Advanced Racing Technologies (ART) sells a very nice laser Toe Angle Gauge. I purchased a (slightly) used one off of a Porsche website to provide an independent way to measure toe angle. Carl Schulhof uses this gauge and his thrust angle strings as he aligns a vehicle. The gauge directly measures the angle between two wheels on opposite sides of a car using a laser (pointer), mirror, and a dial indicator on a pivot. It is very simple and easy to use.
The gauge has two rails. Each of the rails has a set of adjustable pins that engage the face of a wheel. To use the system you first (roughly) set the both of the rails so that the pins contact the wheel thru the centerline of the wheels. It is important to have the rails approximately parallel.
With the rails “roughed-in” you then set both assemblies on a flat surface and align the pins so that they can brought into contact (ends touching) with each other. This ensures that the two sides of the gauge are exactly aligned.
With rails aligned the laser shoots across the gap… and then bounces back (off the mirror)… Showing up on the target above or below the “shutter”. You then adjust the pivot mechanism to line the laser up in the groove on the target and set the dial indicator to “zero”.
Then place the calibrated components back on the wheels ensuring that the “return” laser beam from the mirror is in the same plane as the target (a piece of black construction paper works well for this). Now you “move” the laser spot until it aligns with the target using the adjustment knob on the pivot. The pivot on the gauge is designed such that .001” on the dial equals 1 minute of angle (60 minutes = 1 degree). Clockwise motion is Toe IN… Counterclockwise Toe OUT.
As I worked on the front end wheel alignment on my Lotus I measured the final wheel alignment to be 2 minutes Toe OUT (approximately .010” on a 17” wheel). It is easy to see why our friend Carl likes this gauge… It works well and inspires confidence.
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