Rattlehead

Bjorn, my understanding of the 939 torque converter is that it locks in towards the top of 2nd gear and stays locked in for the rest of the upshifts. I can feel this as sort of an extra 1/2 gear "shift" right before going into 3rd. In the civvy junk, a brake pedal electronic input kicks out the TCC, not the case with the 939's. I cannot remember where I got this info from, so cannot confirm it.

I did find this, which says the lockup operation occurs as a function of governor pressure (vehicle speed).

http://www.lejeune.usmc.mil/mccsss/s...MC/AIM5206.pdf

from page 8:

(9) Lockup operation. Power is transmitted mechanically through the
lockup clutch. Application of the lockup clutch occurs automatically as a function of governor pressure.