Raising the panhard bar raises the rear roll center. Generally, this adjustment causes corner entry handling to loosen and chassis roll to lessen. You can learn the "tuning range" for heights of your panhard bar by testing at the race track and taking good notes!
When adjusting for height, change both ends of the panhard bar. Otherwise you may introduce another handling effect by changing the angle of the panhard bar (more later). Also, if you adjust the height of the panhard bar just at the chassis, the rear roll center may move in the opposite direction(see illus. 1&2). Generally, a 1" change to the height of a panhard bar makes a noticeable change in handling on dirt race cars (asphalt cars = 1/2").
You can increase the panhard bar's effect on tire loadings by increasing the static upward or downward angle of the panhard bar. However, too much panhard bar angle can cause drastic changes in rear tire loadings during cornering and handling may become erratic as a result. Generally, a 1" change to the difference in mounting point heights of the panhard bar makes a noticeable handling change on dirt race cars (asphalt cars = 1/2"). A good rule of thumb is to keep the height difference of the panhard bar mounts to within 10% of the panhard bar's length (for example: 20" panhard bar = 2" maximum mounting height difference). When making changes to the angle of your panhard bar, be aware of any effects to the height of the rear roll center.
In order to determine the ultimate handling effects of the panhard bar's angle, one must consider where the panhard bar is attached to the rear axle--Read on!
If the panhard bar is attached to the rear axle near the center of the rear tire track*, the panhard bar will load or unload both rear tires by a similar amount during cornering. With this arrangement you can increase rear traction, hence tighten handling throughout the corner, by increasing the downward or decreasing the upward (to the right) angle of the panhard bar. You can loosen handling throughout the corner by making adjustments opposite to those listed above.
If the panhard bar is not attached to the rear axle near the center of the rear track, the panhard bar will load or unload the rear tires unevenly during cornering. The closer a tire is to the panhard bar's axle mount the greater the tire is affected by the angle of the panhard bar. Conversely, a distant tire is affected less by the angle of the panhard bar.
Generally, a 6" change in the lateral location of the panhard's axle mount point makes a noticeable handling change. You should keep the following in mind when adjusting the panhard's angle or its lateral location on the rear axle: *Any increase in the load of the RR tire and/or decrease in the load of the LR tire tends to tighten corner entry and loosen corner exit handling. *Any decrease in the load of the RR tire and/or increase in the load of the LR tire tends to loosen corner entry and tighten corner exit handling. *Increasing the load of the rear tires equally tends to tighten overall corner handling. *Decreasing the load of the rear tires equally tends to loosen overall corner handling. *Adjustments to the panhard bar primarily affect corner entry and mid-corner handling.
By now you should have a good understanding of how some of the design elements and tuning adjustments of a panhard bar have a collective effect on handling. If anything you have read is unclear, go back and reread the article before progressing.
A front or rear location of the panhard bar makes little difference on cars equipped with solid rear suspension linkages. However, this is not the case for cars equipped with torque absorbing devices (5th coils, 6th coils, etc.) These devices allow the axle (pinion side) to wrap (rotate) downward during deceleration and upward during acceleration. During axle wrap, the height of the panhard's axle mount point changes. Consequently, both the angle and height of the panhard bar change during axle wrap and handling is affected.
The location of the panhard's axle mount (ahead of or behind the axle), determines whether the mount will move up or down during deceleration or acceleration. During deceleration, the panhard's axle mount point drops if the mount is ahead of the axle but raises if the mount is behind the axle. During acceleration the height of the panhard's axle mount point changes opposite to those listed above.
For tight corner entry handling, the panhard bar should be mounted to the front of the axle. This arrangement causes the panhard's axle mount point to drop during deceleration. Consequently, the height of the rear roll center drops & rear side bite is enhanced. Also, if the panhard is attached to the left side of the chassis the angle of the panhard bar changes during chassis roll so to increase rear traction and further tighten handling during deceleration.
However, if the panhard bar is attached to the rear of the axle the panhard's axle mount point raises during deceleration. Consequently, the rear roll center raises and corner entry handling tends to loosen as a result. Also, if the panhard is attached to the rear of the axle and the left side of the frame, the angle of the panhard bar changes during chassis roll so to reduce rear tire loadings and further loosen handling during deceleration.
The effects of axle wrap on the panhard bar appear to influence corner exit handling to a lesser degree than corner entry handling. At this point, you should be able to analyze any effects the panhard bar may have on corner exit handling.
It should be mentioned that during cornering, a front mounted panhard bar resists axle wrap-up (acceleration) and enhances axle wrap-down (deceleration) whenever the panhard bar is angled downward to the right. A rear mounted panhard bar gives opposite effects. However, the effects to handling appear to be minimal.
AFCO manufactures a complete line of high quality panhard bars and mounts that are designed to provide the geometry needed for superior handling. Hopefully, the parts that we build and the information that we provide will enable you to "Experience the AFCO Advantage!"