Manually Locking My Torque Converter

[vermont_blue]

I'm towing a large 5000# travel trailer with a 2007 Ford Expedition and after much back and forth with the ford dealership they've come to the conclusion that my vibration is coming from my torque converter. The vibration has been somewhat of a mystery for Ford shop but they're convinced it's the TC. With that said i've hired a guy to do the swap. In addition to the TC he's offered to install a toggle switch that will lock the converter to keep it from locking and unlocking on steep inclines while towing up or down the mountains. Has anyone done this before? He's assured me that this will prolong the life of my torque converter and help keep my transmission safe from potential over heating. The only side effect is that my tranny light will flash when TC is locked. Has anyone done this? He's aslo recommended installing an additional trans cooler. What models would you recommend?

[Zaairman]

This is a fairly popular mod with the Super Duty trucks that have the 4r100. It is possible to wire it up so that you don't get the flashing OD light, but that takes more work than just grounding the wire with a switch.

Since you're towing, get the biggest tranny cooler you can fit.

[RSchnier]

I've read of other people who have done this, with good results. The only negative mentioned was that if you don't remember to flip the switch back when coming to a stop, you'll kill the engine! (As one would in a manual, if they forgot to push in the clutch.) But obviously if you're consciously having this kind of mod put in, you know how to use it.