Panhard bar mounting location
A quick review about the panhard bar. It locates and limits the rear end of the race car form moving sideways in a turn. On paved tracks the panhard bar is anchored to the axel on left side and mounted to the body on the right side. Dirt track cars are the opposite as they need maximum traction on dirt.
Lets look at Center of Gravity. We want the lowest COG we can get.
Direct Comparison: High vs. Low Center of Gravity
| Feature | High Center of Gravity (e.g., SUV, Truck) | Low Center of Gravity (e.g., Sports Car) |
|---|
| Rollover Risk | High (Easily tips over) | Low (Slides instead of tipping) |
| Body Roll / Lean | Significant (Heavy weight transfer) | Minimal (Stays flat and stable) |
| Max Cornering Speed | Lower (Must slow down to stay upright) | Higher (Can carry more speed) |
| Lever Arm Length | Long (Multiplies outward forces) | Short (Minimizes outward forces) |
We can not change the COG at the race track but we can change the Rear Roll Center. Why do this?
On dirt and pavement in a turn with a level panhard bar, the lateral force goes straight sideways and the tires are the only counter to this force.
On dirt and pavement in a turn with a level panhard bar, the Rear Roll Center is exactly where the panhard bar crosses the car center line and usually is NOT the mid point of the panhard bar.
On dirt and pavement in a turn with a panhard bar angled downward to the right rear tire will LOWER the Rear Roll Center. This is the static location. The lateral force is now directed to the right rear tire and placed more download force on that tire and adds traction. Note also, as the car rolls over to the right in a turn, the rear roll center will lower due to arch of rotation of the panhard bar.
Yes, the Moment Arm between the rear Roll Center and the cars Center of Gravity is now longer length, but the force angle is greater on the right rear tire. Hence, more grip (traction).
On dirt and pavement car raising the Rear Roll Center will loosen the car in a turn.
