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How to Set up the Suspension on a Remote Control Car
By Joe Rich
The fascination with remote control cars is not likely to fade anytime soon, and when you decide you want to build your own RC car, you’ll need to learn a little about how to put the different systems together for it to be a success. The suspension system is one of these, and if it sounds complex, don’t worry because there are things you can do to make setting up your suspension system a lot easier.
Before we get to setting up the suspension system in your RC car, let’s talk a little about suspension tuning. With most RC cars, there are tons of tuning adjustments available.
It may be difficult to figure out what each of these adjustments do, but once you figure it out for your particular car, that car will be able to work on any surface and on any track you use it on.
In the beginning, it is a good idea to make a note about the setup that comes with your RC car, because if you decide to start tinkering with the car later on and make a mistake somewhere along the way, you’ll at least know how to get it back to its original setup.
There are many options available on most RC cars these days, and it’s good to get familiar with them. The following are some options usually available on an RC car and how they relate to suspension tuning:
- Anti-roll bar: Using only the front anti-roll bar results in less roll on the front chassis, which makes it feel like you’re getting more rear traction. If you use the rear anti-roll bar the rear chassis roll will decrease, which means you get a stronger feeling of steering power and less rear traction.
- Camber: If you give one end of the car less camber, there is less traction on that end. This means if your car is loose, your choices are to either add a degree of rear camber, which is highly recommended, or take out a degree of front camber. Positive camber is not always recommended, unless it’s for off-road vehicles.
- Caster: More caster makes your RC car easier to drive, making it more stable on both straight and bumpy routes. Less caster gives your car more bite, making it easier to handle corners and causing it to have a faster reaction to steering inputs. Of course, less caster can also cause the car to feel a little more “twitchy.”
- Differential: This one is easy to figure out. Looser differentials result in low-traction tracks; tighter differentials result in high-traction tracks. A tighter differential also results in greater acceleration and more instant throttle response.
- Droop: Less droop reduces body roll, while more droop in the front usually produces better on-power steering. Typically, you’ll increase droop on bumpy tracks and decrease it for high-traction tracks. To limit droop, look for screws and screw them either in or out. If there are no screws, you can place small limiters inside the shock itself, on the shaft right below the piston.
Gearing: For pinion gears, the more teeth you have, the more speed your vehicle will have, although you may lose acceleration. With fewer teeth, your car will accelerate faster but you might lose the top end. For spur gears, more teeth results in better
- acceleration but less top end, while fewer teeth results in more top end, but acceleration might suffer.
- Ride height: With high bite tracks, you should use a lower ride height; conversely, on low-traction surfaces, raising the car up slightly will give it a little more traction because it will roll more. This could also help when the car is driving on bumpy conditions.
- Steering throw symmetry: The main thing you want to remember is to turn equally left to right so the car handles the same regardless of which direction it’s going in. To do this, either lengthen or shorten the steering turnbuckles to make the throw even, or dial in or remove your steering throw using the transmitter that has an end point adjustment (EPA). The latter is the easiest option; however, not all cars have the EPA capability.
- Toe in/out: you can adjust this option to either decrease or increase your steering and steering response. Adjust it by turning the turnbuckles that are attached to either the hub carriers or the steering knuckles.
- Track width: Making the track width wider on the front of your car results in a reduction in traction rolling because it slows your steering response and reduces the front grip. Making the track width wider on the rear of the car also results in a reduction in traction rolling. It does this because the car’s rear grip is increased, as is the high-speed steering.
These options are good to learn before you get to the sometimes-complex task of setting up your suspension system because suspension tuning is an important part of that task. Naturally, there are lots more options other than these, but this will provide you with a good foundation before you move onto the next step.
Getting Started with the Setup
The main thing you have to remember when setting up and tuning your suspension system is that each setup is different. What works for one RC car owner may not work for the next one.
What does this mean in practical terms? It usually means that when you’re changing or altering one of the systems in your car, you’ll want to alter just one system at a time, then test out the car to see if it’s working properly. Concentrating on just one system at a time before changing something else allows each system to come out perfect in the end.
With this particular suspension system, there are five aspects:
- Ride height
- Shock angle
In addition, get ready your toe-in gauge, camber gauge, and your ride height gauge. Some of these gauges actually work on more than one part; for example, there are camber/caster/toe plate alignment tools and camber/caster tools that usually cost less than buying each piece separately. As soon as you get to this point, you’re ready to get started.
First Thing’s First: Camber Gauge
Camber gauges sit on a flat surface and you can move them to determine how many degrees of camber that the suspension is set to. Use the numbers on the gauge to set the tool, then get the camber you want by matching the wheel to that angle.
The camber is the angle that the wheel and tire ride relative to the ground once it’s viewed directly from the rear or front. True zero camber is 90 degrees from the ground. Negative camber occurs when the top of the tires lean inward toward the vehicle, and positive camber occurs when they lean away from the vehicle.
To increase steering, most off-road vehicles are set with two degrees of negative camber. This usually results in the tread of the tire, and not the sidewall, remaining on the road as much as possible during the run, which is what you want. As a general rule, negative camber should never go over three or four degrees of negative camber.
All About Caster: Why Is it Important?
Normally, you can change the caster by changing either the caster blocks or the inserts inside of the blocks. Whenever possible, you should have many different caster blocks so that you can tune your car anywhere you go. Caster is the angle that the kingpin lies relative to the ground when you view it from the side of the vehicle.
Zero degrees of caster means a perfect 90-degree angle from the floor. Again, off-road vehicles usually come with 20 to 30 degrees of caster in the front, mostly because of the rough conditions the vehicle is exposed to when it’s being driven.
As a general rule, if there is more caster in the front, you’ll get much better straight-line stability regarding the speed, not to mention high-speed cornering, although initial turn-in might be worse.
If there is more caster in the rear – referred to as anti-squat – and the angle of the hinge pins on the inside rear arms are steeper from front to back, the vehicle likely won’t have much squat when you first start to accelerate. If you combine under-damped rear shocks with a slipper that is overly tight, this can affect the anti-squat settings in a negative way.
But be careful not to add too much anti-squat because this option doesn’t offer a lot of stability when the course is bumpy, and it may make the rear end a little jumpy.
Ride Height 101: What It’s All About
By “ride height,” it means the distance from the ground to the bottom of the chassis of your RC car while it is not being used. A ride height tool is usually slipped underneath the car to measure the ride height. You can often adjust the ride to a particular height using the shock pre-load collars. There are two measures used to set a car for a certain ride height measurement, and they are:
- From a height of one foot, drop a vehicle that is fully loaded onto the ground.
- While the car is sitting on the ground, compress the front and rear suspension one at a time then release.
Regardless of the method you use, pay attention to the distance between the ground and the belly of your chassis, because this is your ride height.
As a general rule, the looser your traction and the rougher the track, the more ride height you should have. Less ride height will result in bite tracks that are smoother and higher. What you do not want is high CG and high grip, because this will result in traction roll, something you should always avoid.
The Shock Angle and Why it Is Relevant
The shock angle is the mounting position of the shocks on both mounts – upper and lower. Your oil and spring choices are going to be important when it comes to the way your RC car handles, but these choices can also affect how the top and bottom of your shocks are mounted. Huh? This is what we’re talking about when we say this:
- On the top, the sharpest steering response and the fastest shock response occur with the outermost mounting position.
- The innermost mounting holes offer smoother shock response and less steering.
- On the front, the bottom mounts affect cornering more than anything else.
- Your inner mounts play up the low-speed steering capability of the car; the front bottom outer holes play up the high-speed cornering ability of the car.
In addition, the mounting positions of the rear shocks affect steering response, but they also control basic handling and even launch factors. The rear’s lower mounting holes affect steering response, while the inner mounts result in less steering but a smooth shock reaction. Outer holes result in sharper steering and less control when the vehicle is being operated in rough or bumpy conditions. When it comes to the top of your shocks, outer holes mean better suspension reaction and more steering; in addition, the innermost mounts usually result in better rear traction, as well as a smoother ride when the vehicle is being driven over rough or bumpy terrain.
When it comes to the perfect suspension setup, there is no “one size fits all.” Indeed, in the end it is a compromise and doing whatever works for you. When setting up your suspension system, you need to do two things over and over again: take it slow and practice. In this area, there is no such thing as too much practice, because this is the only way to make sure you get the setup that meets your needs every time.
Springs and Shock Oil for Suspension Systems
The way shock oil works isn’t that complicated. The weight of the oil inside of the shock – also called the strut – directly affects the dampening rate. If the oil is thick, the piston inside of the shock will be slower, while a thinner oil enables the piston to travel faster inside of the strut. Your RC car can lose traction if this oil doesn’t let the piston travel quickly, especially if the terrain is rough and bumpy. On the other hand, if the oil enables the piston inside of the strut to travel too fast, it is possible for the car to bottom out.
While we’re talking about the shock oil, the weight of the oil goes hand-in-hand with the spring rate. In essence, the springs in your vehicle are there to support the vehicle’s weight, and again, this has a lot to do with the weight of the shock oil. If you want a tighter setup, you’ll want to use both heavier oil and heavier springs. If you use a heavy oil but light springs, the springs might not extend the strut fast enough before hitting a bump, meaning poor performance.
You can use the correct spring rate and oil weight by keeping in mind these simple tips:
- Thicker or heavier shock oil results in less odds of the vehicle bottoming out, less traction when the car is being driven off-road or on bumpy surfaces, better energy absorption when doing higher jumps, and less body roll during high-speed turns.
- Thinner or lighter shock oil results in increased body roll during high-speed turns and more traction during off-road use or on bumpy terrains.
Why an Upgrade?
Suspension upgrades are utilized when you want to reduce the center of gravity, reduce ride height, and improve transitional weight transfer rates under deceleration, acceleration, and even cornering loads. Naturally, the ultimate goal is an RC car that handles better and has better cornering due to higher lateral G-forces. In other words, upgrades make the car better in all aspects.
Upgrades normally consist of replacing certain components so that handling precision is made even better, and the most important components are as follows:
- Anti-roll bars. These were discussed in some detail earlier.
- Suspension bushes. Made out of rubber, these devices isolate vibration and noise to keep the car running smoother and quieter.
- Suspension coil-overs. Once these are installed, you can more easily adjust ride height, damping, and stiffness settings.
- Sports springs and dampers. Normally non-adjustable, they greatly increase suspension performance and come in a variety of types.
- Strut braces. These are perfect for better handling of the vehicle due to better stabilization and improving rigidity.
Upgrades are not required, of course, but most of them are inexpensive and easy to install, and they are highly recommended by most experts.
In the end, setups for suspension systems in RC cars consist of a lot of possibilities for you, and becoming familiar with some of the basics regarding these systems is your first step to finding the right setup for you.
If you’re still confused by some of the terminology or the tips and suggestions mentioned here, not to worry because the more you tinker with your car and the more you practice with it, the more you’ll understand about suspension setups so that you can choose the one that is right for you.