When towing my travel trailer I was wondering if I am supposed to disable the overdrive when approaching a larger hill, or do I just let the truck change on its own. I have noticed that most hills the truck does not down shift, so should I just leave it in OD. I am just concerned about this tranny limp you all talk about. I have no overheating issues as of yet, but appreciate any advice.

As long as your in T/H your good to go.

As long as your in T/H your good to go.

X2!! Love the Allison for towing..;)

T/H X3... Best Trans anywhere for towing.

i have had my 05 lly for about 2 yrs and have always pulled my 5th wheel in od and tow/haul mode. no problems as of yet. i am planning on a trip from cincinnati to st petersburg beach in fla. this year. i have a superchips max/micro tuner and 4" turbo back exhaust and i'm planning on a cold air intake prior to my trip. i only use my truck to pull my 4k lb boat or my 7k lb 5th wheel and its my daily driver. should i consider anything else?

great tranny's for towing, wish my 06 6.0 had one. oh well thats why i kept the ole 01 8.1 work horse.

If stock, let the tranny do the thinkin'.
If modified, your EGT's will tell you when to lock out overdrive.

I agree. I've just completed a 3700 mile trip Vancouver to San Diego and back towing 10,000 # 5th, and in T/H mode it will definitely shift when it needs to; in fact, sometimes a bit sooner than when you'd expect. What a dream to tow with.

If stock, let the tranny do the thinkin'.
If modified, your EGT's will tell you when to lock out overdrive.
:exactly: These aren't the slush boxes found in passenger cars, 1/2 tons and Furds. They are a truck transmission. They are the first and ONLY auto to belong in a truck. The 01 and 02's didn't have a factory OD lockout because in stock form, it isn't needed. Last I checked, the Allison is the only automatic rated to take full (stock) engine HP and torque in OD. If it wasn't built the way it is, I would still be shifting my own gears.

Allison has a strong overdrive. I would downshift if it is hunting gears a bit in hills and gradeds or as a way to controll EGT's(lugging the motor will bring up the EGT's.....need a gauge to tell and its more of a concen for towing with power)

For the most part set her in D and dont worry about it :D

Tow an 8.5k 5er around SW Colo mountains, and am totally in love with the allison. Not only does the t/h mode take care of the uphill work, I have never had to use less brake on any veh. downhill as I do with this setup.

I tow heavy; 24k trailer and load. I leave the trans in OD and set the cruise at 65 depending on the state of course. I find that by doing this I get much firmer and smoother shifts under load, even on grades. Just put in OD set cruise and let the wonderful trans take care of biz. When you are going up a grade, there is a lot less shift shock when you are in OD with cruise on as opposed to accelerating manually. The ECM takes over and does a much better job than we can do.

T/H X3... Best Trans anywhere for towing.

X4...just remember that the t/h mode disengages when you turn off the ignition key! :o:

Just returned from a 2400 mile trip from Wisconsin down into Kentucky and back and found that my mileage is better in tow/haul mode than when I was in regular mode. I am thoroughly impressed with the power these trucks have.