Motors

There are plenty of great sites on the internet that discuss the differences between "open frame", "can" and "coreless" type motors that are commonly used in model railroading.  I won't repeat that information here.  Instead, I will explain how to choose and source the right motor for your remotoring project.

Choosing the Right Motor

Basically, I try to fit the most powerful motor in the available space that allows room for the best drive train components and has room for DCC wiring, if necessary.  The first step is to measure the length, width and height dimensions for the motors location within the locomotive.  Generally, if you have a narrow (~15mm wide) and tall opening in an HO locomotive then your choices are limited to flat can motors.  If your opening is as wide as it is tall then you can use a variety of round can and coreless motors.  If space is at a premium, you can use a rare earth coreless motor that puts out more torque for its size than a comparably sized can motor.  The downside is that these rare earth motors are much more expensive than a can motor.  If you require a double shafted motor then your coreless options get expensive and limited.  For those applications it would be best to stick with a can motor.

Mashima can motors have filled the void left by Sagami when they stopped producing can motors for the hobby industry.  Mashima motors are available from a number of sources, are inexpensive and generally work well.  I have found a few Mashimas that I don't like, but most function well.  I believe that the can motors sold by NWSL under their name are actually Mashimas.  The one downside to Mashima motors is that they don't publish their technical specs so it is hard to compare their torque output to similar sized coreless motors.

Coreless motors are much smoother and superior in many ways over cans, but they are very difficult to source at a reasonable cost.  Buying direct from the main manufacturers (Faulhaber, Maxon and Portescap) can easily cost $100 or more per motor.  A better solution for coreless motors is to look for surplus motors since they can usually be purchased for about half the retail price.  The problem with surplus coreless motors is that there is a limited variety.  The greatest advantage to a coreless motor is the option of putting a high torque motor in a small space.  One thing to note is that these motors usually have a 1.5mm shaft and need to be sleeved larger.  Sleeving a coreless motor is difficult and best done by your motor supplier.

I've read a lot of good and bad reviews for other sources of can motors on the Internet.  The replacement motors from Kato seem to be popular.  Some people are having good success with can motors sold on ebay.  Personally, I haven't tried these sources and can't comment on them.

I don't use any open frame motors.  Although they can be extremely powerful, they draw too much current and cog.  I always replace them with can or coreless motor.

My Favorite Motors

Mashima MH1224 (10mm x 12mm x 24mm flat can).  I have mixed feelings about this motor.  For it's size, it is very powerful and will fit most small HOn3 or N-Scale engines.  I found it doesn't run as quiet as I'd like.  There aren't many choices in the general size so I'm listing it anyway.

Faulhaber 1319SR  (13mm x 19mm coreless).  This is a fantasic motor for medium sized HOn3 locomotives or geese.  It would be suitable for small HO locomotives too.  This is a very powerful motor for its size and readily available.

Faulhaber 1524SR (15mm x 24mm coreless).  This is a high torque coreless motor that is readily available.   It would be suitable for large HOn3 engines,  medium and large HO engines and Sn3 locomotives.

Mashima MH1626 (14mm x 16mm x 26mm flat can).  I have used this motor in small HO steam engines with great succuss.  It fits in narrow boilers, runs smooth and is inexpensive.  It's a favorite of mine.

NWSL/Mashima 1630 (16mm x 30mm round can).  This is one of the most popular motors that NWSL sells.  This motor will work well in most medium to large HO steamers.

Portescap 9 pole 1728 (17mm x 28mm coreless).  I'm experimenting with a couple of these motors.  They are an extremely high torque motor in a fairly small package.   They could be an excellent option for larger HO steamers since it has lots of power and would leave plenty of room for a DCC sound installation.

Poor Motors

I've found that some of the Mashimas are hit and miss.  The 10mm x 12mm x 15mm Mashima has no power and is useless in HOn3, but have been told its a good motor in N-Scale.  The 24mm long version of the same motor is a powerhouse in HOn3.  I've had mixed results with the a number of the Mashimas that look like open frame motors where the brushes and commuter are exposed.  Some run well, others are completely hopeless.  The one "Helix Humper" motor I tried installing was cheap, vibrated and caused a lot of noise.  I haven't found a coreless motor that I didn't like but have had trouble sleeving them.

Sources

My favorite source for motors is Eldon Shirey at http://www.micro-loco-motion.com.  He has hundreds of varieties of surplus coreless motors at reasonable prices.  His true inventory isn't listed on his website, but if you email him with the dimensions you are looking for, he will tell you what he has.  Eldon can also supply you with Mashima motors and will discount in volume.

Northwest Shortline (http://www.nwsl.com/) has a nice selection of can motors in sizes that are suitable for most common model railroad re-motoring projects.  It is very convienent to pick up a motor from them if you are already ordering drivetrain components.  I find that ordering from them direct will get you your parts in one to two weeks.  Their service is excellent.