Set Up a Race Car's Corner Balance — Project Guide

🧑‍🔧 Set Up a Race Car's Corner Balance

Field: Motorsport

Written and maintained by the PhDino author · Last reviewed 21 September 2026 · Every calculator used here is tested against independent reference values · how PhDino checks its numbers

Scale the car's four corners, then use those real weights for weight-transfer and spring-rate setup instead of guessed numbers.

Corner-weighting a race car, meaning putting each tire on its own scale, is the foundation a lot of other setup work builds on. Once the actual weight at each corner is known (not assumed), that same data feeds directly into understanding how weight shifts under braking and acceleration, and into choosing spring rates that are actually matched to what each corner really carries.

This guide runs that sequence in the order a real setup session does: weigh the car first, then use those numbers for the calculations that depend on them.

🧮 Corner Weight Balance 🧮 Weight Transfer 🧮 Suspension Spring Rate

What the four scale readings tell you

Put a car's four tires on four scales and you learn more than its weight. The total is the number that every other calculation needs. The front percentage says how the weight is shared between the axles, the left percentage says how it is shared between the sides, and the cross weight, the share carried by one diagonal pair of tires, says whether the car will turn the same way in both directions.

On a road-course car that has to turn left and right alike, the usual target for cross weight is 50 percent. Oval-track cars are deliberately set up unequal, and the number they want depends on the direction they run. The calculator here defines cross weight as the right front plus the left rear over the total, so make sure that any target you read uses the same diagonal.

How to weigh the car so the numbers mean something

A scale session that is sloppy produces numbers that look precise and are not.

Use a flat, level surface with all four scale pads at the same height, and zero the scales before the car is on them.
Weigh the car in the trim you will race it in: the driver aboard, or ballast of the same weight in the seat, with the fuel level and the tire pressures you will actually use.
Settle the suspension before every reading. Rock the car up and down at each end, or roll it off and back onto the pads, so that friction in the joints is not holding a corner up or down.
Keep the steering straight and the ride heights recorded. Adjusting the springs changes ride height, and a change you cannot see afterward is a change you cannot undo.

Steps

1🎚️Corner Weight Balance
Put the car on four corner scales, in race trim with the driver aboard (or equivalent ballast), and enter each reading. This returns the total weight, the front and left percentages, the cross-weight percentage, and the average corner weight. Hit "📋 Copy Values" once you have a result: the total weight and average corner weight carry into the next two steps.
🧮 Open the Corner Weight Balance calculator
2🔄Weight Transfer
"📥 Paste Values" fills in Vehicle Weight with the real total from Step 1. Add the car's CG height, the wheelbase, and a target braking or acceleration g-force to see how much weight actually shifts between the axles.
🧮 Open the Weight Transfer calculator
3〰️Suspension Spring Rate
"📥 Paste Values" fills in Corner Weight with the four-corner average from Step 1. A front spring carries more than a rear one on most cars, so for a real setup enter the average of the two corners on the axle you are working on, then add a candidate spring rate and motion ratio to see the resulting wheel rate and ride frequency. Run it once for each axle.
🧮 Open the Suspension Spring Rate calculator

Worked example: a 2,800 lb track car: weights, braking and springs

A lightweight track car, with the driver aboard, is on four scales: left front 742 lb, right front 718 lb, left rear 672 lb and right rear 668 lb. Its center of gravity is 19 in high and the wheelbase is 100 in. The plan is to check the balance, find out how much weight moves under 1.2 g of braking, and choose springs for both axles.

Step 1: Scale readings

You enter	Value
Left Front	742 lb
Right Front	718 lb
Left Rear	672 lb
Right Rear	668 lb

The calculator returns	Value
Total Weight	2,800 lb
Front %	52.14 %
Left %	50.50 %
Cross Weight % (RF+LR)	49.64 %
Average Corner Weight	700 lb

The total is 2,800 lb, with 52.1 percent on the front axle and 50.5 percent on the left side. The average corner is 700 lb, but the corners run from 668 to 742 lb, which is normal for a front-engined car with the driver on the left.

Cross weight is (718 + 672) ÷ 2,800 = 49.64 percent. A car that must turn evenly both ways wants 50 percent, so this diagonal is about 10 lb light. Raising the spring perches at the right front and left rear by enough to add roughly 5 lb to each, which takes about the same from the other two corners, brings it to 50 without changing the total.

Step 2: Weight transfer under braking

You enter	Value
Vehicle Weight	2,800 lb
CG Height	19 in
Wheelbase	100 in
Acceleration/Deceleration	1.2 g

The calculator returns	Value
Weight Transfer	638 lb

Longitudinal weight transfer is the deceleration in g times the weight times the center-of-gravity height divided by the wheelbase: 1.2 × 2,800 × 19 ÷ 100 = 638 lb.

It all lands on the front axle. The 1,460 lb the front axle carries standing still becomes 2,098 lb, 75 percent of the car, up from 52 percent. That is why front brakes and front tires are made larger than the rear, and it is also why the rear tires have little to do under hard braking.

Step 3: Front springs

You enter	Value
Spring Rate	350 lb/in
Motion Ratio	0.9
Corner Weight	730 lb

The calculator returns	Value
Wheel Rate	283.5 lb/in
Ride Frequency	1.95 Hz

Copy Values carries the four-corner average of 700 lb, but the front of this car is heavier than the rear, so we enter the front axle's own average, 730 lb per corner.

A 350 lb/in spring acting through a 0.9 motion ratio is worth 350 × 0.9² = 283.5 lb/in at the wheel, because the motion ratio counts twice: it reduces both the distance the spring moves and the force it delivers. The ride frequency comes out at 1.95 Hz.

Step 4: Rear springs

You enter	Value
Spring Rate	300 lb/in
Motion Ratio	1
Corner Weight	670 lb

The calculator returns	Value
Wheel Rate	300.0 lb/in
Ride Frequency	2.09 Hz

The rear corners average 670 lb. A 300 lb/in spring at a 1.0 motion ratio gives 300 lb/in at the wheel and 2.09 Hz, about 7 percent above the front's 1.95 Hz.

Many setup guides start with the rear frequency a little higher than the front so that the car pitches less over bumps, and that is where these numbers land. It is a starting point, not a rule: aerodynamic loads, tire behavior and the surface all move the target.

What it adds up to

The chain found a cross weight of 49.64 percent, 0.36 points short of the 50 percent target, a front axle that carries 638 lb more under braking, and front and rear ride frequencies of 1.95 and 2.09 Hz. Each answer fed the next: the total came from the scales, the braking split came from the total, and the springs came from the axle weights.

Nothing here says the car will be fast. It says the numbers going into every later decision are the car's own, not guesses, which is what corner weights are for.

Notes & limitations

Suspension Spring Rate uses the corner weight you give it. Real cars usually don't weigh the same at all four corners, so use the average of the two corners on that axle, or re-run the step with the specific corner's own scale reading for a more precise per-corner setup.
Gear Ratio & Top Speed, Tire Contact Patch, Aerodynamic Downforce, Braking Distance, Fuel Load Strategy, and Lap Time Delta are all real, standalone checks that didn't get forced into this sequence. There's no genuine shared value between them and a corner-weighting session specifically.

Mistakes that spoil a corner-weight session

These are the errors that make an hour of adjusting worthless.

Weighing on a floor that is not flat. A pad that sits a few millimeters higher than the others changes the readings by more than the adjustments you are trying to make.
Not settling the suspension, so friction holds a corner where the last movement left it and the readings drift from run to run.
Changing conditions between sessions: a different driver weight, a different fuel level, different tire pressures, so that you compare numbers that were never comparable.
Mixing up the diagonal. Some sources define cross weight from the left front and right rear, and the target and the sign of the adjustment flip with the definition.
Adjusting several corners at once. Each spring-perch change moves all four readings, so make one change, re-settle, and re-weigh.
Using the scale weight as the sprung weight for the spring calculation. The wheel, tire, brake and part of the suspension are not carried by the spring, and leaving them in slightly understates the ride frequency.

What the calculators leave out

Weight Transfer here is the longitudinal kind, between the axles under braking or acceleration. Cornering transfers weight between the left and right sides by an amount that depends on track width, roll-center height and roll stiffness, and none of that appears in these three calculators.

Ride frequency is a useful comparison, not a grip measurement. It says nothing about damping, roll stiffness or how the tires behave, and a car with frequencies that look right on paper can still handle badly. Treat the numbers as a foundation to start testing from.

Frequently asked questions

What is cross weight, and why aim for 50 percent?

Cross weight is the share of the total that sits on one diagonal pair of tires. On a car that turns left and right alike, 50 percent means the two directions load the tires the same way, so the car does not favor one direction. It is a balance of the diagonal, not of the sides, and it is adjusted with the spring perches.

What is a good ride frequency?

It depends on the car and its use. Road cars typically sit around 1 to 1.5 Hz, while cars built for the track commonly run higher, and cars that make real downforce go higher still. The example lands near 2 Hz at both ends, in the range of a stiffly sprung track car, but the right number is the one your tires and the circuit reward.

Why does the motion ratio enter squared?

Because the spring moves less than the wheel by the motion ratio, and the force it pushes on the wheel is also smaller by the same ratio. Both effects multiply, so the wheel feels the spring rate times the motion ratio squared.

Do I have to re-weigh the car after I change the springs?

Yes, and check the ride heights and alignment too. New springs change the ride height, and moving a perch changes the corner weights, so the measurements you took before no longer describe the car.

Does weight transfer depend on how stiff my springs are?

Not in the steady state. The weight that moves between the axles under a given braking force depends on the center-of-gravity height, the wheelbase and the weight. Spring rates change how quickly the car pitches to get there, not how much weight moves once it has.