If I say setting up the suspension and shocks are the big obstruct of many RC Beginner on building their RC car, I think that most of you (especially if you are one of the beginner) would agree to it. There are enough tuning options on even the simplest of vehicles to make your head spin. In this article, we will focus on the following five aspects of your vehicle’s final setup for any given purpose: Camber, Caster, Toe-In/Out, Ride Height & Droop and Shock Angle. Also, we will introduce some simple tools to make your set up easier!
Camber is the lean angle of the tires while looking at them from the front or back of the car. If while looking from the front of the car, the tops of the tires lean in, it has positive camber. If they lean out, it has negative camber. Positive camber aids in traction while cornering. The outside tire will have more contact with the ground as the weight of the car pushes towards the outside of a turn. By tweaking the camber, you can adjust your wheels to have more contact on the track surface and then have more traction. More the suspension is stiff, less camber you’ll need.
A trick to check your camber setting is to check tire wear. If it is wearing evenly across the tire, camber is about where it should be. If its wearing towards the outside of the tire, add a little camber. If its wearing towards the inside, you have too much camber. The picture show below is an example of too much camber.
This is the angle at which the kingpin lies in relation to the ground when viewed straight from the side of the vehicle. A perfect 90 degrees from the floor is zero degrees of caster. If the top of the king pin or steering block leans toward the rear, this is positive caster. In the opposite, if the king pin or steering block leans forward the vehicle, this is negative caster. Generally speaking, more caster in the front will offer greater straight line stability at speed as well as high speed cornering, but will sacrifice initial turn in. Caster in the rear is referred to as anti-squat and it is exactly what it sounds like. The steeper the angle of the hinge pins on the inner of the rear arms from back to front, the less the vehicle will squat upon initial acceleration. Bear in mind that under-damped rear shocks coupled with an over-tightened slipper will adversely affect the anti-squat settings. Adding too much anti-squat is also not suggested, as it will offer little stability over rough stuff.
This refers to the angle of the wheels/tires when viewed from straight above in relation to the center line of the chassis. Toe-in will offer greater straight line stability while toe-out will offer greater initial turn-in and sacrifice straight line stability. Again, this is something that can be altered by the shock mounting positions and the bump steer as well as the shock fluid and spring selection.
Ride Height & Droop:
We notice that many of the beginner always get this mixed up. Ride Height is the distance from the ground to the bottom of the chassis on your vehicle while it is at rest. With ride height, a higher car will jump better, but will be less stable in corners. It could even roll over in high traction scenarios (traction roll). A lower ride height will be more stable in turns, and can result in faster cornering speeds. Be careful not to go too low, however. If the car bottoms out on the track it will be thrown around, making it more difficult to drive.
Droop is something different, although it looks like you’re adjusting the height. Droop is adjusted using droop screws that are in the lower suspension arms of your chassis. It is the amount of upward or downward travel of your suspension above or below your ride height. In other words far up the chassis will “raise” after you’ve pressed down on it. The purpose of droop is to help with the weight transfer from front to rear when on throttle or braking. Say that your car is under steering when you let off on the throttle in a turn. What the chassis is doing at this moment is shifting the weight from the rear of the car to the front. When this happens, the rear end lifts a little. By adding more droop to the rear, more weight is transferred to the front tires, giving it more steering and grip, and lessening the load on the rear.
Shock Angle: Shock angle refers to the mounting position of the shocks on both the upper and lower mounts. Not only are the quality your spring and oil choices are the important factors in how your vehicle will handle, but they also govern the position in which the top and bottom of your shocks are mounted. Let’s break down the front first. Up top, the outermost mounting position will offer the sharpest steering response and the sharpest or quickest shock response, while the innermost mounting holes will offer less steering while offering smoother shock response. The bottom mounts on the front are pretty much all about cornering. Inner mounts will accentuate the vehicle’s low speed steering while outer holes on the bottom in the front will contribute to high speed cornering ability.
The rear shock’s mounting positions are also about steering response, but also about handling and launch characteristics. On the top of the shocks, an outer hole will also lend itself to more steering and better suspension reaction, while the inner-most mounts will offer better rear traction and an overall smoother ride over rougher terrain. The lower mounting holes on the rear offer even further options for steering response. Inner mounts provide less steering with smooth shock reaction while outer holes equal sharper steering with less control over rough conditions.
Your head is probably spinning and you have no idea what you just read, but take it slow, follow a few simple rules and you’ll be an expert in no time. Remember to change only one thing at a time and then practice. Make another change and then more practice again. The idea is to take it slow and only make one setup change at a time, this can let you know the effect of each change and let you easier to figure out the best set-up. So, let’s practice more to become a RC expert!
Credit: RC Soup, RC Driver