How to measure you camber using common tools

[Rice-Rocketeer]

Just thought I'd repost a cheap solution to constantly having to measure camber on lowered vehicles. Originally posted by Fritz, Have fun:

There are all kinds of fancy-smancy camber measuring devices. But you can do it quite accurately with stuff every garage should already have: a ruler and a square (that steel 'L' shaped thingie.)

Put the short side of the square flat on the ground (park on a flat surface). And push the other side up against the tire. If the square touches both sidewalls, then you have 0 camber; if it only touches the top sidewall, you have positive camber; and if it only touches the bottom sidewall, you have negative camber.

Now have a friend (or a couple of bricks) hold the square in place while you go find the ruler. Use the ruler to estimate where on the square the center of the wheel is - mark this point with a pencil or some tape. Now measure 7" above this point and mark it too - now measure the distance between the edge of the wheel and this point on the square. Make sure to hold the ruler parallel to the ground (maybe even use a bubble level). Record this value. Now, measure 7" below that center point, mark it, and measure the distance to the wheel again.

Now subtract those two measurements and multiply the result by four - this is your camber in degrees. How easy is that?

Example: The upper measurement is 13/16", and the lower measurement is 1/2". Since 13/16 > 1/2, the camber is negative.
13/16" - 1/2" = 5/16" difference.
5/16 * 4 = 20/16 = 1 and 1/4 degrees of negative camber.

This is usually easier to do if you cut out a round piece of plywood to hold against the wheel - then you can just measure the distance to the square between any two points that are 14" vertically apart, and you don't have to worry about centering the square on the wheel.

Could you explain how the heck you came up with that and how do we convert that to the Metric system for the Non-US'ers???

The actual equation would be:

angle = arctan( h / l )
where h = the difference between the two measurements
and l = the vertical distance between the two measurements.

We used 1/4" = 1 degree because it's simple. Then we picked 14" because it just so happens that arctan (1/4" / 14") = 1 degree. As long as h<<l, the tangent function is reasonably linear; so we can make the approximation of just saying that:
angle = 4 * h (in inches)

To do this in metric, we need to just pick a h to represent one degree, and make sure that the required l is within reason.
If we wanted to pick 5mm for h, then l would be 286 mm.
If we wanted to pick 10mm for h, then l would be 573mm.

That's probably the best: Measure two points 57 cm vertically apart, and you get one degree of camber for every one centimeter of difference between the measurements. angle = h (in cm).