Using smartphone as a tire toe angle gauge - E-Revo VXL

Here is one quick tip for the RC Cars crowd.
I don't like "eyeballing" things that can be easily measured. For example, the tire's toe angle on many RC cars is often adjusted by drivers just by looking at the tires from the top and estimating the angle - hardly a precise method.
Nowadays, almost everyone is sporting some type of a smartphone and every smartphone has built-in an accelerometer and/or gyroscope sensors. There is a galore of apps using these sensors to turn the smartphones into "spirit levels"and as added bonus, they can be calibrated for relative measurements as well (automatically subtracting the angle measured during the calibration process from the current reading). Just to name a few such apps (all Android OS btw) - Smart Tools, Spirit Level Plus, Precision Bubble Level, Gravitometer, etc...

Step 1 - Place the E-Revo VXL on the corner of the table, laying the car body only on the battery compartment door (bottom tires hanging free in the air). Calibration of the software is done on the flat work surface or even better - placing the phone onto the top battery compartment door - exactly parallel with the length of the car. This is the axis that needs to be calibrated - the other (perpendicular) axis is not important for toe angle adjustment and it is OK to be angled (Revo's battery door is angled in such way). The back of the phone should be laying flat over the surface of the door and the phone should be pressed and held firmly when calibrating it. The picture shows almost zeroed X axis - this is the axis running with the car's length.

Step 2 - Place the phone on top of the wheel (even better if you have only a rim with no tire installed), managing phone's orientation strictly parallel to the length of the car and read / adjust the tire toe angle. (in this case - axis X reads 3.1 degrees toe-in a little too much).

Step 3 - After adjusting the desired toe angle, take off the toe push rod on the adjusted side and use it to adjust the length of the other toe push rod. 

That's all - no need for an expensive specialized gauge.