On an RC car there are many components that you can fine tune to see optimal performance for your application. Tuning the suspension setup is just one of those items that should be considered when going for optimal performance. The suspension consists of a handful of different areas that can be fine tuned. If on the track you are fast, a really good suspension tune will make you faster. It’s very similar in tone to differential tuning which was covered in a previous article. If you are just a basher, a specific tune will allow you to make higher jumps. Included in our list for setup basics is spring rate, shock oil, caster, camber and toe.
Tuning Camber
Camber is best defined as the angle that the tire makes as it contacts the ground. Negative camber will have the top of the wheel angled towards the RC car. Where as positive camber will have the top of the wheel angled away from the car.
Typical Camber Settings for all 4 corners is between -2.0 to 0 degrees. It’s recommended to use a negative camber when racing a circuit that involves more corners. For straight line racing or offroad rock crawlers, a zero degree camber is a good place to start. It is very uncommon to see positive camber on most RC applications. If you are driving an RC tractor, look at positive camber.
| Negative Camber | Positive Camber |
|---|---|
| – Increased traction on front/rear wheels while entering a corner – Increased braking in to a corner. – Instability in a straight line – Reduced traction for straight line acceleration. – Reduced straight line braking – Premature tire wear | – Increased stability – Less steering effort to turn wheels – Reduced traction when entering a corner – Reduced traction for straight line acceleration – Reduced straight line braking – Premature tire wear |
If your suspension setup is stiff, you will require less negative camber since there will be less body roll in to corners.
Tuning Caster
Caster is best defined as the angle that the suspension makes between the upper and lower steering pivot points when viewed from the side of the vehicle. A good practical example would the looking from the side of the front wheel of a bicycle. A bicycle is known to have positive castor. A good example of negative castor could be found on the front wheels of a shopping cart.
On a bicycle, it is not too difficult to ride one without using your hands to steer. This is because of caster. Positive caster allows the front wheel to try and get back to center.
In general you always want positive castor for RC specific setups.
| More Negative Caster | More Positive Castor |
| – Decreased steering effort – Weaker in straight line tracking – Less stable at higher speeds | – Improved straight line tracking – More stable at higher speeds – Increased steering effort – Produces negative camber when cornering |
Toe in / Toe Out Settings
Toe in an RC car setup refers to the angle that the tires make relative to the direction that they point in. This can be viewed directly from the top of the RC car. Toe out refers to tires that are pointed away from the car where toe in represents tires that are pointed inward.
Keep in mind that excessive toe can result in wasted power and increased levels of drag. Typical Toe ranges from -2.0 to 2.0 degrees in the front
| Toe Out [negative toe] (Front Wheels on a 4WD vehicle) | Toe In [positive toe] (Front Wheels on a 4WD vehicle) |
| – Reduced under steer – help free up the car during initial turn in when entering a corner | – Reduced over steer – Enhanced high speed stability |
| Toe Out [negative toe] (Rear Wheels on a 4WD vehicle) | Toe In [positive toe] (Rear Wheels on a 4WD vehicle) |
| – No real benefit | – Improved grip – Enhanced high speed stability |
Suspension Shock Oil
The weight of oil that is used inside of the shock also known as the strut changes the dampening rate. A thicker oil will slow the piston inside the shock. A thinner oil will allow the piston to travel quicker inside of the strut. If the shock oil does not allow the piston to travel quickly when an RC car goes over a bump, the car can lose traction. If the shock oil allows the piston inside the strut to travel too quickly, the car is at risk of bottoming out.
Suspension Spring Rate
The springs ultimate purpose is to support the weight of the vehicle. The spring rate goes hand in hand with the shock oil weight used. If you plan to use a tighter setup, you will want a heavier oil with heavier springs. If you use a heavy oil with light springs, when the spring compresses while going over a bump, the light spring will not be able to extend the strut quick enough before it hits another bump. This will caused weak performance. Instead use a spring rate that matches the oil weight you plan to use.
| Thicker / Heavier Shock Oil | Thinner / Lighter Shock Oil |
| – Reduced traction on an off road / bumpy surfaces – Reduced body roll in high speed turns – Improved energy absorption in higher jumps (bashing) – Reducing the odds the vehicle can bottom out | – Increased traction on off road / bumpy surfaces – More body roll in high speed turns |