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A "Classic" WM(26)D

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#1 havlicek


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Posted 26 November 2017 - 07:59 AM

...certainly the slot car motor equivalent of a "WMD", and a "26" sized Mabuchi, hence the title.  Sometimes I just can't help myself.  :D  

This started out as one of my early rewinds, and as I sometimes did, I kept this one in a little box to revisit later.  I gave it a couple of drops of oil fired it up and...YIKES.  The motor absolutely screamed to life, drawing almost 4 amps, although not getting all that warm, considering the frightening sound it was making.  I took apart the motor and found a #28 double-wind lurking in there on a Mabuchi stack with a Mura com.  Well, (*as Joe Kenda might put it)..."my my my, now that explains everything!

So even though the motor seemed awfully happy with such a silly arm in there, I didn't like the old com being there on such a hot wind, and a 4 amp Mabuchi is just silly.  I had done a ton of work already to the setup.  Both the can and the end bell had been adapted to ball bearings, the end bell got "the treatment" with the brush tubes soldered to the "pentroof" hoods, and those brush tubes had been substituted for the larger "36D" sized ones.  On top of all that, I had made a full-can shim out of a slightly smaller industrial motor.  These had to be installed with my arbor press they're such a tight fit, and into that went a set of STOUT magnets.  The original paint, and my earlier black and white sticker remained, along with the original "Classic" sticker.

Determined to get the current draw down, and to use a modern com for a little bit of insurance, I pressed a Mabuchi 26D stack onto a new drill blank shaft, spaced that and powder coated it.  I then wound me up a #29 double wind (*I mean, we're talking "vintage" here right?).  I reassembled the motor with it's new heart, and it still winds like ku-raaay-zee, but current draw was down to just under 3 amps..."mo betterer".  I then substituted the 4-coil springs I had on there, for a set of lighter ones and revs sounded no different, but current draw was down even further to just above 2 amps..."mo bettererestest"!  Spring tension is a funny thing, but the way I "figgerz", if the motor sounds no different with a lighter pair of springs, but current draw comes down, the motor is telling you that it had more spring than it really needed.

Sometimes I'll do what seems like (*and really is) a silly amount of work on one of these old motors and still wind up asking myself...why?  Not this time.  This is a "ballz-to-the-wallz" Classic 26D.

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John Havlicek

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