This feature - What is Stagger?

Have you ever wondered what 'stagger' is? Many times when I was a spectator in the stands I heard drivers mention it but was never really sure what it meant. In this article, I will attempt to explain just what stagger is and how it affects the car.

What is Stagger?
Basically, stagger is what causes the sprintcar to "track left" (turn left naturally). It's main function is to assist* the stability of the car through the sharp turns required on a speedway track. Stagger is achieved on a sprintcar by running a larger rear wheel on the outside.

The amount of stagger a car has is normally referred to in inches. The measurement itself comes from the difference in circumference between the outside rear tyre and the inside rear tyre. Below is a typical example.

outside rear tyre circumference = 104 inches
inside rear tyre circumference = 85 inches
Stagger (outside minus inside) 104-85 = 19 inches

*There are many factors playing a part in the car's turning capabilities, stagger is just one of them.

How does it work?
The diagrams below show the basic principles involved.

So how does this affect the car?
Well, the greater the amount of stagger, the more the car will turn in towards the infield. The greater the stagger, the greater the 'turning force' acting on the car.

So how do you use it to set the car up?
The general train of thought is that if the track is grippy (soft) you look for as much stagger as you can get. The thinking here is that you will be going through the turns faster and will therefore need the car to be turning into the infield sharper to counteract the forces pushing it towards the wall (the greater the speed, the greater the forces pushing the car out towards the wall). The sharper the car turns toward the infield, the greater the driving-force the rear wheels will have in keeping the car tight into the turn. (Hope your not confused!). Of course, the amount that the car goes sideways has to be balanced with the outright speed of the car through the turns as there is no point in having the car shooting off into the infield because it is working too hard against the cornering forces!

Once the track hardens up and grip becomes hard to find, stagger is normally lessened. This is largely due to the fact that the speeds will be slower (most of the time) and you do not want the car to slide too sideways on a slick track as too much time is lost in wheelspin (with a hard track you cannot rely on the tread blocks on the tyres to 'dig' into the track for grip and push the car towards the infield - which is what you need when the car is sideways).

Ever wondered why Sprintcar drivers sometimes turn right while driving down the straights?
This is because the stagger on the car is wanting to turn the car left, and the force is so great that the driver has to turn right just to stay pointing straight!

Hopefully this little article has done enough to shed a little light on the topic of stagger.....

Our next feature will be about driver safety and will cover the gear that Stevie wears, plus the inbuilt safety features of the car.

Cliff.

If you have any comments on this feature article, or questions you would like answered, please e-mail us.