We are going to discuss one of the most important parts on the racecar today – the shocks. The shocks are extremely important because they control how the car reacts all the way around the track. Shocks have many adjustments and can really make or break the car’s performance.
The main adjustments on a shock are compression and rebound. The Fox Shocks we use are double adjustable, and you can easily adjust the rebound and compression by clicking the knob on the top and bottom of the shocks. The top of the shock knob adjusts the compression and the bottom of the shock knob adjusts the rebound.
A shock has many adjustments and the first would be the rebound setting inside it. Rebound in shock terms is how fast the shock comes out when the shock is compressed on the racetrack. An example would be your RF (right front) shock set at click 8. The 8th click could be 600 pounds at 1 inch of speed on the dyno. You can adjust the shocks rebound higher or lower by simply screwing out or screwing the adjuster knob.
If you went to click 4 on the rebound shock it would be more rebound force and hold the car down more. If you went to click 12 it would mean less rebound and let the cars corner come up faster.
You want to keep the RF corner of the car down when the track is faster so you can steer into the corner and exit of the corner. When the track starts to get slick you would want to reduce some rebound so the car doesn’t stay down on the RF and not transition the weight to the rear of the car.
The track getting slick and slowing down means that the track doesn’t have as much grip and needs less force holding the front of the car down. If you leave too much rebound in the RF when the track gets slick, then it could result in a sideways running car and less traction to go down the straightaway.
The next adjustment would be the compression on the shocks. Compression is very simple. It is when the shock compresses and the amount force it takes to compress the shock. The RF corner of the shock would require more compression at a higher banked or a higher speed track. You would need the compression at a higher speed on the shock dyno because it is far less than the rebound inside the shock.
An example would be the compression set at click 12 on the shock. The 12th click would represent 100 pounds of compression at 5-inch speed on the dyno. If you were going to a slower race track, then you would typically want to go towards click 16 and less compression. A higher speed track might require you to go to click 8 to keep the car up under the faster speeds.
An example of compression and rebound on the racetrack could go as follows:
Volusia County Speedway (higher speed and big corner racetrack)
This racetrack starts out very fast and has a lot of force on the RF corner of car. A safe setting would be to set the RF rebound at click 4, which would be 800 pounds at 1-inch speed on the dyno.
I would want more rebound to keep the RF corner of the car down, so I can steer into the corner properly and continue through the corner.
If I was at this high-speed track and the nose did not want to stay down I couldn’t carry enough speed into the corner. I add more RF rebound, so it will keep the car down, and I can carry speed into the turn.
The car needs to stay down all the way through the corner because if it starts to raise up before I get on the straightaway then I would have to let out of the gas to keep the car from pushing.
The same type of track would require more RF compression in the shock. You would want to increase the compression because the high speeds will make the car slam down on the RF corner of the car. A car that slams down too fast because of less compression makes it very difficult to drive and you just cannot keep speed.
The rebound setting in a shock is typically more important than compression, but at the end of the day each adjustment can really make or break your performance.
It takes a lot of trial and error to find what does and doesn’t work. Every driver is going to want slightly different settings to match their driving style, but these guidelines give you a starting point.
You might also enjoy to read this previous Tech Made Simple feature:
Tech Made Simple: The J-Bar