Hyper F-C Bump Rubber, Soft

The Hyper Racing F-C (Full Control) Bump Rubber is 4" tall. The advantage of a tall bump rubber is that it can have a lot of engagement before the spring rate becomes infinite. This happens at about 2-¼" on this bump rubber. On a normal 2" bump rubber this happens at about 1" of travel. When the spring rate becomes infinite, the car gets really tight. On a wingless car, this can happen on entry when the driver lifts or if there is any kind of roughness in the track.

A bump rubber is used to keep the car from bottoming out and to add spring rate and therefore dynamic corner weight when the chassis travels far enough to get into the bump rubber. Generally, bump rubbers are used on the left rear shock.

It is used on a wingless car to add traction on corner exit. As the car squats on the left rear under acceleration, if set correctly, it will compress the bump rubber and add a lot of left rear weight, which can, if not excessive, add traction. The timing of when the chassis hits the bump rubber is very critical. Use the bump shims (packers) to set the bump gap to control when and how much bump rubber engagement and therefore left rear weight is added.

Do this with the driver in the car and the left rear shock adjusted to minimum rebound dampening. This allows the car to find its true static ride height. Note the distance of how much the left rear has to travel before it hits the bump rubber. This is called the bump gap.

A bump rubber can be used in winged racing for some situations to keep the car from bottoming out on the left rear on entry.