I did this for the first time this season, and after looking at a lot of gauges, I used a laser level to do it without dropping a few hundred on a gauge. I clamped the laser level onto the brake rotor, with the laser shining out to the front, and had it project onto a board with a piece of paper that was about 2-3 feet in front of the car. With the jack I raised and lowered the spindle in increments of 1" and marked on the paper where the laser was shining. After your done, you can remove the paper, and measure how far the dots move in and out, thus your bump in and out. The thing I like about this method, is that by projecting out in front of the car 2-3 feet, you are magnifying the bump in or out, making it easy to see slight differences as you move the spindle up and down. To get the true bump you just have to do a little math.
This seemed to give true numbers and the best part that this was free to do, I can spend the money on other things. Hopefully the above makes sense, if not I can take a picture or draw a sketch.
