Muscle Car Suspension Basics - Turning The Corner

If You Want To Maximize Handling, You Have To Understand The Basics Of Suspension Design And Spend Money Where It Counts Most

Stephen Kim Sep 1, 2009 0 Comment(s)
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You always want to fine tune with the sway bars and shocks. Also, as soon as you put more load into a car with stiffer springs and sway bars, you need to strengthen the chassis with subframe connectors.
-Kyle Tucker

Quick Notes
What We Did
Introduce you to suspension basics.

Bottom Line
The technology is here to transform any muscle car into a corner carver.

Cost (Approx)
As little as $43 for shocks and more for complete out-of-the-box packages

The import guys-at least the two that are still left-think that coilover technology descended from the chariots that travel the golden streets of heaven, but coilovers are actually very simple devices. Aftermarket tubular control arms are superior to stock arms in almost every respect, but it has nothing to do with the fact that they're built from tubular steel. Such misconceptions aren't so much the product of misinformation as they are the consequence of not having enough information. Likewise, while it's no secret that stiffer springs, bigger sway bars, and adjustable shocks can dramatically improve a car's handling, very few people truly know why. Understanding the principles of suspension design at the most fundamental level is mandatory in order to improve your car's handling, so we'll take a crack at explaining it all.

Some of the information here may seem very rudimentary, but the extreme nature of suspension dynamics requires starting at square one. For instance, a few millimeters in additional sway bar thickness may seem insignificant, but such a miniscule change in diameter can yield a 50 percent increase in bar stiffness. Likewise, if you want to cut your car's body roll angle in half, but don't think sway bars are worth the money, then you'll have to double your current spring rate.

In addition to explaining the fundamentals, loads of hot-button topics need to be addressed. Is stiffer always better? Are linear rate springs junk? Are you man enough for double-adjustable shocks? Do coilovers deserve the hype? Are four-links just for drag racing? Should you replace your knees with urethane bushings? If you want to turn the corner in your understanding of suspension design, then turn your attention to the next page. To get the down-low on suspension tuning, we enlisted the help of Kyle Tucker of Detroit Speed and Engineering, Tom Brown of Heidt's, Bret Voelkel of Air Ride Technologies, and Chris Alston of Chassisworks.

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As a result of a larger diameter and a shorter swing arm length, the bottom sway bar is substantially stiffer than the unit on top. In practice, this is because the front sway bar (bottom) must endure greater cornering loads than the rear bar (top). However, differences in sway bar design between a matched set of front and rear sway bars clearly illustrates the effects of diameter and swing arm length on overall stiffness.

Sway Bars
Whether you call them sway bars, antiroll bars, or stabilizer bars, they are one in the same. By attaching the left and right sides of a car's suspension together and anchoring them both to the frame, sway bars help resist body roll by increasing roll stiffness. In the front suspension, the sway bar anchors the lower control arms to the frame. In the car's posterior, the sway bar usually attaches from the rearend housing to the frame. As a car's body begins to lean upon corner entry, cornering loads twist the sway bar. Consequently, it is the bar's torsional stiffness that determines how much the body roll is reduced.

The three primary factors that determine a sway bar's torsional stiffness are its diameter and swing arm length and whether it is of solid or hollow construction. In regards to sway bar diameter, stiffness can simply be expressed as diameter. For example, take two sway bars that are identical in every respect except for diameter. A 32mm sway bar (324 = 1,048,576) is approximately 70 percent stiffer than a 28mm one (284 = 614,656).

This exponential relationship means that a small increases in diameter substantially increases stiffness, which is important to keep in mind when shopping for a new sway bar.

Although not quite as extreme as tweaking diameter, changes in swing arm length dramatically impact sway bar stiffness as well. The swing arm is the portion of the sway bar that extends from the frame to the control arm or rearend housing. Lengthening the swing arm reduces sway bar stiffness, while shortening it increases stiffness. For example, shortening the swing arm from 10 to 5 inches results in a sway bar that's twice as stiff.




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