How to measure your camber to be able to choose the right camber kit?
There is alot of people out there are wondered what camber is and why does that affect your suspension set up, here is an article we have found from one of the automotive discussion forum to share with everyone. You will need to know the camber of your car to be able to choose the right camber kit.
What is "camber"?. In layman terms, it's how far the your rim and tire combo tilt in or out. Why would this change? Because a double wishbone suspension system is designed to change camber settings as load is increased or decreased on that corner. When you take a turn, most of the weight of the car is on the outside tires so the spring compresses, and the top of the tires tilt in, giving it negative camber so that more of the tire's contact patch comes in contact with the road. When you straighten out again, camber returns to normal. But if you artificially reduce the height of the strut and spring combo, it has the same effect. It tilts the top of the tires in producing perpetual negative camber. It does gives you better handling because the suspension is always in "heavy cornering" mode. But it also puts all the weight of the car on ONE side of the tire's contact patch when you're not turning. This wears out your tires MUCH faster than normal on that one side. This is where a camber kit would be needed to push out the upper control arm a little more and produce more positive camber so you don't need to get new tires every few months.
Now let me say this: suspension geometry is by no means simple. There are MANY variables that affect it and because of this, you can't oversimplify it. There is no magic number, no certain drop height that'll tell you with absolute certainty that your camber is not within the manufacturer's specifications anymore and will need to be corrected with the aid of a camber kit. Camber, and indeed all of suspension geometry is affected by EVERYTHING you do to it.
Have you gotten bigger rims? Smaller rims? Bigger tires? Smaller tires? Blew a shock? Changed the shocks? Got a big system in the back? Ride with 4 friends all the time? All these things and more affect your suspension geometry. The only way to TRUELY know if your camber is within specs is to get an alignment and have a computer crunch the numbers and give you a yeah or a nay. Here's some examples for you.
1. You get a new set of 15x7 Rota's with 205/50/15's on them. You change the shocks for shorter yellows BUT you keep it at near stock height.
The smaller rims, tires and shocks produce more negative camber but you haven't dropped it?
2. You get a new set of 18x7.5 Volks with a set of 215/35/18's on them. You keep the stock shocks BUT lower it 2 inches and put a 200 lb system in the back.
The 18's produce more positive camber while keeping the stock shock height and then you lower it 2 inches and the extra system produces more negative camber. Does he need a camber kit?
You see what I mean? Here is a cheap and effective way of estimating your camber:
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).