Rear main bearing tolerances

[Dave Wortley]

James, looking at your photo you are measuring the vertical movement between crankshaft and the rest of the engine. The A7 rear main set up is notorious for developing  slackness between the bearing inner race and the crankshaft journal.The inner race wears away the crankshaft journal. So as Chris says that's the first place to check for play. It should be an interference fit here and then originally the rear main internal clearance ( total clearance between inner and outer races/ rollers) was a tight "0" fit. I think that is the SKF system of bearing clearance. Tony Press will be able to put a figure on that. My bearing books are at home and I am away at the moment. If the crankshaft journal is worn considerably then you may need  to look at finding a different crankshaft. 
Good luck,
Dave