Transmission Swap

dmjr77 · January 27, 2004

Is it possible to swap out a Allison Transmission and put in a 4-L85E? The truck is a 2001 2500HD 4x4 with a 8.1L

Cool Zr2 · January 27, 2004

You can do almost anything to anything if you study up and put your mind into the project.

Shaners · January 27, 2004

I suppose it would be possible... The 8.1L is hooked up to the 4L85E in the 2500 Avalanche and the 2500 Suburban. It would involve both mechanical and electronic swaps...

I'm not sure why you'd want to make the changes though...

linda · January 27, 2004

only reason i can see would be because of the horses the Allison consumes.....but you can defeat a lot of that with a good westers tune, and removing the torque management. I definately wouldnt want to give up my 5 speed auto.... , but to each thier own.

BlackSilver · January 27, 2004

Is it possible to swap out a Allison Transmission and put in a 4-L85E?

Why would you want to?

dmjr77 · February 1, 2004

The reason why I want to swap it out because of the problems that the Allisons have. I also drove one and they rob the horsepower from the 8.1L

bluenote · February 1, 2004

The reason why I want to swap it out because of the problems that the Allisons have. I also drove one and they rob the horsepower from the 8.1L

They do rob a bit more power from the engine than the 4L85e does, but that's easy to overcome. As far as the "problems" that the Allison transmissions have, you'll have to explain that one. The features and capabilities of the Allison 1000 are far better than any of the other GM transmissions, at least in regards to towing or hauling a load. Maybe if you're interested in drag-racing your truck, I could see where the Allison wouldn't be the best, but then again there are guys who have their Duramax/Allison trucks done into the 11 second range in the ¼ mile.

MCourson · February 1, 2004

I too am curious of these "problems".

dmjr77 · February 2, 2004

The reason why I dont like the Allison Transmission:

1. That I dont like the fact that it is shifts from 4th to 5th gear to many times.

2. When you put it in park it makes that horrible bang

3. When you shift into gear, it takes longer for them to enagage into gear (my 4L80E goes into gear quicker)

4. If you have a problem after the warranty runs out, you end up spending big bucks to replace them since GM Techs are not allowed to service Allison Transmissions.

I have driven 3 Allisons and I have freinds who have had them and traded either to a 6.0L or went down to a 1500.

tmf6902 · February 2, 2004

I don't know for sure but I bet some of those problems can be fixed with an updated TCM flash......and the bang into park is completley normal. Atleast that's what my allison video says. I dunno after I put my Wester's in that thing shifts real smooth, and I've never had a problem with it search for gears, or delaying. in fact I just had my truck at the dealer this past week and they test drove it, service manager drove it (they couldn't figure out what was wrong with it so he took it out) and he told me it was the smoothest best shifting allison he ever drove.

dmjr77 · February 2, 2004

If I was to sink 30k or more into a truck that bangs into park, I would be upset that I did. I feel that GM should do domething about it.

silverado3500 · February 3, 2004

Let me know if you plan on doing this mod, and if your ally has lower miles on it, i'd be glad to take if off your hands. I've got a 4L80E thats shot (still works and shifts good but its on its last leg because the previous owner ran it out of atf) and I'm planning on converting it to an allison.