Torque Converter Lock/Unlock

[Jackpine]

Originally Posted by Sburn

Interesting subject. Like Jack, I drive a gasser, so it's not always apples-to-apples with the diesel rigs.

But on the subject of T/C locking/unlocking, I was going though the transmission part of the factory service manual (2007 F150) one day. Ford's own transmission road test procedure suggests that the T/C should stay locked when letting off the gas above ~40MPH and unlocking only when the brakes are applied. But my truck has never done this, either when stock or w/ Gryphon. Letting off the gas unlocks the T/C, brakes or not.

From what I've read here and other places, it doesn't sound like anybody's 2004+ F150 stays locked when tipping out of the gas. So who knows what Ford was thinking...

Not trying to hijack this thread, but Sburn, have you noticed that the TC will remain locked when you're coasting downhill with the cruise control on? (At least mine does). So it attempts to hold the speed in this situation. Tap the brake (releasing the cruise control) and the TC immediately unlocks.

Wonder if the diesel strategy is the same?

- Jack

[Sburn]

Originally Posted by JackandJanet

Not trying to hijack this thread, but Sburn, have you noticed that the TC will remain locked when you're coasting downhill with the cruise control on? (At least mine does). So it attempts to hold the speed in this situation. Tap the brake (releasing the cruise control) and the TC immediately unlocks.

Wonder if the diesel strategy is the same?

- Jack

Jack, that's exactly what happens in cruise.

Other thing I've noticed it that, under certain conditions, the trans will go from 4th unlocked to 3rd locked instead of the more usual 4th unlocked -> 3rd unlocked. Condition seems to be: long uphill, no cruise, 50+ MPH. Key thing might be time under a certain load. It does not behave that way on my daily commute going up the same percentage grade on a somewhat short grade. But out on the Interstate, where that percentage grade might go on for miles, it will do the 4th-U - > 3rd-L shift. Some flavor of TFT control, perhaps?

As for thread hijacking, I get the impression that Cody knows his transmission stuff cold ans seems happy enough to talk about it with us.