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9/24/2010 8:01 pm  #1


So your best car falls off. What now?

I ran into this very same problem, as have everyone else at one time or another. When I first started racing, I had no idea about armature reconditioning or recharging the magnets, or anything else that would help a motor after it has lost its edge. When that motor tanked, I was stuck with a boat anchor that used to be the quickest car in the class. Understandably, there wasn't much help offered to get it running again either! So here are a few tips for new guys on keeping that motor running.

First is to get the armature reconditioned. There are many companies who will do this for you for a very reasonable price. The arm is put in an ultrasonic cleaner  after it arrives. Then reconditioning the armature consists of turning the commutator in a lathe to get a true, round surface. After that, it is dynamically balanced, new dye is applied to the stacks and its ready to reassemble.

Second is to send the can with the magnets and get them zapped, or recharged. Magnets lose strength over time, and from heat. Replace the oilites before you send it out. If you dont have an armature slug that matches the airgap of your motor for installing oilites, there is another way to do it. Just take your armature and wrap it with tape until it just fits inside the magnets. Make sure the seam of the tape is between the magnets at either the top or the bottom. This will center the arm in the magnetic field as close as you can get without specialty tools. Remove the old oilite and put the new one on the arm and solder it into the can using the tape wrapped arm to center it.

Both of these services are offered by the same companies.

I personally use the USPS Priority Mail to send mine. It is cheap, quick, and I have had no issues with them at all. Its kind of nerve racking to send your motor out the first time for fear of it not returning, but it will.

When it returns, reassemble the motor, shimming the arm for minimal side play. Just make sure it isn't binding. Then install your brushes and springs. The next step is to break-in the motor.

IMHO, the best way to do this is the water break-in. Submerge the motor in a glass of water, run it on 3 volts for 45 seconds. Remove from the glass and dry the motor out by blowing in it or whatever means you have at hand. There will usually be some brush dust in the grooves of the commutator after this. Take an Exacto knife, and using the BACK edge, lightly clean out the grooves. Put some oil on the oilite bushings and run the motor for a bit and make sure everything is as it should be. Put your gear back on and you're back in business!


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
 

9/25/2010 5:07 am  #2


Re: So your best car falls off. What now?

Good Post Steve B ,  after the last time I raced I went back and cheacked my records and had Three motors that steadily dropped time each pass, instead of just buying new one I had  the magnets Zapped,and comms turned,new brushes,and they are back to where they were when I started keeping track! could have almost bought another as it was a S16d but if your running Grp12 or 20's or bigger defenatly a money saver!

 

9/25/2010 6:01 am  #3


Re: So your best car falls off. What now?

Thanks David! I usually used the services of Alpha in Wisconsin. They charge $6.00 to true and balance the arm, and to zap the magnets. Priority mail was 2.00, and you could put alot of arms and cans in the package for that amount. If you send them out on Monday, you will have them back by Friday. Excellent service!

Typically, most over the counter motors will be faster when they come back because the arms have settled in and have a better balance after reconditioning, and the magnets lose some strength from the time they are made to when you get to use them.

If you recondition an arm 3 or 4 times, you can put a ton of runs on it before it goes up in smoke. Pretty good deal IMHO.


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
     Thread Starter
 

9/25/2010 11:41 am  #4


Re: So your best car falls off. What now?

I guess the good thing with a bracket car is you can delay the work, til cashflow allows, by increasing the dail-in accordingly.  With Heads up or Index, you just dont make the field.

Mark


Any sufficiently advanced technology is indistinguishable from magic
 

9/26/2010 10:46 am  #5


Re: So your best car falls off. What now?

The problem with a motor once it starts slowing down, it doesn't level off, it just keeps slowing down more and more. Making it hard to guess just how much to adjust your dial-in.


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
     Thread Starter
 

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