TRACTION BARS EXPLAINED

Traction Bar Setup Sheet

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Traction bars or anti-roll/sway/stabilizer bars have been around for a long, long time. The technology is nothing new. Their components can be found in all types of racing, mostly in asphalt racing, due to their ability to resist roll. High g-forces generating high roll angles make this attribute a very desired effect...for asphalt. Wait a minute, last time I checked my tires, they have grooves in them, to remove dirt...from a dirt race track. So why would we run a traction bar (anti roll bar or sway bar) on dirt micro & mini sprints & midgets?

To understand how a traction bar affects the handling of a car, back up to the beginning and read Rethink Dirt: Advanced Dirt Track Theory. This article will form the foundation of thought needed to fully understand why a traction bar effects a car the way it does. Or proceed ahead, and catch up on the theory later!

So what does a traction bar do? It restricts the roll of the car by increasing roll resistance without affecting the vertical or up and down movement of the suspension. Many have spent nights trying to figure out how a traction bar pushes down on the left rear as the car rolls to the right and it is because of this action that gives a traction bar its advantage. Not true at all, it does not transfer weight to the left rear when the car rolls right. This can be proven very simply by placing the car on a set of scales and rolling the car right. The scales will surely read an increase of weight on the right side.

A very important concept here to understand is that when the roll resistance is increased in the rear, the car will be looser. If the roll resistance is increased in the front, the car will be tighter. Very simple. On race cars on dirt, the advantage comes in by giving an easy way to adjust the race car. Dirt has the characteristic of changing very drastically, very quickly. If there was a quick way to adjust the car, it would be an advantage. Yes, there are wings and shock adjusters, but they do not adjust roll resistance, which is one of the best ways to adjust the race car. In order to do things "right", drivers would be changing out bars three times a night. Since nobody wants to do this, drivers end up favoring a slick track or a wet track depending on what torsion bars are in the car.

The traction bar allows changing of the roll resistance simply by adjusting the roll screws on the ‘U’ stop. It has been said that “backing the roll screws off will make the car bounce off the right rear when it hits the roll bar screw”. This simply is not true. The roll resistance comes in gradually starting with 0 pounds of increase and goes to about 30 pounds after the first inch of travel depending on the bar.

The beauty of our ‘U’ stop adjuster is that the roll left and the roll right resistance can be adjusted separately. If the ‘U’ stops are mounted on the right side of the car, the top screw will adjust the roll right and the bottom screw will adjust the roll left. The roll left screws will affect the car on corner entry or when the car is winged down, the roll right screws will affect the car on corner exit or when the car is rolled right.

Start out a heat race with the roll right rear screw set at minus 2 turns, then as the track goes slick, crank turns out of it, to as many as minus 7 turns. In the feature, start out with minus 6 turns on the roll right rear screw then if the track takes rubber, crank in on this screw. It can be cranked the whole way in until the knob can't turn in any more. This makes for a huge adjustment and can easily be a race winner.

Use of the front traction bar can be very effective in making the chassis tight. This is definitely a good deal on a wingless car, but on a winged car, avoid the tendency to make the car too tight. 

To make car tighter on entry

  • Add turns to the roll left front screw
  • Take turns out of the roll left rear screw

To make car tighter on exit

  • Add turns to the roll right front screw, generally this one is adjustable from the cockpit
  • Remove turns from the roll right rear screw, cockpit adjustment

If the car is generally too loose:

  • Unhook the rear traction bar
  • Use to a softer rear traction bar (.500 or .450)
  • Use a stiffer front traction bar
  • If using softer rear torsion bars, raise the car back up to achieve the same or higher ride heights

 If the car is generally to tight:

  • Unhook the front traction bar
  • Crank in on the rear ‘U’ stop screws
  • Use a softer front traction bar (.400)
  • Use a stiffer rear traction bar (.600, .625, .650)


Starting Point for U-stop Turns of the Traction Bar:

  • Roll left screw front: minus 4 turns (bottom)
  • Roll right screw front:  minus 5 turns (top) 
  • Roll left screw rear: minus 4 (bottom)
  • Roll right screw rear: minus 6 (top)

These turns are set with the car on the ground and the race setup in the car. Set the U-stop screws the same as torsion screws. Turn them down with your fingers just until they touch the head of the allen bolt, then back them off to the designated amount.

Notes:

  • On the Hyper Chassis, use a .525 traction bar in the rear and a .450 in the front.
  • When using a rear traction bar, mount the rear panhard bar mounted in the lower mount on the left rear bearing carrier.
  • Make sure none of the shackles have any binds. This is critical and needs to be checked after each race.
  • The advantage of the traction bar is to allow easy adjustment of chassis balance. Be conscious of track conditions and adjust the traction bars accordingly, this should be one of the first and favorite adjustments to your car.
  • Before getting in the car, check to see where the roll right (cockpit adjustable) screws are set to avoid guesswork.
  • Adjust the roll left screw before getting in the car, since it is not adjustable from the cockpit and can make big changes in how the car enters the turn.
  • On rough tracks, it is better to use LESS traction bar, not more. The roll resistance needs to be soft to absorb the bumps. This is true in both the front and the rear. If the car is hopping, that is a sure sign of too much roll resistance, or too much left rear tie down.
  • On a rough track, the car may need to be raised to avoid excessive bottoming out.