Caster, camber, toe explained
09-17-2007, 08:02 AM
#1
Caster, camber, toe explained
Because I hate it when I realize I have no idea wtf is going on... I did some research about caster, camber, and toe.
TOE
Toe deals with the leading edges of the tires. If the leading edge of each tire point towards each other, it is toe in. If the leading edges are pointing away from each other, it's toe out.
Toe is a trade off between directional stability and minimal tire wear + power loss. Two front wheels that are set up with toe-in are on a intersect path with one another -- disturbances cause them to move a straight amount, so that a wheel will end up rolling straight (remember it started off pointing in). Toe out wheels are on a divergent path so disturbances cause the wheel to point even more out (as if it was turning).
For the lowest tire wear and power loss, toe should be set to zero when driving in a straight line. Toe in discourages turn in (or the initiation of turning) while toe out encourages it. In other words, toe it gives you straight line stability and toe out gives a quicker steering response.
Toe is impacted by dynamic situations. Wheels under torque (front wheel drive, awd, 4wd) the tire will toe-in. Wheels being pushed with toe-out. Your bushings will also affect how much static toe you need to set -- softer rubber bushings will give you a better ride, but will move a fair amount under load. Stiffer polyu or steel bushings will move less.
Conclusion:
RWD: static toe in a small amount
Others: static toe out a small amount
Chevy SS specs: .10 +/- .20* toe
CASTER
Caster is the steering pivot axis is tilted forward or back when viewing the wheel from the side. Negative caster is when the pivot axis is forward (the wheel is further back in the wheel well from center), and positive caster is when the pivot axis is rearward (the wheel is further forward than center). The pivot axis is usually at the hub.
Positive caster tends to straighten when the vehicle is moving forward. It provides increased straight line stability and increase the steering effort.
Most cars aren't very sensitive to caster, but caster should be the same on both sides in theory (but Chevy specs have a built in offset to the R side). A typical range is 3-5 degrees positive caster.
Cross caster is the amount of difference between the settings on each side. In theory, cross caster should be zero. Chevy specs allow for -.50 +/- .50. Zero cross caster should eliminate the vehicle pulling to one side or the other.
Conclusion:
3-5 degrees of positive caster with 0* cross-caster
Chevy SS specs: L 4.10 +/- 1.00*, R 5.10 +/- 1.00*, cross-caster -.50 +/- .50
CAMBER
Camber is the measure of how far the wheel is tilted relative to vertical. If the top of wheel leans in towards the frame, it has negative camber. If the wheel tilts out (away from the vehicle) it has positive camber. Camber has a major impact on the road holding ability of the vehicle.
-.50* camber (typically) provides the maximum cornering force. So this should be easy right? Wrong.
As a vehicle rolls into a corner, the suspension deflects vertically. This deflection can cause large changes to camber as the wheel moves up and down. In fact, the more deflection travel a wheel must accommodate, the more difficult it is to maintain the ideal camber. We're not talking high lift vehicles, either -- smooth riding cars have enough deflection to make camber tough.
For these reasons, the suspension should be designed to cause camber to become increasingly negative as the wheel deflects upwards. However, to boost understeer, many stock cars are set up such that deflection causes positive camber (understeer is safer and more stable than oversteer, but is slower through the twisty bits).
Conclusions:
-.50* camber relative to the road (the ideal)
Chevy SS specs: 0.10 +/- .50 with 0 +/- .50 cross camber (relative to the chasis!)
TOE
Toe deals with the leading edges of the tires. If the leading edge of each tire point towards each other, it is toe in. If the leading edges are pointing away from each other, it's toe out.
Toe is a trade off between directional stability and minimal tire wear + power loss. Two front wheels that are set up with toe-in are on a intersect path with one another -- disturbances cause them to move a straight amount, so that a wheel will end up rolling straight (remember it started off pointing in). Toe out wheels are on a divergent path so disturbances cause the wheel to point even more out (as if it was turning).
For the lowest tire wear and power loss, toe should be set to zero when driving in a straight line. Toe in discourages turn in (or the initiation of turning) while toe out encourages it. In other words, toe it gives you straight line stability and toe out gives a quicker steering response.
Toe is impacted by dynamic situations. Wheels under torque (front wheel drive, awd, 4wd) the tire will toe-in. Wheels being pushed with toe-out. Your bushings will also affect how much static toe you need to set -- softer rubber bushings will give you a better ride, but will move a fair amount under load. Stiffer polyu or steel bushings will move less.
Conclusion:
RWD: static toe in a small amount
Others: static toe out a small amount
Chevy SS specs: .10 +/- .20* toe
CASTER
Caster is the steering pivot axis is tilted forward or back when viewing the wheel from the side. Negative caster is when the pivot axis is forward (the wheel is further back in the wheel well from center), and positive caster is when the pivot axis is rearward (the wheel is further forward than center). The pivot axis is usually at the hub.
Positive caster tends to straighten when the vehicle is moving forward. It provides increased straight line stability and increase the steering effort.
Most cars aren't very sensitive to caster, but caster should be the same on both sides in theory (but Chevy specs have a built in offset to the R side). A typical range is 3-5 degrees positive caster.
Cross caster is the amount of difference between the settings on each side. In theory, cross caster should be zero. Chevy specs allow for -.50 +/- .50. Zero cross caster should eliminate the vehicle pulling to one side or the other.
Conclusion:
3-5 degrees of positive caster with 0* cross-caster
Chevy SS specs: L 4.10 +/- 1.00*, R 5.10 +/- 1.00*, cross-caster -.50 +/- .50
CAMBER
Camber is the measure of how far the wheel is tilted relative to vertical. If the top of wheel leans in towards the frame, it has negative camber. If the wheel tilts out (away from the vehicle) it has positive camber. Camber has a major impact on the road holding ability of the vehicle.
-.50* camber (typically) provides the maximum cornering force. So this should be easy right? Wrong.
As a vehicle rolls into a corner, the suspension deflects vertically. This deflection can cause large changes to camber as the wheel moves up and down. In fact, the more deflection travel a wheel must accommodate, the more difficult it is to maintain the ideal camber. We're not talking high lift vehicles, either -- smooth riding cars have enough deflection to make camber tough.
For these reasons, the suspension should be designed to cause camber to become increasingly negative as the wheel deflects upwards. However, to boost understeer, many stock cars are set up such that deflection causes positive camber (understeer is safer and more stable than oversteer, but is slower through the twisty bits).
Conclusions:
-.50* camber relative to the road (the ideal)
Chevy SS specs: 0.10 +/- .50 with 0 +/- .50 cross camber (relative to the chasis!)
Last edited by TurboBerserker; 10-19-2007 at 07:52 PM.
10-16-2007, 09:33 PM
#2
Because I hate it when I realize I have no idea wtf is going on... I did some research about caster, camber, and toe.
Caster is the steering pivot axis is tilted forward or back when viewing the wheel from the side. Positive caster is when the pivot axis is forward (the wheel is further back in the wheel well from center), and negative caster is when the pivot axis is rearward (the wheel is further forward than center). The pivot axis is usually at the hub.
Caster is the steering pivot axis is tilted forward or back when viewing the wheel from the side. Positive caster is when the pivot axis is forward (the wheel is further back in the wheel well from center), and negative caster is when the pivot axis is rearward (the wheel is further forward than center). The pivot axis is usually at the hub.
As for negative caster, can't say much good about it but think of how unstable a vehicle would be with the front wheels in a negative relation to the "kingpin" axis....the front wheels would want to wobble like a shopping cart
10-19-2007, 07:53 PM
#3
This is backwards...positive caster has the wheel further forward (pivot axis rearward), and vise-versa. All vehicles are now designed with positive caster for straight line stability, better road feel, and steering wheel return to center after making a turn. Some downsides of positive caster include increased steering effort at low speeds (which can easily be remedied with power steering), and a vehicle's tendency to want to follow the curvature of the road...part of why chevy trucks have more positive caster on the right side to help combat the effects of road crown.
As for negative caster, can't say much good about it but think of how unstable a vehicle would be with the front wheels in a negative relation to the "kingpin" axis....the front wheels would want to wobble like a shopping cart
As for negative caster, can't say much good about it but think of how unstable a vehicle would be with the front wheels in a negative relation to the "kingpin" axis....the front wheels would want to wobble like a shopping cart
Corrected it above.
10-25-2007, 05:50 PM
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you will want the left side caster lower than the right this will help it stay straight due to road crowning the vehicle will always pull to the side with the lowest caster having the left side a little lower helps offset the pull that the road crowning causes
11-11-2007, 01:53 PM
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keep in mind on front wheel drive vehicles camber will often be negative and most other angles will be set different from that of rear wheel drives just because of the way the front wheels pulling affect the travel of the wheels.
too much positive caster will create a shimmy, if excessive enough, and increased camber roll on turns which if you do alot of low speed turns will wear the tires more. too little positive caster will result in reduced steering effort for parking lot manuevers (probably not enough to feel) but will reduce steering wheel return. 3.5 to 4.0 degree positive with about .2 more positive on the passenger side will on 90% of vehicles result in a very good driving car.
too much positive caster will create a shimmy, if excessive enough, and increased camber roll on turns which if you do alot of low speed turns will wear the tires more. too little positive caster will result in reduced steering effort for parking lot manuevers (probably not enough to feel) but will reduce steering wheel return. 3.5 to 4.0 degree positive with about .2 more positive on the passenger side will on 90% of vehicles result in a very good driving car.
07-26-2008, 09:08 PM
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keep in mind on front wheel drive vehicles camber will often be negative and most other angles will be set different from that of rear wheel drives just because of the way the front wheels pulling affect the travel of the wheels.
too much positive caster will create a shimmy, if excessive enough, and increased camber roll on turns which if you do alot of low speed turns will wear the tires more. too little positive caster will result in reduced steering effort for parking lot manuevers (probably not enough to feel) but will reduce steering wheel return. 3.5 to 4.0 degree positive with about .2 more positive on the passenger side will on 90% of vehicles result in a very good driving car.
too much positive caster will create a shimmy, if excessive enough, and increased camber roll on turns which if you do alot of low speed turns will wear the tires more. too little positive caster will result in reduced steering effort for parking lot manuevers (probably not enough to feel) but will reduce steering wheel return. 3.5 to 4.0 degree positive with about .2 more positive on the passenger side will on 90% of vehicles result in a very good driving car.
The new GM 900 utiliites and trucks can toleratel high negative cambers and high positve casters, with fantastic handling performance. Add a performance/comfort drop coil, which there are only 1 on the marktet that will address BOTH, the handling will signifiicantly improve, plus will be able to handle more negative cambers without any bad tire wear.
mike
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12-20-2008, 02:08 PM
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Is there anything available on the market to help freeze the camber settings/make adjustments easier?
For Z06's, Pfadt has a camber kit:
http://www.pfadtracing.com/catalog/p...products_id/44
It removes the eccentric cams and replaces them with aluminum blocks with different lateral offsets of their holes. Different offsets result in different cambers. I was curious if anything like this exists for the trucks. For those of us that do our own alignments, makes camber adjustments much easier and prevents the alignment from ever slipping.
For Z06's, Pfadt has a camber kit:
http://www.pfadtracing.com/catalog/p...products_id/44
It removes the eccentric cams and replaces them with aluminum blocks with different lateral offsets of their holes. Different offsets result in different cambers. I was curious if anything like this exists for the trucks. For those of us that do our own alignments, makes camber adjustments much easier and prevents the alignment from ever slipping.
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