Part 2

The Repairs.

by Tom  Dandes


Today we will continue on with the sidewinder buildup. I left you last time with the inspection phase complete and the car in pieces.


In this section we will repair each of the cars problems starting at the front and working to the back of the car.



Disclaimer 1: Here again, if you do not agree with the repair tips, do not understand the procedures, or feel you donít have the skills to complete them then donít do this. Take the car to someone you trust and let them work on it.


Disclaimer 2: Some of the tips here may or may not be allowed for competition. Always check first before you modify your car so you can still be in within the rules. Remember cheaters never win (but we will pass you before we crash).






Loose body parts can be a real pain. I actually had a mirror come off a car and wedged itself in the track slot. The next time the car came around it snapped the guide completely off the chassis. Not my idea of fun.


Also about half of all the gear noise problems you come across are from loose plastic body parts not bad gears. Cars with loose body parts vibrate and can sound just like a blender getting ready through a melt down.





Both the bottom and right arrows point to the problems on this car where the plastic parts were not melted together to form a tight bond. They rattle.


Some CA glue was used to tighten these areas up. It was also used to reinstall all the parts that fell off the car we found in Part One. Now it is nice and tight. If there is any noise now itís not coming from the body. No more rattles. No more loose parts. Easy fix.






One trick that was taught to me was to make sure the body does not bind or bow the cars chassis. The chassis should lay in the body without the body sides having to be pried apart.


(The exception to this is some cars have plastic tabs that lock in the chassis and hold it in place. They also use one screw to hold the chassis to the body. These are the exceptions not the rule).


Bad chassis to body alignment can be critical to some cars. An example is on some cars with front motors. Screwing the chassis to the body can bow the chassis severely. When this happens it causes the drive shaft and pinion gear to either move forward or backward. The pinion now no longer aligns to the crown gear and results in stripping out the gear set. Fortunately sidewinders donít have this same problem.


What needs to be done to a sidewinder chassis is for the edges to be sanded down so that it lays inside the body. Leaving the chassis loose like this will also help cure some handling ills because the body and chassis no longer fight each other.


Another trick is after the chassis has been sanded down is to leave the screws for the chassis loose. You tighten the screws down until snug and then back them off until they just release from the chassis. Now place a piece of tape (I prefer medical gauze tape) over the screws to keep them from dropping out onto the track. Leaving the chassis screw loose helps to prevent chassis bind and again can improve handling.



Our body showing signs of were there needs to be work done.


The photo above shows the chassis fitted to the body. As you can see the highlighted areas of the chassis do not allow the body to fit without it being pried apart. The front of the body also hits the chassis keeping the chassis screw holes from centering to the body posts.



Light sanding on the chassis and will help correct this. Just sand small areas of the chassis and then trial fit. Then sand some more. Continue until the chassis just rests inside the body. The thing about getting the chassis sanded to fit is there is no need for huge gapes between chassis and body. The chassis just needs to rest inside. So again light sanding.






Tire truing has been around for a long time. Yet it still amazes me how many people donít check their cars tires. On small tracks cars that have a lot of magnet will hide the fact that the tires are out of round.


Put that same car on a large home or wood track without magnets it will show up real quick.


Our car has some bad tire and wheel issues weíll address. Something to note here is that if a tire cannot be trued it needs to be replaced. There are many good sources out there for stock or aftermarket tires so it is no problem if we have to toss one out.


The procedure listed below is for tires and rims that are off the car. There are other procedures to use if you want to true your tires while they are on the car. I have used them and they work fine.


I true all four tires. But to do this they have to be removed from the car. I also true one tire and rim as a set so the procedure listed below works best for me.


Tool and parts needed:


  1. 3/32 rod or axle 2 inches long.
  2. Wet and dry sand paper 500 grit.
  3. Ĺ X Ĺ square piece of wood molding about 6 inches long.
  4. Small drill press on low speed (Dremel will work but lowest speed possible).
  5. Small container for water.
  6. CA glue.
  7. Toothpick.



Home made sanding stick.


You can save some money and cut a 2 inch wide strip of the sand paper and glue it around the wood molding with contact cement. Now you have a water proof sanding stick.



BEFORE YOU START: If you do not know drill press safety procedures or know how to operate a drill press DO NOT ATTEMPT TO DO THIS MODIFICATION.


(Improper use of a drill press can result in serious injury. I have seen more than one person wound around a drill press screaming for help. So if you have any doubts take your car to some one that knows how to operate the equipment).


If you like the painted tire lettering on the sides of your tires then do not do this modification. You will end up removing most if not all of it.



STEP ONE: Take a 2 inch long piece of 3/32 Brass rod and insert it into the hub of one rim. This will be used as an axle to ensure the tire and rim is straight for truing. The brass rod should not spin in the hub.


(NOTE: If the brass rod does spin a small amount of CA glue applied by a toothpick to the inside of the hub will hold it in place (Remember to use a small amount you do have to remove the rim later).



Brass rod inserted into rim.


STEP TWO: Insert the rod and rim into the drill press and tighten the chuck. Start the drill press on the slowest possible speed (You can use a Dremel but I prefer the drill press. It turns slower and allows you to use both hands).


NOTE: Before proceeding to step three I need you to understand to lightly sand the rims. If you sand too much it there will not be enough plastic to keep the tire from spinning on the rim. The idea is to remove the plastic casting nubs and to ensure the rim is round nothing more.



Center section of rim being sanded.



STEP THREE: Using the sanding stick you made from wood molding and sand paper lightly sand the center rib of the hub until smooth. This will remove part of the plastic casting nubs left on the center of the rim when it was made.



Sanding the edge outside of the center rim section.



STEP FOUR: Using the sanding stick lightly on the flat areas around the outside of the center hub. Sand the rim until smooth and the plastic casting nubs are again removed.


STEP FIVE: Shut off the drill press and let come to a complete stop.


STEP SIX: Wet one tire and slide it back on the rim that is on the drill press. Make sure it is the correct tire (front tire and front rim) and that it is mounted the same as it was on the car. Wetting the tire helps to slide the tire on to the rim.


STEP SEVEN: Turn the drill press on. Wet the sanding stick from the container of water and place the sanding stick against the flat area of the tire first (a light pressure is all that is needed). Keep the tire wet by dipping the sanding stick in the water. The water will keep the tire from overheating.



Sanding the flat area of the tire. I use my finger to dip in the water to keep the tire wet.



Continue sanding until the surface of the tire is flat and no longer bounces against the sanding stick. It doesnít take much to get the tire flat but you do need to take your time. If you try to rush it you will apply too much pressure to the tire and it will spin on the rim. This will cause the tire to start bouncing again because its relationship to the rim has changed. The idea is to get one rim and one tire matched to each other and to operate as a set. Once you feel the tire is flat proceed to step eight.



Squared tire #1, and bevel edged tire #2.



STEP EIGHT: Now take a look at the corner edge of tire #1 above. You will notice that it has a flat squared surface. Flat square edges with no bevel will cause the tire to catch on every seam, joint or rail of your track and help it to de-slot or flip the car. Just like in step seven above sand the outside edge of the tire until it is rounded the same as tire #2. Take you time and keep the tire wet.


STEP NINE: Once the tire is true and the edges are beveled. Shut off the drill press and allow it to come to a complete stop. Hold the drill press chuck I one hand and with the other remove the tire and rim and tire from the axle leaving the axle behind in the drill press. Place this trued rim and tire to one side. It is now matched and ready to be put on the car.


Repeat the above steps until all four of your tires are true.







The other problem with the chassis was front axle slop. This can cause the front wheels to rub the inside of the chassis, and the body. None of this is a good thing.


Here you have to make a decision.


By fixing the axle slop you may now have the front tires touching the track. On some cars the tires roll on the track and on others they were not made to. Some veterans prefer to have their cars work like a tricycle, because it is less drag with the front tires not touching.


Others will disagree. They will tell you that if they can be made to roll on all fours than do it. After all it is scale racing and cars do have four tires.



It is your choice.



WARNING: On some cars the chassis and the front plastic axle housings are not one solid piece. If your car has a separate front stub axle housing that snaps into the chassis do not do this modification. Fly Corvettes come to mind. On this type of car there is not enough plastic material to drill out and install brass tubing. You will ruin the snap in axle housings (I know because I broke a new Corvette).



Tools and parts needed.



For this fix you will need some tools and parts.


  1. 1/8 outside diameter brass hobby tubing. This tubing has an inside diameter of 1/32. The same as the axle. It can be bought at any hobby store and some hardware stores.
  2. Mini tubing cutter.
  3. Measuring device. A ruler or micrometer will do.
  4. A 1/8 drill bit.
  5. A 7/64 drill bit.
  6. Some way to hand turn the drill bits slowly. (I use an old drill chuck I robed from a dead electric drill as a pin vise. Or use a manual hand drill).
  7. Flat jewelers file.
  8. Round jewelers file.
  9. 500 grit sand paper. (I prefer automotive wet and dry paper. It lasts longer).
  10. 500 grit we and dry sand paper
  11. A pencil to mark the tubing for cutting.
  12. Some CA glue.
  13. Two toothpicks.
  14. Pliers.
  15. Two number #3 stainless steel washers(These can be found in the specialty nut and bolt section of hardware stores).
  16. Permanent marker.



Drilling the stub axle housing


STEP ONE: The first thing to do is to start small and use the 7/64 drill bit to drill out the two front stub axle housings. Warning: go slow with this as you can break the plastic housings (I recommend not using an electric drill. If the electric drill binds it can break the plastic housing).


STEP TWO: Now use the 1/8 drill bit and do the same thing. Again go slow.


STEP THREE: Once the holes have been enlarged measure the axle housing to find out how much tubing you need to cut. You will need two pieces.



Measuring stub axle housing.


NOTE: Once you have your measurements add 1/32 to each piece and mark it with the marker.


STEP FOUR: Now using the tubing cutter cut two pieces of tubing.



Tubing cut for inserts



STEP FIVE: Use the sand paper to sand down the raised edges left on each of the tubing by the tubing cutter. Here I have them on a round file to make it easy. Just a light sanding is required here. Too much and youíll have to cut new tubing because the outside diameter will be too small to use.



Sanding edge off brass tubing.



STEP SIX: Place a small drop of the CA glue on the end of a toothpick. Use the toothpick as an applicator to place the CA glue on the inside of one axle housing.


Start one piece of tubing in the hole you drilled for the axle. Use the pliers as a press and push the brass tubing all the way in until both ends of the tubing are flush to the plastic axle housing.



Pressing in brass tubing.



STEP SEVEN:Do the same to the other side of the chassis and then let the CA glue dry.


STEP EIGHT:Use the flat jewelers file and file the ends of the brass tubing and the plastic housing. This area needs to be flat on the inside and the outside of the chassis. You need this to provide a good flat running surface for the wheel hubs and the stub axles to turn against.


STEP NINE: Use the round jewelers file on the inside of the brass tubing to remove any burrs left from the tubing cutter and the flat file. Using your stub axle, insert it into the brass tubing to check your progress. The stub axle should slide in easily and not catch or bind.


NOTE: Do this to both sides of the brass tubing, And to both sides of the chassis.



Completed flush bushings.



This is what you are looking for when you are finished filing down the brass tubing. The brass tubing is now flush to the plastic axle housing and the axle housing now has a flat surface. This is why I said to cut the tubing 1/32 longer than needed.


STEP TEN: Take the two #3 flat washers. The washers will have a slight concaved surface to them. Remove the concaved surface of the washers by placing some 500 grit sand paper on a flat surface and slide the washer on it until flat.



Completed front-end assembly.



STEP ELEVEN: Reassembly.


Place the washes on the stub axles. Put your favorite lubricant inside the brass tubing and press the stub axles and washers into place. Adjust the stub axle in or out of the hub until the tire spins freely and there is little side-to-side play in the axle.


Or you can leave out the stub axles and use one solid 3/32 axle going all the way across the chassis. Again your choice.


(Youíll notice with this mod that the axles no longer move around inside the axle hub and that they spin freely and smoothly. Also the car will no longer look like front end has collapsed).








When it comes to sidewinder gear sets there is something everybody should realize.


1.      All gear sets whine. It is a fact of life. A good gear set and motor will have a slight whine to them. But grinding gear sets are another thing.


2.      Some gear sets just have to be ran to get them to quite down. This is because of the material they are made of and the pitch (angle of the teeth) they have. Time will improve them.


3.      Gear sets have different pitches to their teeth and different pitches should not be mixed.


The problems we have are:


1.      Pinion gear made to long causing it to rub the wheel and tire.


2.      Some motor shafts are to long causing them to rub and grove the tires.


3.      Bushing clearances that are to tight causing axle binding.


4.      Axle bushings that spin in the chassis.


5.      Spur gear depth was not far enough on the axle causing knurled area of the axle to bind the axle shaft.


6.      Spur gear side mating surfaces not flat.








Problem: Spur gear hits and grooves the tire.


Tools and parts needed:


1.      Two inch piece of brass rod or steel rod for the pinion gear modification.

2.      Jewelers file set.

3.      Drill press on low speed.

4.      CA glue.

5.      Gear puller/press.

6.      Black permanent marker.



Pinion and spur gear.


STEP ONE: Place the pinion against the spur gear. You will notice that about half of the pinion hangs over the side and never contacts the spur gear. It is this half of the pinion we want to remove. Use a marker and mark the excess area of the pinion.


BEFORE YOU START: If you do not know drill press safety procedures or know how to operate a drill press DO NOT ATTEMPT TO DO THIS MODIFICATION.


STEP TWO: Using the axle press place the pinion on the piece of brass rod and press it on until the end is flush. If the pinion is loose add a small drop of CA glue before adding the pinion to the shaft.


Pinion marked for machining.


STEP THREE: Place the brass rod and pinion in the drill and start it spinning on low speed.




††††††††††††††††††††††††††††††††††† Flat file.††††††††††††††††††††††††††††††††††††††††††††††††††††††††††† Flat file showing thin side with no teeth.



STEP FOUR: Remove a flat jewelers file from the set. Look at the thin sides of the file. One side will have teeth and the other side wonít. We want the thin side without teeth pointing straight up.(It has to face upward).



Flat file against pinion.


STEP FIVE:Place the large flat area of the file against the black marked area of the pinion and hold it there with light pressure. The file will slowly remove material as the pinion spins in the drill press. Keep in mind you only want to remove the black marked area only.


(The area of the file that has no teeth will keep the other half of the pinion from being turned down or damaged).


STEP SIX:Remove about half way down into the pinion gear. Do not remove all of the material. Leaving this excess will ensure the pinion does not spin loose on the motor shaft. Once you are half way remove the file. You will see that the pinion is now stepped.


STEP SEVEN:Shut off the drill press. Allow it to come to a complete stop.


STEP EIGHT:Once the drill press has come to a complete stop remove the pinion gear and shaft from the drill press.



Turned down pinion.


This is what you should have ended up with. Notice the stepped pinion.


Half of the teeth have been removed. Now the pinion is the same width as the spur gear and there is no way for the tire to rub pinion.



V file and pinion gear.


STEP NINE:Use the V shaped file from the jewelers file set and remove any burs left from the turning process. File the gear teeth lightly you just want to remove the burs and not damage the teeth.


STEP TEN:Using the gear press remove the pinion from the shaft and set aside until you are ready to reinstall on the motor. If any CA glue remains on the pinion gear use finger nail polish remover.



This completes part two of sidewinder blueprinting. Part three of this series will continue with modifying the spur gear, motor shaft, axle, and guide modifying. The last phase will be reassembly.


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