Allison Auto, No 'Park' in Low Range?

[27RMT0N]

So I was reading over the manual for my 'new to me' chip truck, a 2006 GMC 5500 with the 6.6 Duramax and Allison Auto, I think the 1000?

I actually do use low-range a lot: towing the chipper up steep gravel roads/driveways (I'm talking 'side of a mountain' roads here), backing the chipper into positions up steep gravel driveways, pulling over trees, skidding logs, all sorts of things. With my F350 I usually just put it in low and leave it there until I'm done with that bit of work where it's necessary, as it makes it easier on the clutch/trans than roasting it in high-range doing low-speed, high-load jobs. The manual here says specifically not to use 'park' while in low-range, and while not the end of the world, it means either having to switch back to high-range every time I want to stop the truck for a little while (say, when moving between already staged piles of brush to chip) or apparently risking damage. Anyone have any insights into this limitation of the Allison trans?

 

[chiselbit]

I saw that too. Didn’t make much sense, but I did what they recommended, only takes a few seconds to switch out of low.

 

[evo]

Apples and oranges but on my 95 Isuzu I have no park. Allison tranny...

Put it in neutral with the parking brake? Mines on the dive shaft so that might have something to do with it too

 

[Reach]

My thinking is that the gear reduction in low can put too much stress on the park pawl, increasing the potential for a transmission failure when you’re sitting still on a hill. If it’s flat ground, just use neutral and the parking brake if yours works. Or shift up a range.

 

[27RMT0N]

Yah, that could be it. I'll do some experimenting with just neutral and the parking break like evos truck, but for whatever reason that seems sketchy to me on anything other than flat ground. Yah you can chock the truck (and in many situations should anyways) but that adds another even more inconvenient level to the start/stop process.

 

[evo]

Yah, that could be it. I'll do some experimenting with just neutral and the parking break like evos truck, but for whatever reason that seems sketchy to me on anything other than flat ground. Yah you can chock the truck (and in many situations should anyways) but that adds another even more inconvenient level to the start/stop process.

IT is sketchy... And I use chocks on flat ground... But it's a option and not too big of a deal to toss a chock on a fender move 10-20'. most of the time it's all in the same path as walking from the drivers door to behind the chipper (or back)