One of the relatively inexpensive and common ways to improve handling on a vehicle is to add or upgrade sway bars. These bars, often referred to as antisway bars, antiroll bars or stabilizer bars, essentially help a vehicle that is leaning on its outside wheels as it traverses a curve to pull down on the suspension on the inside of the vehicle to reduce the amount of lean the vehicle is sustaining while in the curve.
It is an interesting concept to take a vehicle that has independent suspension, and then add a bar and end links to connect those two sides of the vehicle together — effectively taking away some of the “independent” component of the suspension. It is a bit counterintuitive, but sway bars reduce lean, and reducing lean helps camber while in corners, and the right amount of camber ensures the tire interface with the racing surface is maximized, which increases grip. More grip equals faster lap times.
Based on the above information, you might be thinking, “OK, I need more sway bar!” But, that may not be the case. You might need more sway bar in the rear, maybe less sway bar in the front. Maybe remove one sway bar altogether. Determining the best sway bar setup for your car depends on many factors like suspension design, spring rates, tire treadwear number, alignment, and class rules. What I have found is the best way to dial in a setup is to have an adjustable sway bar that allows me to make quick adjustments at the track to help make the car do what I want it to do: go fast!
I like the ability to tinker on a car and adjust it to do my bidding on track. Instead of “driving around” a handling problem, I like to see if I can solve the problem and then to go on course and attack the track with confidence. Having adjustability in my suspension — spring rates, ride height, dual-adjustable dampers, alignment, sway bars — lets me dial in the setup for good handling.
When looking to upgrade a sway bar, before you try to reinvent the wheel, find out what bolt-on parts your competitors are using, especially the ones who are in front of you on the grid. When we were working on a 10th-gen Honda Civic, we took the advice of other Civic owners who unanimously agreed, “If you want the car to rotate, the car needs a big rear bar.” We settled on a bar from Karcepts because of two things going for it: 1. The bar was massive. 2. The bar was adjustable. Add to cart!
We removed the anemic stock rear Honda bar, which was worth around 525 pounds per inch of anti-sway, and then installed the main component of the Karcept bar, a hollow baseball bat of a rear bar. The bar uses arms that have four different bolt hole options to attach the end links for adjustment. With four holes on each side of the bar, that provides seven different adjustment spots to dial in the handling of the car.
The closer the end link is attached to the bar, making the arm of the bar shorter, the stiffer the bar. For those of you who are interested in math, on the 0.95-inch wall Karcepts rear bar, here are the different amounts the bar is rated at based on the different adjustment holes used:
Hole 1/1 = 814 pounds per inch (hole farthest from the bar)
Hole 1/2 = 899 pounds per inch
Hole 2/2 = 997 pounds per inch
Hole 2/3 = 1,119 pounds per inch
Hole 3/3 = 1,265 pounds per inch
Hole 3/4 = 1,450 pounds per inch
Hole 4/4 = 1,678 pounds per inch (hole closest to the bar)
The rub with adjustability is that you can adjust a car to be perfect. And, you can adjust a car and screw it up. A systematic approach can help you dial in a setup the correct way. Once we installed the adjustable rear sway bar into the car and adjusted the end links to the perfect length, then we started to create a way to track our changes to the car. The first thing we did was mark the holes on the sway bar so we had a reference to where things were and a vocabulary to discuss changes.
Numbering holes on a sway bar with a Sharpie may seem elementary, but when you are at a race track and you are looking to make quick changes, you don’t want confusion. Yelling out of your full-face helmet, “Adjust the bar to be looser,” doesn’t mean the person underneath the back of your car burning their forearms on the exhaust actually knows what “looser” means. By numbering the holes all you need to say is, “Put the bar in position 5.” Everyone should know what that means: Bolt the end link in the hole that says 5 on it.
We have covered the importance of checklists here on the Toolshed Engineer in the past. We continue to use our handy checklists, only we upgraded the checklist with the addition of our new adjustable sway bar to match the way we numbered the holes on the sway bar. It is as simple as filling in a circle. We all got lots of practice doing this taking the SAT tests in high school. The concept is the same.
The next thing to do is test the car. When we put the bar at full stiff, position 7. I immediately spun the car on track. Whoops! Too much bar. Easy fix. We brought the car in, used a 14 mm end wrench, changed the setting to position No. 3 and then headed out on track to see if I was happy with the car.
If the car pushes, I increase the stiffness of the rear bar — making the arms shorter — higher numbers on the adjustment holes. If the car starts to rotate too much, I decrease the stiffness of the bar, making the arms longer — lower numbers on the adjustment holes. I keep testing and making changes until the car is neutral.
I record the adjustment settings for each track we go to. Sometimes I like a little more rotation in a car — Buttonwillow. At other tracks, I want less rotation — Willow Springs. By having an adjustable sway bar, I can dial in that adjustment for each track and write down the changes on our checklists for future trips to the same tracks. The key to any adjustments is to make one adjustment at a time and then document those changes. Keep notes on your setup and then watch your lap times fall and your position on the podium rise.
Having the ability to adjust the handling of a car can really improve your lap times. Adjustable sway bars are about as easy as it gets when it comes to quick changes at the track. So, go forth, test, adjust, and chase that personal best.
Rob Krider is a four-time NASA Honda Challenge 4 National Champion and the author of the novel, “Cadet Blues.”