The left rear (LR) slider is one of the most important parts of a dirt modified. It works the exact opposite as a coilover would. A coilover’s job is to compress when weight falls onto it. It’s supposed to compress and hold onto it based on the spring weight of the spring. A coilover is supposed to get shorter from hole to hole when weight is applied as it compresses and will expand when the weight comes off the spring.
A sliders job is to EXTEND and get longer/taller. Instead of trying to compress like a coilover which lowers that corner of the car, it’s trying to raise that corner of the car and get longer hole to hole. This is why we want these in the LR as we want the car to roll over onto the right side, onto the RF and RR.
Imagine putting a jack just in front of the LR tire under the driver seat and jacked up the chassis. This is what we want the car to look like when we are in the corner. We can’t ride around with a jack under the car so we have a slider to raise the LR of the car, transferring weight from the left side of the car in the corner to the right side. The state in which the car is hiked up in the LR is called the Dynamic state, or at drop, or full droop. Many different terminologies or names for it.
When setting our car up in the garage, 90% of what we do is while the car is at drop/full droop/dynamic. We get the car to its dynamic state by literally putting a jack under the LR and jacking up the chassis. We jack the LR up until our LR tire just barely starts coming off the ground. This is also when our droop chain gets tight. Anytime the droop chain is tight means the car is at full droop.
When we put the slider on, we need to adjust the length of it to get it on the car. Obviously the car needs to be up off the ground to install it which means the car will be at full drop. Remember, the slider is always trying to extend and get longer in length from heim to heim, upper bolt hole to bottom bolt hole.
Because the car is in the air, you have to keep adjusting the length of the slider (heim to heim measurement) in order to bolt each end of the slider into the car. The upper heim is bolted to the chassis and the bottom heim gets bolted to the birdcage on the rear end. This measurement is called center to center. When we jack up the chassis, our center to center length gets longer as the rear end stays on the ground while the chassis raises. Once we get the car to full droop, our chain gets tight and now the rear tires begin lifting up and off the ground and our center to center stops growing.
Now that the slider is installed in the car and we are still at full droop, let’s talk about preload or, what’s also referred to as “bite”. Most of us run a 16″ long spring in our LR sliders. I currently run a 16″ 150lb LR spring in my slider so we will use that as a reference.
To get our drop load/preload/bite, we simply compress the spring x amount at full droop. I run 1.5″ of drop load in my spring. This mean it compresses my 16″ spring to 14.5″ at full droop. To figure out how much bite this gives you, it’s the weight of your spring multiplied by how many inches you have it compressed. Every inch your spring is compressed gives you the weight of your spring. So with my 150lb spring compressed 1″, I have 150bs of bite. I run mine compressed 1.5″ right now which gives me 225lbs of bite. Or, 225lbs of drop load. 1.5″ of preload. How much the spring is compressed or how much preload the spring is set to, determines your ride height.