Dirt stock car right front spring

The last two articles in this series focused on the balance of left side weight and wedge and how they work together to get the car to turn smoothly through the corner. Now we’re going to look at how the right front spring rate works to help maintain a balance while the car turns through the corner.

Since the car is turning left and decelerating into the corner the majority of the transferring load is going to the right front corner; and since the left rear tire is usually the heaviest tire on the car, the right front spring rate goes hand in hand with how much wedge there is in the car. Turning into the corner usually begins on the end of the straight when the driver is still on the gas. If there is too much wedge in the car, the car will resist turning in to the corner. This gives the driver a tight feeling. So the easiest fix to this tight feeling is to take wedge out of the car. Doing this in the pits by turning on the spring adjuster nuts is one way to do this, but then the car might not have enough wedge to get off the corner. So, probably the best way to do this is to take the wedge out of the car dynamically. We can do this by softening the right front spring rate. This will dynamically take out wedge, but on turn exit the weight will transfer back to put at least some of the wedge back in the left rear.



Softening the right front spring rate

I believe the easiest way to think about balancing the car is where you need it to be in a dynamic state. Then make your adjustments to get the car balanced. For instance, at turn in, if the car has one hundred and twenty pounds of wedge and is tight; softening the right front spring fifty pounds per inch may dynamically take enough wedge out of the car to allow it to turn neutrally into the corner. There are other effects to this than merely the mathematical dropping of spring rate to allow this to happen.

As the right front spring rate is dropped the total combined spring rate in the front is decreased and the front ride height is lowered dynamically. As mentioned previously in my article about  the aerodynamic effects on a dirt stock car, lowering the front ride height puts more air over the top of the car and cuts the air going under the car. This creates more aerodynamic down force on the nose and also helps the car turn better into the corner. There are too  many effects going on here to just mathematically figure out that you need to put this spring in to take out this much wedge to get the car to turn. It probably could get figured out by taking into account all the effects, but the easiest and best way is to test it in actual situations on the track, and keep good notes.

Too soft of a right front spring rate?

One big effect that has to be kept in mind is the effect of loosing drive off the corner. If the right front spring rate is too soft for the amount of wedge run, the car could suffer from a lack of drive off the corner or become loose off the corner. In this case the right front spring rate could be increased to keep wedge in the car and tighten the car on exit. You may really have to analyze what is going on with the car, because part of balancing the car is getting the rear tires to traction up equally and drive the car off the corner. The car can also be loose if the right rear tire is not loaded enough. Softening the right front spring rate can also add traction by dynamically loading the left front and right rear more; this also compresses the right rear spring more and adds side bite, which will turn into forward traction off the corner. It seems, lately at least, keeping the right rear tire loaded with traction is the key to good side bite as well as good forward bite.

All these variables add into a well balanced car; get one out of balance and the entire car will suffer at some point on the track. Analyzing all the variables, along with good crew communication and making the correct adjustments are the keys to keeping ahead of the competition.

Till next time; race hard.

Kevin