going4#1

I'm not sure that you can really rank parts of the car in any order. I mean you've got a group of integrated systems (powertrain, powerplant, suspension, radio, body, etc) but one isn't more important than another. The order of importance is completely up to the driver/mechanic in terms of which system needs attention most.

For example, if your car pulls to one side heavily, wasting time tuning the clutch is pointless. If your radio is glitching or your servos are acting weird, spending time on camber and toe won't get you racing. Bad fuel mileage is a smaller problem than a busted rear wing. A busted/warped wheel is a bigger problem than the two speed timing. The system you need to look at first is the system that is working least.

I would say though a lot of beginner racers pay a lot less attention than they should to the clutch which often results in blown bearings, overheating, poor fuel efficiency,etc. A lot of medium level racers will spend time getting it working to an adequate level but often stop playing with it once the car is driving okay. Well, at least I do that. It's typically the experienced/sponsored/pro drivers that really push hard to get the max out of the clutch. I'd have to say that getting the 'right' clutch setting takes significant experience.