Post by Andrew Rowland on Apr 24, 2016 7:39:36 GMT -5
So the long awaited Scalextrix Mclaren M23 conversion to Policar gearbox has finally been completed! I nearly gave up a dozen times. Got there in the end. I’ll work on the How-to in due course but the photos here show the basic elements. 1. carve up the underpan (available separately item no. W9425). 2. Insert the gearbox and running gear into the chassis. 3. Minor modifications to the underside of the body and driver. 4. Assemble the Policar DFV kit and exhausts. 5. Minor modifications to the rear wing. 6. Screw it all together and off you go!
B) 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 Slot.it (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 wheels and tyres: I have used the original wheels and tyres from the car as they look good and mounted them onto a slot.it axle.
f) Front axle Any normal axle should work. Around 46mm length.
g) Guide etc. The Policar range is designed to use the Slot.it 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 Policar body part set: PCS02p2
i) A donor Scalextric Mclaren M23!
1.1. Start by removing all of the screws from the car. Some have 7 and later ones have 9!
1.2 Top Body:
Pull the top body off. The driver is often glued to the underpan so this can take a little bit of force but don’t break anything!
Remove the driver from the top body careful not to break the steering wheel.
On my car the two pins that hold the air intake box to the main body were not soldered or glued so this also came away separately.
1.3 Underpan and engine:
Hold one of the front stub axles hard in a thin nosed pair of pliers and carefully twist off the front wheels one by one. Turn back and forth slowly until it breaks free then rotate off. Try not to break the inner hub as we want to reuse these wheels!
Pull up and off the top engine detail. This is a lovely piece of plastic moulding and is held by four tiny pins under the bottom of the axle near the tyres. I released these carefully first with a tiny screwdriver.
I then found that the trick was to unclip the axle and wheels from the underpan and that brought all the engine detail off with it. (I did break one radius arm!)
Unscrew the guide, unclip the motor and finally we have the underpan on its own.
Alternatively just buy a new underpan….
You need to cut the underpan up until it looks like this:
As much accuracy as possible here and keep trial fitting the conversion chassis as possible so they are a snug fit together.
2.0 Sub assembly:
2.1. Now we can turn to assembly of the Policar DFV and Hewland gearbox. This should be self explanatory but good instructions exist on the www.policar.it website if you need help. Be careful to dry fit parts before gluing to ensure any moulding swarf is removed and each part fits perfectly. Do not use the air inlet trumpets as they will not fit under the air box in this car.
2.2. I have run out of parts when making this model so reference the March 761 photos. I painted up the engine using metallic grey for the engine block and gearbox and silver for the air intake trumpets (I repeat not needed in this build). 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....
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.
2.5 Now assemble the Policar gearbox. Again use the Policar website for information on how to do this successfully. DO NOT modify any part of the gearbox at the rear but DO cut off the front-most screw fixing position.
2.6. Now take the 3D printed chassis. You will need shortened screws for the two rear most motor mount fixing screws. Slide the completed motor mount with motor, gears etc. into the back of the chassis.
2.7 Slide in the front axle and push on the front wheel/tyre combination. You can also add the guide or perhaps do that later.
2.8 Once you have the rolling chassis you can offer up the underpan to the underside:
2.9 Yours will have a 3D printed pin that goes up through the hole at the front of the piece of underpan that you have cut. Solder this to hold the front of the underpan up solid against the new chassis. My prototype did not have this but this is a necessary improvement I added at the end.
3.0 Main Body:
3.1 Cut out the back and sides of the driver’s seat as shown. Note that you might see that I have also thinned out the small tabs with the holes in that accept the pins on the air box. This should not be necessary as there should be sufficient clearance. I did this as I worked and slowly learnt what was necessary to remove!
3.2 Test fit the top body on the chassis a couple of times to make sure everything is a clean fit.
3.3 Add the engine detail. Again I do not have the parts so have a cut down piece that shows the general idea….
3.4 Cut the driver as shown.
About 1.5mm off the whole bottom and then use the cube missing to cut a slot from front to back as shown. I fear you have to cut through the legs to get him seated far enough down.
4.0 Rear Wing:
4.1. Slice off the cylinder and two rectangular pins on the back of the Policar gearbox down to the level of the gearbox.
4.2 Drill a 1.5mm dia. hole 2mm behind the existing hole.
4.3 Trial fit the Mclaren rear wing to ensure everything works as per the diagram:
Depending what colour chassis you bought a bit of touch up colour on various parts of the conversion chassis will help transform this to a wonderful looking model…