Fray Car Tuning
By Tim Leppert
Gear plates and matching

OK Here we go:
You will need:
1.) The radio (AM and tuned to no station)
2.) A power supply rated for 18-20 volts. Plugged in to the same receptacle as the radio.
3.) A small, sharp pointed probe, or toothpick
4.) A set of sharp pointed tweezers.
5.) Some Wizzard brand brushes (do not scrimp on these. They are the ONLY brushes I use)
polish faces on a piece of paper setting on a hard, flat surface.

OK
Find That good chassis, throw on some shoes and let's get to it!

First, make SURE you know which direction your power supply is running. and where to place magnets for proper rotation. The best way to do this is to take a car you know runs in the proper direction and test the supply.
The arm should rotate clockwise when all is right.
THIS IS IMPORTANT!!!!!!!!

Now that we have that done, let's start testing.
Grab that good plate, an arm and brushes, assemble with clamp
spool it up and remember the tone. Then turn the chassis around and spool it it up backwards, you should sound better forwards than backwards.

Don't change anything yet.

We want to "seat" the brushes.
We do this by getting the arm running and pressing the brushes against the com, GENTLY.
Try to stand up the chassis and get it running and use the toothpick to do this. Press in the center of the valley of the brush tensioner. You should feel the brush directly thru your fingers.
You will hear the revs go down a little, then release and repeat. Don't allow the arm to stall when you do this. This should gain some revs for you.

The next thing to listen for is spinning brushes. This is something you don't want. If you have a good solid tone, your good.
If it sounds like you are slightly changing the position of your controller, you have a brush spinning.
To stop this you will need to scratch an "X" in the bottom of your brushes and then reseat. This should correct the problem.

Now we get to the good stuff.
If your arm spins faster in the proper direction (clockwise) skip this next step.
If your arm spins faster counter clockwise, then we need to correct it.

Remove the arm but not the brushes. Align your chassis so that you are looking from the back to the front. You should be looking at the front brush.
The right side should be higher than the left. To do this, remove the brush and grab the "v" with your tweezers from the side you want to be higher.
GENTLY tweak it up, and replace the brush and inspect.
This is a very delicate adjustment, so go slow.
Simply turn the chassis around and repeat for the back brush. Try to get them looking the same.

When this is done to your liking, we will move on to adjusting tension. There are many ways to do this, and I will not get into all of them here. This is my favorite method,
Remove the arm and brushes. Looking from the top, place the toothpick in the valley of the tensioner and gently push up. this will bend the spring at the root of the "v" not back by the rivet. Do this a little at a time, checking your progress with the brush.


But try this test first.

Turn on the radio, turn the station selector to a spot were there is no signal.
Now spool up your chassis. You will hear the static change. This is a poor man's oscilloscope. It will let you know how efficient your little motor is running. As you play with the brushes, adjusting and changing, you will find that the static will get louder and softer depending on your adjustments.
The quieter you can get the signal, the better your arm will perform.
You will also find that certain arms are quieter than others in that chassis.

Avoid over adjusting the brush tensioners. they are very delicate. if you get into trouble and bend one the wrong way, you can save some of them by making a little lasso out of dental floss and pulling it back.

Never try to add tension with the chassis assembled. Always remove the arm and brushes.

When you have it close, start changing out arms looking for the one that sounds good.

Next Installment: Rear End Gearing
Previous Installment: Armatures

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