NickW
06-09-2011, 12:16 AM
csmarx-
Road racing karting is quite different than sprint karts. We race on big tracks such as Road America, Barber, Daytona, etc. The speeds are much higher than sprint, and races last between 30-45 minutes. There are over 30 classes at the National WKA level between lay down and sit up karts.
Basic kart dynamics- the rear axle connects both rear wheels, no diff, usually a steel pipe either metric or imperial measurement depending upon place of manufacture. Front end designs are quite different, each bringing positives and negatives to the table.
One thing you mentioned was how you turned a kart, by trail braking. In road racing we try not to do that. Our setups do not require trail braking- we adjust our traction initially with axle flex and tire compound and size- the balance of enough traction and yet enough slip to keep the chassis free is what we are aiming for. Ackerman causes chassis jacking- some karts like more, some like less. Scrub radius determines how quickly the chassis initiates the turn in, some chassis makers design a lot of scrub radius (usually for beginners who need less twitchy setups) into the kart. Drivers fine-tune their weight jacking with several tools available- widening/narrowing front track width, adding/removing seat struts to outer bearing carriers, changing seat stiffness, adding or removing chassis stiffening bars, changing hub length to affect axle stiffness, widening or narrowing hubs to affect rear track width, and loosening/tightening the front pan to affect front chassis stiffeness.
One thing that is very different from a car is brake bias. A vast majority of brake power is derived from the rear of the kart- rear tires are bigger than fronts usually, weight bias is rearward on sit up karts, and the axle acts like a locked diff. On lay downs we also get the rears to lock up before the fronts also- if the fronts lock up first you lose steering control at the limits.
A properly set up road racing kart handles quite similarly to a car in basic dynamics, just that everything is magnified quite a bit.
I think that's a good start for a basic primer... :)
Road racing karting is quite different than sprint karts. We race on big tracks such as Road America, Barber, Daytona, etc. The speeds are much higher than sprint, and races last between 30-45 minutes. There are over 30 classes at the National WKA level between lay down and sit up karts.
Basic kart dynamics- the rear axle connects both rear wheels, no diff, usually a steel pipe either metric or imperial measurement depending upon place of manufacture. Front end designs are quite different, each bringing positives and negatives to the table.
One thing you mentioned was how you turned a kart, by trail braking. In road racing we try not to do that. Our setups do not require trail braking- we adjust our traction initially with axle flex and tire compound and size- the balance of enough traction and yet enough slip to keep the chassis free is what we are aiming for. Ackerman causes chassis jacking- some karts like more, some like less. Scrub radius determines how quickly the chassis initiates the turn in, some chassis makers design a lot of scrub radius (usually for beginners who need less twitchy setups) into the kart. Drivers fine-tune their weight jacking with several tools available- widening/narrowing front track width, adding/removing seat struts to outer bearing carriers, changing seat stiffness, adding or removing chassis stiffening bars, changing hub length to affect axle stiffness, widening or narrowing hubs to affect rear track width, and loosening/tightening the front pan to affect front chassis stiffeness.
One thing that is very different from a car is brake bias. A vast majority of brake power is derived from the rear of the kart- rear tires are bigger than fronts usually, weight bias is rearward on sit up karts, and the axle acts like a locked diff. On lay downs we also get the rears to lock up before the fronts also- if the fronts lock up first you lose steering control at the limits.
A properly set up road racing kart handles quite similarly to a car in basic dynamics, just that everything is magnified quite a bit.
I think that's a good start for a basic primer... :)