Yes find flat ground. For a standard car If the left and right sides are the same height as the front and back wheels its probably close enough I would think especially if you turn the car 180 degrees on the same spot and repeat to doublecheck.
There was very little difference in the number of threads, to get the same ride height on each side with an unladen car.
Then again I was usually using 10Kg front springs which wouldn't deflect much for the slight weight difference compared to standard road springs.
Originally Posted by Caldo Bollente
Find it tricky doing it that way as it is near impossible to find a flat enough surface. Have you measured off the threads as well TB, is there much difference? Be good to have an idea of weight distribution over each side to maybe compensate by a mil or two, but then get to thinking about driver load and how much juice is in the tank and it just doesn't seem worth the bother.