Marcelo,
For your first question, about Parma and Trinity S-16 competing with RJR or Koford S-16, I am not sure if it is a performance question or a rules question. In most S-16 racing, the promoter or sanctioning organization sets the rules (perhaps even just a local raceway), but most places allow any true S-16 specification arm to race with any other. Some places require only Parma or Trinity made in China, because they are generally a bit slower and always less reliable than American made armatures. Incidentally, Koford does not make a S-16 arm, but ProSlot does. It is also marketed by FastOnes and several other 'blueprinters'. As for modifications, again the promoter decides, but most rules allow any springs, any brushes, any setup sold with the armature inside (both new and old Parma and Trinity), magnets zapped, matched, and glued but NOT shimmed, no spring insulation, no shunt wire, no timing limit (except Challenge Cup, limited to 25 degrees and by inference, not allowing the Trinity Adjustable Timing setup).
Your Trinity armatures seem to be one (.486 length) that was intended to be a true S-16, but is a few thousandths short of the minimum specification of .490", and one that was marketed as an "outlaw" Super 16. Some raceways allow them in the regular S-16 races, claiming they are hard to tech without requiring a teardown: Most sanctioning bodies do not consider it a true S-16. The shortstack arm will run faster and hotter, and should use a gear ratio to reflect higher RPM.
I have not tried, or heard anything much about the SmartBrake. If you feel you need an adjustable brake, you should probably just mount one to the controller. One thing I am sure about is that it cannot increase brakes over a standard three wire resistor controller setup, although it may very well provide effective partial brake control. From its description, it seems to be similar to the Cidex variable brake scheme, which uses a diode to limit the reverse EMF brake spike. Speaking only as a private person and in my opinion only, I would use a variable resistor for limiting brakes.
Good luck and good brakes. Techman

Rob,
I, and most every other motor builder around, use armature 'slugs', available from Koford, Camen and others in a large variety of diameters. If you have access to a small machine shop or that sort of equipment, you could graft some limiters onto the slug that would hold the magnets exactly 180 degrees apart. The problem is that you would need a different jig for each diameter, and also for different magnet heights. The combinations become mathematically daunting! I would reccommend just using the slugs, and measure between magnet tips top and bottom with a calipers to set the 180 degree separation.
Good luck and good motor building. Techman

Chris,
With the shaft parallel to what? Most entry level slotcar motors will use no more than 40 watts at 9 to 12 volts if the load is not too severe. As DC motors go, all slotcar motors are relatively high RPM. Get one that is balanced for maximum rotational speed under load.
Good luck, with whatever the project is.
Techman

Chuck,
Thanks for asking your question here: You aren't the only racer who is hard on axles and Ben always can use more material for 'best of T-man' compilations!
To be prepared for axle damage, have the spare ready with all its flats, duplicate washers, tires, and spur gear. If you really want to move fast, keep several extra allen wrenches loaded in the spare components.
If you break or bend the axle, you should be able to remove it from the car by loosening only one setscrew, maximum (thats if you break off the gearside tire). Any other break should be removeable with just a firm pull to squeeze the spur past the pinion.
If you really want to go fast, actually practice the procedure. It can be done quite rapidly: I once witnessed Mike Swiss tear down the axle assembly, REPLACE A BEARING, and put it back together in under a minute (Beuford's car, 1991 Nats main). Even at group 7 speeds, it took under 20 laps!

Sure Greg, no problem! The white wire of your controller is connected to the positive side of the battery or power supply - actually, to the relay that turns the track on and off, which leads to the battery. The black wire connects to the positive braid on the track. The red wire connects to the negative track braid AND to the negative side of the battery or power supply. This is for a positive gate track (the most common method). It is also possible to reverse the connections at the battery, creating a negative gate track. It is important to know which you have because transistor controllers are designed for one or the other. A resistor or diode controller doesn't care.
Brakes are actually generated by your motor as it coasts, and switched on when the wiper in the controller touches the portions of the control that connect directly to the red wire. The (relatively) small reverse current being generated by the coasting motor is fed back to the motor (essentially by connecting the two sides of the braid together) and causes it to slow quickly. Adjustability of braking can only be done to reduce, but never increase, the brakes that you get from a stock controller setup. In this case, a variable resistor is added to the red wire to reduce the braking voltage.
Good luck, and good braking! Techman

Jacob,
Red dot magnets are made by Mura. They are the same magnet used in the production motors, but the match is usually pretty good. They are probably the most widely used magnets in any brand of C can, as both Koford and Champion also resell this magnet. Gold dots are the FastOnes version of whatever magnet he's selling: There are 16d, Super 16d, and C can gold dots.
They are all rezapped factory stock magnets for the class they are sold as. The C can magnets are Mura. The only white dot magnet I'm aware of right now is one of the RJR single sets (as opposed to quads).
The Koford group 12 arm is wound on a somewhat heavier blank than say, a ProSlot or Camen. This makes it better suited to drag racing. I hadn't heard of any particular problems with them at the Nats, but then I would also be surprised if many were even tried. My copy of the Nats techsheets shows that in the 16 cars that made the two Boxstock mains, 13 arms were ProSlot, two were FastOnes (which are made by ProSlot) and one was a Mura. In the Cobalt 12 class, 3 racers listed ProSlot, 2 Camen, one Koford, one Wright (actual manufacturer unknown) and one didn't list his arm on the sheet.
Techsheets frequently lie, but its a safe bet Koford arms were much more common in the Group 27 and 7 classes.
Techman