The caster angle in turn determines another important parameter, namely mechanical trail. Still looking at the vehicle from the side, the mechanical trail is the distance between the center of the contact area and the point of junction between the ground and the steering axis. To explain this, we introduce another parameter: the mechanical trail. Why can a caster angle be good for one car but may not be ideal for another? On Assetto Corsa Competizione we can in fact find cars like the Porsche 911 GT3-R that require a low caster angle, equal to +6.7 degrees and other cars that require a higher angle, such as the Ferrari 488 GT3 Evo and the Mercedes AMG GT3 Evo, greater than +12 degrees, and then there are cars like BMW with a caster angle of about +9.4 degrees. In common road cars the caster angle value is usually between +3 and +5 degrees and is usually more pronounced on rear-wheel drive cars. In fact, on those with front-wheel drive and all-wheel drive it tends to be more contained, because there is already a self-aligning effect caused by the traction, which produces a forward displacement of the center of the contact area of the tire, which generates a moment which tends to bring the wheels parallel to the direction of travel. These cars have a low positive caster angle as the steering needs to be light and manageable and to reduce vibration. In sports and competition cars, the caster angle can assume much greater values (for example between +12 and +13 degrees). I'd like to dial the rear to about -1.25 and the front a little closer to -2 but I'll need to change to camber plates in the front to achieve that and I'm not sure if there is enough room in the rear to squeeze out less camber.The first purpose of the caster angle is to give stability to the steering wheels, which would otherwise be unmanageable. Since the center of the contact area is some distance away from the steering axis extension, a realignment moment (torque) is generated every time an attempt is made to deflect the wheel from straight travel. This self-aligning moment is felt every time the steering wheel is turned, noting a certain opposition of the same, which tends to return to the “center”, that is to the zero angle. If the angle is small, the realignment will be slow and bland, vice versa with higher angles there is a more marked return of the steering and a greater hardness of the same. I'm currently running -1.5 front and rear. Spring rates, suspension geometry, sway bars all play a role in determining how far to really go. The whole idea for increasing negative camber is to counteract the tendency of camber to go positive during hard cornering.
Switching that around will have positive effects on the handling, which in fact is reducing some negative camber out of the rear and increasing negative camber up front. Manufactures typically spec the vehicle to have less camber front and more in the rear for a conservative driving feel. There is too much detail to get into without getting into specifics of the exact specs of the vehicle and the goals of the "handling".įor a street vehicle, average joe who does minimal enthusiastic driving, it won't matter. I'd agree for the front, but excess camber in the rear does not make a car handle better necessarily. maybe your TOE is way out? Toe and Camber will effect one another during alignment, but a competent alignment person should know this.Įven less camber from -1.5 is -1.2 or -0.8 and will not handle better, more negative camber equals better handling.
Factory adjustment should allow you to get closer to spec. If that isn't possible, something is wrong. I'd ask for it to be brought down to -1.5* though. The only way to get even tire wear with negative camber is to offset the inside shoulder wear with frequent canyon driving (cornering forces) to wear out the outside shoulder as well. 2.0 is a bit high for street tires/commuting habits. I asked for rear camber to be reduced to -1.5* last time I was in the shop. Negative camber is good for cornering handling for many reasons, but negative camber also decreases straight line traction. Therefore, decreasing the life of your tires (uneven tire wear). If all you do is straight line driving, or you do a lot of burnouts, the insides of your tires are going to wear quicker than the outside.
Negative camber accelerates wear on the inside of the tire. Camber dictates WHICH part of the tire gets worn when being dragged. so not sure why people are speaking in absolutes.Īnything other than 0 toe is going to increase the RATE of tire wear since the tire will be dragged down the road (pigeon toed).
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