Hello Summit Racing addicts like me! So you’ve built a hot engine and are on a first-name basis with your local delivery drivers, but now your machine is twice as scary with twice the horsepower, right?
Most 1950s to 1970s cars were pretty darned awful when it comes to handling. Over the decades, there has been steady improvement, and now even your average economy rental cheapie handles pretty dang well, and even has shocks that actually work! And with modern stability and traction controls, they even do a lot, and some even ALL of, the driving for us. The relentless march of technology—mostly great, sometimes annoying.
BUT, every car is built by the manufacturer for a purpose, and every driver has their own personal tastes, so let’s talk about how to set up suspension.
Performance Suspension Setup Basics
Here’s a super simple suspension sentence: When you turn your steering wheel, weight transfers over to the outside. Your suspension controls how it transfers side-to-side, which determines how well the car will turn. If the weight transfers more to the rear as the car turns into a corner, the back tires will lose grip first. If it loads the front more, then the steering tires will lose grip first, and the car won’t turn enough.
If your suspension is too soft for you, you will feel the car flop over. There will be a feeling of lack of control. This is why sporty cars are stiffer: more driver control.
If it’s too stiff, the tires bounce off the bumps and lose touch with the ground. So a perfect handling car gives the precise control and keeps the tires connected to the ground.
Everyone wants/needs a certain level of comfort, and most of us like a ride that soaks up the bumps and doesn’t crunch the kidneys. So here’s the challenge for suspension engineers: get the comfort and still have good control. And each of us likes these things in different proportions, right?
Modern cars often have a button that electronically adjusts the suspension (usually shocks), because most of us don’t want to same ride quality all the time. And really modern cars have suspensions that are always adjusting themselves according to some computer algorithm (magnetorheological, just call ‘em mag shocks). These have become very effective. They read your driving by steering inputs, how hard you brake and get on the throttle, and adjust for it in milliseconds.
The performance aftermarket offers all kinds of adjustable shocks and springs to make your car feel the way you want. But what do you want? I’ll tell ya how, based on a life of racing, driving, testing, and reporting on cars. (Hey, I make videos on YouTube, so you know I know what I’m talking about.)
What do you want? Stability!
You can’t ride a horse that throws you outta the saddle. Another way to say it is control. You’ve gotta have a car under ya, as they say at the Indy 500. After a strong sense of control comes everything else. Quick responses, lots of tire grip, traction under acceleration, all those other good things about driving.
When you want to set up your car, always think about how a change will affect weight transfer, because that determines your grip and handling balance. Balance is another way of saying stability and control. Get the front and rear of your car working together in a predictable way.
A stiffer suspension transfers weight more quickly for faster steering response. Summit Racing has an amazing variety from which to choose. I got a full UMI Performance spring-bar-shock-bushings setup for my Randit 1977 Trans Am that I love, and you can go all the way to an entire chassis. They can reduce body roll, which also keeps your tires at a more correct angle. They give the driver more feel for what’s happening. Shocks control the weight transfer, and can give good driver feedback as the body is rolling and weight is transferring, as well as helping keep the wheel in good contact with the road over the bumps. A suspension is a package, all working together.
It can be confusing because there is a range in which the package all works best together. The magic and voodoo is in feeling out which changes improve the car for you, and which do not. For instance, if a shock is too stiff, and you make it more stiff, the car’s reaction can become sudden, snappy. But if the shock is too soft and you stiffen it, control will improve. So an adjustment can have either effect, for better or for worse, depending on where in the soft-to-stiff range the car started.
Here’s a little chart that gives a simple rule of thumb for some of the most common adjustments.
Common Suspension Adjustments
|Front Sway Bar||Stiffen||Soften|
|Rear Sway Bar||Soften||Stiffen|
|Front Tire Size||Decrease||Increase|
|Rear Tire Size||Increase||Decrease|
|Front Wheel Camber||Decrease||Increase|
|Rear Wheel Camber||Increase||Decrease|
Tire size has a very strong effect on handling balance. If you put fat tires on the back to put power down better at the drag strip, you will find that the car will not turn as well. Wider fronts will likely improve turning ability.
Notice I did not mention shocks. It takes a lot more description. As mentioned, the same adjustment can have either effect, depending on where in the soft-stiff range you started. And, shocks only affect handling when the suspension is moving. So their greatest changes will be felt when you turn, because the body is rolling over. Think of the shock adjustments like the sway bar changes in the chart, but only temporary, because once the weight all transfers to the outside and the car takes a set, the shocks no longer have as much effect. This is in the middle of a corner, steady state, as you wait for the car to aim at your apex and the road begins to open up so you can add power. In a long turn like a 180 degree, this can be a long time.
In steady state cornering, your springs, sway bars, alignment and tire size have a much stronger effect than the shocks, typically. So when you want to improve your car’s handling, think about where in the corner the issue is. Entering, middle, or exiting? This is very important. This is how a pro driver thinks. (Or maybe just his engineer—they are a team.)
A good-handling car practically drives itself. For an excellent example, drive a 2016-22 Camaro SS 1LE. Or any 1LE. Pretty much does everything right. This would be a good reference for your hot rod. And no, I’m not on Chevy’s payroll. But I did buy one with my own hard-earned bucks, because of the handling.
We are just scratching the surface of one of my very favorite subjects: making a car handle better.
I hope this simple introduction helps make you enjoy your car more, and sound smarter to your buddies.
How to Tell If Your Car is Handling Well
I’ll leave you with a never-fail guideline that will tell you how your car is handling, and it’s free!
If you are nervous, scared, uncomfortable, worried about maybe crashing your car, then it is oversteering. Too tail happy. Too loose. The rear tires slide too much.
If you are frustrated, angry, mad at your car ‘cause it just won’t turn, then it is understeering. Plowing. Pushing. The front tires slide too much.
If you are smiling and happy, life is good, in love with you car in the corners, then your handling is about right.
Or—and this happens a LOT—you are just not driving the car hard enough to get near the limit of the tires. But in an emergency, or perhaps leaving Cars & Coffee, you will, and then you will discover how your car really handles, at a possibly very stressful and dangerous time. This is why I recommend trying autocross, a pro school, or track day to learn more about your car in a safer environment.
Here’s to the best way to use all that Summit Racing horsepower: handling.