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Fly March 761 Policar conversion

This build differs from the other conversions that I have so far done in that it is the first car that has the rear engine and gearbox detail visible which is so characteristic of the 1970's cars.

Consequently I have decided to integrate the Policar engine and gearbox body parts to make the whole thing look great and remove the large drum which was Fly's solution to hide the crown gear when they designed the car.

I list the parts needed for this build as usual:
1. You will need:
a) A Shapeways chassis available here:

Policar parts numbers necessary to complete the gearbox:
PC-H03 - motor mount
PC-PPA01 - set of bushings
PC-PGS8018/17/16 - rear axle with gear. note choose either of the 18/17/16 denotes which gear you prefer. standard cars come with the 17 tooth version.
PC-PGI2516-PL - crown gear and spacers
PC-PPI429015 - pinion
PC-H04 - motor mount screws - The gearbox has a unique screw fixing so you will need these whatever motor you wish to use (see also below).
PWH1218-Pl - front wheel hubs. These come in sets of 4 so you only need one pack for two conversions.

c) Policar parts numbers I suggest but that might be interchangeable:
PC-PMX01 - motor. Note that the Policar gearbox has a single central top screw fixing position and so if you don't use this motor make sure yours has this hole! Also potential club rules might legislate for a single motor formula in due course.
PC-PPA02 - rear axle stopper - you may choose to use other types but be careful with sizes and what will fit.
PC-H05 - gearbox to chassis fixing screws - these are the correct size but other (and potentially other) types will also fit.

d) Other parts to complete the build:
Rear wheels and tyres
I have used Ostorero Lotus 79 wheels and tyres as I have them and because they are round and grippy.
The RS Scalextric replacement aluminium hubs available through pendles are a good option as the hub in this case does not get in the way or look too bad. Tyres to fit are probably available from various producers.
The design parameters are that they should be about 21mm dia. and 14-16mm wide. to match the ones on the model.

e) Front tyres:
I have used the original tyres from the car as they look good and mounted them onto the Policar front wheels.

f) Front axle
Any normal axle should work. Around 46mm length.

g) Guide etc.
The Policar range is designed to use the CH85 screw in pick up. Others may fit to your choice.
Wire (thin as possible is suggested.
Braids (thin).
Eyelets or grub screws to your choice.

h) To these items must be added the body part set:

1.0 Diassembly:

1.1. Start by removing the body and rear wing mounting screws in the normal way.

1.2. Now we need to take apart some of the body parts but without breaking them or the thin plastic pins that hold them together

I use a scalpel with sharp 10A blade to cut the top of the soldered joint off. Essentially you need to cut a small donut of plastic weld off to reveal the cylindrical pin underneath.

There are four that need to be cut off in order that the whole engine and radiator part can be removed.

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In some of the photos you will see that the driver has also been removed. This is not necessary.

1.3 Here you can see how I am then cutting down the original body mounting pillars. Cut them down flush with the top of the top body mounting moulding (the blue bit in my picture. I use a small saw but a dremel can also be used. Once cut down tidy up the outer edge of the cylinder so no swarf is protruding.

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How it looks with the pillars cut down:

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1.4 The engine and radiator part you have removed needs further disassembly. By cutting off the welded donuts again remove the two radiators and the roll over bar.

Unfortunately my donor car as shown in the photos does not have a complete part since in designing this conversion I cut things up before fully working out the solution.

These photos should give an idea of what these items look like. There is no reason why you need to cut the engine part up as I did provided you end up with two whole radiators with two mounting pins and a roll over bar, also with two mounting pins.

2.0 Sub assembly:

2.1. Now we can turn to assembly of the Policar DFV and Hewland gearbox. This should be self explanatory. Be careful to dry fit parts before gluing to ensure any moulding swarf is removed and each part fits perfectly.

2.2. I painted up the engine using metallic grey for the engine block and gearbox and silver for the air intake trumpets. If you are careful the basic black is fine for the rocker covers and the exhausts although I'm sure people will use their own colour schemes.

I picked out some bolts on the rocker covers with silver too and aim to add some 'Ford' decals to them too although haven't done so yet....

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2.3. The exhausts are best assembled first then added to the engine.

2.4. I took a part from Policar pack PCS02p3 to complete the exhausts but I suggest a bit of brass rod inside some plastic tube or some plastic tube will be adequate. You can even use a bit of drinking straw or maybe the parts from the donor Fly model.

2.5. Now take the 3D printed chassis. You will see there are three parts joined as one with thin vertical columns. Cut the columns off flush with the chassis and then trim them off the two separated parts.

Edit: On 04.01.2017 the arrangement of the three pieces was changed from the image below but the pieces are all identical. Andi.

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2.6. One part we will call the oil tank and the other the airbox mount.

2.7. Take the oil tank and fit the engine pins into it. Turn over and weld the pins in using a soldering iron or similar.

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2.8. Take the roll over bar and fit that into the remaining two holes. Again turn over and weld in with the soldering iron.

2.9. Now is a good time to paint the oil tank piece. I did this in silver to look like raw aluminium.

2.10. Take the two radiators and slip the pins into the pins on the extreme edges. Make sure they are pointing backwards and fitted in from below when the engine is the right way up. Remember fit twice and weld once!

My radiators have unfortunately been cut down for earlier scratchbuilds but obviously yours will be full length. DON'T CUT THEM DOWN LIKE MINE!!

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2.11. Now you have the complete rear assembly dry fit the whole thing to the body. It should fit snuggly so that from the rear the back of the side pods sit right up flush with the underside of the main body. You may need to ensure some of the welds are flattened to achieve this.

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Assembled from the top:

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2.12. Airbox. There are two types, high and low. Detach the original airbox and intake block from the main engine piece. I have done this twice. One was a case of removing the donuts and the pins slid out and on the other the whole thing was glued up so the pins broke off.

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If you have the high airbox breaking the pins is not an issue because the airbox mount has a tall fin which does not require the pins.

If you have the low airbox it is more important to try to retain the pins (at least some of them) intact.

2.13a. For the high airbox remove the flat plate from the airbox mount as shown.

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2.13b. For the low airbox cut off the high fin part and retain the flat plate with the four holes.

2.14. Then weld in the mount to the top of the new engine between the air intakes. You will need to slightly force this in as it is a tight fit.

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Don't glue the air box in yet in order you can get it properly aligned at point 3.6.

3.0 Main Body:

3.1. The bottom of the seat needs some cutting out as shown. I suggest this is done prior to fixing the whole engine assembly to give better access and avoid damage to delicate parts.

Make sure the bottom of the driver is carved out as shown.

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3.2. Now you should assemble the Policar 'working' gearbox and screw it to the chassis. Ensure the motor mount to chassis screws are short or cut the tops off once assembled to ensure they do not protrude as this can fail the body.

3.3. Test fit the chassis in the body to make sure it all fits. Take care that the chassis sits flat on the screw mounting points.

3.4. Bend out the motor soldering points as they can foul the back of the seat otherwise.

3.5. Once everything fits snuggly weld the oil tank (with whole gearbox and DFV detail) to the main body and then screw the body to the chassis.

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3.6. Once in and the whole body and engine is assembled try fit the air intake to check it aligns well with the body. Once it does glue it in.

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4.0 Rear Wing:

4.1. Take the rear wing and cut off the small side fins at the bottom. 'Round' slightly the base without breaking into the screw hole inside.

4.2. Cut off the two little fins behind the rear top gearbox mounting screw position. Drill out the existing hole using a 3mm drill. Do this gently, I did it by hand, working up from 2mm to 2.5 to 3mm. Push the wing base into the hole ensuring it is a tight fit and vertical so that the wing sits horizontally.

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You will need a screw of about 7mm length to screw up from below through the Policar gearbox into the rear wing.

4.3. I didn't but putting some epoxy to seal the rear wing to the top gearbox would help give this screw good 'bite' without splitting the now fragile wing base.

Go easy when screwing through the gearbox base. Turn in and back frequently to 'cut' the thread to avoid any splitting.

5.0 Finally:

5.1. Assemble the front axle, Policar wheels, original tyres, guide and wires and its all done!

Bottom view:

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Top view:

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5.2. Stand back and check out this amazing looking car.

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Further possibilities:
I have not but one might adapt the rear radius arms that came with the donor car and glue them above the engine. Or Policar parts such as anti-roll bars and suspension parts could be added at the rear. Or scratchbuild your own additions to make things look even more realistic!


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Discussion Starter · #5 ·
Thanks Stoner, yes I guess that is what I'm about. Trying to stimulate people into new possibilities. At the very heart of it I just love 1970's F1 cars!

This is certainly not the 'easiest' of the conversions as you say but I am keen to ensure there is plenty of options to race against the Lotus 72. It has taken some considerable ingenuity to make this one work..... Including several rounds of 3D prints which are unlikely to ever get paid for. Not that I'm complaining at all because the thrill I get in seeing these things racing is what its all about.

I'm now embarkng on the Scaley Mclaren which is even harder because they insist on not following the normal chassis and Body top separation.... Anyway I think there is a solution so we shall see.

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