What is a load number, it is a number that represents a weight for that corner of a race car, not to be mistaken with wheel load or a scale number? Load number is an amount of weight that the car is applying to the spring when the car is setting on it and may vary with different arms or spring locations. I feel best if we break this down into different categories to explain what is going on, we have a lot of terms and often use them to cover different things like wheel load. So, lets break them down and see what we have.
· Wheel load:
· Load Numbers:
· Scale number:
· Down Number:
· Static Wheel Load:
· Dynamic Wheel Load:
I am sure I have missed some, terms use to be a name that we used to describe a condition or an action now they are a name to describe something cool to sale. Don’t be fooled by the name but don’t be afraid to ask, we all are a little confused by things.
Wheel Load: This is the most often missed used term there is now in racing passing the horrible term side bite. Wheel load is the amount of weight that is setting on the tire at a given position, regardless the position, so your scale number is your wheel load at static. This is not the way this term is being used in a lot of cases, guys are using their smash numbers or load stick numbers as a wheel load number and that is just wrong.
Scale number: Yes, it is the same thing as what we have be using as a wheel load number. When you roll your car on the scale and the right front weight is 515 this is your right front scale number and you right front wheel load.
Load Number: The amount of weight that the spring is seeing at a given height. If you are on a Late Model and the given number is 606 @ 18.250” than that spring is compressed to 606 pounds of rate when the shock is 18.25” center to center. This allows you to change springs to any rate because the center to center number at 18.25” will always be 606 pounds. This is also known as your smash number.
Down Number: Is a number that is coming from the spring smasher that repents a total load between the spring and the bump stop. It is the compressed value of those two items at a given amount of compression and not the amount of load that the tire sees. Example is 1900 lbs of down number.
Static Wheel Load: This is the same as your scale number and wheel load, it is the amount of weight that is setting on your tire when your car is setting static.
Dynamic Wheel Load: The amount of weight generated by the car and the compression of the spring when the car is in a dynamic posture or down on the right front. This number is generated by a pull-down rig and not a spring smasher. This is the load the tire is seeing and includes all the given factors that will change the amount of load at the tire when the car is in this position.
What is a setup stick and what is a load stick? A setup stick is a device that has a load call on it and a fixed length of rod that will fit in the shock mount position when the car is setting on the ground. At this point it has no load on the device and is setting there like a shock. When the car is jacked up the load from the spring will load the stick making the load cell read a rate from the spring at that height. This allows you to change springs and go back to a point (ride height) with the same load. A load stick can do the same thing while allowing you to adjust the car up and down to see how the load is changing. The load stick is often used to create the down number for that spring at dynamic position, this allows the changing of springs while keeping the same number at dynamic.
Why is everyone so hyped up about load numbers:
Has load numbers made thing better, maybe: has load made thing easier, yes. Is this the answer to all of life problems, no and yes that statement right there will start an argument we a few people? This is something we have been doing for years but we just didn’t know it when we scaled our cars. Now I do think it is better in the fact that it is more accuracy way of setting ride heights and changing springs at the track. But will it take the place of scaling a car. For a lot of guys, the answer is yes but it shouldn’t. So let’s look at why, when you use a load number can it tell what rear percentage you have and it if you are on a standard spring package in the left rear (200 for a modified) do you really know how much and what to do next. I feel when setting up load numbers you need to 1st scale the car so you know exactly where you are at and do it on a standard spring package at ride height. You must establish that the weight that is setting on all four corners is setting there correctly, with out that your car will be unbalanced and the right rear tire load will be either low (no grip) or high (wear out tire).
Let’s look at it like this, if some placed a large amount of weight on the car somewhere would our load numbers be able to see this, NO. This is why we get ourselves in trouble with the weight jack bolts, they aren’t intended to add wedge to the car, they are there to allow you to establish the correct right height, the wedge is created by adding lead to the car. Now don’t shout me down, we use the bolts to add wedge at the track all the time and this is okay, kind of like they say, what happens at the track should stay at the track.
All this is different when we move from car to car, and it applies better to a coil over car or I feel so. When looking back on what we discussed hear is where you need to be with a lot of cars when establishing load numbers.
· Scale your car to your desired percentage on a standard spring package.
· Make sure your cars weight is disturbed correctly in the car.
· Establish your center to center number of your coil overs and do a good job at this.
· Smash your coil overs at the given heights that you determine and document that number.
· Example the right front is 18.250 c to c at a weight of 610 pounds.