Anyone here like to discuss their approach to damper setup for non/low downforce racing cars?
This is something no-one ever wants to talk about because they either haven't a clue, or they feel they have an advantage, and do not want to give it away.
I propose that discussion amongst race engineers will benefit everyone.
I will briefly describe my own approach, in hopes that some of you will add your own thoughts/experiences.
First off, all my experience is with sedans, either tube frame, or production tubs. Mostly solid rear axle.
I start by calculating critical damping of the sprung mass, and use a digressive piston with no preload to approximate a linear curve with the damping set at approximately 35% of critical.
Determining a starting point for the compression damping requires a bit more guesswork. So much guesswork that I am embarrased to describe it. The first thing I do is calculate the rebound force at the wheel for the front and rear. If there is a drastic difference between the two, I take that into account so that total damper force at the wheel is relatively equal at both ends of the car.
(By total damper forceI mean compression and rebound combined for each end of the car.)
I then use a digressive piston with very little preload, and set damping to approximately 50% of the rebound in the high speed range.
Once on the track, I start by varying the rebound damping until the driver feels that the car has "just enough" stability. Sometimes this results in gobs of rebound damping and the car starts to lose grip over rough surfaces. In this case I increase the preload to bring up the low speed damping, and then re shim to bring the high speed rebound back into a reasonable range.
Once this is done I try to make the car work over the curbs by varying the compression damping. In my experience, a softly sprung car will benefit from large amounts of high speed compression damping, while a very stiffly sprung car will normally need very little for best feel over the curbs.
Lastly, I look at tire wear/abuse during a long practice run, or a race. If the tires go off easily, reducing compression damping will usually make the tires much happier. The end result is normally a highly digressive curve.
Finally, once the driver is happy, I try to convince him to run less rebound. It is common for the driver to complain that the car is harder to drive, but the end result is better lap times unless the driver is relatively inexperienced,in which case he will drive the car harder with more rebound damping because the car feels more stable.
This is a very simplified description of my usual approach, and I would like to hear how the rest of you tackle initial damper setup.
I am sure I can learn something from all of you.
Paul Yaw
This is something no-one ever wants to talk about because they either haven't a clue, or they feel they have an advantage, and do not want to give it away.
I propose that discussion amongst race engineers will benefit everyone.
I will briefly describe my own approach, in hopes that some of you will add your own thoughts/experiences.
First off, all my experience is with sedans, either tube frame, or production tubs. Mostly solid rear axle.
I start by calculating critical damping of the sprung mass, and use a digressive piston with no preload to approximate a linear curve with the damping set at approximately 35% of critical.
Determining a starting point for the compression damping requires a bit more guesswork. So much guesswork that I am embarrased to describe it. The first thing I do is calculate the rebound force at the wheel for the front and rear. If there is a drastic difference between the two, I take that into account so that total damper force at the wheel is relatively equal at both ends of the car.
(By total damper forceI mean compression and rebound combined for each end of the car.)
I then use a digressive piston with very little preload, and set damping to approximately 50% of the rebound in the high speed range.
Once on the track, I start by varying the rebound damping until the driver feels that the car has "just enough" stability. Sometimes this results in gobs of rebound damping and the car starts to lose grip over rough surfaces. In this case I increase the preload to bring up the low speed damping, and then re shim to bring the high speed rebound back into a reasonable range.
Once this is done I try to make the car work over the curbs by varying the compression damping. In my experience, a softly sprung car will benefit from large amounts of high speed compression damping, while a very stiffly sprung car will normally need very little for best feel over the curbs.
Lastly, I look at tire wear/abuse during a long practice run, or a race. If the tires go off easily, reducing compression damping will usually make the tires much happier. The end result is normally a highly digressive curve.
Finally, once the driver is happy, I try to convince him to run less rebound. It is common for the driver to complain that the car is harder to drive, but the end result is better lap times unless the driver is relatively inexperienced,in which case he will drive the car harder with more rebound damping because the car feels more stable.
This is a very simplified description of my usual approach, and I would like to hear how the rest of you tackle initial damper setup.
I am sure I can learn something from all of you.
Paul Yaw
