Shock Adjustments In RC Cars

Shocks basically serve two purposes. They keep your chassis off the racing surface and keep the tires on track. The way that they accomplish this is to use a spring in combination with a damping medium, normally oil and a piston, to control the motion of the shock shaft throughout its complete range of motion.

The function of each of the components needs to be understood individually to have a have a better understanding as to what each one does and how it complements the other in performing the function of the shock.

Springs control the ride height of the car. Normally, it is best to use the softest spring that will keep the chassis off the ground. There are exceptions to this (as any other) rule but not too many. Once you have a basic 'feel' for the adjustments, you will know when you need more spring.

Piston and shock oil are there to control the motion of the spring. Without them the car would just bounce until the energy that was put into the spring by the suspension dissipated itself. A full scale car with worn out shocks tend to wander and bounce after hitting a bump. Dampers absorb the excess energy stored by the strings when the car goes over a bump. Without dampers the car would bounce up and down uncontrollably.

An important consideration about the car is the shock length adjustment. This is one criterion that is often overlooked even by old racers on the track. A formula 1 car (full scale) has about 2.5 cm of suspension travel at both ends. A rally car has as much as possible at both ends. All shocks are not the same. This example basically it gives an idea of which adjustment to make first if your car is not handling the way that you would like it to.

Generally speaking it is normal to have the front end a little stiffer than the rear. This will make it so that your car does not tend to 'hook' or 'oversteer' in the corners. If while making a turn the car turns to much, making the rear-end slide it is known as over-steering. A car with a little bit of 'push' is much easier to drive than one that is constantly trying to swap ends.

If more traction is required then the suspensions need to be softened at that end of the car. For example, if more steering is required, lighter oil in the shocks should be put or lighter spring should be used. It important to remember which component controls what. If there is excess ride height, a spring that is one softer should be chosen and see if that works first since it is the easier swap. If that allows the chassis to button out, then put the original spring back on and start experimenting with lighter oils in the shock or pistons with more or larger holes in them to reduce the damping effect. Usually it is easier to change oil than it is to change the pistons.

Making the opposite adjustment at the other end of the car has similar effect. For example, if a bit more steering is needed, the rear end should be stiffened a bit and that should give a bit more front end bite. It will also allow the back end to be a little more 'loose' in the turns. Loose is fast but too loose is hard to control.

Obviously, if less steering is needed or more rear bite, adjustments opposite to the ones mentioned above should be done.