eclipse spanker

Okay, everyone is always talking about how different the suspension has to be on your car, depending on what you will use your car for; either drag racing or autocross.....but what are these differences ? I know for one that camber is an issue; drag cars should have zero camber to maximize the area of tire contacting the ground for max acceleration, whereas autocross suspension should have some type of camber in order to negotiate corners much better.
What are some of the other major factors to take into consideration, when setting up your car's suspension for drag or autocross ( tension? softness ? differences between front and back setup ?)

MrFatbooty

It's all about weight transfer. A drag car transfers weight from font to back. A car that that turns transfers weight diagonally.

Check out www.turnfast.com for plenty of info, that's a lot easier than me typing out some kind of essay.

Shingoblade-GSR

One quick thing I should mention: the drag crowd and the road racing crowd (US) are somewhat similar in that both use higher springrates in the rear. Why? For the drag guys the weight transfer goes to the rear as stated by MrFatBooty so they want stiffer springs in the rear to counter this action and keep traction on the front wheels. (opposite of a RWD car).

The road racing guys use higher rates in the rear to help the car rotate better under braking. Note that this is for US only; the JDM road race/auto-x setups are opposite (for reasons why turn to the road race/autox forum)

Shingo

eclipse spanker

OK, but in terms of drag racing, wouldn't stiffer springs in the rear also equate to a little more resistance to the front tires during launch ? You figure that the rear wheels are not powered, so hypothetically, the more firmly attached to the ground the rear wheels are, the more resistance you get to the front tires and their foward motion ( even if it is only like a couple of tenths of a second) . I suppose, like everything else, there is a happy medium that should be achieved with spring stiffness in the rear.
I'm gonna check that website out also, FatBooty. Thanks for your input guys.

MrFatbooty

Stiffer spromgs don't give you more traction. The reason you stiffen up the rear on a drag car is because when you accelerate from a stop the front of the car tends to lift up. If you stiffen up the rear suspension it helps limit that since when the front goes up the rear has to go down. In effect it keeps the front end planted for more traction.

The autocross and road racing setups in this country at least tend to favor very stiff rear suspensions to help the car rotate. Playing with the stiffness ratio from front to back changes the relationship between when the front and rear tires break traction. The natural tendency of a front wheel drive car is for the fronts to slide first, and this is understeer. Understeer is slow. Stiffening up the rear helps to keep the car more neutral in the corners and allows it to slide around more.

Definitely check out that site, it will answer any question you can think of.