What's the fastest you go before you turn on the OD. The truck's definitely more responsive in city driving but I don't want to kill my fuel mileage with the higher rpms.
Thanks

 

Its the RPM's and slipping that generates heat and kills your transmission. If you are operating below 50 you should turn the OD off, exspecally if you are towing.

 

I don't. It just seems to give more RPM's at the same speed. And the TC seems to slip more than w/OD on - this goes for first through third gears. I want better MPG. I'd like a TC lockout adjuster for my trans.

 

I keep it off under 50. I did not noticed any real difference in mileage.

 

I actually get better mileage cruising at 55 in 3rd than I do in OD. This is with a 2nd gen though.

 

not a slushbox, but i'll throw it into 6th at 70kph once the engine is warm...

 

I would guess best mileage with 410 Rear end and a 47RE would be around 1800 RPM. Drive accordingly.
RJ

 

Thanks for the replies. The truck seems fine up until 40 mph and that is where it feels like it needs to shift. Unfortunately that's where the DTT TC like to lock and unlock too. I will drive accordingly....

 

My DTT likes to shift around 45 mph with 3.55 Rear and 285's. I have much nicer street manners punching the OD off until around 55. This may not be best for mileage..around 2100 rpm...but prevents loading up the engine by keeping the shift into OD above 1500 rpm. If hauling heavy I go to 60 mph or 65.
RJ

 

I would like to change mine so it stays off until
i want it on. I don,t use OD that much.
Anybody know of a way to do that?

Frank

 

If your talking about OD being automatically off until a preset speed, and not having to do it manually with the shifter buttom, there is a way. The DTT Smart Controller will allow you to pick a speed at which OD engages. Problem for me is it will disengage at same speed...going into 3rd with the converter locked up. Can make for abrupt downshifts if set higher than 45 or 50 mph!
RJ

 

I have the controller RJ but i would like the OD to stay
off when i start the truck. I know theres away to do it.

I most be getting old ,i,m starting to forget to hit the
button.
Have a good one ----Frank

 

MacB,

Do a search their is a way to rewire the switch backwards.


good-luck

 

Along those lines, I drove to work today with OD turned off after reading this post yesterday. I sure don't feel it going into lockup. Is there any other way to tell if it's locking up in 3rd? It's supposed to feel kind of like a shift, but I swear I don't feel it. Maybe that explains my crappy mileage in town.

Neil

 

With my DTT I can't always feel the 3rd gear lockup but I could definitely feel it with the stock converter. I definitely feel it unlocking though..