I am curious if the 6 speed transmission will be able to hold 6th when you're towing or will it want to shift to 5th all the time? Do you typically have to tow in 5th gear? Can you switch the tranny to "manual" so that you can make it stay in 6th and lug the motor instead of downshifting? Just a few questions! Ha Ha.
Thanks for your answers.

6th gear is overdrive. If you are towing in overdrive with very much weight, you will really stress your converter and clutches.. You should put it in m and not go past 5. This replaced the o/d lockout on the 5 speed trannys on 01-05 allisons.

Over 16k on mine, I put it in T/H and D. The truck runs like a scalded cat and never has hunted in 6th, it will drop out to 5th as needed and in a 40 mph head wind with the Toy hauler stay in 5th if you want to go 70, trans temp was normal 195 ish and thats it. I love the extra gear, normal towing it gained me 1+ MPG and alot less noise in the cab. Trans is smarter than you think.... Oh and 5th gear is also OD.

You are right
Allison 1000 (MW7)

Type: 6-speed automatic
First: 3.10
Second: 1.81
Third: 1.41
Fourth: 1.00
Fifth: 0.71
Sixth: 0.61
Reverse: 4.49

Final drive ratio: 3.73 ratio standard on all models

What is 5th gear ratio on a 5spd allison?

What is 5th gear ratio on a 5spd allison?

Same as fifth on the 6 speed tranny; 0.71 to 1.

Just put it in Tow/Haul and go. The transmission knows what gear it need to be in depending on your load.

It will hold 6th just fine but I found I gain 1mpg better in 5th from 6.5 to 7.5

With 10,000# I put it in drive and and TH mode and go. It stays just fine and doesnt lug. It shifts when it wants to.

So there's not an overdrive disable option anymore?

So there's not an overdrive disable option anymore?

The range selection mode took it's place.

T/H in D and set cruise on 80. I can't recall if it has ever downshifted going up hills or not. I don't tow that heavy, 6500-7000lbs max with a car and open car trailer.

T/H rocks, just leave it in there and drive. The computer is smarter than you are. :D

I got my new truck and the manual shifter will NOT hold a gear, it just limits the top gear that the tranny will shift to. I'm not exactly sure where the manual shifting adds any useful value to the truck.

I got my new truck and the manual shifter will NOT hold a gear, it just limits the top gear that the tranny will shift to. I'm not exactly sure where the manual shifting adds any useful value to the truck.
Downshifting down grades, and the ability to downshift prematurely before hitting a upcoming hill.

mine wont hold 6th on grades towing and some grades i need to go down to fourth. my lb7 with a tuner solved this, could run any hill in 5th :ro)

I played with the M mode, seemed like the tranny pretty much did what it wanted anyway. I learned the tranny is smarter than me. Toy box 8000-10,000 lbs holds sixth fine with torgue to pass without downshifting. It takes a pretty decent grade to cause mine to downshift, then it just pulls like a champ.

dane

On edit, we put my buddies 05 Powerstroke on the same load and it was a joke, absolutely terrible, couldn't hold 70 on near flat ground and stay in overdrive, lousy gas mileage. Not impressive. A loud engine is one thing, a loud engine that won't pull good is another. Just one observation.

Don't try to out think the Allison...that's why we paid the extra money for it, so it could do the thinking and figure out what gear is should use. Put it in D, push T/H and all you have to do is to keep the truck between the white lines. With a 14k 5er, I can cruise at about 62 and higher in 6th.

Made a trip from Pa to Fl with 1600 miles on truck. A lot of mountains 16ft box trailer and I could count on one hand how many times truck shifted to 5th only 4th once. Couple weeks later same trip same load had to shift more than the first trip like the truck lost power. Someone said it was because the alli was still learning on the first trip. But even on the 2nd trip only shifted to 4th once.