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Cr08, Thanks for the details. Where did you get the hardware sync 3 hardware? Does CyanLabs charge for their updater?

I know this is an ancient thread, for those who may be arriving here via Google, this sound turned out to be a failing fuel pump in the gas tank. It was replaced, the noise went away.

I believe SS’s theory on cause of failure. I’ve been saying the following for a long time. Ford says “ under certain driving conditions”, failures may occur. We need to “figure out” the conditions and mitigate the conditions. Perhaps, the salient point to longevity of the transmission may be avoiding / mitigating the conditions that cause a clunk. A clunk would seem to be caused by an abrupt change in torque like backing off accelerator momentarily (perhaps to engage EV mode when battery SOC is high). Thus, there would be momentary regeneration torque (negative torque to wheels) followed by EV motor torque (positive torque to wheels) as accelerator pedal is pushed to maintain speed. It seems that ICE to EV or EV to ICE torque transfer under normal driving is always seamless as the torque demand on the shaft would always be in same direction and likely the same and not cause a clunk as when going into regeneration (no positive torque demand). I also believe that it may take a substantial number of times of this reversal of torque to shift bearings on the shaft for the clunk to occur. The axial force that the bearing retainers are “holding against” act like a “slide hammer” against the retaining surface. I have heard clunks on rare occasions from front. But, I’m not sure at what speeds or what my exact driving condition were at the time and whether the clunk was from transmission. I’m fairly sure the clunks have occurred at lower speeds (maybe under 45 mph) and not say above 65 mph. I don’t believe I’ve ever experienced a clunk shifting into reverse. I also don’t believe the clunks have occurred when torque was transferred from ICE to EV or EV to ICE. About 70 % of my miles are high speed miles. I always thought (like SS said) the clunks, if from transmission, were an anomaly caused by the control algorithms.