Differential preload 915
 

When measuring differential preload is it the static breakaway torque reading or the to keep it moving dynamic torque reading, that is the spec?

You're measuring it while it's turning. You need a dial or beam-type wrench. Clicker type doesn't let you see how much torque it takes to keep it turning

How-To: Porsche 915 Transmission Repair Tutorial Part 5 - Porsche Wiki

That's an excellent question (and answer) .. one that I haven't seen asked before on Pelican. The term "breakaway torque" can be misleading (just as a memory pointer can) for this particular job.

Same deal when measuring diff bearing preload. The pointer will always show a deceivingly higher value than true dynamic turning torque. The needle may bounce around initially while turning, but do it for awhile, and the mean value will become evident.

Thanks, I guess I need more preload. I need to get new bearings first and recheck. I am using a beam torque wrench. Startup torque was about 20 in lbs but running was only 5.

Ha ha .. I misread your initial post to say LSD breakaway. If you are measuring with used diff bearings, you may already be in the proper range.