Tech Help, Motors

Winds of "Double," "Triple," or Quad" refers to the number of strands of wire wound around the armature, double being two strands, triple being three, quad being four, and quint being five. The type of wind is for fine tuning your motor's power band. In general, winds with fewer wires give the impression of kick-starting your wheels, while the winds with more wires will bring you up to top end speed more slowly.
If you have a very slick track, then winds like single and double may cause your wheels to spin; other winds--triple, quad, quint--may give your car better traction. In addition, the less turns of wire, the less run time you will have, because fewer wires will draw more power from your batteries.
The performance gains by changing the type of wind is subjective and may be noticed only by experienced racers with vehicles that respond well.

4 Will comm drops ruin your comm?

Comm drops will not usually ruin your comm, but most of the time can ruin your brushes.

5 Can you explain turns?

Turns refers to the number of times the wire was wound around each armature arm. The fewer the turns, the higher the rpm (revolutions per minute), or top end speed (the highest speed attainable by that motor). So, if you wish the fastest motor, choose a motor with the fewest number of turns. Keep in mind that the fewer the turns, the greater the battery draw, which means lesser run time.

6 On average how many runs can I get out of the brushes on my stock motor?

In competition you should change them about every 5 runs. In just everyday running you might want to change them after 20 runs. (for Mod. make it every 10 runs). True the comm before installing new brushes.

7 Are there any specific motor lathes recommended?

Hudy, Trinity, Fantom, and Integy make good ones. The old Reedy comm lathes are no longer in production.

8 My Reedy motor, running at the lowest speed, got very hot quickly, unlike it would if I ran it near top speed for twice as long.

Check the gear mesh and for anything that could cause binding, that would prematurely heat up the motor. Also if you have the motor under geared it could have the same effect.

9 Could you send me the specs (RPM, torque, power, efficiency) on the Reedy MVP Plus?

These are approximant specs on the motor: RPM, 23 to 25,000. Torque, 6.8. Wattage, 98. Efficiency, 67 at 22.0 amps.

10 The motor, battery, and ESC get extremely hot after about 3 min. The motor gets so hot that the solder joints release. I am also melting Tamiya plugs on battery and ESC.

You might have the motor and pinion set too close. Make sure that the gap is set correctly: Loosen the motor and back it away from the spur gear. Now take a strip of paper and place it between the pinion and spur as you move them together. Tighten the screws and then turn the spur gear and get the paper out; that should give you the proper mesh. Also make sure that you do not have the motor overgeared, that would make it run hot also.

11 There are sparks that come from inside of my engine. It still runs.

The sparks that you are seeing is the motor arcing. Nothing to be afraid of.

12 Do you think I should use softer springs when using serrated brushes? I've heard it gives less punch, but will the commutator wear more.

Lighter springs produce less amp draw and longer comm life. Lighter springs are not "required" with serrated brushes.

13 With the motor so close to the speed controller and receiver, how do you keep the electronics from picking up noise from the motor and glitching?

As long as the speed control is not in direct contact with the motor there should be no problems as far as glitching goes. You should always run three capacitors on your motor. This helps cut down most of the radio noise that causes glitches.

14 When setting up a comm-lathe, where should the bit line up on the comm?

The comm lathe bit should line up just below the center of the surface of the comm.

15 What is the purpose of the degree marks on the outside of the motor can?

The purpose of the degree marks on the can is to let you know how much timing is in your motor. The more timing, the faster the motor, but with less torque, and your battery life will be decreased. Less timing means less top speed, but more torque, and more run (fun) time.

16 Can the motor get too hot from being undergeared? I know it will if I have the truck over geared.

No, undergearing will reduce the load on the motor. It will increase run time and decrease top speed.

17 How do soft and hard brushes affect my motor's wear and performance?

Harder brushes are harder on your comm, but do provide a little more power than softer brushes.

18 I know the formula to find the ratio, but how do I know if I'm overgeared or not?

The motor will always be hot at the end of a run. There are two things that I use to determine first if I am geared correctly for the track size or to watch for overgearing. For overgearing, my rule of thumb is this: Five minutes after the race the motor will still be warm but I will be able to hold it in my hand without feeling like I am going to get burned. You can also watch the motor brush braided wire. If you are overgearing the motor, the braid will begin to discolor and turn a dull yellow gold. If you overgear to this point, the brushes will have to be changed to help prevent damage to the commutator.
Brushes normally only last for about 10 to 15 runs before they start to do damage to the commutator on the motor.

For racing, remember one gear ratio will not work for all size tracks. Do not try to be the fastest car on the straightaway. It is more important to be quicker in the infield. At best you will only be able to gain up to about ½ second on the straight if you are faster, but if you are quicker on the infield you can gain as much as 3 to 4 seconds a lap depending upon how many corners you have each lap. Every corner is a chance to gain on the other drivers by being quicker out of each corner.

19 I am having a difficult time understanding the gearing concept. I know how to figure the final ratio, etc. but what I don't understand is why the motor runs hotter when I put in a bigger pinion.( an 18 to a 23) because if I put a bigger pinion in with my 87 spur gear, the final drive ratio tells me that the motor is turning less turns to produce one tire rotation, so if the motor is working less (less turns) why does it run hotter?

You misunderstand the mechanics of power and rpm. Yes, a larger pinion will mean the motor has to turn less rpm to move the wheel one rotation but this means the motor will have to use a lot more power to make that wheel turn one rotation. In electric motors, using more power also means the motor will generate more heat. Think of it as the difference in starting a car in first gear as opposed to fourth gear, or a ten-speed bike starting out in low gear as opposed to high gear. It is possible to start and run a car in fourth gear, but it does not accelerate quickly and the motor gets a lot hotter, or your body has to work a lot harder on the bike. You have a limited amount of power for each motor. The trick is learning to gear a car or truck to take advantage of the rpm range of the motor, but still keep the motor within its power range. As you have seen, gearing up too much creates a lot of excess heat.

20 Is a higher wind in a motor better?

It all depends on what you want from a motor. A higher wind motor will be a little slower, yet easier to drive. A lower turn motor will be faster and a little more difficult to drive.

21 Does a stronger magnetic force field in the motor necessarily mean it will go faster?

The stronger the magnets are in a motor, the stronger and more efficiently the motor will run.

22 Would it be an advantage to have individual cells or matched cells?

Having individual cells or matched cells will make only a small difference.

23 What exactly does 'single' and 'triple' mean on the inside of the motor?

'Single' and 'triple' refers to the number of strands of wire for that particular wind. 'Single' would be one thick strand, while 'triple' would be three thinner strands.

24 What exactly is achieved by dyno-ing a stock motor, and is it really worth my time & money to have it done?

Dyno-tuning stock motors gives you the feeling of knowing how your motor compares with others. Most people look at the rpm. I think that is the third thing to consider. You should look at the power numbers and torque numbers. If they are good you will have a good stock motor; all you do is adjust your gearing to those numbers.

25 When reading the specs on a motor should the power be a higher or lower number and should the efficiency be higher or lower?

The higher the better for both readings.

26 When is it better to use the 4 Mag design over the 2 Mag?

A four magnet will give you more top end rpm. A two magnet will be a little more torque.

27 What the differences between the Kr, Pt, Ti versions of modified motors?

Kr = mid comm, laydown brushes, four magnets.
Pt = small comm, stand up brushes, four magnets.
Ti = small comm, stand up brushes, two magnets.

28 Is part #777 really $29.99 for a pair of brushes?

Yes, that’s the price of premium brushes which outlast regular brushes.

29 Whenever we use a fan clip-on heat sink on our cars, we experience glitching.

Make sure that you do not have any power wires running near the receiver.

30 I messed up the timing on my Kr motor.

The timing on the KR should be set on the first timing mark (12 degrees).

31 Is there any other way to break in a motor besides running it 3-5 min on a 3-5 volt battery?

You really want to run the motor in at low voltage for several minutes.

32 I would like to get more top speed along with torque in the lower end. Right now I'm running a 21t pinion with the stock spur. I was considering going up in spur and down a couple teeth in pinion. What should I do to get good top speed but keep the zip?

You cannot get more torque and more top end at the same time. If you choose more of one, you’ll get less of the other. If you have a short track, you may want more acceleration than top end, because a short track will never let you get to top end anyway. If you have a large track, you may want more top end than acceleration.

33 With the Mamba brushless system in place, what pinion and spur gear combination do you think I will get the most speed out of the truck?

Brushless motors produce more torque so you can gear them a little higher than a brushed motor. I would go up one tooth at a time until the desired speed is obtained.

34 Is the KR more powerful than the Ti Worlds?

If everything besides the magnet count was equal, then yes. However these are two different motors. The Ti is better for small to medium tracks where acceleration is important. The Kr is better for high speed tracks were RPM is more important.

35 How to tune my motors with timing?

Here's what the #9656 Complete Tuning Guide: B4 eBook says: "Motor timing is accomplished by loosening (but not removing) the two top screws of the endbell (not the brush hood screws) and turning the endbell slightly. Then the screws are tightened again. Turning the endbell to the right on Reedy motors gives you more rpm and less torque, to the left results in less rpm and more torque. The timing has already been set optimally by the factory, so carefully mark a tick mark on the can aligned to a tick mark on the endbell ... so you can later return it to its original position. Reedy strongly recommends you keep the factory /setting. Do not turn your endbell to the left beyond the timing point on the can."

36 Why is #737X brushes the best for off road?

Because they make good power and need less maintenance than other brushes.

37 I want some info about my discontinued Reedy motor.

Try http://aedownloads.com/pdf/oldMRmotors.pdf

38 I'm thinking about purchasing a new motor. Any recommendations or advice for me?

Your motor selection will depend on what you plan on doing with the car. Do you plan on racing or just playing in a parking lot with your friends? If you plan on racing what class do you think you will run? What batteries are you going to use? If you plan on using low cost low mah stick pack batteries then you may as well forget modified. Ok now that I am done babbling I would suggest you look at the Reedy Quad 19 turn spec motor. It will give you near modified speed and close to stock runtime and drivability.
We have an article online that will help you choose a motor. IN the Reedy section, choose: "Buying Your Next Electric Motor."

39 What is the smallest size that a stock motor comm can be cut before performance fades?

The smallest the comm can be cut is .270 of an inch.

40 Running stock tonight my motor got so hot it unsoldered the connections to battery wire and fused the engine and battery connectors together

The positive and negative wires touched together. This shorted out the motor, which explains the solder melting.

41 I soldered the connections to the motor. Every now and then it cuts in and out. Are my connections good?

The motor may be dirty. Try and clean it out with a can of motor spray that is available through your local hobby store.

42 How many turns on the Reedy Mini Max?

The Reedy Mini Max motor is approximately 19 turns.

43 Does the Reedy Stock MVP meet ROAR requirements?

It does.

44 How fast does the 1:18 car/truck go? How fast does the "Reedy mini-max" modified motor go?

The stock vehicle out of the box will have a top speed in the area of about 20 mph. The Reedy modified motor will be slightly faster the stock motor.

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