A Six Month R/C Itch, and a Decade-Old M03.

Preparing a 10 year-old M03 for a "Mini-Comeback"

July 12, 2013: Two weeks to TCS.

    After deciding to give RC another try, post baby, I went looking for a fun alternative to the
 perennially boring Touring Car classes. I was burnt out with no money, so fun had to mean cheap.
After contacting Dan Garber on an "arrive-and-drive" F1 ride for Regionals, I went looking in boxes for a whip of my own. Something I could work on and race on my tight schedule and mediocre budget.

    As stated in my first post, the Mini class kept coming to mind, cheap, fun, popular in the Tamiya circles, and competitive. After requesting that my father rummage through his hobby graveyard, he came across one of my old boxes, left behind in a presumed trade for something long gone. Inside, an M03, half-built ten years ago, then forgotten. EUREKA!

    But how to resurrect a car built a decade ago to be competitive in 2013 against the newer M05's and M06's?

Do tell, you say?

Step one: Teardown

    As with any car with some age on it, the first thing I like to do is tear the car down to it's screws, whether it's needed or not. This way there's no question as to what you have. Once stripped, I make a list of the items needed, or things I missed in the original build. In this case, a set of pre-mount TCS mini tires and a body. Next to the nitty-gritty.

Step two: Spin baby (bearings)

    Bearings, right behind shocks as the most tedious and time-consuming maintenance items, but just like those fluid-filled units from hell, they're critical to the car's performance on every level.
In this build, seeing as how we are looking for every advantage possible in a speed-controlled class, the first step is to hose these bearings clear of the factory grease. Although it seems miniscule, this grease slows the bearing down significantly compared to one with a light oil. The factory goop will help increase bearing life, but we're building a race car here, not a grocery getter!
Because of the time this car sat, and my reluctance to buy decent equipment, all of the wheel bearings were seized up upon inspection. It seemed as though the grease that was used during manufacturing had crystalized during the cleaning and had froze every single bearing. Keep this in mind with cars that have sat, particularly those in a damp environment. Good thing we checked, and good thing I had spares, because we are doing this on the cheap.

Step three: Just the Facts (clean and inspect)

    Even though this was a car built with primarily new parts, I didn't really trust myself from ten years ago. My attention to detail has undoubtedly gotten better, and either way, not a bad idea to check. Following some simple guidelines laid out on RC-Mini.net, I went about freeing up the drivetrain and inspecting the parts I had originally used. I went ahead and used a new gear set, instead of the worn-in set I had used on the original build. The last thing I wanted was a noisy drivetrain, and this way the newly installed drivetrain would break in together over the testing time I laid out, becoming smoother and more free as time went on.

    The last unit addressed was the diff. I had originally built the car with a open gear diff, which would work ok, but I wanted better than OK, I wanted drive out of the corner. What I built was what I call a "ratcheting" diff. this is essentially a stock gear differential found in the original M03 kits, but with one extra shim on each side to close the gap between the spider gears and the ring gears on the outside. this gives a "ratcheting" feel, like a True-Trac differential on a full size car. Minimal give, meant for maximum pull out of the corner and good rive going in. This setup will give more understeer to the car, but with the low-grip parking lot we would be racing in, and the unknowns of this car and a un-tested setup, I was happy with an easy to drive diff.

    Once the diff was completed, it was back together with some Ti hex-head screws left over from a previous build. If you have the means, I can't stress enough, the ease of using hex hardware over the factory Phillips head screws. Not only is Titanium much lighter, but the hex heads are far less likely to strip out under frequent use. Food for thought.

Step four: Shocks

    Have I stated yet in this post, how much I hate shocks? Messy bastards, air bubbles, leakage..... ugh, but I digress. These little guys are important, no doubt, and I wanted to get them right, or at least close. I had already built the car with Tamiya's "super mini" plastic shocks, and these would work just fine. No they aren't fancy blue, threaded body, blah blah blah.... Who am I kidding, I'd have bought the TRF shocks if I had the money, they are much easier to work with, and the threaded bodies make ride height adjustments so much easier..... but this is a budget build. That money went to diapers.

    Anyways, Two hole pistons all around, 50wt oil all around, Tamiya 'old-school' blue springs up front, and Tamiya 'old-school' yellow springs in the rear would get me started. I also built these shocks with internal spacers to limit droop, and I'll post those at a later time with my final setup.

Step five: Electronics

    As I stated before I didn't have a ton of time to mount everything perfectly, and based on lack of 'said-time' I figured it wouldn't matter much anyway, as I'd be trying just to make the Main, not win it. For my servo, I used a Savox SC-1251MG low-profile unit, which gave extra room behind to mount a switch out of harms way, as well as to save weight. These are great servos for the price (69.99), have good speed, and are durable as hell. I also used a LRP Quantum Comp 2 Speed control and a Spektrum SR300 receiver. None of these break the bank and can be had on a budget, yet all are/were top notch products.

Step six: Finishing touches

    With the car nearly complete, I settled on a Suzuki Swift body using the "M" (M meaning "mid') configuration of the M03, which would aid in the stability of the car. A body using the "L" configuration would have been ideal, but with the budget tight, and an unpainted Suzuki available at my disposal, I couldn't say no. With the car coved by the Japanese hatch body, I wrapped the car in Tamiya Type A premounts with the soft insert. These little puppies gave plenty of grip for a car with an imperfect setup, and while it may not have been the fastest choice for tires, it was a blast to drive and plenty competitive to my surprise.

Final thoughts

    For a car that was pulled from a box after sitting ten years, finishing 4th overall at the Northwest Regional was a pretty awesome accomplishment. I found a good baseline setup, and created a very competitive car from a pile of parts and a Top Ramen budget. The M03 is alive and well amongst the best M05's.

A full write-up of Regionals is to come, as well as photos and a current setup.
Do it on 60d's!

-Jesse

M_