Race Engineering: Racing car damper ratios
Typical racing car damper ratios are 0.65-0.7 in ride where 1 is 100% critical damping.
This compares to 0.2-0.3 in a passenger car.
There is a lot more to damping that damping ratios.
- Tyres don’t like surprises
- For maximum grip the aim is to minimise contact patch load variation
- The challenge is to optimise for heave, pitch, roll and skew with only 4 dampers – one on each corner.
- You will target different rates depending on whether you’re targeting ride (body control), grip (contact patch), aero (minimise pitch and max body control)
- 1/4 car models are helpful but the front is connected to the back so half car is the minimum
- Tune for linear rates then add “nose” at lower speeds
- Driver feels lower speed adjustment (up to about 50-75 mm/s)
- Grip is influenced greatly by higher speed damping driver can’t feel – especially around wheel hop frequency (circa 10-15 Hz typically)
- The vertical tyre stiffness can change with frequency of road inputs – there are papers on this.
- Road roughness will have an impact on grip so it is important to know what surface you are on – these have been profiles with PSD’s in military use.
- How freely an individual damper transitions from bump to rebound can have a big effect – there is more than just the force velocity curve to consider with dampers.
This is Today I Learned Motorsports is part of a growing collection. Snippets of things I am learning day to day and sharing with you so I don’t forget! Share if you like it. Click here for them all. Sign-up below to never miss the new ones?
