Super Stock Tuning Guide

16 ohm may be a good choice. I was just trying to set it low enough so there would be no problem meeting it, but I see that opened up its own can of worms!! A guy shouldn't have to buy 100 arms to find find the one freak that measures 15.1 ohms. Stand by for updates!!! lol

When selecting a motor I look for one that has a flat comm plate. Doesn't do any good to have the face of the metal plates not making contact with the motor brushes. Even small waves can cause the motor brushes to bounce in their holders - no electricity transfer means no power.
I chuck the motor up in my dremel (the chuck is available at Walmart for ~ $11 and it holds the motor perfectly centered by holding the shaft.

Here is a stock motor that has nasty fouling on the comm plate.


I then use a flexible very fine grit polishing wheel (I bought a gunsmithing polishing wheel kit with a wide variety of grits) that I hold in my hand and touch it against the shaft & comm face while it is spinning and also to remove the old crusty layering that has built up on the copper face of the comm plate. Clean as a whistle afterwards.



After the polishing is complete I can rotate the Dremel shaft by hand very slowly and I hold the motor at this angle so that I can look across the face of the comm plate and look for how flat it is. While you are rotating it you can see if it is flat or has rolling hills. Believe me you can't imagine how wobbly the comm plate can be. There are remedies to fix a comm plate that isn't flat but it doesn't always work.

So you think you've got a fast car? Could be lots of vibration that makes it sound fast when it really isn't. I used to use the old "ear dyno" but it lies to you big time. So the simplest solution is to make an inexpensive dyno. Radio Shack or eBay sells this voltmeter. I got a motor from a tape deck and glued it onto the voltmeter. Then I soldered the leads to the motor, put a hub and tire on the motor shaft...voila! Instant, portable dyno.
Just make a power supply and solder alligator clips onto the wire ends. Then attach the clips to the pickup shoes of the chassis and then lower the rear wheel until it contacts and spins the dyno wheel. It will read a number on the volts - the higher that number then the faster the motor is spinning. You can use this dyno to help you find the fastest combo for your car. Swap between top plates, try different motor brushes in each cup, gently press up against the motor brushes on the underside and if the motor wants more spring pressure then it will respond with more rpms... Be VERY careful when adjusting the motor brush springs upward - you can ruin them easily by putting too much bend in them. You must remove the top plate and motor brushes to be able to properly adjust the pressure of the motor brush springs. Remember to match your power supply to what the power supply will be for the track that you are going to be running on since some motors run very well at 18 volts but terrible at 13.8 volts. One simple solution for an adjustable power source is an old train transformer that has the handle on it to allow you to increase/decrease the amount of power. Use your newly acquired voltmeter to set the DC power output of the train track transformer.

How to balance a motor? I like razor blades, long ones too. I bought some at Home Depot and then got a couple bolts, washers & nuts and sandwiched the razor blades in between the washers. Works well enough for me. I do the initial balancing on this device then move the motor over to a jeweler's balancing tool. It's got very fine/sharp edges to rest the motor shaft on to do very detailed balancing.


Once the motor stops turning I use a Dremel diamond wheel to cut a slot into the metal lam and remove metal. Remember it is the side that ends up on the bottom that you want to grind away at. Remember it's a diamond wheel - it will buzz clean through the metal lam in a hurry so go slow and don't take off too much. You'll also cut into the wires and ruin your motor if you get careless. (BTDT).


Here are some slots that I cut into the lams to remove weight.


Another method of balancing is to add lead weight. You can cut slivers of lead off fishing weights to add to the motor. Remember, if you use this technique that you will have to add the lead weight to the TOP of the motor when it stops on the razor blades. You can see a square of lead on the right side of the motor that I added on the top of the comm plate and to the inside of the end of the lam. I use super glue to attach it to the comm plate.

Excellent tuning tips Tony. These are very helpful.

Here are some that have been adjusted for LOTS of pressure. Of course you can adjust them too much and totally dork them up ruining the chassis.


Ruined motor brush spring: