Understanding RC Wheel Adjustment: Camber, Caster, and Toe

If the wheel and tire angles are too far from the ideal settings, even the best-equipped remote-controlled car with tires that are precisely matched to the terrain would handle poorly. Like full-size automobiles, RC models with independent, adjustable suspensions enable exact adjustment of camber, toe-in, and caster to optimize handling. You might wonder what RC wheel adjustment is and how it impacts handling. Let's get started.

RC Wheel Adjustment: Camber 

Your car's wheels appear to be vertical or slightly skewed toward the chassis if you get down to tabletop level and gaze at it directly from the front or back. What you're seeing is the camber angle of the wheels. The wheel may tilt toward the chassis by up to three degrees of negative camber, or it may have zero degrees of camber, which means the wheel is entirely upright. Although a positive camber is rarely employed unless you're modifying the left front wheel of an oval racer, it would be present in a wheel that tilts out.

Most likely, you're wondering why the wheels aren't just mounted vertically, as that makes the most sense. The contact patches on the tires and how they alter when the vehicle turns corners provide the solution. When a car rotates, the tires lean with the chassis, which leans toward the outside of the turn. When you need more grip to turn a corner, the tilted wheel and tire produce less traction since the tilted tire's contact patch is less than a vertical one. A small amount of negative camber is adjusted to compensate for the tilt. This brings the tire closer to vertical as the vehicle turns, giving you the most grip possible.

The ideal environment depends on you, your car, the track conditions, and your tires. The recommended angles in your manual are a good place to start. When modifying the camber (or any suspension setting), make sure to set each side of the car equally and work in small increments—even a half-degree can have an impact.

And the perfect setting? You, your vehicle, the track, and your tires play a role. Your manual's suggested angles are a solid starting point. Make sure to adjust the camber (or any suspension setting) evenly on all sides of the vehicle and in small steps; even a half-degree change can make a difference.

Due to their opposing threads, turnbuckle links can be turned to either lengthen the link by unthreading both rod ends or shorten it by threading the ends deeper. Most models that include turnbuckle links also have a wrench that fits them. These are the optional TUBES linkages for Traxxas.

Turnbuckles are absent from models with pivot ball suspension. Instead, the pivot balls are threaded into or out of the suspension arms to adjust the wheel's tilt.

Use a camber gauge to measure your car's settings precisely. This aluminum JConcepts gauge is a high-end variant, while RPM's plastic gauge is a traditional (and affordable) option.

RC Wheel Adjustment: Toe

Look at your car from above now. The front tires may point slightly in or out or straight ahead. Even though the rear tires are pointed directly forward, they are most likely leaning slightly inward. As you might expect, wheels pointing in have toe in, wheels pointing out have toe out, and zero toe is when the wheels are heading straight ahead. Like camber, turnbuckle links adjust front toe-in, but the rear toe is often fixed and may only be altered by switching the hub carriers or rear arm mounts.

The most common toe angle adjustment influences the car's stability on straightaways and cornering aggression. Most models include one or two degrees of toe-in, which sacrifices sensitive turn-in for improved straightaway stability. The car's turn-in reaction improves at the price of stability on the straightaways when toe-in approaches zero or surpasses zero to become toe-out. Instead of measuring the toe precisely, most drivers set it by giving the left and right turnbuckles an equal number of rotations. The correct setting is whatever feels best on the track. If the rear toe is reduced, the car will feel looser in corners and better grip on straightaways. It is worthwhile to experiment with the rear toe if you have the track time to spare, even if many drivers keep with the stock settings.

RC Wheel Adjustment: Caster

Compared to camber and toe, caster is more difficult to visualize; nonetheless, the following example will assist. Keep in mind that the steering arm's pivoting kingpin is inclined backward. The caster angle, in this example thirty degrees, is the angle created by a vertical line and the kingpin angle. Casters enable the tires' wheels to self-center, which improves straight-line stability. The tire's contact patch is far behind the steering axis and track surface intersection when the line is extended through the kingpin to the track surface. Like a furniture caster, the wheel "wants" to line up behind the steering axis.

As the wheels steer left and right, the caster angle also influences the camber angles of the tires, which is a more complicated discussion. What matters most is how you will feel behind the wheel. While greater caster angles make the car more stable in a straight line, they also make turning more difficult, and vice versa. 4WD buggies only have about 10 degrees of caster, whereas 2WD buggies (like the Traxxas Bandit in the picture) can have up to 30 degrees. Less caster is needed for a 4WD vehicle because its powered front wheels make it more stable than a 2WD model. Most models install new, cheap caster blocks to set the steering caster. If your vehicle has optional caster blocks, we advise trying them out.

Make Small Changes, Test, and Keep Notes

Remember only to alter one setting at a time and to make tiny adjustments as you play around with your car's settings. If you change several things at once, you won't be able to identify what is helping or harming you. Instead, thoroughly try each new setting to see how it affects the vehicle. Make notes on the configurations you like best so you can quickly reset if you're unhappy with your adjustments. And enjoy yourself as usual.