Weight Transfer Calculator
Calculate weight transfer during acceleration from vehicle weight, wheelbase, CG height, and g-force. See dynamic axle loads for drag racing traction planning.
Typical passenger car: 18-22 in. Sports car: 16-19 in. SUV/truck: 24-30 in.
Percentage of total weight on the front axle. Most FWD: 58-63%. RWD: 50-55%.
Typical drag launch: 0.8-1.5g. Street launch: 0.3-0.6g.
How Weight Transfer Works
When a vehicle accelerates, inertia causes weight to transfer from the front axle to the rear axle. This isn't the physical movement of mass — it's a shift in the normal forces acting on each axle. The result is more grip at the rear tires and less at the front.
The Formula
ΔW = (W × a × h) / L
Where W is total vehicle weight, a is acceleration in g's, h is the center of gravity height, and L is the wheelbase. Three things increase weight transfer: more weight, higher CG, and shorter wheelbase.
Why It Matters for Drag Racing
Tire grip is proportional to the normal force on that tire. A rear-wheel-drive drag car needs maximum weight on the rear tires at launch. Understanding weight transfer helps you optimize:
- Suspension setup: Softer front springs and stiffer rear springs (or a four-link) allow the rear to plant harder.
- Ballast placement: Adding weight toward the rear increases static rear weight, and keeping it low reduces CG height.
- Wheelie bars: When weight transfer is extreme enough to unload the front wheels, wheelie bars prevent the car from flipping.
Center of Gravity Height
CG height is the most influential and hardest-to-measure variable. Typical values: sports cars 16–19 inches, sedans 20–22 inches, trucks/SUVs 26–32 inches. Lowering the car reduces CG height, which reduces weight transfer — this improves handling balance but can reduce drag launch traction.
Braking Weight Transfer
The same formula applies in reverse during braking — weight transfers forward, loading the front tires. This is why front brakes are larger than rears on most vehicles, and why nose-heavy cars often have excellent braking performance.
Frequently Asked Questions
How do I estimate my car's center of gravity height?
The most accurate method is to weigh the car level, then raise one end a known height and re-weigh. The CG height can be calculated from the weight shift. As a rough guide: sports cars 16-19 inches, sedans 20-22 inches, trucks/SUVs 26-32 inches. Lowering a car 2 inches typically reduces CG height by about 1 inch.
Does a longer wheelbase help or hurt drag racing?
A longer wheelbase reduces weight transfer for a given acceleration because the lever arm is longer. This means less rear tire loading at launch, which can hurt traction. However, longer wheelbases are more stable at high speeds and less prone to wheelstands. This is why dedicated drag cars are often shortened but pro-class cars use wheelie bars instead.
How much weight transfers during a hard drag launch?
A typical 3,500 lb muscle car with a 108-inch wheelbase, 20-inch CG height, and 1.0g launch transfers about 648 lbs to the rear axle. That's nearly 19% of the car's total weight shifting rearward. On a sticky track with slicks pulling 1.5g, that jumps to nearly 1,000 lbs of transfer.
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