Some thoughts about the 2003-2011 Dallara chassis...
They took a somewhat radical approach to the design of the front end of the car, specifically the suspension. As you can see from the above picture, the frontal area of the car was able to be reduced dramatically. Most cars in racing use a double wishbone suspension, with pushrods supporting the sprung weight of the car. This setup usually has the coil-overs sitting longitudinally on the chassis just above the pedal box. Dallara decided to stick the coil-overs UNDER the pedal box in the dead space under the drivers legs. By doing that, the top of the chassis can be slimmed down and thus reduce the aerodynamic drag of the car. My first impressions of this car was one of awe. Awe of the amount of engineering and work that went into the ability to WORK ON the car. Everything has been laid out in logical ways, and made to be repaired or replaced VERY quickly. Access panels and openings in the front made everything easy... TIGHT, but easy. Some mechanics whined about the shocks being UNDER the car, but honestly, I didn't care. Once you get the hang of it, you see its a pretty cool way to do it. With a good paint job, it looks really beautiful.
The adjust-ability of everything on this car was impressive. I haven't ever before or after worked on a car that can be adjusted in so many ways so radically. The thing is, when there are 50 things to adjust, and most have a range, not a number of set points. The car has an INFINITE number of different setups. These are all handy as a team and driver work to engineer the car into a best setup for the day. Want a narrower track width? Done. Wheelbase shorter? Easy. What about roll centers? Easy. Bump steer? Bump caster? Motion ratio of the spring? Kingpin angle? Caster, Camber, Toe? All are easily changed. Its just amazing what all you can do to help make the car behave better. Most sports car guys will change the roll bars on their street machine. Well, we can too.... but we can also change the stiffness DURING THE RACE. Springs? Some guys will have a stiff road car that has about 300 lbs/in springs; with the kind of downforce involved in these cars, they use a spring that can be upwards of 4,500 lb/in!!! And you can change springs inside of 5 minutes. ANY spring is available. Anything from 1,000 to 5,000 lbs/in. Another cool thing about these cars is the ability to use ride height on each corner for aerodynamic aid.
Gearbox was made specifically for this car, and had a 6-speed sequential with the differential integrated into the same box. And what a gearbox! The gears are all strait cut, with dogring engagement. The gears go together onto a sub-assembly called a "stack" that can be quickly changed or replaced, even in a pitstop. Pretty cool. On the front of the box, there is what is called a "drop gear" that can be used to adjust the final drive ratio without the mess and time of replacing the ring and pinion gears like you would have to do in a normal sports car. The whole box is lubricated by its own oiling system, and oil cooler with a pump. Its a robust, reliable, and REALLY light gearbox from Xtrack.
What a great car, fun to work on, and built well. We could change an engine in about half an hour! Pitstops in under 8 seconds! I single handedly took the whole car apart from race ready to chassis and parts in 4 hours. Massive brakes, great powerplants, fast on a huge variety of tracks, and makes exciting racing!