When setting up a car for road racing, corner balancing is an important aspect of preparation. So, you’ve installed coilovers on your car, set a rough ride height, reinstalled the wheels and tires, and set it back on the ground to see if any further adjustments need to be made. Sure, the car sits how you want it to, but is the weight of the vehicle evenly distributed throughout all four corners of the car? Probably not. Changing the weight distribution of the car affects how it behaves when cornering, which can be a good or a bad thing.
Properly corner balancing a vehicle will improve its performance out on track, and that’s why we reached out to Kenny Brown Performance and Maximum Motorsports for some further insight on the practice.
What Is Corner Balancing?
Often referred to as “corner weighting” or “scaling,” corner balancing is the adjustment of spring perches on the car to obtain a balanced diagonal weight on the tires using four individual scales. A common analogy for corner balancing is a basic four-legged table. In order to distribute weight evenly, all four legs have to be the same length, but if one leg is shorter than the rest, the whole table becomes unbalanced and wobbly. A car’s wheels function in very much the same way.
Corner balancing adjusts the diagonal weight distribution (the weight that sits on each tire contact patch at rest). This means that the driver should be in the car with the fluids topped off and a proper amount of fuel in the tank to simulate race-weight conditions as accurately as possible. It is important to clarify that static weight can only be changed by physically moving weight on the vehicle. This includes relocation of batteries, lead ballast etc.
Take your time and take notes and take notes and take notes. – Kenny Brown, Kenny Brown Performance
With static weight distribution, there are two factors that are used to measure a car’s corner weights – left weight percentage and rear weight percentage. Left weight percentage is calculated by adding the left front and left rear weights, then dividing the sum by the total vehicle weight. The reason for the importance of the left side is compensating for the weight of the driver. The rear weight percentage is calculated by adding the left rear and right rear weights, then dividing the sum by the total vehicle weight. A lot of electronic scales will calculate these percentages for you.
The diagonal weight is the ‘cross weight,’ which is an important aspect of corner balancing. For example, the left front and right rear should weigh the same as the right front and left rear – a 50/50 cross balance. Cross weight is also referred to as “wedge.” If the cross weight is over 50-percent, the car has wedge; if the cross weight is under 50-percent, the car has what’s called reverse wedge. One of the problems with cross weight is that it will change the handling balance from a right to a left turn. When racing on a road course, the cross weight should be as close to 50-percent as possible, or at least within a percent or two either way. That will keep the handling balance similar in a right-hand turn compared to a left-hand turn.
If the car’s cross weight isn’t balanced, the car will turn better in one direction than it does in the other. On some tracks, such as Road Atlanta, there are significantly more right turns than left turns, so a biased cross balance might be in your favor. Not all tracks are like that, but not all tracks have an equal amount of left and right turns.
“In some situations, the driver may want the car to handle asymmetrically for certain tracks. To get a desired asymmetry, the car needs to start with a symmetrical baseline,” stated Jack Hidley of Maximum Motorsports.
Corner balancing can also be done by adding weight to the car where it is needed or by relocating select components to other areas of the car. In the past, enthusiasts have used nearly anything they could find to add weight to their car to get a near-perfect cross balance. We’ve seen weight plates made from dumbells, gallons of water, sandbags, and lead weight bars etc.
We asked Kenny Brown why an enthusiast racer would want or need to corner balance their car:
“If you break it down to the core function, driving a race car on track boils down to weight management. Managing the car’s weight on each of the tires to maximize grip; rear for traction, front for braking, left/right for cornering. Having the corner weights close at static, makes this function a little easier. Having said that, the higher level of performance and skill set of the driver and the closer to the car’s maximum, the more important corner-weights become. For novice and intermediate drivers, corner weights aren’t as important as honing their basic driving skills.”
How To Corner Balance Your Vehicle
Not pictured are our ramps. We used two aluminum ramps in the front and a couple of 2x4s in the back.
When corner balancing a vehicle, there are quite a few aspects to take into consideration. First, you want to make sure your scales are on level ground. Any difference in the height of the scales will cause your measurements to be incorrect. “The scales must be placed on the ground, and then the height of each scale checked relative to the other scales, using an accurate method such as a water level or a laser level,” explained Hidley. “Whichever scale is higher than the others is designated as the primary scale. The three lower scales must have their height raised to match the primary scale. The scale heights should be adjusted so all are with 1/16-inch of the primary scale.”
We added dumbell weights to simulate the weight of our driver.
Before the car even touches the scales, it needs to be set up exactly how it would be out on the track. That means that the car needs to be aligned, have the ride height set, tire pressures set, and weight added to simulate the driver and fuel load. The next step of preparation is to disconnect the sway bar. Disconnecting one end would work, but disconnecting both ends will relieve more friction from the suspension.
One thing that you absolutely need to corner balance your car is a set of ramps – one behind each scale so it is easy to roll the car on and off of the scales.
“After several height adjustments, or even every adjustment, the car must be rolled off and back onto the scales. Doing so will allow the tire’s lateral position to readjust itself, avoiding binding from suspension scrub,” Hidley added. “Never lower a car directly onto the scales.”
Once your car is on the scales, you can now see how its weight is distributed throughout all four tires. If one corner of the car has more weight on it than any of the others, you can reduce the weight by lowering the ride height in just that corner.
“This will decrease the weight on that corner, and also on its diagonally opposite corner,” Hidley explained. “If one corner of the car has too little weight on it, you can increase the weight by raising the ride height in that corner. This will add weight in that corner and its opposite corner as well.”
Brown said, “Take your time and take notes and take notes and take notes. Corner weighting a car is extremely time consuming, every adjustment needs to be noted with the result. You can’t rely on memory. The more experience someone has in corner weighting a car, the quicker and easier it is because they have a thick notebook of adjustments and results to reference.”
It is also very important to make small adjustments to each corner, checking your results on the scale, and logging them as you go. Another point to make light of is that the stiffer the suspension is, the less vertical height adjustment you need to make.
“One turn on a typical coilover sleeve can make a significant change to the weight,” Hidley added.
Taking your time and understanding the consequences of the changes you make is key when corner balancing a vehicle. With the slightest misunderstanding, the wrong changes can be made and your car won’t handle as you expected it to.
“The biggest mistake we see is people not understanding what can be accomplished with corner weighting, and what cannot. We frequently see people make references to using corner weighting to change things that it cannot change,” said Hidley.
With all of this information about corner balancing flowing through our heads, we can’t wait to test out the handling on Project M-Track3r when we take it to the track. We’ll also be corner balancing Project Habenero Hatch as well when the time comes. We would also like to thank Kenny Brown of Kenny Brown Performance and Jack Hidley of Maximum Motorsports for all of their helpful insights and tips.