Dampers

As they were in Star Mazda, or in any other car really, dampers are of great importance. Matthew Rogers try to understand and clarify how dampers work.

Shock absorbers (also known as dampers) are designed to “dampen the oscillation of the spring after the wheel travels over bumps and dips.

There are many different explanations and examples of how to understand shocks, however shocks article at TurnFast! seems to explain everything quite clearly.

Without shock absorbers, the vehicle’s springs will continue to “oscillate” or repeatedly compress and uncompress, or “bounce.” This reduces the tire grip with the racing surface due to erratic shifts on the suspension and tire contact patch.

The stiffer the shock, the faster the weight transfer occurs. This will help the vehicle have very responsive steering, but the transfer can be too fast for the driver. This does not necessarily mean the faster the car will corner, but rather the faster that the weight will come to rest on that corner of the car as it is shifted either in corner entry or corner exit.

During cornering in particular, the driver must be able to induce smooth weight transfer and feel the tires reach their maximum grip. If the weight transfer occurs too fast, the driver will not feel the tires approach that peak grip, and will likely overshoot the traction capacity of the tires causing excessive sliding or spins.

Summary

The shock’s purpose is to control the oscillation of the spring’s response to bumps and dips. The stiffer the shock, the faster the dampening. The shock also controls the rate of weight transfer. The stiffer the shock is for compression (or “bump” as it is often called), the faster weight transfer occurs which determines how fast the tires will take their “set” in a corner, and the resulting steering responsiveness of the car.

It is possible to have too stiff a shock which will overpower the springs, and results in weight transfer being too fast for the driver’s experience and sensitivity to feel when maximum tire grip is achieved in a corner (generally resulting in a lot of spins).

Shocks need to be selected knowing the ratings of the springs.

Below is a general guide from Raceline Central that should assist you in fine tuning your shocks.

  • bumpSHOCK COMPRESSION:
    • FRONT
      • The stiffer the front shocks, (higher the number) the tighter the car will be when braking.
      • The softer the front shocks, (lower the number) the looser the car will be when braking.
    • REAR
      • The stiffer the rear shocks, (higher the number) the looser the car will be under acceleration.
      • The softer the rear shocks, (lower the number) the tighter the car will be under acceleration.
  • reboundSHOCK REBOUND:
    • FRONT
      • The stiffer the front shocks, (higher the number) the tighter the car will be under acceleration.
      • The softer the front shocks, (lower the number) the looser the car will be under acceleration.
    • REAR
      • The stiffer the rear shocks, (higher the number) the looser the car will be under braking.
      • The softer the rear shocks, (lower the number) the tighter the car will be under braking.
  • Shock synopsis:
    • RF (Right Front)
      • Higher compression will tighten the chassis entering a corner.
      • Lower compression will loosen the chassis entering a corner.
      • Higher rebound will tighten the chassis accelerating out of a corner.
      • Lower rebound will loosen the chassis accelerating out of a corner.
      • Overall stiffer RF shock will tighten chassis, weaker will loosen it.
    • RR (Right Rear)
      • Higher compression will loosen the chassis accelerating out of a corner.
      • Lower compression will tighten the chassis accelerating out of a corner.
      • Higher rebound will loosen the chassis entering a corner.
      • Lower rebound will tighten the chassis entering a corner.
      • Overall stiffer RR shock will loosen chassis, weaker will tighten it.
    • LF (Left Front)
      • Higher compression will tighten the chassis entering a corner.
      • Lower compression will loosen the chassis entering a corner.
      • Higher rebound will tighten the chassis accelerating out of a corner.
      • Lower rebound will loosen the chassis accelerating out of a corner.
      • Overall stiffer LF shock will loosen chassis, weaker will tighten it.
    • LR (Left Rear)
      • Higher compression will loosen the chassis accelerating out of a corner.
      • Lower compression will tighten the chassis accelerating out of a corner.
      • Higher rebound will loosen the chassis entering a corner.
      • Lower rebound will tighten the chassis entering a corner.
      • Overall stiffer LR shock will tighten chassis, weaker will loosen it.
  • Asymmetrical changes:
    • The stiffer the shock, the less grip that tire will have.
    • Stiffer rebound on the left shocks will help the car turn in by slowing weight transfer to the right.
    • Stiffer compression on the right shocks will help the car turn in by also slowing weight transfer to the right.
    • Softer rebound on the front shocks will loosen the chassis exiting the corner.
    • Softer compression on the rear shocks will tighten the chassis exiting the corner.
    • Doing just the opposite mentioned above, on either compression or rebound will produce just the opposite results.
    • Asymmetrical changes seem to have a greater influence than individual shock changes.

Check Matthew’s wikidot site with more info about iRacing setups here.

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