I just read a really nice write-up on sway bar physics. I also watched a video discussing suspension behavior on rough roads.
Let's assume the following:
- A front-wheel drive vehicle being driven around a corner at a speed which, on a dry, smooth, level road, would be just about the maximum speed it could take before beginning to understeer.
- For simplicity, any sway bar changes would be done to the front and rear in such a way that the TLLTD would not be affected.
- Shocks, struts, springs would not be changed.
- By "rough" roads I mean typical non-perfect driving conditions that you may encounter on a daily basis: Think patches, seams, and potholes on highways, think ripple, ruts, and depressions (e.g. typical road wear near stop signs, on roads frequented by trucks, etc.) on urban roads, post-construction patches, stripped roads being prepped for resurfacing, raised manholes, drain depressions, that kind of thing. It's a wide definition, but I don't mean off-road or post-apocalyptic conditions.
In this case, how would a stiffer set of sway bars affect vehicle handling on rough, uneven pavement? Every discussion of suspension theory and physics I see usually seems to assume good road conditions.
For example, consider the scenario above, cornering left at speed, then in the turn I hit a fairly large, say 2-3cm deep pot hole with the front left wheel.
From my limited understanding the effect of a sway bar that was too stiff would be one of the following, either:
- The left strut would expand into the pothole, exerting downward force on the wheel.
- Via the sway bar, some of this would also be transferred to the right side, exerting an upward force on the right side of the body.
- On exiting the pothole, then, something... complicated would happen that I can't figure out.
- The left strut would want to expand into the pothole.
- The left side expansion would be limited via the swaybar by the downward force present on the right side due to the turn.
- The left wheel would then take longer to regain contact with the ground, causing the right wheel to experience more lateral force (that was no longer being absorbed by the left wheel), and the car would more readily understeer. And maybe some other complicated thing would happen.
Am I on the right track with one of those assessments? What would the effect be?
Also as a (perhaps too broad) corollary question: What impact should rough road conditions have when deciding on an ideal sway bar configuration?