I have a 97 F-350 7.3 DRW/SUPCAB/TPSD. with Banks Stinger and Transcommand set up, I have a qusetion on the overdrive on/off feature maybe I can get some answers.
Whats happining: When going down a grade with the 5er conected overdrive is off and in 2nd gear, the truck is using the moter to slow down the truck and trailer, but if I tap the brakes I can see a change in the engins RPM ( down ) and the unit starts to gain speed, then if I tap the accerlerator peddel the RPM's go up and the moter again starts to slows down the unit. also if I dont tap the brakes and coast the trans will then disingage as if I touched the brake peddel.
I never noticed this before in the 11 years of use, untill last year when I lost my brakes on this same hill, I am not new in trailering and have never lost the brakes on any grade but this one. these are what I experanced with my tranny as stated above on this hill this time. it's like the tork-converter was disingaging and allowing the truck to free roll down the hill.
I also do regular Trans Oil changes every 12k and always get a clean bill of health from Ford when done.
In a nut shell is this normal for this transmission?

TT2

 

I think it's normal. If I remember correctly, when you're cruising or on deccel, the converter is "locked up". When you tap the brake, the converter solenoid "unlocks" allowing the freewheeling (or braking) until you touch the accelerator again putting it back in lockup.

 

Thanks Rudyf6 for the info, but what about it disingaging after a couple of minuts with no peddel fuel or brake is this normal to.

 

Sorry dude, but I'm not really sure about that one. I've had 4 or 5 different E4OD/4R100's over the years, and each one was a little different in different circumstances. My current ride (04 F350 6.8 4R100) will "unlock" during a no-load coast, but will usually stay locked up with a load. Never tried with a lower gear though.