Hi, I’ve been into R/C cars now about a decade (after the time as kid in the ’80s), cars varying from onroad to offroad and something in between. I started in early 2000 with onroads, then moved to offroad racing (nitro powered buggies) and now past couple of years back to onroad. Nowdays I run only nitro cars. I’ve tried electric powered cars but I don’t get the excitement I get with nitro. Therefore I’ve recently abandoned electric cars completely.
Onroad does not mean necessarily a race track. A race track is fun, but not a necessity. We run cars that can also handle parking lot conditions and not limited to a race track alone. The scale is 1:8 so they are larger than the “typical” 1:10 scale which helps in this type of action . Tires are rubber and we prefer GT style bodies with at least two doors and a cockpit for two drivers.
I used to race “official” races, but not anymore. That is more related to time & availability than a will doing it. But I find it almost as fun racing with friends on a parking lot. To be honest I’m rather competitive by nature and a bad loser, hence running with friends is way more relaxing for me than competition which requires careful preparation and focus every time to succeed even moderately.
Ok, let’s go to the subject: Building a R/C GT Super car.
My real-life archetype or “role model” is the Ferrari F40 GT super car. In R/C world it consists of the following components:
- Chassis - Italian BMT 081 “rally game” race chassis with belt drive/power transfer
- Body - F40 from Deltaplastik.it
- Engine - Sirio RR Sti .21 class onroad/rally game motor
- Tuned exhaust for the motor - Sirio EFRA 2058 or 2013 (nowdays illegal for racing)
- Clutch - Sirio Centax
- Tire - Ipanema Sports 17mm hex wheels and rubber tires/slicks, wide type for the rear
- Electronics including the receiver, the receiver battery and servos for gas and steering
- INS-BOX / air filter for the motor
Extras:
- Custom modified 2-speed transmission for optimal combination of top speed & acceleration from Kyosho Evolva 21 class onroad racing car
Chassis
This chassis is very interesting in many ways. First of all, it’s a bit older design dating back to days when BMT still manufactured Lola type 21 class onroad racing cars. It seems to come from the Sirio factory since the manual has Sirio logos printed on it. Today, I think RC Modelstore / iRacing.it has the rights for the BMT 081 car and the BMT brand.
Distinctive is that the rear shocks are placed in front of the rear suspension arms whereas in newer desings the rear shocks are typically all the way back behind the suspension arms. The good thing is that there the shocks are very well protected from hits from behind. On both ends of the chassis it has relatively large and strong ball differentials that can be adjusted “outside”, meaning that adjustments can be done with a hex driver without opening or removing anything. In between there are three wide and strong belts from Optibelt (German) that transfer power from the motor to the diffs via a center “gear box”. Gear box is single speed out-of-the-box but as I will describe later I have custom installed a two-speed unit instead for increased top speed with a nice combination of acceleration.
Drive shafts are some lightweight material, looking polished aluminum that are actually very durable since there’s practically no wear after driving the car around 100 tanks of fuel (~12 liters). Suspension arms have pivot ball (a.k.a pillow ball) style suspension hubs for the wheels on each end, hence suspension (camber, toe-in, toe-out) being easily adjustable. Also front caster, droop (a.k.a outward suspension), inward suspension for the front can be adjusted.
Shocks.. (story continues as soon as possible)