[Jeff Lee]

What is it that measures shock travel and records it on the data logger? Whatever that thingamajig is called, you need to fabricate one for the nose of the differential and actually measure the movement from the base angle. You could build a mechanical apparatus not using a data logger.
I know a guy that was video'ing the movement with a strobe light on his BBC SS car back in the '80's. I don't remember if it was a 4-link or ladder bar car. But as I recall, it was difficult or impossible to keep the pinion angle below zero with shocks and chassis tuning that would enable the car to launch correctly. This was a National record holding car.