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Going MOD: Getting Started

Posted 06-26-2011 at 11:07 PM by color0
Updated 06-29-2011 at 09:27 PM by color0
If you're like me, you probably started racing Mini-Z's in slower classes first, to build up some experience and "feel" for how the cars work. Now you've gotten the hang of Kyosho stock, 80t or 70t motor racing and want some more attitude out of your car, so you're thinking, "Hm... should I go Mod?" That's exactly where I was standing just a few weeks ago, so with my most recent experiences at RC Kenon and Cruzin with RC's, I may be able to offer a little helpful insight.

Firstly, let's talk a bit about motors. Mod classes vary by track/racing series, sometimes it's completely open motor choice (most club racing), sometimes you're limited to one brand (PN World Cup), sometimes Mod even denotes a handout, high-power motor. When given any sort of choice, Mod class is the great equalizer: you get to pick whatever power level suits your driving (both style and skill level) the best. If you don't think you're quite ready for a 31-turn handwound monster, don't buy it! Put in something more controllable, more mild, like a PN 43t, or use transmitter settings to limit the throttle on the monster motor so you don't have a car that outdrives you. In a sense, Mod class is the most flexible class: if you have bad batteries, you're free to compensate with a hotter motor; if you want more power to pass people on the straight with, go ahead and go hotter. There's no "battery wars", no "hot motor/FET/etc. of the day", there's only you, your car setup, and how well you can wheel it around the confines of the track you race at with the people you race against.

About the motors themselves, there is one general rule, and that is that every motor has a different powerband. Some people like punchy motors, some people like smooth ones -- I don't know which ones are punchy, but I know the PN 32t and 33t are smooth and so I bought myself a 33t. I personally like my cars to always be linear, and easy to drive. Any kind of on-off throttle response doesn't work for me, since my car is often not *quite* hooked up I need to have very fine control over the power applied to the wheels. Of course, the 33t is also on the "hot" end of Mod motors, so just in case I suck at driving, I turned my throttle end point to 55 (down from 60, the max, which I used in Stock 70/80t). Even so, the 33t with a decent pack of batteries is plenty fast -- so much so that I was overshooting the apexes a lot when I first put the motor in! A handy little trick for that (which I had forgotten! Props to Grant M. for reminding me): backwards throttle trim! Somewhere between 5 and 10 clicks back seemed to be the ideal for me: I tried 15 clicks back (more on this later) at the last Mod race I just raced but the throttle started to get a little bit too sensitive.

With the backwards throttle trim acting as a crude drag brake, I've so far managed to drive my now-Mod car pretty much the same way as a Stock 70t/80t car, with the exception that in slow, technical sections, you can't goose the throttle (instead you have to feather and baby it). Part of this is pure physics and the limitations of tire grip, but the other part is that Mod setups do have to change a little bit from Stock setups to handle the power. At Kenon, I first switched from PN 8 slicks to PN 6 slicks to handle the extra power, but kept the same 15 X-pattern front tires and almost everything else from my RCX 80t setup since "they had been working just fine". Hah, well, my car pushed like a pig. The 15 X-patterns are a great low-scrub tire for Stock racing, but once the speeds come up, you have to find a way to slow the car back down (and while you're at it, turn the car!). So I did not get a chance to test it, but I imagine my RCP Mod setup would be much more refined with softer fronts and the same 6 slick rears. A good Stock setup will probably get you 90% of the way in Mod with just a tire change, but the other 10% will probably be applicable to Mod only and not Stock compatible.

So off the top of my head there are a couple setup factors that I would recommend/should stay in Mod:

1) Gigantic wings. You may need them in Mod if your rear end isn't planting itself enough, but in Stock, more often than not they're just adding unnecessary drag. As proven at RCX by Ryan Sagisi, the stock wings do tend to have less drag, and will make a small but important difference on long straights and sweepers. That said, if you've got ridiculous power, that wing is going to come in handy to keep the rear wheels ahead of the fronts.

2) Larger, stabler bodies. I've written before about good racing "staple" bodies such as the Lexus SC430 and Ferrari 360GTC/F430GT. They're consistently good because they provide a good balance between agility and stability for Stock, but in Mod classes, now that we have more grip and more power than ever, the fastest bodies in Mod are the ones that keep the car best facing the right direction. Mosler MT900, Ferrari FXX, Ferrari 599XX, McLaren F1 GTR longtail, etc. all of these are BIG bodies by Mini-Z standards, and they seem to be making the best performances in high-level Mod racing. You'll find that they're also all 98mm wheelbase: the longer-than-94 wheelbase is more stable, without taking too much weight off the rear wheels as a 102mm wheelbase does (Le Mans prototype bodies). Stability makes a Mod car easy to drive, which makes it easier to lay down more power, which will make you faster.

3) Gumball tires. Mod racing demands as much grip as you can get, as demonstrated by my test at Kenon. Even if a front tire scrubs more or provides more rolling resistance, you're pretty much going to want it if it has more grip. This is in stark contrast to Stock racing, where everything is centered around good handling balance and low scrub, maximum efficiency racing. Unless the surface is too slippery, for Stock I generally use the tire that has just enough rear grip for me, and pick a front tire to go with it. Any more friction than necessary is going to steal precious power away from turning the wheels! But in Mod, since you can put in as much power as you like, that no longer matters anymore! So gumball tires it is for Mod, not so much the case for Stock.

As I continue learning Mod racing I'll be writing more of my blog posts from both Stock and Mod perspectives, so hopefully all of us can learn a bit more from my changeover period. Next week I'll be writing a bit about my RCP vs. carpet changeover (that's a lot of change in a small time...!), pros and cons and what changes you can expect to make switching between the two surfaces. Thanks for reading!
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