[Jonny042]

For those wondering about a real-world "C" measurement on a contemporary sports purpose 911, in the second post of this thread I mentioned that a had a ride height of 151mm (accounting for the 19mm raised spindles).

So if measured by the factory method, I would have measured 170mm.

From a geometry standpoint, it would be equivalent to 170mm-19mm = 151mm

Put another way, the car was lowered 43mm from the stock 108mm (to a measurement of 151mm) via the torsion bar adjusters, and another 19mm as a result of the raised spindles, to the final measurement of 170mm.

This is the ride height at which I measured and determined that 42mm of spacer was optimal for that setup.