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Policar conversion How-To for Scalextric Tyrrell P34

9148 Views 4 Replies 5 Participants Last post by  Kevan
Tyrrell P34 Policar gearbox conversion for Scalextric 1976 model

How to:
So as ever you will need a donor car. Currently I think Scalextric have only released the car as a twin set so you have a choice of either car or both!

This conversion is reversible for the Scalextric P34.

1. Disassembly:
Disassemble the Scalextric car by removing all screws. Set aside the rear wing, top body and screws. You don't need anything shown here:

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2. Assemble the other components:
This conversion requires the engine and gearbox detail from the Policar March 701 as well as the Policar complete gearbox Policar. It may prove more economic to use a complete Policar March 701 as a donor for parts, especially as the detail comes ready painted.
A. You will need a complete Policar gearbox (narrow type) or the wide type can be cut down. This can be assembled from all the components or more economically bought as a single piece (part code PCH01as).

B. Engine and gearbox detail parts:

C. Rear wheels and tyres
The aluminium hubs available through Pendle Slot Racing, part PCS-321413 are a good option as the hub in this case does not get in the way or look too bad. They also have F22 compound tyres compatible with these wheels, ref. PCS-321413T.
The combination is slightly too large in diameter when assembled, presumably to allow them to be glued and trued.
I have also used Ostorero Lotus 79 wheels and tyres for these type of conversions.
The design parameters are that they should be about 21mm dia. and 14-16mm wide.

D. Front wheels and tyres
The only available wheels and tyres are those created by Pendle Slot Racing for their resin Tyrrell P34 kits. These parts are not currently listed on their site. Contact Pendle Slot Racing to purchase these items separately.

E. Compatible Chassis available here:
Ensure you buy the 1976 Scalextric P34 conversion chassis, not the 1977 Resin body conversion chassis.

F. Front axles x 2 - length XXmm. You will need to cut axles down as nothing this short is available on the market.

G. Guide, braid and wires. I recommend a thin wire, very thin braid and guide CH85 (screw in) although clip in CH66 will also fit.

H. If you are not using a donor Policar March 701 you will also need 2 x 6mm M2 long grub screws and special screws PCH06. Finally you will need a couple of extra body screws. There are numerous types available and you probably have some in your parts bin!

3. Building the Policar engine and gearbox.
To assemble the detail parts if you are not using a donor Policar March 701 see the instructions here:

Pages 5-9 and 15-18 are most useful. Do not add the roll over bar and the rear radius arms. You can add the part with the shock absorbers but will need to cut off the vertical March 701 wing supports as these are not needed for this model.
I would recommend painting these parts before further assembly.

If using a donor engine/gearbox detail this will be disassembled from the donor body by cutting off the soldered tabs underneath and pulling the whole assembly vertically upwards.

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The rear wing is removed by screwing out the long grub screw that holds it in.
The extremities of the radius rod detail should be removed to allow the rear wheels to fit close enough together and the vertical parts for the wing support should be cut off.
Ensure you also set aside for re-use the rear exhaust ends that fit in the back of the gearbox to complete the look of the new model.

These photos show the parts you need, how they can be disassembled and decorated as well as the areas that need to be cut off:

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4. Preparing the new chassis:
Cut the 4 front wheel inserts, the mounting bridge and the rear wing support from the main chassis by carefully cutting the thin sprue connections.

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Once detached trim the sprue from both the chassis and each of the separated parts.

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5. Fitting the gearbox and engine detail to the new chassis:

Remove the front most mounting hole from the gearbox as this is not needed for this build.
Screw on the gearbox to the chassis using one front screw.

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Take the mounting bridge part and screw it to the chassis. Both the Policar gearbox and this mounting bridge can use the original Scalextric screws.

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Use a 6mm long M2 grub screw to screw on the rear wing mounting block to the rear of the gearbox detail part. Screw the grub screw all the way up to provide space for the other M2 grub screw to come up under it. The rear wing pushes down solidly into this piece whin ch is designed to look like a small oil or water tank. It should be painted silver or metallic grey or even black to your choice.

The whole engine and gearbox detail part can now be pushed down onto the two holes in the bridge. The two holes may need slight opening up with a drill bit but are made small to create a strong fit. Once correctly test fitted this should be securely glued in place only on the mounting bridge. DO NOT glue any other part of the engine / gearbox detail at the rear. If you want to disassemble you can now release the two screws that hold the mounting bridge to the chassis.

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To ensure everything is tightly fitted screw the gearbox to the engine detail from below using the PCH06 screws, either side of the pinion and the other M2 grub screw at the rear under the wing support.

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6. Fitting the body to the chassis.

First fit the guide, braid and wires. The wire must be very thin to pass over the front axle next to the central pillar. Then assemble the two front axles. Ensure the axles run freely. If they are a little tight due to printing swarf run a 3/32 reamer through from side to side. The axles should spin freely without excessive movement. Grub screw adjustment holes have been provided but these are probably not necessary.

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You can see from this photo where I have removed the top body section (YOU DO NOT NEED TO DO THIS), that the body is fixed at the front by a small tab that hooks over the front of the body inside. This is because the guide is now pushed as far forward as possible and sits where the old Scalextric mounting screw was.

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The mounting screw pillar must be cut off flush with the inside of the body.

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The central tab on the chassis doubles as a potential grub screw point on the top of the front axle.

To assemble the body slide the chassis into the nose of the body underneath and push it forward until you feel it engage the tab so that the rear two screw positions align and the front chassis is not below the bottom of the body. It should make a nice, tight assembly.

Now screw the two rear screws in. Use any body screws for these or your preferred type.

Note: if you want to explore body rock you will need to investigate trimming of the forward tab to provide movement. I have not tried this and would welcome feedback.

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7. Go and test!

Thank you for your custom.


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Very informative, Andi :)
Having all the extra little parts as part of the main chassis print is the work of GENIUS!

Most impressive.
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Policar F1's have only just started appearing on our track, they're fantastic! This is a brilliant way to resurrect a Scaley Tyrell.
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