Sway-Bars
What Is A Sway-Bar?
A Sway-Bar is a solid metal link that connections the left side of the suspension to the right side of the
suspension.
What Does a Sway-Bar do?
During cornering, the outer or right side suspension compresses due to the cornering forces of the
chassis. By design, a Sway-Bar will rotate upward as the RF suspension compresses. Because the bar is
also hooked to the LF suspension, the LF suspension will compress as well, increasing roll resistance of
the chassis. Sway-Bars are typically only used on the front of most 1/10th scale Dirt Oval Chassis. Some
racers will attempt to run rear Sway-Bars in extreme traction situations. We will focus only on Front
Sway Bars
How Do We Control Roll Resistance?
Sway-Bars are available in various diameters. The larger the diameter or “heavier” your Sway-Bar is, the
more the LF suspension will compress as the RF compresses, thus increasing roll resistance. The smaller
the diameter or “lighter” your Sway-Bar is, the lesser the LF suspension will compress as the RF
compresses, thus reducing roll resistance.
Roll Resistance Cheat Sheet:
- Heavier/Thicker bar = Less Chassis Roll (Used to take away steering)
- Lighter/Thinner bar = More Chassis Roll (Used to add steering)
Why would I use a sway bar?
Sway-Bars only have an effect on the suspension as the chassis rolls side to side. This means that if you
compress the front suspension equally left and right, the Sway-Bar will have no effect on stiffness of
your suspension. Sway-Bars are especially helpful when you want to use softer springs, while still
maintaining roll resistance in the corners. Running a front Sway-Bar paired with softer springs can help
the chassis absorb bumps and improve straight line handling, while still maintaining a nice balanced feel
upon corner entry. The tricky part is, running a Sway-Bar adds several more factors to your chassis setup
“package” and that can further complicate things and make it harder to hit that magic setup. In
extremely high bite conditions, a Sway-Bar will help prevent Traction Rolling.
Keys to A Properly Working Sway-Bar
To check your Sway-Bar for proper operation, you must ensure that the Sway-Bar creates equal
resistance on both sides of the suspension. The best way to do this is to remove all 4 tires and the front
shocks, and set the chassis flat on a setup board. Lift the LF suspension up about ¼” and note how much
the RF suspension reacts. Now do the same to the RF suspension, and take note of how much the LF
suspension compresses. A properly setup Sway-Bar assembly will have the same amount of lift on the
opposite side from the side you compress, at the same amount of compression. If your Sway-Bar does
not have equal leverage on both sides, you will need to play with the length of the Sway-Bar links or the
Torsion Arm mount depending on the type of Sway-Bar you are using.
Should I be using a Sway-Bar?
In general, if you are racing on a high bite, high speed surface, you should consider trying a Sway-Bar.
Chassis Tuning 101
Matt Murphy’s Dirt Oval Chassis Tuning Guide