This is a method estimating the front end caster using a digital camera and using Windows Paint to estimate camber angles from the picture.Normally one would take 2 pictures from each wheel, one full left and a second full right. For this approximation we will assume both wheels are identical and simply use one camber picture from each wheel when the steering wheel is cranked full right.NOTES ABOUT THE CAMERA SETUP:1. Camera lens should be in line with the outside side of the wheel.2. Camera should be mounted on top of a stand (I use a bin that sits upside down on the ground) that sits on the ground such that the camera is parallel to the vehicle. The vehicle needs to be parked on a flat surface BUT being level is not a requirement.This first picture is taken in line with the outside of the drivers side wheel and measures a camber of NEGATIVE 2.5 Degrees.This second picture is taken in line with the outside of the passengers wheel and measures a camber of PLUS 3.5 Degrees.This picture is taken with the camera resting on the drivers side fender and captures the drivers side wheel to be cranked about 30 Degrees to the right.This picture is taken with the camera resting on the passengers side fender and captures the passengers side wheel to be cranked about 33 Degrees to the right.The estimated CASTER (K) is found as:K = ( 180 / pi ) * ( ( C1 - C2 ) / ( T1 - T2 ) ) Where: C1 is the +CAMBER when the DS wheel is FULL LEFT or the PS wheel is FULL RIGHT. C2 is the -CAMBER when the DS wheel is FULL RIGHT or the PS wheel is FULL LEFT. T1 is the +TURN ANGLE when DS wheel is FULL LEFT or the PS wheel is FULL RIGHT. T2 is the -TURN ANGLE when DS wheel is FULL RIGHT or the PS wheel is FULL LEFT.In this case:K = (180 / pi) * ((+3.5 - (-2.5)) / (+33 - (-30)) )K = 57.32 * (+6.0 / +63) = +5.5 Degrees

Actually that would be camber, not caster.

ScottG wrote:Actually that would be camber, not caster.Caster is derived by taking two camber readings, one (+camber) is from full left and the second (-camber) is full right. Then the two camber readings are used in the caster formula as shown.

Caster angle.You can have all the camber angle in the world and no castor.Or you can have way too much camber on truck suspensions without effecting caster much. That is what happens when the suspension components are badly worn - you can see it by the way the wheels tilt inward badly. What you are measuring is purely camber:Camber angleAlso, you can't really tell much with the wheels turned because camber changes - especially if ball joints are worn.

Quote: "you can't really tell much with the wheels turned because camber changes"Yes, the camber changes because of the caster angle. :) By taking a camber reading at full left and another camber angle at full right we can derive the caster angle.

See formula (8) in this Reference

Estimating Caster Using a Digital Camera | Good Sam Community

17 Replies

Harvard
Explorer
Jan 30, 2015
Here is a little more detail on the technique of how to use the camera. If you need assistance in interpreting the pictures using paint, post the pictures and I will do what I can on your behalf.

1. The steering wheel should be cranked to the right and the front wheels are to be stationary, in the same position, for all four pictures.

2. The crank angle picture is with the bottom of the camera resting on the fender well located (fore and aft) above the axel.

3. The camber angle is captured with:
a. The camera lens horizontally positioned approximately in line with the outside side of the wheel as if there were no hub cap involved if there is a hub cap.
b. The camera lens is vertically positioned at approximately axel height on a stand that ensures the camera bottom is parallel to the "even" ground on which the vehicle is parked.
c. A distance of 5-6 feet from the wheel is good. Close ups for camber shots would not work out.

Older cameras are BEST (typically less then 3600 x 2700 pixels (2.0-2.5 MB)). Newer cameras are an overkill and would make for much larger then required resolution (and files too big for uploading here).

The object here is to attempt to give you some idea of the current caster settings of your vehicle. Having that information will help you decide if you want to enlist the services of a professional alignment shop.
Harvard
Explorer
Jan 25, 2015
So, here is an example of the target vehicle for this whole exercise.

This is a Ford E350 Class C sitting on a parking lot at a casino in Laughlin, NV. The question is, does this vehicle have a caster of +5.0 or over? The only inconvenience to the owner was to crank the steering wheel full right and allow me to take 4 pictures.

The left hand wheel camber measured about NEGATIVE 1.1 Degrees

The left hand wheel was cranked about 27 Degrees to the Right.

The right hand wheel camber measured about POSITIVE 2.6 Degrees

The right hand wheel was cranked about 32 Degrees to the Right.

The Estimated Caster K"

K = (180/3.14) X (2.6 - (-1.1)) / (32 - (-27))
K = +3.6 Degrees

In my opinion this vehicle caster could be set better FOR HIGHWAY DRIVING.

Just to confirm, it appears the shims are fixed shims probably installed on the production line.
Harvard
Explorer
Jan 25, 2015
This post is to demonstrate that the ground must be an even surface BUT it does not need to be level. Here is the same 2007 Honda Civic parked sideways on a 7 Degree Boat Ramp.

I am using this car for experimenting because it is easy to set up quickly in any parking lot as we are sitting in an RV park for the winter.

The Left Hand wheel Camber turns out to be about NEGATIVE 2.4 Degrees

The Left Hand wheel is cranked about 33 Degrees

The Right Hand wheel Camber turns out to be about POSITIVE 5.7 Degrees

The Right Hand wheel is cranked about 38 Degrees

The estimated caster K:

K = (180 / 3.14) * ((5.7 - (-2.4)) / (33 - (-38)))
K = +6.5 Degrees.

This vehicle has McPherson struts (I think) so they are fixed at +7.0 Degrees according to the Honda Specification.
Harvard
Explorer
Jan 21, 2015
Here is a 2007 Honda Civic EX, Honda Spec for Caster is +7.0 on each wheel.

It is crucial that the camera sit on a stand which is parallel to the ground surface. The ground surface must be flat BUT not necessarily level.

Steering wheel is full right.

Drivers side camber measures NEGATIVE 1.853

Passengers side camber measures POSITIVE 4.618

Drivers side turn measures 27 Degrees

Passengers side turn measures 28 Degrees

Estimated Caster K:

K = (180 / 3.14) * ((4.618 - (-1.853) / (27 - (-28) )
K = 57.32 * ( +6.471 / +55 ) = +6.7 Degrees
as opposed to specified + 7.0 degrees.

Note: Measured resolution of camber degrees based on pixel counts in the high resolution original JPG files. (and yes, pixels have been confirmed to be square :B)
Gdetrailer
Explorer III
Jan 18, 2015
Harvard wrote:
This is a method estimating the front end caster using a digital camera and using Windows Paint to estimate camber angles from the picture.

Normally one would take 2 pictures from each wheel, one full left and a second full right. For this approximation we will assume both wheels are identical and simply use one camber picture from each wheel when the steering wheel is cranked full right.

This first picture is taken in line with the outside of the drivers side wheel and measures a camber of NEGATIVE 2.5 Degrees.

This second picture is taken in line with the outside of the passengers wheel and measures a camber of PLUS 3.5 Degrees.

This picture is taken with the camera resting on the drivers side fender and captures the drivers side wheel to be cranked about 30 Degrees to the right.

This picture is taken with the camera resting on the passengers side fender and captures the passengers side wheel to be cranked about 33 Degrees to the right.

The estimated CASTER (K) is found as:
K = ( 180 / pi ) * ( ( C1 - C2 ) / ( T1 - T2 ) )

Where:
C1 is the +CAMBER when the DS wheel is FULL LEFT or the PS wheel is FULL RIGHT.
C2 is the -CAMBER when the DS wheel is FULL RIGHT or the PS wheel is FULL LEFT.
T1 is the +TURN ANGLE when DS wheel is FULL LEFT or the PS wheel is FULL RIGHT.
T2 is the -TURN ANGLE when DS wheel is FULL RIGHT or the PS wheel is FULL LEFT.

In this case:

K = (180 / pi) * ((+3.5 - (-2.5)) / (+33 - (-30)) )
K = 57.32 * (+6.0 / +63) = +5.5 Degrees

You do realize that the camera lens is going to severely distort your photos?

This effectively skews the perceived angles and bending things in your photos. Camera lens are not linear at any distance, the effect gets much worse when taking extreme up close or far way photos. Some lenses are better than others but since a lens bends light as a primary function there always will be errors..

It is best to leave this to a properly equipped shop if you don't wish to take your life in your own hands..

On edit..

Perhaps you will understand what I am talking about with the following pix as and example of a camera lens "bending"..

Please note, the item in that pix is FLAT but yet the error from the lens doing its job has BENT the item..

Also note worthy is the angle and height from object can majorly skew the pix..
Harvard
Explorer
Jan 18, 2015
Yes, the purpose of this technique is to establish larger variations in caster. For example, the Ford E350/E450 has a normal caster range from +1.5 to +7.5 and the goal is to determine if it would be worthwhile to seek other caster options from a professional. I do not plan to go into business. :B:B
VintageRacer
Explorer
Jan 18, 2015
The OP's formula accommodates different and non-standard angles by going back to first principles on the measurement, so it would work fine. Using standard angles makes the change from camber to caster automatic and easy, though. Agree on the need for level and square to have truly accurate measurements, but I never drive on level and square roads, so for his purposes his way gets him the information he needs.

Brian
randallb
Explorer
Jan 18, 2015
The primary reasons for measuring caster are; to make the vehicle track straight, to ease turn in or improve straight line stability. In order to make sure your measurements are accurate the amount of wheel motion must be strictly controlled. In theory you must start with a reading at true straight ahead and then your other 2 per wheel measurements must come from the exact same turn in/out point. The industry standard is 20 degrees but if you want to use more there is no reason you can not. You will not however be able to have a discussion with any one else about the effects of your caster settings on handling. Just using your steering stops is not accurate. You could easily be 5 degrees of turn in/out off from one side to the other at the stops. If you are not using turntables the load from the tire into the suspension will also cause inaccuracies in the readings. Now for the big question, Is the surface the vehicle is sitting on perfectly level side to side and front to back? If not none of your measurements are valid.
JaxDad
Explorer III
Jan 18, 2015
Harvard wrote:
Quote: "you can't really tell much with the wheels turned because camber changes"

Yes, the camber changes because of the caster angle. :) By taking a camber reading at full left and another camber angle at full right we can derive the caster angle.

Seems like a valid way of doing it to me. I think my western friend has it right.
j-d
Explorer II
Jan 18, 2015
I think we're on different sentences on the same page. Of the three primary angles, Caster/Camber/Toe, Toe is the only one that can be set independently. At least without modifying the geometry that's built into the chassis. Changing Caster to get more with be limited by acceptable Camber.

I visited John at the iconic Henderson's Line Up in Oregon. He worked in the shop 25 years, doing loads of alignments. Said "Caster is the Change in Camber as you Steer."