What the Hell is Corner Balancing?
Corner balancing is one of the most commonly overlooked things in the world of suspension. The definition of a corner balance is the process of shifting the weight carried by each wheel to evenly distribute the weight of the car across all four wheels. You are properly “corner balanced” when you have even weigh distribution between your driver front and passenger rear tire and also even weight distribution between your passenger front and driver rear corners. Some special applications require a different corner balance setup like 40/60 distribution with more weight in the rear. Some weight can be moved around by physical moving parts of the car (i.e. relocating your battery from the front to the rear, removal of spare tire, etc.), but the corner balancing process is mainly focused on shifting the weight of the vehicle by adjusting the spring height of each shock/coilover.
As with all things suspension related, everything is affected by everything and your corner balances play a large part in the forces that act on your suspension under acceleration, braking and especially hard cornering. A properly corner balanced car has a planted feel on the track and provides predictable reactions under racing conditions and when traction is broken. A commonly used analogy for corner balancing is to imagine a four legged table. A corner balanced car is like a table with all of it’s legs at an even length and does not wobble. If one leg of the table is shorter than the other, the table wobbles when pressure is applied to a corner and this represents a car that is not corner balanced. These wobbles translate into unnatural weight shifting and decreased grip overall when it matters.
Corner balancing is usually reserved for track and racecars as it greatly affects the suspension characteristics under heavy loads. Most track cars are equipped with adjustable coilovers that simplify the job of adjusting ride height over each coilover perch, which in turn changes the weight distribution of the vehicle. Sometimes the process is as simple as adjusting your ride height, but if the weight imbalance is extreme, physically relocating or removing parts would be a way to achieve that ideal 50/50 distribution for most racers. Adding weight to your car sounds like the opposite of what you should do if you’re racing but in some cases extra weight is needed in a corner during balancing and there are numerous race cars with simply a metal plate or weight bolted to the body to dial in the weight distribution, this weight is usually called a ballast.
The actual process of corner balancing involves four specially made scales that need to be used on a perfectly flat surface to accurately read the weight distribution across the car. These individual scales usually connect to a central computer that displays all of the values you are adjusting for. Adjustments are made mainly at the spring perches to adjust the ride height at each corner. These adjustments include changing the amount of weight resting over the spring perch in relation to the other three springs and is a very intuitive and time consuming process as the values for each corner change in relation to each other so be sure to document everything as you go.
When performing a corner balance you must be sure that your car is exactly the same as it would be under track conditions. The weight of the driver over the left front of the vehicle needs to be accounted for, along with all of the fluids topped off or at whatever levels are optimum during competition driving along with proper tire pressures. Not only does the weight distribution across left-right and front-rear planes matter, the cross weight of the car does also. You can find the cross weight of your vehicle by adding wheel values that are diagonal to each other (ex. RF tire + LR tire = cross weight) An unbalanced or improperly cross weighted car might have the tendency to understeer in a left handed corner while oversteering in right hand corners due to the amount of weight sitting on each tire during the turn being uneven.
If you are corner balancing alone it’s a good idea to add roughly your weight to the driver seat to simulate your weight on the left side of the car to properly balance it. If you’re a sizable racer, missing 150+lbs of weight when corner balancing will throw everything off. Take some time to also disconnect your sway bars both front and rear to relieve the tension in the suspension to get the accurate weight distribution. Taking time to do these two things while corner balancing will be sure to provide you with the most accurate weights.
Whether you’re doing this at home with your own scales or taking your car to a shop, the process is the same but the more people you have, the faster, easier and safer the process is. Once the car is set up to simulate race day conditions (mentioned above) the process can begin. The car is rolled onto the scales and the first measurement is taken. Your two main values to aim for should be an 50/50 left and right side weight ratio and a proper “corner balance”. This means that your vehicle’s weight is distributed evenly on a diagonal plane across the car. If you were to draw a straight line from your driver side rear wheel to your passenger side front that is your cross weight and you want that weight to be equal to the cross weight of the driver front and passenger rear.
TAKE NOTES! Literally. As you should already know one suspension adjustment affects everything and your corner balancing changes are no different. Document every change every time you adjust a spring perch while corner balancing and be sure to roll your car off of the scales every time you make changes. The more time and more often you corner balance your car the more notes you will have. This in turn leads to a faster and easier process every time because you have a solid book of adjustments and notes so you’re not building from scratch. Also, take notes.
The whole process involves a lot of trial and error along with developing a feel for the actual process in the beginning. A lot of the benefits of corner balancing are seen with higher end and racing spec springs that usually come with higher/stiffer spring rates. Most road cars for every day use sit on springs that are softer than 300lbs/in. Adjustments on spring rates softer than this have a smaller affect on your suspension than making the same adjustments on a stiffer corner. The whole corner balancing process shows most of it’s benefits in racing use instead of just daily driving. If you corner balance your daily driver Honda Civic you could have spent that time and money elsewhere because you’ll never be under conditions to feel the benefits.
In the end corner balancing your ride should not be overlooked if you’re serious about your vehicle’s suspension and your track times. This should process should be done in conjunction with suspension tuning to add the final touches to your suspension. With a basic understanding, some confidence and a good set of scales you can dial in your suspension on your own. Ideally if you can work something out to where you can get your suspension tuned at a track or AutoX event you will be able to see exactly what effects the changes you are making are having on your car’s handling and will make you a better racer overall.