HOW TO BUILD -

  A 1/32 Production Car

 This article will show you how to build a Parma International 32 kit from scratch. This is an updated version of the article originally written by Paul Bucknell. These are not the easiest cars to set up and there are probably a number of ways you can build one. I'm not saying this is the best way or the only way - I can only say that it works for me. The car I built for this article used a Plafit Cheetah motor so my 7 year old son could enter some BSL rounds during 2002. BSCRA production racing now mandates the JK Falcon which is pretty similar to the Cheetah  The current BSCRA regulations allow a Mura Super Wasp,  Pro Slot Super Wasp or RJR Hornet to be used. The general principles hold good however, irrespective of which motor you use.

What to buy:

The easiest way is to get a building kit Parma part number #420-D. These are available from most slot car suppliers in the UK. The kits contain all the parts you need except a motor, pinion and body shell. The photograph below shows you all the parts that form the kit.

These are the additional parts you will need to but to build up the car  in this article: 1 Parma 1/32nd Intrepid body, a set of metal axle spacers, a set of steel guide spacers, a set of Teflon guide spacers, 1 Pinion (64 pitch) and 1 Plafit Cheetah or JK Falcon motor. You will need another gear the same make, type and size to fit the axle bearings later. You can then keep this gear as a spare.

Paul built his car using a 10 tooth pinion, some other  builders recommend an 11 tooth pinion

Getting Started:

The first thing you need to do is ensure that your brand new chassis is actually straight. You can do this by placing a straight edge (I use a steel ruler) on the underside of the chassis along the lateral and longitudinal axes. The picture below shows what I mean.

If the chassis is straight, there should be no daylight between the straight edge and the chassis. If it isn't straight, carefully bend the chassis until it is.

Fitting the Axle Bearings:

Once your chassis is nice and straight, you can fit the rear axle bearings. To ensure that the axle is level, you should fit the bearings in the chassis, put a lightly oiled axle through them to ensure that they are aligned and fit the gear you are intending to use on one end of the axle and another identical gear on the other end of the axle. NB it is important that both gears are new when you do this. A used gear will be worn slightly and your axle will therefore not be level. Use axle spacers to ensure that you have enough room to get in with your soldering iron without melting the plastic gear. The chassis should now look like this.

Once all this lot is in place, put the chassis on a flat heatproof surface and carefully solder the rear axle bearings in place. Make sure that you don't solder the axle in place and be sure to keep the hot iron away from the plastic spur gear!

The most common reason that a car will handle like a London Bus is an incorrectly fitted slot guide. The easiest way I've found to do this is as follows:

First thread the nut onto the guide making sure that you keep the nut straight in relation to the guide post. Many slot racing suppliers have a tool to do this job so you can make life easier by asking them to thread the post for you. Then put Teflon washer onto the guide post, fit the guide in the chassis, put another Teflon washer on and then fit a steel washer before fitting and tightening the nut. Tighten the nut until the guide will not turn easily in the chassis, then gradually slacken off the nut until the guide turns freely but has no vertical slop. It is not uncommon for me to spend 20 minutes or so doing this. It is worth investing time in.

Fitting the Front Axle:

There are three sets of holes you can use for the front axle, Paul generally uses the rearmost set. Some other builders recommend using the front most set.

There are various ways of setting up the front axle, different people will tell you the way they've found works best.  Here are 3 methods

(1) The simplest method is to assemble the axle wheels and spacers leaving everything free to rotate.  I'd recommend this for beginners - as you gain more experience you might like to try one of the others.  The other methods are different, not necessarily better - some competitors find this first method works best.

(2) First, with the slot guide and braids in place, thread the front axle through the holes you want to use. Then place the chassis on a slot board, centre the axle in the chassis and put your finger on the axle and push down gently. Then carefully solder the axle to the centre section of the chassis only whilst maintaining the downward pressure with your finger. Forgive me if I preach to the converted, but do be careful with the soldering iron whilst it is close to your fingers!  Look at the diagram below to see what you must do. The spacers and wheels are then left free to rotate on the fixed axle. 

(3) Start off following (2) above. Once you have soldered the axle in place in the centre section, slip the brass front axle spacers in place on each side and press down on the outer section of the chassis. Then solder the spacers to the chassis (not the axle!) . The wheels are free to rotate on the fixed axle and the spacers which are attached to the pan section can rotate very slightly relative to the axle.

The outer section should protrude slightly below the centre section. Look at the diagram below.

Fitting the Pinion Gear:

The next thing we need to do is solder the pinion onto the motor. This is one area where many cars have their Achilles Heel. Soldering a pinion on is not difficult. All you need to do is make sure that your soldering iron is big enough for the job, and keep the motor shaft and pinion clean. First, degrease the motor shaft with a clean rag with a splash of lighter fuel. Then gently clean the hole in the pinion with a small round file. Next push the motor shaft through a sheet of paper so that the paper protects the rest of the motor from the soldering flux.

Then put a blob of flux on the motor shaft and apply the hot soldering iron and a small amount of solder. The solder should flow all round the shaft to tin it. Allow the motor shaft to cool for a couple of minutes and then put another small blob of flux on the shaft. Place the pinion on the end of the shaft (it won't slide right down). Wipe the end of the soldering iron clean on a damp sponge and apply the hot iron to the pinion. After a few seconds, the solder on the shaft should melt and the pinion should slide smoothly into place. Keep the heat on for about another 15 seconds and then leave the motor to cool for 2 or 3 minutes. The pinion should now be rock solid on the shaft. Tear the paper off the motor and the pinion is now ready.

Fitting the Motor:

The chassis and motor are now ready to be fixed together. First fix the spur gear onto the back axle with about 1 cm protruding from the boss side of the gear. Next, clean the top edge of the motor where it will touch the motor bracket with fine emery paper and also clean the motor bracket where it will touch the motor. Then, thread the axle into the rear bearings, and put the chassis onto a flat heat proof block. Place the motor into the chassis and ensure that the gear mesh feels smooth. Once you are happy with the gear mesh, hold the motor in place and solder in the motor along the edge you just cleaned. Look at the picture below to see what I mean.

Then turn the car over and solder the motor to the chassis as in the picture below.

Make sure that both the solder joints you have just made are firm. The most common source of car shudder is a broken solder joint under the car between the chassis the motor (the last solder joint you made) so always check this joint first if your car exhibits this problem.

Completing the Chassis:

Believe it or not you've nearly finished. First you need to space the rear axle out. Stuart Strachan has done an excellent article on this which is available on the BSCRA web site at www.bscra.fsnet.co.uk/spacers so I won't repeat how to do that here. The rear wheels supplied are somewhat over size and need to be reduced in diameter. If you have a tyre truing machine, you probably don't need me to tell you how to do it. If you don’t own a machine, this is what to do.

Fasten the wheel onto a straight axle and place the axle into an ordinary electric drill. Then hold the drill in a vice (be careful not to over tighten the vice) and switch the drill on. Hold a flat board with some emery paper glued to it against the tyre being careful to avoid the tyre becoming conical. Check the tyre diameter regularly until you get the diameter you require (about 17mm). Then do the other tyre. Make sure that both tyres are the same diameter. Then round the corners off on each tyre for both the inside and outside edges. The best thing I've found to do this is an emery manicure board. Be sure to ask 'er indoors first or you risk being severely beaten up!

Slide the front wheels onto the front axle and then hold them in place with the spring retainers supplied. I always solder these retainers in place and I recommend that you do too. Then you need to wire the car up. The red wire (positive) should go to the left hand side of the guide when looking in the direction of travel. The black wire should go to the right hand side of the guide. BSCRA is in the process of changing the track polarity so you may want to check this out for your club first.

Bend a piece of 18g piano wire to the shape shown in the picture and solder it in place where indicated.

You then need to paint and mount the body.

Painting and Mounting the Body:

First you need to cut the body out as follows: Using a ruler and marker pen make a mark each side on the body 32 mm down vertically from the extreme rear edge of the rear wing. Draw a line across the back of the body joining these two marks together. Then stick a piece of masking tape along the full length o f the body each side from the line you have drawn to the front of the car. The picture below shows what I mean.

Then carefully cut the body out along the lines you have just marked. Place the completed chassis on a slot board, and put the body on top of the chassis. Use the marker pen to mark the position of the holes for the body clips. And then use a pin to pierce the shell in the correct places. Fix the body to the chassis with the clips and mark the position of the front wheels on the outside of the shell using a self adhesive round label (about £1 from good stationers) . Remove the shell from the chassis and mark the position of the wheels on the inside of the shell using more round stick labels. Mask of the windows and then spray the shell any colour that takes your fancy. When the paint has dried, remove the masking for the windows and front wheels. Tape an interior and driver into the body and once again mount the body on the chassis, securing it with the clips. Then trim any excess shell from beneath the car and carefully cut out the rear wheel arches. Mark on a couple of racing numbers and hey presto! You're ready to go!

You will probably find that you need to fix some lead onto the car in order to make it handle properly. This will vary from track to track and the best way to make a reasonable start is to ask one of the quick guys down at your club to show you how they have set their cars up. Then try experimenting by removing and adding lead until you are happy with the car.

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