Allison question?

[GMC6000]

Well, I finally did it. I traded my 04 6.0 gas for an 05 Duramax. Impressive performance unloaded, but when I hooked up to my 35' 5er I was less than impressed with the transmission. In T/H mode it seemed to not want to up shift as it should. While pulling up a short hill, but fairly steep, it downshifted but would not shift back up once I crested the hill and regained my cruise speed. I had to take it out of T/H to make it upshift. Is this part of the learning curve of the allison? If it is, how long does it take to learn? Makes me want my 4L80 behind the Dmax.

[bluenote]

You could be experiencing a bit of "learning" on the part of the Allison. I know mine takes a few miles of towing each time we hook up the 5er before it settles back in. Also however, the t/h mode does change the shift points. It will not generally shift into 5th until you are about 62 mph. I like to tow about 60 mph, so I just run it up to that, disengage t/h for a couple seconds, let it upshift, then re-engage t/h. Another thing to consider is use of cruise control. If it's relatively flat terrain, or only gradual grades, cruise is usually fine. However, sharp grades (even fairly short ones) don't work as well with cruise. When we hit that kind of territory, I leave the cruise off. I can usually feather the throttle enough to hold 5th gear. Once you have downshifted, it does sometimes take a bit longer to upshift back again, but that's just the way it works. Once you've towed downhill on some decent grades a couple of times, I'll bet you'll forget all about that hydramatic tranny.

[work'n 8.1]

With my 8.1 in tow/haul it won't shift until 3K. At first it seemed really high but thats the way its designed. If I'm crusing say at 2500 RPM I either disengage tow/haul or speed up to get it to shift them reduce my speed. You will get use to it. Believe me the Allison is much much better than your 4L80.

 

Bryan

[SimplyRAD]

Questions:

 

Doesn't the manual say to engage/disengage t/h mode when in park? Does it hurt the circuits when engaging/disengaging while driving?

 

I know I have had some "hot" circuit connections and had to rewire a circuit board coming from the tcm to a board which was also connected to the stearing column. So, I no longer switch t/h mode while driving.

 

Just curious.

[bluenote]

Questions:

 

Doesn't the manual say to engage/disengage t/h mode when in park? Does it hurt the circuits when engaging/disengaging while driving?

 

I know I have had some "hot" circuit connections and had to rewire a circuit board coming from the tcm to a board which was also connected to the stearing column.  So, I no longer switch t/h mode while driving.

 

Just curious. 

 

<{POST_SNAPBACK}>

 

 

I've never seen that in my owner's manual and can't imagine it would hurt the circuits. I regularly turn t/h on and off while driving. My truck is 4½ years old now, with 109K miles and it hasn't hurt it yet.

[dewfpo]

I turn T/H mode on/off all the time while driving as well. No problems. My manual doesn't say you can't do this.

 

DEWFPO

[nalineeds24s]

Well, I finally did it. I traded my 04 6.0 gas for an 05 Duramax. Impressive performance unloaded, but when I hooked up to my 35' 5er I was less than impressed with the transmission. In T/H mode it seemed to not want to up shift as it should. While pulling up a short hill, but fairly steep, it downshifted but would not shift back up once I crested the hill and regained my cruise speed. I had to take it out of T/H to make it upshift. Is this part of the learning curve of the allison? If it is, how long does it take to learn? Makes me want my 4L80 behind the Dmax.

 

<{POST_SNAPBACK}>

 

 

My 04 Denali does the same thing. After i get back on level road and it does not shif back into hi, I turn off T/H then turn it back on ofter the shift. I guess thats just the way it is.

[billcar9999]

Well, I finally did it. I traded my 04 6.0 gas for an 05 Duramax. Impressive performance unloaded, but when I hooked up to my 35' 5er I was less than impressed with the transmission. In T/H mode it seemed to not want to up shift as it should. While pulling up a short hill, but fairly steep, it downshifted but would not shift back up once I crested the hill and regained my cruise speed. I had to take it out of T/H to make it upshift. Is this part of the learning curve of the allison? If it is, how long does it take to learn? Makes me want my 4L80 behind the Dmax.

 

<{POST_SNAPBACK}>

 

 

 

 

I think the answer is 50 miles to learn for a new truck. The adaptive learning is always on. Some people say you have drive it hard from time to time to keep it snappy.

 

Bill

[Shawn T]

Well, I finally did it. I traded my 04 6.0 gas for an 05 Duramax. Impressive performance unloaded, but when I hooked up to my 35' 5er I was less than impressed with the transmission. In T/H mode it seemed to not want to up shift as it should. While pulling up a short hill, but fairly steep, it downshifted but would not shift back up once I crested the hill and regained my cruise speed. I had to take it out of T/H to make it upshift. Is this part of the learning curve of the allison? If it is, how long does it take to learn? Makes me want my 4L80 behind the Dmax.

 

<{POST_SNAPBACK}>

 

 

 

 

Man, I think you are the first person that I have ever heard complain about the Allison. If your 05 was used then yes the learing curve is over. I bought mine with 0 miles on it. And after a few trips around town, stop and go, it settled down (about 50 or 60 miles). Unless you go on a 2500 mile trip without shifting a gear, I don't think your going to notice a "learning change" in the tranny unless you get your TCM flashed. I pull about 10,000 lbs. through the Utah and Colorado mountains. I put it in T/H and forget about it. Maybe because I am above 70 mph, unless the turns get tight and the incline/decline is great, it seems to upshift to OD at the precise time and RPM. Trade your Alli for the 4L80E, you will have a bucket of gears laying on the road after the DMax torques right through it. The 4L80E is geared to high in 1st, it robs low end torque and HP in my opinion, but in contrast the OD is geared way to low for a DMax.