[Cglrcng]

Warning: (Don't do it...illegal in Stock and S.S., I looked.) An FRC wheel encoder is about the circumference of a dime or smaller, and a quarter to a half inch thick, the counter ticks in the 360 degree are only separated by hundredths of an inch to a 1/6th of an inch. Forget engine RPM, or a driveshaft sensor, the real key is the wheels that stay hooked up, never leave the ground, never spin, and a sensor that measures the whole quarter mile. From start to finish down to fractions of the last inch (if the track is a full exact 1,320', and you know exactly where that begins and ends, and you can position exactly the start point.

Have I thought about it, sure, so I looked it up...not permitted. Do I have one installed? Absolutely not, but last week I was installing front end parts a 10 pc kit on my neighbors 2004 Toyota Sienna Van, and proudly right there in both front calipers (that I needed to remove to uninstall and hang up next to the caliper were 2 ABS brake sensors, about the circumference of a nickle, and 1" thick, and low and behold, they are simply wired wheel encoder magnet pickups counting the rotor vanes. A simple wheel encoder already installed on that vehicle stock.

I have no idea if that vehicle is even in the guide, but they are a part of the stock ABS brake system and could easily though illegally be used to determine actual track position accurately as long as it does not do wheelies.. lol.