I tow a dump trailer loaded with 2 cords of firewood about twice a weekend for delivery.(Weather permitting) The truck seems to handle the load just fine with tow/haul mode on and in overdrive. I was just wondering about what the load limit is before turning the O/D off? No problems so far, just curious.

I think the limit is when the tranny shifts out of O/D into fourth ;) These allison trannys are built tough to take a beating and tow a lot I wouldn't worry about it.

The only time you should use that is if you are towing enough weight that the transmission is hunting between 4th and 5th. I don't imagine you will ever have to worry about it.

I don't know if there is a "limit" per se, but I turn o/d off when a.) the tranny starts to "hunt" (which, with the Alli is not very often), b.) I want to maintain RPMs up a grade without losing any speed (thus heavier throttle) or c.) in a strong headwind (to make maneuvering easier--better response from the engine).

I tow a 10k# camper and the tow/haul works great. That's an understatement, of course. Tow/Haul with the Allison is the best equipment for towing that I've ever used. Truly remarkable.

Be sure you don't ever lug the engine. I'll admit that I don't exactly know why you shouldn't, but folks on this site sure tell you not to enough. Other than that, I would think that as long as you're within weight specs for your truck you probably wouldn't do any damage running in o/d.

Rip

Just forget you even have it. A lot of people *****ed to GM they couldn't shift manually into fourth gear. Those same people now know they aren't half as smart as the Allison's TCM. Later! Frank

My 01 in strong headwinds and steep grades would hunt between 4th and 5th. Had the dealer install a switch on the dash to keep tranny out of 5th. I only use it in extreme towing situations. I tow a 46ft, 10000#, 12.5ft high trailer with a lot of wind drag.

My 01 did not have the switch, I added one and foud that I only need to use it out west pulling the long grades to keep it from hunting 4-5. My fifth wheel weights in at 16,500 loaded plus the 4 of us and the truck about 24800 gcw and it's not used very much.

FYI The US Army commercials state that the Allison transmission in our trucks is the same one used in the Armys APV (Armored Personnell Vehicles) and that they are "bullet proof". Now thats a heck of a transmission in my book not only that but the motor will shut off if it runs out of oil. Some kind of kill switch in there.

Has anybody found a PTO provider that sells the parts to install on the two PTO connections for these trucks. I want to install a Generator and a Compressor. Kinda like the new Chevy hybrid that has a magneto between the engine and the tranny and no starter nor alternator. TIA, Joe

FYI The US Army commercials state that the Allison transmission in our trucks is the same one used in the Armys APV (Armored Personnell Vehicles) and that they are "bullet proof".
That'd be a Stryker. They are quieter than the Dmax. Not really an APV, it's a light fighting vehicle.

I let the Allison decide, I always leave it in Tow/Haul and OD when towing. It seldom comes out of OD in level 2 Juice mode.

Ditto. Tow (stock) a 12K# Fifth Wheel in T/H and don't take it out of OD unless I'm going through mountain passes. The Ally is incredible! (although won't handle as much torque as some the hot-rodders here would like!!).