Calculator Inputs
Example Data Table
| Setup | FL | FR | RL | RR | Total | Front % | Cross % |
|---|---|---|---|---|---|---|---|
| Road race baseline | 640 | 625 | 610 | 600 | 2475 | 51.11 | 50.10 |
| Oval tight setup | 660 | 615 | 600 | 625 | 2500 | 51.00 | 51.40 |
| Rear bias test | 610 | 605 | 655 | 650 | 2520 | 48.21 | 50.00 |
Formula Used
Total Weight = FL + FR + RL + RR
Front Weight % = (FL + FR) / Total Weight × 100
Rear Weight % = (RL + RR) / Total Weight × 100
Left Weight % = (FL + RL) / Total Weight × 100
Right Weight % = (FR + RR) / Total Weight × 100
Cross Weight % = (FL + RR) / Total Weight × 100
Longitudinal CG = Rear Weight / Total Weight × Wheelbase
Lateral CG Offset = ((Right Weight - Left Weight) / Total Weight) × (Average Track / 2)
Target Cross Change = Total Weight × (Target Cross % - Current Cross %) / 100
How to Use This Calculator
- Place the race car on level corner scales.
- Add the driver, fuel, and race load condition.
- Enter front left, front right, rear left, and rear right weights.
- Enter wheelbase and track widths in the same length unit.
- Add target cross weight and target front percentage.
- Enter movable ballast data if you want a ballast position estimate.
- Press the calculate button.
- Review the result above the form.
- Download the report as CSV or PDF when needed.
Race Car Weight Distribution Guide
Why Static Balance Matters
A race car feels fast when weight supports each tire correctly. Static distribution is the first check. It shows how much mass rests on each corner before the car moves. This calculator helps you read that balance with simple corner scale numbers. It also adds wheelbase and track data, so the results connect to real chassis geometry.
Reading the Main Percentages
Front percentage describes braking load and turn entry behavior. Rear percentage affects traction on exit. Left percentage matters on oval cars and cars with heavy driver offset. Cross weight, also called wedge, compares diagonal load. More cross can tighten a car in one direction. Less cross can loosen it. Road race cars often seek near neutral cross when the driver is seated. Oval cars may use a planned bias for the main corner direction.
Center of Gravity Estimates
The tool also estimates the longitudinal center of gravity. It uses axle totals and wheelbase. A higher rear percentage moves the center point rearward. A higher front percentage moves it forward. The lateral estimate uses left and right totals with average track width. It is a useful guide. It is not a substitute for professional chassis measurement.
Using Target Values
Use the target fields to compare your setup with a goal. The calculator shows the change needed in cross weight. It then gives an approximate corner change pattern. Raising load on one diagonal lowers the other diagonal. Real adjustments depend on spring rate, anti-roll bar preload, ride height, and tire pressure.
Measurement Conditions
Fuel, driver weight, and ballast should be measured in race condition. Place the driver in the seat. Add fuel for the session you want to study. Set tire pressures first. Roll the car, settle the suspension, and measure again. Small errors can hide a real trend.
Setup Notes
This page is best used as a setup notebook. Record the baseline. Make one change. Measure again. Compare percentages, diagonals, and center estimates. Over time, the numbers show which changes help balance, grip, and repeatable lap performance.
Record Keeping
Keep notes beside each measurement. Track temperature, tire age, ride height, and bar settings. These details explain why numbers changed. They also stop guesswork after a busy test day. Good records turn one scale session into a setup library for future races, similar tracks, and later reviews too.
FAQs
What is race car weight distribution?
It is the share of total car weight carried by each axle, side, and corner. It helps explain balance, grip, and chassis response before the car enters a corner.
What is cross weight?
Cross weight is the combined load on front left and rear right, divided by total weight. It is also called wedge in many racing setups.
Is 50 percent cross weight always best?
No. Road race cars often start near 50 percent. Oval cars may need a planned bias. Driver style, track direction, tires, and suspension design matter.
Should the driver sit in the car during scaling?
Yes. The driver affects left, right, front, rear, and cross values. Scale the car in the same condition used on track.
Does fuel level change the result?
Yes. Fuel weight and fuel tank position can shift axle percentage and cross weight. Use the fuel level that matches your setup goal.
What does a positive lateral offset mean?
In this calculator, a positive value means the estimated center of gravity is shifted toward the right side. A negative value means it shifts left.
Can this replace professional setup tools?
No. It is a planning and estimating tool. Final chassis tuning should use quality scales, careful measurement, and track testing.
Why does one diagonal change the other?
Corner weight adjustment moves load through the chassis. Adding load to one diagonal usually removes load from the opposite diagonal.