Go and have fun!