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Tony's Tech Corner
Tamiya Mini 4WD Tech Tips
by Tony Papagna , Faxtrax Staff Writer
After the overwhelming success of the Box Stock Tamiya race at the El Sobrante Stroll on Sunday, September 19, 1999 I noticed something! I had help build nearly 20 different Tamiya Mini 4WD kits. There were no tricks, but everybody did something special to make those cars fast. I saw firsthand what works and what doesn't work. Of course a trick is a trick no matter whether it is Box Stock or up to Open Class. My suggestion to Box Stock racers is not to worry about the course layout, choice of wheels, or body style --- these simply don't matter because it all evens out in the long run. So, what makes the difference between a fast and slow Box Stock Mini 4WD? Let's first look at what makes a car go SLOW!
DIRT = SLOW: Of course, too much dirt causes grinding and friction. It gets into your gears, rollers and even in your motor. Yes, dirt is everywhere and even dust is the scourge of all Tamiya racers, not to mention hair in your running gear which is a disaster! If you use grease, beware that it is a magnet for all this harmful junk. Too much grease will collect dirt by the pound (well, maybe that's an exaggeration, but you get the idea). If you use just enough grease and wipe of the excess, it will stay cleaner for a longer time. On the other hand, if you use too little grease, that's almost better than too much!
CLEAN = FAST: If you have the time, clean all your gears, shafts, axles, rollers, bushings and even your tires. Use a plastic-safe fast drying spray cleaner such as Performance Plus. It's best to disassemble your car and clean each piece, then re-grease. This should be done between heats if you can work that fast, or at least after each weekend of racing. Only be satisfied with a spotlessly clean car. A great way to clean tires is to lay out a strip of duct tape, and run the tires along the tape. This makes for really clean tires! Thanks for reading this tech tip, and I can't wait to see you for October races on the 2nd, and the 16th.
Next month's tech tip will be on motor break in. See ya then!
So you just bought a new motor! Was it a Plasma ? Ultra ? Atomic ? These are my favorite Tamiya motors, but they all need some kind of break-in method.
There are many ways to break in a motor, and everybody has a different way of doing it, so I will tell you of a few that I know work best. The first method is to just open the package and race it. This is not my first choice, but it has to do in a bind.
The best method to get the most horsepower and longest life from your motor is to run it slowly for the first 5-6 minutes by using a single battery or one or two batteries on their last legs. First, add one or two drops of commutator lubricant, then run it. After the first 5-6 minutes clean the motor with motor spray then add two more drops of com lube and run the motor for another 5 minutes with 2 new batteries.
Please note that the motor should be running free with no load - out of a car is best - so use a motor clip and connect the battery with alligator clips and a battery holder. You can buy a battery holder at Radio Shack for 69¢. I have heard some people like to break in their motors in a glass of water, the theory being that it creates less friction.
I have also heard of using a light oil and adding graphite powder to polish the comm. This works well but its really hard to get all the graphite powder out of the motor, and I found it did more harm than good! The most important thing is after each weekend of racing, spray clean the motor and add more lube drops to the com and store it away! Use old motors for practice and save the fast ones for the races. Speaking of the races, see ya at Fastrax on Sunday for the races!
Next month... battery care...
Lets say that everybody at the race has done everything right to their cars. What will set you apart??? The answer is......Batteries !! of course!!
Two years ago the big craze was the little yellow SANYO 1.2v 700mAh. They have a good discharge rate but they don't last, not even for a 3 lap race. I have found that you need at least 1000mAh for a good technical course full of turns, jumps or hill climbs. Tamiya makes a fine 1000mAh NiCad battery available from your local Mini 4WD dealer, or by mail from Fastrax for $10.95 per pair. Fastrax Raceway also carries Fuji 1000mAh and Sanyo 1100mAh batteries ($24.95 per set of four), and the same batteries "zapped" (high charge shot through them) for $5 more. These are all the best batteries available to Mini 4WD racers.
One alternative is the new Nickel Metal batteries. The advantages of Nickel Metals are they don't need to be discharged before charging and they last longer then nickel cadium batteries. The down side is that they don't have a good discharge rate and they can't be "trained". You might be saying to yourself, "what, I have to "train" my batteries?" Well, in a way you do.
You can train your NiCads (Nickel Cadmiums) and this is the big battery secret. But, it takes investing in some good charging/discharging equipment. FIrst, you need a good charger, one that has a peak detection. You can get a good one starting at around $100 at any Hobby store that has R/C supplies. And get a good discharger, Okami ($29.95)or Tamiya ($14) available at your local Mini 4WD dealer, or by mail here at Fastrax Raceway. Some chargers will come with a built in discharger. You can expect to pay $300- $500 for such a unit, but they do everything for you! Or, you can use any method to drain the batteries completely.
After complete drainage, let the batteries "rest" for 8-10 hours. Then discharge them again!!! I use a digital volt meter to see how low the batteries are. I like to go down to 0.05 volts. Most dischargers will only go down to 1.00v and they drain very s-l-o-w-l-y! You want to have your batteries completely drained in 15-20 minutes. The reason for draining your batteries as quickly as possible is that this is the part that simulates race conditions. When you find a way to drain your batteries quickly, be very careful that your batteries don't get too hot. If this happens, stop the discharge until the battery cools down. Too hot means you can't hold it in your hand !!
Next let your batteries rest again for 2-3 days and do it again --- yes, repeat the same process to the same batteries!! Then, the day before the race you will want to start charging up your batteries.....but guess what??? You first discharge them one more time!! In this final discharge, be careful to keep an eye on your volt meter so that you do not discharge too low.....this will cause the battery to negative discharge.
Remember, the batteries start losing power as soon as they come out of the charger so you will want to start the charging process as close to race time as possible. If you have a peak charger, you can bring it to the race and have your batteries ready, fresh and hot right before you go to the start line. But don't cut it too close or you might get disqualified. Always be ready and PLAN AHEAD!