I was asked in another thread to explain the process of water dipping slot car motors, I asked the same a little while back and got some really excellent advice from other members of our community so I'd like to share my experience....
....Firstly in the vast majority of cases (I've dipped a heap of motors now) the process works. The only caveat I'd like to place on this is DO NOT DIP FF STYLE MOTORS! I tried to dip one and wrecked the windings. I can only put this down to the cans on these motors have no holes/vents in them (the motor I tried was a Scaley FF), I believe that the water needs to free flow through the motor during the process, the lack of openings in the can doesn't facilitate this....
Having said that, I have dipped FC/SCX motors and have had wonderful results.
How wonderful you may ask? OK, a stock Scaley motor will get between 10600RPM and 11000RPM at the back wheels (DS pocket checker), I regularly get 11800RPM after dipping, and have a couple of Scaley stock motors that reached 12200RPM :) That's a serious advantage to be had in stock class racing or even messing around on your home layout, you WILL notice the difference in lap times.
How easy is the water dipping process??? Dead easy, if I can do it anyone can!!!
The Process....
OK, you've unsoldered your new stock motor from the wires and got it out of the chassis, and yes its fine to give it a few laps beforehand to see how it goes, no need to take off the pinion either, you can "check glue" it before you put the motor back in the car.
Solder on a pair of long leads onto the motor tabs, any wire is ok, I had some thick aftermarket silicone wire kicking around so I used that, stock leads are fine too, it doesn't matter that much really.
As far as a power supply goes, I use an adjustable type, I run my motors at 3 volts, as I use my supply for tyre truing as well, this is a handy choice for me as its always on my workbench.
You will need a container, I use a good old high tech plastic VEGEMITE jar (hee hee, what did you expect????), and you will need some water. I recommend distilled water, this stuff generally gets put in clothes irons to stop the guts rotting out of them, its cheap, cheaper still if you hook into your partners supply!!!
I use good old tank water though, being the ultimate tight ass (Lutheran/Dutch Catholic extraction), the price is right for me and where I am located means there is no goobies in the water off our roof....
OK, you've got the motor hooked up to the power supply and FULLY SUBMERGED in your container of water, now to give it some juice.
I run the motor at 3 volts for ten minutes, then I stop, reconnect wires to the opposite terminal and do the same again. I repeat this cycle three times for a total of 60 MINUTES.
You may find that the water discolours during the process, don't freak out, its normal, the black colour you see is bits of carbon from the brushes floating around in the water, it isn't going to hurt anything.
(EDIT) Forgot this bit, its important!!! After you have dipped the motor, you need to get the water out of it :) I give them a bit of a shake, let the water run out, then hit the motors up with a liberal dose of CIRCUIT BOARD CONTACT CLEANER. This is found at electronic and car parts shops (REPCO in Australia is a great place to get it, as they sell a cheaper no frills type cleaner that is dirt cheap in comparison to the name brands). Give it a liberal spray, make sure you squirt it into the can openings bearings etc, it dries well and doesn't leave any residue inside the motor. Finally after your freshly broken in motor is dry, oil the bearings and re-wire it into the chassis.
What the water dipping process does is it seats the motor bushes precisely to the commutator. A new motor brush is square, it makes limited contact with the comm, after running in the motor brush cuts/wears in to the curve of the commutator. This ensures maximum volts are passed through the motor. A sign of a well run in motor is the lack of "arcing" between brushes and comm surface, efficiency, that's the goal.
Essentially water dipping is a break-in procedure without all the heat/load (often high) of running a car around the track as often happens. The brushes seat nicely and the comm gets a nice polish too :)
The process itself has been around for yonks, R/C car guys used to water dip stock Mabuchi (540) motors back in the '80's to get a competitive edge on their rivals, its still a valid process today.
