Today, after waiting much too long thanks to the postal service, once again another RC car arrived at my home today. This time it’s a Tamiya F103LM Audi R8R. The Audi R8R was prototype racing car built for the 24 hours of Le Mans (linky linky). I’m not going to talk about the real car, just click the link if you’d like to know more about that. The F103 on the other hand is a very interesting chassis and the F103LM is an interesting variation on that chassis.
The Tamiya F103 is a 1 to 10th scale formula 1 chassis mainly used for formula 1 models, but Tamiya soon realized that there are more possibilities with this chassis besides the formula 1 cars. Well, it wasn’t really soon as they did not do this with the F103′s predecessors, the F101 and F102, which could also be the perfect base for other car types. On the other hand, Tamiya had their group C chassis back in the days of the F101 and F102, so this kind of variation was not needed for the F1 chassis’ back then. So what is so special about the F103LM? Like the F103GT the F103LM is basically the same as it’s formula 1 counterpart. The suspension is the same, they’re all rear wheel driven chassis’, they’re all very low and light weight, the motor mounts are the same, so what is the difference? The difference is the main chassis plate and the type of wheels to be mounted on the chassis. The F103GT only takes standard touring car wheels as the F103, F103RM, F103LM and F103LM Special TRF take only F1 style wheels. The F103GT is the only variant that is not 200mm wide as it’s only 185mm wide making it suitable for fitting 190mm touring car bodies. The original body was a Le Mans type car though (Courage LC70 Mugen) and that is where the F103LM comes in. This chassis variation was meant for 200mm Le Mans style bodies. The F1 style wheels are slightly smaller in diameter as touring car wheels and they are also quite a bit wider giving the F103LM it’s wide tread. The main chassis plate of the F103LM is also a bit different and so is the upper deck. The main chassis is wider than the original F103 chassis giving it more room for electronics and the possibility to mount the servo horizontally instead of vertically. Also the upper deck doesn’t reach all the way to the front.
On the next few pictures it’s very obvious that the F103GT and F103LM are based on the same basic platform. The 3 main differences are the orientation of the steering servo, the width of the main chassis, the shorter upper deck on the F103LM and the plastic “bathtub” on the front half of the F103LM’s chassis. This bathtub was the first thing to be removed though. It hardly adds to the chassis’s stiffness and it prevents the mounting of a full size servo. Some aluminum hop up parts are already on the way to give the F103LM a slightly higher bling-bling factor and also improve setup possibilities. You can also see that the front bumper piece is slightly different and also has different body posts. The rear body posts are the same as on a stock F103GT. The rear body posts on my GT are taken from a Tamiya TA-05 to be able to fit a body that is higher in it’s rear as the Courage LC70.
On the last picture you can clearly see the difference in tread width between the F103GT (top) and the F103LM (bottom). The difference in tire diameter is also quite visible.
When this car is finished it’s going to be a blast to drive. When the hop ups are done I’m still going to need to replace the motor and the pinion and spur gears. I want this thing to drive smooth and silent.
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