Bump Stop Setup

A bumpstop are pieces of rubber or plastic attached to front shocks to limit shock travel.  They are applied to the front only, because this is where the race cars chassis will have the most travel through the turns.

it seems to simple doesn't it?  A little piece of polyurethane that's shaped like Homer Simpson's favorite food "A Doughnut."  But I assure you, all that was simple ends as soon as the bump stop is put onto the shocks.  Teams want to limit the shock travel with this because the springs and shocks work together under a cup car and the team that could figure out the right match would win.

The bump stop fits into a small cup that slides on the shock, and there are a number of different sizes, and levels of hardness to choose from.  The advantage is the ability to run softer springs in the front of the car without the worries of bottoming out the chassis or rubbing the exhaust.  The height of the bump stop is very important to how the car handles through the corner.  If you don't have the correct heights on the bumpstops, the shock can actually hit the stop and then bounces back and tries to rest on the other bump stop.

Just like all the other adjustments on the race cars chassis, there isn't a specific number for setting bumpstop height in order to gain a couple of tenths.  Teams can control the height of the bumpstops by using shims.that are produced in increments of .01-inch.