Think of it this way: the sealed endbell motor is kind of like what you’d find under the hood of a Ford Taurus. Well built and understressed, it offers moderate performance balanced against long life. It’s the kind of motor you can pretty much ignore. Keep the fluid levels up, change the oil regularly, get it tuned once in a while, and you’ll see well over a hundred thousand miles before any major work needs to be done. Trinity’s P2K is more like the motor in Ford’s Mustang GT. This V-8 powerplant revs higher, produces significantly more horsepower, is much more stressed, and resides under the hood of a vehicle that tends to be, shall we say, whomped on more often than its pedestrian Taurus sibling. Different motors, different applications, different performance, and different maintenance requirements.

So, on the surface, you’d think that everything was hunky dory for us parking lot folks: either our motors are sealed and can’t be altered, or everybody gets access to the same performance. And that would be true if we all just raced once or twice per year, but that’s not the case. While representative samples of both of these powerplants are pretty consistent out of the box, real differences emerge over time. Just like any complex mechanism, a motor’s performance will deteriorate significantly with use, even if broken in properly and maintained religiously. This article will give you some tips to ensure that your motor remains in top operating condition for as long as possible. In fact, follow these rules and you will find that your motor even improves somewhat with age. We’ll cover some basics regarding the Mabuchi first, and then move on to the P2K.

The Sealed Endbell Conundrum

After years of working with sealed endbell motors, I can tell you for a fact that they do not all perform equally. Among long-time Tamiya aficionados, the Johnson and Mabuchi motors are known to have very different power levels. Even Tamiya, the sole US distributor of these products, acknowledges that the matte-finish Johnson has a distinct horsepower advantage over the much more glamorous chromed Mabuchi. That’s why they hand out Johnsons at their annual National event in Los Angeles. Unfortunately, there seems to be no rhyme or reason as to which motors come in which kits, so you’re pretty much in the hands of the Japanese motor gods when you open the box containing your new pavement weapon. Don’t get me wrong- the Mabuchis are just fine for practice, and their slightly lower power output will give you more control on days when the asphalt is particularly slippery- but grab the opportunity to pick up a Johnson if your only legal motor is a Mabuchi. In the long run, your car will simply go faster. The good news here is that the motors are very consistent from example to example, so you don’t have to buy a dozen Johnsons to find a fast one.

Here’s another great truth: proper break-in really improves the performance of any sealed endbell motor. For years, racers simply oiled the bushings, slapped the motor in their car, and figured that it would break in with use. Then a few of us started to experiment with different break-in methods and discovered a series of steps that made these motors spin faster and produce more power. We’d show up at the track with cars that were supposed to be equal, but ours were quicker out of the corners and had a higher top speed at the end of the straightaway. Not only that, but these faster motors seemed to hold their edge for a long, long time. Like the sound of that? Follow these three steps with your next new Johnson and I think you’ll agree that the performance advantage is worth the extra time.

1) Before ever running your new motor, lubricate the bushings at both ends with a lightweight oil like Mobil 1 5 weight. Do this three times, allowing the oil to soak in for several hours between applications. To enhance the flow of oil into the bronze bushings, place the motor in a warm, dry place like a sunny window or the top of the refrigerator. Do this once in the evening before going to bed, again in the morning before leaving the house, and once more when you come home. By the second evening, your motor will be fully lubed and ready for the next step.

2) Unlike their hotter stock and modified siblings, sealed endbell motors experience very low levels of internal stress and are manufactured using very hard brushes and fairly soft springs. This combination makes seating the brush face fully against the commutator a difficult task. Simply putting a fan on the motor and running it for awhile on a four cell pack or low voltage power supply will cause the commutator to become significantly worn before the brushes are broken in. That’s why these motors should be water dipped.

Simply fill a medium sized plastic or paper cup (fast food soft drink cups work well for this task) with clean cold water from the tap. Connect the motor to a low voltage power source (use either a four cell pack or the low voltage tap on a power supply- never use a six cell pack or AC power for this) and lower the motor into the water. Yes, I know it sounds weird, but trust me here. After the motor has spun fully submerged for a minute or two, you will notice that the water is starting to get dirty and gray colored. Pull out the motor, dry it off, and place a few comm drops- any good brand will do- on the commutator where the brushes rub. Put a small plastic fan blade on the motor and run it for two or three minutes (the fan blade keeps the motor cool and puts a slight load on it). Then remove the fan blade, empty the cup, refill it with clean water, and repeat step one for another minute or so. This time, the water will be less dirty, but that’s OK. Dry off the can, lube the bushings again, and run the motor with the fan blade attached for four or five minutes until it’s warm and dry.

3) Now that the break in process has been completed, lubrication becomes critical. Make sure that you place a drop of oil on each bushing after every few runs. On a really hot day, or in sedans like the TA02 where the motors tend to run very hot, do it after every single run. This ensures that the bushings are fully soaked with oil, so that lubricant flows constantly from the pores of the bushing onto the motor shaft. This technique reduces friction as much as possible and extends motor life.

Along with lubrication, proper gearing determines how long your motor will last. A closed endbell motor that is overgeared is very soft on acceleration and feels draggy through the turns. Experienced racers feel that proper gearing is so precise that they calculate it by the number of millimeters of tire rotation that occurs per motor revolution. I won’t go into the specific formulas here, but I can suggest specific gearing recommendations - Place your questions the Discussion section of HobbyWorks.com and I will respond. If you’ve already figured out the formula, start in the vicinity of 50mm/revolution and work your way up or down from there. Heavier cars or trucks should be in the mid 40’s while F1 and Mini cars can push into the low to mid 50’s depending on the weight of the car and the length of the longest straight track section.

Cleaning these motors is very easy and takes only a few moments. Remove the motor completely from your car and use a soft, clean paintbrush to knock the asphalt dust off of the exterior. If you absolutely have to flush your it out with motor cleaning spray, go ahead, but compressed air is just as effective. A can of high pressure air from a camera, computer, or office-supply store costs about as much as a can of motor cleaner and does as good a job, but it’s easier on your hands and the environment. Regardless of which method you use, try to get as much of the parking lot grit and dust as you can out of the can. Since you can’t really get to the commutator to clean it, the best you can do is remove the big stuff from inside. Some racers even like to quickly water dip their motors for twenty seconds or so, just to ensure that all of the nasty stuff gets removed. After the cleaning session has ended, remember to lubricate those bushings!

It also helps to check the end play on sealed endbell motors from time to time. There’s a small phenolic resin washer at the top of the armature that often disintegrates after just a few hard runs. Unless your car is designed so that the pinion runs very close to the bushing, a hard hit to the left side of the car can cause the brushes to jump off of the commutator. Nasty! Where the pinion stands well off of the motor, a series of small washers or a metal spacer between the pinion and the bushing will keep the armature from sliding too far off of the intended path.

Stock Motor Refresher Course

In contrast, stock motors, especially the new rebuildable motors like the Paradox and P2K, are pretty easy to break in and maintain. That’s because they’re more highly stressed, so the brushes break in very quickly. Even though a ‘real’ racing motor has a much shorter working life than a sealed endbell powerplant, there are several things you can do to make one of these last an entire season.

First off, stock motors are made to tighter tolerances than kit motors, so it helps to loosen up the bushings a little bit. This relaxes its grip on the motor shaft and allows it to spin faster. Trinity makes an excellent product for this purpose called Bushing Buster, but you can also use valve grinding compound or thinned metal polish like Brasso or SimiChrome. Place a few drops on each bushing right where the motor shaft comes out, and run the motor for several minutes on a low voltage source. Make sure you don’t overdo it, because a bushing that’s too loose will allow the shaft to bounce around, resulting in reduced power output! Afterwards, flush out the bushings and clean off the shaft with motor spray or denatured alcohol to remove all of the residue.

Brushes on stock motors break in very quickly because of the heat, stress, and brush spring tension found on most good high performance examples, so there’s no need to water dip a motor of this type. Most racers find that a four or five minute session with the small plastic fan blade and a low voltage power source works just fine to get an initial seat on the brushes. After that, it’s just a matter of running a pack or two through the car in practice before they are fully seated and ready to go.

However, lubricating the bushings is just as important as it is on a sealed endbell motor. Because the motor shaft actually rides on a thin layer of oil, you must make sure that the bushing is fully penetrated with a lightweight lubricant. Trinity, NifTech, and many other companies make high performance oil specifically intended for stock motor bushings, but five weight Mobil 1synthetic lubricant is less expensive and readily available.

However, gearing is much more critical on open endbell 540 motors. It’s very easy to fry an otherwise good stocker in a single run just because you got too ambitious with your gearing on a hot day! That’s why you need to make sure that you don’t install a pinion gear that’s too large. With heavier sedan cars, aim for a 28 to 32mm rollout on hot stockers, which works out to a 69/23 spur/pinion gear combination in a TA02. If you’re running a TL01 with stock gears, you’re OK with the largest pinion that fits, but all bets are off if you’ve installed Tamiya’s high-speed gearset. The knowledgeable folks at Hobby Works can recommend the correct range of pinions for your particular car, but since these motors have such a narrow ‘sweet spot’, you won’t need very many!

Every dozen runs or so, expect to replace the brushes and springs. These only cost a couple of bucks, and will keep your motor operating at peak performance. For most racers, that means a set of replacement brushes every three race meetings- that’s not so bad! Because of the excessive dust caused by most high performance brushes as they wear, however, these motors need to be cleaned more frequently. In between weekends, remove the motor from your car and brush off the road grit. Use a comm stick (Trinity, Parma, and other companies make very good ones) poked through the brush hood to clean the oxidized copper and oil from the commutator. The rounded edge of a rubberized comm stick is a good tool to clean the curved face of the brush, but be careful not to scrub too hard, because you’ll alter the curvature of the break-in surface. A quick shot of motor cleaner or compressed air will clear out the brush dust; put it all back together and you’re ready to rock!

Every four dozen runs- that’s six race weekends, or halfway through the season- you should completely disassemble the motor and either replace the armature (balanced dyno’d arms are less than 20 bucks), or have it cut by someone with a modified motor lathe. Then clean the interior of the motor thoroughly with motor spray, let it all dry out, lube the bushings, and replace the brushes and springs when you put it back together.

There you have it- a handful of tips that will keep your powerplant running at peak performance for the entire race season. This is the same stuff that the fast guys do to keep ahead of the pack, so no more excuses- it’s your turn to go out there and be fast!