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Policar Conversion Chassis for Scalextric Williams FW11

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This is a how-to thread to convert the 2023 release Scalextric Williams FW11 into a Policar racer.

It will NOT help convert the older, original Scalextric Williams FW11.

The chassis can be purchased here:

You will also need:

1. A Donor Scalextric Car (e.g. C4318)

2. A Policar 'wide' style gearbox (e.g. PCH03-51z17).

3. You will also need some rear wheels and tyres.

There are several combinations. The design diameter of the finished tyre is around 19.5-20mm although 20.5-21mm will also work.

Two examples:

NSR wheels 5026 with NSR tyres 5285 (19.5x13mm Ultragrip)

Pendle Slot racing wheels PCS-32131114 with Pendle Slot racing tyres PCS-321413t (21mm diameter until trued and glued)

4. A Guide - I recommend SICH85 from

5. Braid and wire are free choice.


A. Unscrew the body from the chassis of the donor car.

Keep the screws and discard / recycle the rest of the chassis.

This is a simple gorgeous body from Scalextric... except that massive bulge over the crown gear!

Cut that off straight across the body.

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Just behind the little round decals.

Paint the resulting edge dark blue so that the cut is less visible (not shown).

Take the chassis and separate into the 3 individual pieces: The chassis, the 'forward screw bridge' and the 'gearbox cover'.

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Flip the body over and cut off the end of the front screw mounting post. It needs to be about 0.5mm below the flat plate under the driver. I cut mine down with a saw flush with the plate and then trimmed a little further with a scalpel. A dremel would be a good way to cut it down too.

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Then take the forward screw bridge and screw it onto the main body.

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Open up the two new chassis mounting screw holes with a 1.6mm drill bit as they may be clogged with dust from the manufacturing process.

Screw on the rear gearbox detail with a countersunk screw (the original one should fit). I used one I had in the spares box.

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Flip the chassis over.

Cut the back off the Policar motor mount (leaving the bulkhead just behind the rear spur gear), and trim off the detail on each side so that it slips down into the chassis and backwards under the gearbox detail.

Check that everything fits snug and flat. Sometimes the motor mount forward screw mounting sprue is a little bent downwards. It could be cut off or trimmed underneath to make everything sit perfectly flat.

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Once it all sits flat screw it on with minimum 3 screws from below.

The underside of the motor mount is designed to protrude 0.5mm below the bottom of the chassis. This will be almost imperceptible to the eye but you should be able to feel it with your finger.

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Now dry fit the body ointo the chassis. Check that the forward screw bridge is at the correct height and allows the body to sit down flat onto the chassis. If there is a gap you probably need to trim the original central front body mounting post a little more.

In the above photo there is a gap between the gearbox and the body. This was my error in assembly and I trimmed the gearbox. Don't cut anything and it should fit well.

The chassis and gearbox cover should all be painted black (or purchased directly in black), and the rear of the body (the elliptical curved bit) should be painted dark blue to match the elegant curve of the back of the body.

That's it - it should all run very smoothly...

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Enjoy racing these beautiful cars...

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Another smart looking Williams for the fleet.
Nice one.
I've painted the chassis.

This car is for me the absolute best looking F1 car off all time.
Even better than a Lotus 72 or 79, my other two favourites...

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I've painted the chassis.

This car is for me the absolute best looking F1 car off all time.
Even better than a Lotus 72 or 79, my other two favourites...

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I thought the 1974 Ferrari B3 was your favorite. ;)
But seriously, a fantastic looking conversion of the beautiful Williams car. Gonna buy the chassis!
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