When winning and losing can be determined by mere thousandths of a second, it’s important not to overlook any opportunity to maximize a car’s performance. Typically, a drag car’s engine, transmission, and suspension setup are carefully scrutinized and optimized, but one area that’s often overlooked and can significantly impact how a car performs is its weight and balance. Scaling a race car is how you make sure the vehicle is properly balanced.

For those who want to take their programs seriously and are looking for a competitive advantage, having a well-balanced and properly scaled car ensures maximum traction, improved handling, and optimal weight transfer, all of which contribute to quicker and more consistent runs.

Why You Should Scale Your Vehicle 

Ideally, a drag car needs to be properly balanced to maximize traction while also maintaining enough control over the front end to keep the car stable and drivable. Unbalanced cars face a wide range of (potentially dangerous) issues. Most successful drag cars have a slightly rearward-biased weight balance, with approximately 50- to 55-percent of the weight over the rear tires — depending on the specific chassis and class, of course.

Scales are the best way to “true up” a race car and make sure it’s properly balanced at each corner. That balance is going to impact every aspect of how the car reacts during a pass.

If there’s too much weight hanging on the front of the car, weight transfer can be negatively impacted, which reduces traction and wheel speed at the launch. Similarly, if a car isn’t balanced correctly on its left and right, it may tend to pull toward the heavier side during a run. Contrastingly, if there’s too much weight in the back, the front end can either lighten or lift (hello, wheelies!), which can hurt elapsed times as well as the driver’s ability to steer and control the car.

Eric Saffell, a National Account Manager at Longacre Racing Products’ parent company, AFCO Performance Group, has seen a lot throughout his impressive career in the industry. Saffell explains what the goals are when it comes to corner balancing a vehicle. 

“We use four corner scales to optimize chassis setup and prepare for a successful test session/race event. Using practiced methods, we have targets that we look for when comparing one corner to another so that the vehicle will perform as desired.”

By using a set of four-corner scales, however, racers can make sure their car is properly balanced before they strap in and make any necessary adjustments to optimize performance. Longacre Racing Products has a comprehensive line of race scales, alignment tools, racing gauges, and other products designed to make scaling and balancing any setup a simple process.

Tips For Scaling A Race Car

It takes more than just putting the scales under a race car’s tires to properly scale it. Saffell revealed some important tips to get the most out of a scaling and balancing session for seasoned drivers as well as rookie racers.

“First and foremost, it’s important to ensure that the surface being used is flat,” Saffell notes. “If you aren’t sure if it’s flat, an easy way to check is to hose down the floor and let it show you where the high and low spots are. If the spot can’t be made flat, you’ll need to find a new one.”

A good set of scales is critical to getting a car set up. The scales need to be accurate and adjustable so you can get the correct readings. Longacre offers scales that work with an App to assist with setting your car up.

Once an appropriate location has been found, set up the scales, power them on, and set the unloaded weights to zero. If you’re using wired scales (such as Longacre’s Elite Wired line) as opposed to wireless (like the Elite Pro Wireless), it’s important to avoid walking on the wires.

Next, prepare the car and make sure it’s in race-ready condition. This includes making sure the air pressure in the tires is set to race pressure, all fluids are filled to the proper levels, all body panels (hood, doors, deck lid, etc.) are installed and secured, and the driver is in his or her seat along with all of their safety equipment. “You’ll also want to bounce the car at each corner prior to scaling, too, this will make sure the suspension has settled,” noted Saffell.

You can use the scaling process to help set up your vehicle’s suspension before you go to the track. This will help make sure the car will launch straight and not wander around during a pass.

With everything confirmed, it’s time to move on to the actual scaling and corner-weighting process. “Make sure you center the tires on each scale pad. In the rear, lift the car from under the center of the rearend, then lift the tires slightly off of the pads to remove any binds,” Saffell explains. “For the front, pick up each wheel by positioning a floor jack under the lower control arm individually to remove any bind, lower the suspension, and re-center the pad under the tire.”

It’s important to make sure the car has settled correctly and nothing is bound by bouncing it at each corner again. For accurate readings, it’s also critical to remove any preload in the suspension and the anti-roll bar, and make sure the doors of the car are closed, as even something as simple as that can impact the overall balance of the car.

As you work on scaling the car you’ll need to watch the percentages closely. The goal is to obtain the right balance for your vehicle’s application.

You’ll need to check and record the weight readings at each corner to determine the overall balance and distribution. From here, any changes to ride height, ballast placement, or suspension can be made to achieve the desired weight balance and distribution.

As Saffell points out, weight transfers diagonally — raising the left front corner will increase the weight on the right rear — so to move weight without changing ride height, work diagonally.

“If the right rear needs to be heavier, start with two turns tighter (clockwise) on the left front shock and add two turns tighter (clockwise) on the right rear. If the right rear needs to be heavier, start with two turns tighter (clockwise) on the left front. Add two turns tighter (clockwise) on the right rear. Loosen (counterclockwise) the right front two turns and loosen (counterclockwise)  the left rear two turns,” he clarifies, regarding optimizing the chassis with more weight on the right rear without changing its overall ride height. “The goal is that the front ride height doesn’t change and we don’t change how the chassis transfers weight front to back, either.”

Each corner weight is going to help paint a picture of what needs to be adjusted. It’s important to make all adjustments diagonally across the vehicle.

After scaling the car, and while it’s still on the pads, always bounce each corner aggressively and compare the “after” scale numbers to the original readings before bouncing. If the numbers don’t match, there’s a reason. Common causes can be a component that’s bound up, a coil spring or leaf spring failure, bad ball joints, or compromised Heim joints. One last check that’s critical to remember is making sure the coil springs have seated properly after returning the car to the ground. If they haven’t, the corner weights and ride height will be impacted — and that defeats the entire process of scaling the car in the first place.

Finally, it’s time to load up, head out, and gather some real-world results and data. After scaling and balancing a car, evaluating changes in on-track performance (whether expected or unexpected) is an incredibly useful tool when making suspension adjustments.

After each run, carefully review the data and address what the car is, or isn’t, doing. “If it launches to the right, we’ll need the right rear tire to have more influence on driving the car forward, assuming the rear end is square in the chassis,” shares Saffell.

Keeping the vehicle centered on the scales is important. You also need to make sure all of the bind has been removed from the suspension.

By properly balancing and corner-weighting a drag car, you’ll enjoy straighter launches and a more consistent chassis as compared to simply slapping a Band-Aid on the chassis issues by adding preload to the suspension. “The addition of preload in the rear suspension links can increase bind and cause tire spin through dips and bumps in the track surface,” Saffell warns.

Taking the time to make sure a car is scaled and balanced correctly before ever pulling into the waterbox not only contributes to quicker passes, but it makes a safer car overall with better and more predictable handling. Optimizing both side-to-side as well as front-to-rear weight bias is essential for maintaining stability at high speeds and improving traction during hard launches.

While many other factors can contribute to a car’s overall weight and balance — such as its engine placement, transmission choice, ballast locations, the chassis itself, shock and strut settings, spring rates, ride height, and even high-speed aerodynamics — knowing how and where weight is placed can make troubleshooting and tuning easier in the long run.