Bookoi wrote:added some front bump rebound to cope with the bump at McLaren. It helped settle the car over the bump and the car seemed a bit more responsive in the corners, but I think I killed off some of the traction.
Whilst bump/rebound will help against bumps. I feel I should explain what this actually does in the simplest way I can.
Bump and rebound stiffness is all about the shock absorbers. Bump is when the shock is compressing, rebound when it's retracting. The softer these settings are, the quicker they will compress/retract. Mainly, this is used for weight transfer under braking. We use this massively in autograss to unsettle the rear to help us kick it out for the corners. The best way I can explain this is key pointing what or which way you set these to get the desired effect. So.....
Front Bump- Softening will make the front dip more quickly under braking, making the rear light and therefore more twitchy when entering corners. Obviously, the harder you set this, the slower it will dip therefore slowing down the transfer of weight from back to front.
Front Rebound- When set at soft. As you accelerate out of a corner, the front of the car will raise very quickly, transfering the weight to the rear. This is ideal if you have a rwd car. Fwd cars obviously not so much. You need the traction and if the weight is to the rear, you have no weight pushing down on the front wheels therefore no grip and less drive coming out of the corner.
Rear Bump- Like front bump but in reverse. This comes in to play with front rebound under acceleration.
Rear Rebound- Again, like front rebound but in reverse and comes in to play with front bump under braking.
Hope this explanation makes sense. There's a very fine balance with this and if you get it wrong, it can be difficult to get it back unless you mark down each change you make. So make small differences that you can easily remember what you've changed. This way if it doesn't feel any better. You can put it back where it was.