Adjusting the suspension of an RC vehicle is every bit as in-depth as working on a full-scale car. In fact, there are almost more adjustment possibilities in RC, since hobbyists are capable of disassembling and wrenching on the entire vehicle with minimal tools and space. To newcomers, and even experienced hobbyists, it’s easy to get lost in suspension tuning. Changing a single aspect of the suspension can drastically affect the vehicle’s handling, so it is important to know not only how to adjust the suspension, but also how the adjustment will impact the vehicle’s performance. To lend some expert guidance, we have enlisted the help TLR’s highly decorated pro driver, Mike Truhe.
Mike Truhe is a former national champion in both electric and nitro off-road. How’s that for street cred?
Camber is the vertical angle of the wheels relative to the ground. Camber is adjusted by shortening or lengthening the camber links. Negative camber tilts the wheels toward the center of the chassis, and positive camber tilts them away from the center. Camber angles are relative to the tires lying completely flat on the ground with maximum contact patch (0 degrees). The vehicle will have the most forward traction at 0 degrees. Mike suggests, “More camber will help the car be a little smoother, but at times make the car not have enough forward grip. More camber can also help your car on bumpy tracks slide over the bumps and not catch and flip.” Adding negative camber counteracts body roll, but at the expense of forward traction. Adding negative camber to the front will reduce the vehicle’s aggressiveness a bit, but also adds stability, as there is less tire surface to get caught in ruts or imperfection on the track. Adding negative camber to the rear will reduce forward traction a bit but add steering response, making the vehicle whip around corners easier.
Camber adjustments are typically made in one-half to one-degree increments, and change how much of the tire contacts the track surface.
CAMBER LINK POSITION
Many vehicles allow the camber link to be mounted at different positions on shock tower and the wheel hub. Adjustments are made by removing the link assembly itself and reattaching it in different positions. On the wheel hub, utilizing the longer link will lessen camber change as the suspension compresses, causing the vehicle to turn in harder. Using the inside link lessens turn-in, but improves response at mid to exiting the turn. On the shock tower adjustment, raising the mounting position helps keep the vehicle flat and smooth out response. Lowering the mounting position creates a more aggressive and responsive feel, but at the sake of overall stability. Utilizing the inner or outer positions on the shock tower has the same effect as changing the link at the hub.
Altering the car’s caster angle typically requires replacing the caster block.
Caster refers to the angle of the wheel hub vertically. On generalizing caster setups, Mike suggests, “More caster will transfer more weight front and rear good for a looser or bumpy track.” Adding caster (leaning the uprights further back) will generally give less initial turn-in, but more on-power steering and better straight line stability, while decreasing caster will generally add some turn-in, but at the expense of on-power steering and straight-line stability.
right: It’s important to re-check your camber after changing the position of the camber link.
The horizontal angle of the wheels, relative to the center of the chassis, is the toe angle. Toe adjustments are made to the front end by widening or shortening the turnbuckles. Toe-out results in increased low-speed steering and improves steering response coming out of the corners, and front toe-in can improve straight line stability. Rear toe is usually adjusted by replacing the rear bulkhead or suspension arm mounts. Rear toe-in improves traction, but it conversely decreases steering. Rear toe-out is never utilized.
When adjusting front toe, make adjustments equally on both sides to ensure your vehicle tracks in a straight line.
The pistons are adjustable by replacing them with pistons with either larger or more overall holes. On smooth tracks with large jumps, using smaller pistons helps to absorb impact and maintain traction. Mike adds by saying, “Less or smaller holes will give the car less roll, good for high-traction surfaces.” On rough tracks with smaller jumps, using larger pistons increases the shock’s movement and ability to absorb ruts and other imperfections.
Right: Shock pistons are often marked to indicate the size of the hole (in this case), or by a numbering system specific to the manufacturer.
The viscosity (thickness) of the shock oil affects the shock’s reaction to suspension compression. Using thicker shock oil helps the vehicle absorb large jumps better, but at the expense of being able to absorb smaller jumps and imperfections. Mike summarizes it by saying, “Thicker oil makes everything happen slower. The more traction the track has, generally the thicker your shock oil will be.” In hot weather, you need to increase the weight (thicker oil) to create the same response.
Right: Be sure to keep an assortment of shock oils, especially when the weather changes while racing outdoors.
Shock springs are adjustable by changing to springs with more or less spring rate (stiffness). According to Mike, “Stiffer springs will give you more traction, but too stiff of a spring is not good on bumpy tracks, causing the car to hop around.” Using stiffer springs helps to gain traction and steering response on tracks with lots of bite and also helps the vehicle to recover its ride height after landing large jumps. Softer springs are helpful on loose tracks to slow the vehicle’s response and allow the shock to compress more easily on small imperfections. Stiffer springs in the rear can improve traction.
Right: Shock springs are typically denoted by color. Many cars use different length springs front and rear, so it’s important to keep them separate.
Some vehicles allow the battery to be placed in variable positions toward to the front or rear of the chassis. This is typically accomplished using foam block spacers, or battery compartment mounting positions on the chassis itself. Placing the battery toward the rear will improve rear wheel traction, and front placement will increase steering response. Battery placement also affects how the vehicle behaves on jumps, with rear placement causing the vehicle to jump nose-up, and front placement results in a slight nose-dive.
Right: To make finer adjustments to the car’s weight distribution, cut the large foam blocks used in the battery tray into smaller slices.
As the vehicle corners, centrifugal forces cause the suspension to flex and the outside wheels to roll onto their outer edges. The result is unwanted body roll on sweeping turns and decreased stability into and out of corners. To counteract body roll, swaybars can be installed, which help the wheels to remain flatter through turns. Mike advises, “The more traction the track has, the thicker the swaybar should be used.” While it may aid in stability, however, a stiff swaybar in the front can reduce steering response.
Right: Most manufacturers offer swaybars of different thicknesses to change the effect of the swaybar.
The wheelbase is the difference in space between the front and rear wheels on the chassis. Wheelbase adjustments are made by using spacers between the end of the suspension arms and the end of the hingepins — either pushing the arm forward to pulling it back. According to Mike, “High traction or high speed tracks usually run a longer wheelbase.” Increasing the wheelbase distance will generally make the vehicle more stable, especially on rough tracks or at high speeds. Decreasing the wheelbase, however, will improve the turning radius and result in more reactive steering.
Though wheelbase adjustments are made in fractions of an inch, they have a profound effect on the weight distribution and turning radius of the car or truck.
In many ways, adjusting a vehicle’s suspension has the greatest effect on overall performance — more than upgrading the powerplant or spending hundreds on aftermarket parts. RC vehicles are every bit as adjustable as full-scale race cars, and understanding suspension adjustments is an integral part to becoming a good racer or even setting up the perfect backyard bashing machine. Many suspension adjustments can be made without spending a dime, and those that do cost money tend to be relatively nominal, so take the time and experiment with suspension adjustments. Learning the mechanics of your vehicle and how to manipulate the suspension is a huge part of RC success.
A big “thanks” goes out to TLR and Mike Truhe for their expertise and help in the writing of this article!
Mike says: When trying out different suspension setups, remember that sometimes little changes make big differences
Make adjustments individually: In order to determine and get a feel for new adjustments, make them individually, instead of making several at once. This will help you to gauge the effect of new adjustments so that you can better learn how to manipulate the suspension to a desired feel and performance. Also, keep in mind that changing one aspect of the suspension can result in changes in other areas. For example, if you lower the ride height, you will gain positive camber. On making adjustments, Mike says, “When trying out different suspension setups, remember that sometimes little changes make big differences. Just give a few things a try and I’m sure you’ll feel the differences and find out what works best for you.”
Mike says: increasing the wheelbase distance will generally make the vehicle more stable ... decreasing the wheelbase, however, will improve the turning radius.