what is caster angle

Our mission is to help you modify your car the right way, whatever your budget. While camber is the side-to-side tilt of your tire, caster, also known as “mechanical trail” is the front to rear positioning. Camber and caster adjustment bolts are a possible option. Just know that any significant upgrades to your vehicle’s engine will need you to tune your vehicle to prevent engine damage. Caster is the measure of how far forward or behind the steering axis is to the vertical axis, viewed from the side. The angle between the drawn line and vertical is the caster angle. The only downside to positive caster is that it increases the effort it takes to steer your vehicle. Firstly, it’s important to note that you can’t always adjust your car’s caster, especially in front-wheel drive vehicles. A Quick Summary of Caster Angle: Keep it Positive. Positive caster improves your vehicle’s responsiveness when rounding corners and improves your vehicle’s stability when traveling at higher speeds. Also, zero caster provides easy steering input without the extreme instability of using negative caster. Or maybe you’re trying to figure out why your vehicle isn’t handling right after that last tire change and don’t want to spend a ton of money trying to improve it. If you have a high speed, high performance ride, your sports car will need more caster to handle better on the straightaway and when coming out of turns. In simpler words - picture the side of a vehicle, now imagine a vertical axis (line) that runs straight through the center of your front wheels. Caster is the measure of how far forward or behind the steering axis is to the verticle axis, viewed from the side. Did you miss the lessons about camber and toe? It sounds simple, and it is, but drivers often overlook it. No matter what you do, chances are, there's going to be a front end, or 4-way alignment involved at the end. A final change you can make to improve your vehicle’s handling is to keep an eye on your vehicle’s tire pressure. Discussion Starter • #1 • Mar 21, 2012. Ever been in an old car that has very heavy steering? The front steering forks on a motorcycle are an easy-to-see example of how caster works. Caster angles over 10 degrees with radial tires are common. What is the Caster Angle? Caster. Excessive caster angle will make the steering heavier and less responsive. Required fields are marked *. Keep in mind that while this method will allow you to change the caster angle by a few degrees, you won’t be able to turn a negative caster into a positive caster or vice versa. Casters are used in numerous applications, including shopping carts, office chairs, hospital beds, and material handling equipment. The better traction while cornering is similar to a vehicle with negative camber, as it keeps more tread on the ground despite the sharp angles. In this guide, we break down everything there is to know about caster angle, it’s different types and the various handling effects it has on your car. There’s simply no need for a vehicle with a zero caster. For modern vehicles however, power steering has made that advantage obsolete. It is the angle between the pivot line (in a car an imaginary line that runs through the center of the upper ball joint to the center of the lower ball joint) and vertical. As an Amazon Associate we earn from qualifying purchases. If you liked what you read here leave a comment below or check out some of our other guides for even more automotive knowledge. You can add or remove shims from the rear bolt or where the upper control arm attaches to the hub. So, focused on racing cars and on positive camber, we can resume the two primary benefits: When cornering, the vehicle weight shift is met with a maximization of the tire contact patch on the outside front wheel that’s under maximum cornering load. This increases the stability of the vehicle in straight line situations, increasingly important at high speeds. Now it’s the time for Caster to be analyzed. It doesn’t make much sense without a little context — how can a tire tilt from front to rear since it’s a circle? For a kart, which has no differential on the rear axle, the caster is a key factor which determines different aspects of the set-up. The rear suspension on … This effect is best visualized by imagining the unrealistically extreme case where the steering axis would be horizontal-as the steering wheel is turned, the road wheel would simply change camber rather than direction. An example of caster in action is the front wheels on a shopping cart. If your car doesn’t provide a way for you to adjust the caster independently, your only hope is to adjust the camber and hope that it shifts the caster to spec. A zero/neutral caster setting would result in a perfectly vertical spring/shock with the center of the wheel positioned directly “south” of the strut mount or upper ball joint (depending upon the vehicle suspension type). The only notable advantage to having negative caster is that the steering input effort required is very low making the steering very easy to turn. Camber is positive (+) when the top of the wheel leans outwards (away from the car) while it is negative (-) when it leans inwards (towards the car) at the top. Cross camber may also be specified, but not usually both. In the automotive field, negative caster gives no feedback to the driver in terms of wheel position. The camber angle is measured in degrees. If you’re looking for a cheap way to get a little more out of your car, adjusting your caster angle might be just what you need. If you increase the degree of the positive caster angle too much, it will create more heaviness in the steering. This is called cross caster and the difference is called the spread. The advantages of positive caster angle on a race car. As long as your vehicle has power steering, and unless you drive a Model T or other antique vehicle, there are no disadvantages to positive caster. A caster (or castor) is an undriven wheel that is designed to be attached to the bottom of a larger object (the "vehicle") to enable that object to be moved. Caster a little more complicated than camber and toe. What to read more about tyres and suspension: caster? A good example of extreme caster angle would be the front suspension on a chopper motorcycle. Can we get a vrooom over here? Wheel Alignment: Caster Angle. Some front-end alignment calls for different right side and left side caster. While a positive caster has several advantages, there are no advantages to a negative caster in modern vehicles. So, since the wheel rotates about a tilted axis, the wheel gains camber as it is turned. It is the angle between the pivot line (in a car an imaginary line that runs through the center of the upper ball joint to the center of the lower ball joint) and vertical. So today we are talking about Caster. In automobile racing, positive caster angle may be adjusted to optimize handling characteristics for a particular venue. How to Adjust. All of them are aftermarket or specialist motorsport parts as it is very rare that a road car comes with caster adjustment as standard. Caster affects a vehicles resistance to turning, and changes the amount of camber gain a wheel has when turned. A larger contact patch means more grip, and that’s never a bad thing. The main disadvantage to positive caster is that the steering requires a higher amount of input effort to turn the wheel. Find them out in our mechanical lessons! Wider wheels in the rear of your vehicle will give you more traction when both braking and accelerating. Can you detect a caster problem on your own? The angle between a line drawn from the car suspension strut to the ground (pivot point) and the tyre contact point. Whether you’re heading to the track or the highway, these are advantages you want on your vehicle. Wanting safer, cheaper and smoother motoring? So keep it positive! Caster, also known as the caster angle, is the slant measured from the top of steering axis to the bottom of the wheel when the former is attached to the latter. We may be given a small commission when you purchase a product from our site. Even if your power steering fails, modern vehicles are incredibly difficult to drive without power steering, regardless of the caster angle. Making any changes beyond a few degrees would require a significant overhaul of your suspension system, and this isn’t a common way to alter your vehicle, so you’ll likely end up needing some aftermarket parts. Caster and Camber Angles. Your email address will not be published. Caster is positive if the line is angled forward, and negative if backward. The caster assembly (302) has a caster pin (604) at an angle with respect to the board plane. This is an angle that can be measured and adjusted, following a four wheel alignment check on your car. Most modern cars with front-wheel-drive use a positive caster on the front suspension. But unless you have a vehicle without power steering, you won’t even notice the difference. A vehicle's camber affects tire wear and stability. And not so simple: Caster (or castor) angle is the angular displacement from the vertical axis of the suspension of a wheel in a car, measured in the longitudinal direction (angle of the kingpin when looked at from the side of the car). One advantage of using zero caster is that it retains the slight reduction in kingpin torque before reaching the limit of adhesion, which is useful for a driver to know when the limit is near. These camber changes are generally favorable for cornering, although it is possible to overdo it. Another way to improve performance is with the help of a staggered wheelset. The only advantage to negative caster is that it’s easier to turn the steering wheel. In performance driving circles a caster increase – sometimes to the maximum available setting that the vehicle will accommodate – is credited with improvements in vehicle handling, maximum traction, and steering responsiveness. Because of this, there isn’t much need for vehicles with zero caster. You get better handling when cornering, better stability at high speeds, and better straight-line tracking. Caster angle definition: the forward or backward tilt of the steering axis in a vehicle, when considered from the... | Meaning, pronunciation, translations and examples Power steering is usually necessary to overcome the jacking effect from the high caster angle. But what is caster angle, and how does it affect your ride? Caster angle provides directional stability, and ease of steering. Vehicles with SLA suspensions use the upper and lower ball joints to create the angle, and those with struts use the center of the … The caster angle is the angular displacement of the steering axis from the vertical axis of a steered wheel in a vehicle measured in the longitudinal direction. If your upper ball joint or strut mount is located more toward your vehicle’s rear than the lower ball joint, your vehicle has a positive caster. However, some vehicles do have ways for you to adjust the caster angle. These are eccentric bolts that can change your angle by a few degrees. Weather changes drastically alter your tire pressure, and unless you’re keeping an eye on it, you’re losing traction every time you step in your vehicle. When it comes to positive caster, there’s nothing to not love. (The real caster is zero because the wheel patch is simply offset from the vertical and there is no relative angle between the steering axis and vertical, but we can compare this example to a wheel with negative camber for the position of the pivot). Disadvantages of a negative caster angle. Primarily because most mods that are popular on a Jeep involve the suspension. Positive caster creates a self-aligning torque. Power steering is usually necessary to overcome the jacking effect from the high caster angle. Furthermore, performance upgrades, like aftermarket turbos, intakes, and exhaust systems, are great ways to improve your vehicle. There are several advantages to a vehicle with a positive caster — these include increased steering angles and better straight-line tracking. 1,747 Posts . Your email address will not be published. They run a large amount of positive caster to make the cart track straight without wandering. It is also the type of caster that is used on a shopping trolley (or hospital beds, office chairs…) and is the reason why wheels can wobble and turn easily. Historic and class cars had negative caster, which made their non-powered steering systems much lighter. You get slightly worse handling than positive caster and somewhat better handling than negative caster. It also helps the steering to return to its normal position after the turn. Zero caster is when your upper ball joint or strut mount is directly in line with the lower ball joint. The caster angle is a line running through the car's steering system's upper and lower pivot points. It’s also incredibly rare. However with power steering systems this is not an issue. If the vehicle has power steering, they opt for positive caster, and if they don’t, they use negative caster — it’s just that simple. Caster angle refers to the location of your vehicle’s upper ball joint or strut mount compared to the lower ball joint. 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