Slot machine addiction
Iremember the first time I heard about runningin electric motors by fully immersing them in water. It took me straight back to the time I’d decided to try to streamline my morning ritual by making toast while showering. Instead, I prefer to drop electric motors into a jar of kerosene.It sounds crazy, I know, but running-in slot car motors underwater is a real thing. It works a charm, too, typically bringing up to a 10 per cent gain in motor rpm – and consequently, in your car’s top speed.
The principle is that running the motor for about one minute in fluid, at very low voltage (typically 3-5V), beds in the spring-loaded brushes against the commutator – very much like bedding-in a set of drum-brake shoes. The liquid both provides load on the motor and carries away the tiny swarf.
I prefer kerosene because it’s easier to clean up afterwards, in terms of avoiding corrosion. The clean-up part – and other tricks – will require that the motor be pulled apart.
If you’re not that committed, plenty of gains can still be had with a dry run-in, either in or out of the car. It’s important to do this straight out of the box: once you’ve run the motor at full speed, any manufacturing imperfections will be etched there for eternity.
If you’ve got a variable-voltage power supply, you can simply turn the car upside-down and run it at 3V for about 30 minutes. Alternatively, put the car on your track, elevate the rear tyres, and sticky-tape your hand-controller onto a light throttle setting.
The next level of commitment is a dry run-in with a proper internal clean-up afterwards. Mark the motor’s direction of rotation first.
Remove the motor and tape it to something. To create a load, I pinch a square of masking tape to create an air-paddle. Run the motor at 3V; I’ll run that puppy for half an hour or more.
At this point, it’s the same process for a wet run-in, albeit minus the paddle. In fact, you’ll need to remove the pinion gear, best accomplished with a pinion-puller tool (in various levels of trickness, from $10 to $70).
For a wet run-in, place the motor in a small jar and pour in enough water or kerosene to completely cover it.
Tape the wires to the outside of the jar, attach the alligator clips and run it for five minutes.
Now the tricky part. Wrap the motor in a towel and shake to help it dry. Bend out the small tab on each side of the motor housing and carefully slide out the whole gizzards. You’ll feel a bit like James Bond disarming a nuclear weapon.
SCX-type motors have their brick-shaped brushes held into the plastic housing by tiny hairpin springs, easily disengaged. When sliding the brushes from their tubes, remember that you’ll want to put them back in exactly as they came out.
The more common Mabuchi-style motors, as used by Scalextric, have their brushes attached to fine, rocker-type arms. Reach inside the plastic housing with a toothpick and lift them slightly, to clear a flange at the end of the commutator. Now slide out the gizzards.
Wipe down everything with cotton-tips and isopropyl alcohol, including the magnets inside the can. See the three splits, each at 120 degrees on the commutator? Remembering the direction of rotation, I run the back of a scalpel carefully along each leading edge, creating a tiny chamfer. Run a toothpick along each channel to clean it out.
After reassembly, I like to leave the motor for another day or two before running it. And it never ceases to amaze me that not only does this work really well, but that it works at all. There
are few muscle cars as celebrated as the XB Falcon hardtop Mad Max Interceptor, which will very soon finally reached hobby scale thanks to Scalextric (catalogue C3697). Scalextric is the only manufacturer producing the big Ford ‘tudors’, including another new version in Allan Moffat’s 1978 Bathurst XC (C3741).
Both are available to pre-order now. On the other side of the fence, Chevrolet’s 1970 Camaro gets another outing in the Brut 33 livery (C3612) in which Stuart Graham won eight rounds of the 1975 British Touring Car Championship.
Meanwhile, Spanish outfit Slot Racing Company will soon reintroduce its Ford Capri 2600, in both bulgeguarded RS and blister-guarded LV versions. Perhaps the best known of the liveries first time around in 2013 were the 1972 Paul Ricard 6-Hour car of Jackie Stewart/Francois Cevert (SRC-301) and the 1973 Le Mans mount of John Fitzpatrick/ Hans Heyer (SRC-401).
Those keen to get beyond the regular RTR (ready-to-run) selection should take a look at the expanding catalogue of Australian kit models from Adelaide specialist MJK Engineering. To go with their impressive stainless-steel chassis, wheels, gears and urethane tyres, there’s now a range of plastic bodies including VH Valiant Charger and XW-XY Falcon GT. Older tin-top fans might prefer MJK’s Holden EH and FJ, the Jag Mk2 or Valiant S-Type. Left, top: Trick Slot-it “Boxer” type motor on left (note 24,000rpm at 12V, versus SCX RX-81 16,400rpm Left, below: Regular Mabuchi 18,000rpm in front, Scalextric Sport ‘FF’ motor (narrow, long can, for F1 cars and other compact fitments). FF is available in various rpm versions, this green one 25,000rpm. Left inset: Mabuchi-type Pro-Slot motor 26,000rpm! 1. Motor immersed in kerosene in glass jar, wires taped to top so they don’t fall in! 2. When it comes to pinion puller tools, various types available. The writer has three of them. To re-install pinion gear, one also needs a pinion press or tools that do both jobs. 3. Motor direction is marked with a pencil. 4. Standard SCX-type motor, showing how the ends of its brushes are exposed, making them really easy to remove. The red arrow points to the square end of the brush, which has a vertical groove in it. In that sits the end of a spring, which you can see coiled around a post immediately below the brush. To the left of the brush is the other end of the spring, held under a tab. All you need to do is push that out from under the tab, rotate it away from the motor, so that the other end of the spring will release the brush. 5. After bending back tabs on side of motor to open can, the gunk is cleaned out. 6. These are the brushes inside the Mabuchi’s end-bell. (Not bell-end). They’re tensioned by metal spring-arms that are moulded into the plastic. Here the brushes’ inside surfaces are cleaned. 7. Copper-coloured part is the commutator; the little black lines in it are from the sides of the brushes wearing in against it. 8. It’s important to moisturise. With the back of the scalpel blade, the leading edge of one of the commutator gaps is scraped. This helps the brushes to slide over it a bit faster. 9. Scraping any gunk out of the commutator gap with a toothpick. Could have found a sharper one. 10. The Mabuchi motor’s brushes. 11. It’s important to manoeuvre the brushes out of the way when removing the gizzards and when reinstalling so the bearing and flange can clear them. 12. Note gizzards only half-way into end-bell; brushes sitting on flange, next step they will seat against the commutator. 13. Using MB Slot press to reinstall the pinion gear. 14. A mini-dyno! At 12V, the run-in Mustang clocks 24km/h, versus non run-in Camaro – identical motor, gearing, tyres, etc – which ‘only’ does 22km/h.