The Dynamic / GE Slot Car Motors
By Ye Olde Editor

By 1967, the horsepower race was on in the slot world. The 500 size can was being refined to new levels,
with Champion and Mura both making their own motors instead of buying Mabuchis.

The result was that at any given time, all commercial rewound motors were approximately the same power.
The Pros could coax a more out of them, but the average guy had the same power as everyone else.

Several companies took the approach of trying something different. One of them was Dynamic.
They got GE to modify one of their standard motors to slot specs, looking for more power and torque
than any rewind on the market. And they got what they wanted. Unfortunately, it wasn't exactly what they needed!!!!!

The "stock" wind is about 75 turns of 27ga wire - for about a 0.4 ohm resistance. The peak torque is more than 10 TIMES
greater than Dynamic's own Green Hornet 36D rewind! Granted, the Green Hornet only has stock magnets,
but even so, the GE is a BRUTE!

All of this torque is developed at relatively low RPM, and therein lies the problem.

Tom Malone did a comprehensive article on the GE motor in the September 1967 issue of Car Model Magazine.
Check out the Motor Article Search Index to read the whole thing.

He discusses the big problem with the GE Motor: excessive "brakes".
The high torque, low RPM, big strong magnet approach yields a car that stops abruptly, in a "tail-out" attitude.
Malone talks about using "taller" gearing (2.5:1) to try to get the car to coast more.
He also got the revs up by  going to a much hotter than stock, 40 turns of 28ga double wind.
But the results didn't change that much.

Let's take a look at this motor (Click on photos to see larger size):

Here's a closeup of the "Dynamic Powered" foil Sticker. Note the one small diameter cooling hole on the top and bottom. If you look closely at this photo, you should be able to see the numbers 3ADM4 just above the cooling hole. The shaft is .093, only comes out one end, and there are no flats on the shaft.>>>
	<<< Shaft end view, with a Champion 707 as a size comparison. By 1967, the 707 size motor was obsolete. Both motors had an 0.093 shaft diameter.
Here's a look at the brush end of the case. The screws that hold the brushes in, also secure the endbell to the can. >>>
	<<< If you look closely, you'll see that the brushes have a shunt wire out to the mounting tab, for maximum current carrying capability.
With the brushes out, just give the shaft a tap, and the endbell pops off. Unlike a Mabuchi, the shaft doesn't have any splines, so the armature slides right out. Big diameter, short stack.>>>
	<<<Look closely and you'll see the amazingly thin (less than 1/8" thick) yet powerful magnets. They are molded in, so there is no spring clip to mess with.

Dynamic offered both an inline and sidewinder frame for this motor.
The sidewinder version needed an idler gear for clearance,
since it was set up as a true sidewinder, not an anglewinder “Big Jack” Garcia,
head of Team Dynamic briefly campaigned the inline version in the Pro wars,
with minimal success.

Here are drawings of the frame from the 1967 Dynamic Catalog:

I’ve run one of the inlines, and it had a nasty habit of plowing straight ahead when you wanted it to turn!

These were made available in a few RTR’s – here’s my Dodge Charger – Low, Wide and Warped!

After re-reading all of this, and thinking about it for awhile, I think I would have
taken a different approach. I'd want to reduce the power & torque, while raising RPM.

First I would try to decrease the effectiveness of the magnetic field. Since the magnets
are molded into the can, I would skim the armature diameter to open up the air gap.
Since the magnetic attraction between objects is inversely proportional to the square of the distance,
opening the air gap by .0025" would result in a 1/3 decrease in the magnetic effect.

After re-reading all of this and Gary’s letter, and thinking about it for awhile,
I think I would have taken a different approach. I'd want to reduce the power & torque, while raising RPM.
First I would try to decrease the effectiveness of the magnetic field. Since the magnets
are molded into the can, I would skim the armature diameter to open up the air gap.
Since the magnetic attraction between objects is inversely proportional to the square of the distance,
opening the air gap by .0025" would result in a 1/3 decrease in the magnetic effect.

Next, I’d go to a milder wind than stock. Try 29ga wire – maybe 85 turns. Don’t balance the arm yet.
See if this makes the car a little more drivable. If there is improvement, try another wind with more turns of 30 ga wire.

Once you find what gage wire seems to help, then I’d go with a double wind equivalent of this gage.
In my own winding experience, I’ve always found that a double wind increases RPM and decreases torque.
Remember that you go 3 wire sizes smaller ( i.e. double 33 equals single 30) for the same overall resistance.

Well, that’s about it. If anybody has any other thoughts or experience, I’d love to hear what you have to say.
*************************************

Dynamic / GE Motor Parts List:

Part	Number
Silver Hornet Motor 75T of 28Ga Wire	208
MKIV Silver Hornet Motor Originally 45T of 27Ga Wire, then 40T of 26 Ga Wire; Dynamically Balanced	213
Brush Assembly	220
Endbell	221
Wound Armature	222
Can with Magnets	223

Dynamic Frames for GE Motor:

Part	Number
DynaFlex I/L Chassis & 208 Motor	254
DynaFlex S/W Chassis & 208 Motor	255
Brass I/L Scratch Builder Motor Mount	343
DynaFlex I/L Chassis Complete	453
DynaFlex S/W Chassis Complete	454
DynaFlex I/L Rear Mount	478
DynaFlex S/W Rear Mount	479
DynaFlex Complete RTR I/L Chassis w/ body mounts	2010
DynaFlex Complete RTR S/W Chassis w/ body mounts	2011

Dynamic 1/24 Cars:
All featured the DynaFlex Die-cast aluminum Inline Chassis
& GE Silver Hornet Motor #208 ("Stock" version)

Body	Kit or RTR / Number	Colors
Mirage Can-Am	Kit  / 2023	Black, Red
McLaren MK6	RTR  / 2003	Orange
Chaparral 2F	RTR   /2025	White
Ferrari P4	RTR  / 2006 *	Red
Ferrari 3-liter V12 F1	RTR  / 2007	Red
McLaren M6GT	RTR / 2006 *	Orange
Dodge Charger	RTR / 2004	Blue

*  These cars were numbered alike