4spd vs 6spd Allison question.

I think the story was a pickup question. I feel for our lly the 5 speed is so good adding the 6th would not be needed. The 06 with more HP and torque is a different issue. But the 8.1 gas engine also had the 6th gear later. It would be nice to hear from any owners with this combo. I did talk to an 8.1 with the manual trannie and he did not like it for towing his alpenlite.

chevman PS we all like different stuff

Also its likely that the 5spd Allison has 6th in it. You can find how to enable 6th by googling the topkick trucks as there are some that had it done. I will try to find it. Google Allison 5spd to 6spd. Pickup need a valve body conversion, medium duty can be flashed.

All 8.1s were not paired with the Allison. Suburbans were 4L80Es due to frame differences between the trucks and the SUVs. Still an awesome combo.
Allison is a great trans if you don't overload it. Lots of pepped up Dmaxs have blown the trannys pretty quick. You can get away with a little, but not a little too much.

ramyankee wrote:
Well I thought my Allison was a 4spd. Surely no expert so maybe mine is a 5spd.
No, mileage is not the biggest deal at all but just figured if I do upgrade may as well go with a truck combo I really like.
The diesel combo is at least $10000 more because for a diesel my pick would be the LBZ.

If your cluster has PRND321, your gears are 1,2,3 and D is drive & overdrive unless OD is off (by pressing and holding the T/H button).

That setup means you can manually limit it to any of the 5 gears.

minnow wrote:

trail-explorer wrote:

ramyankee wrote:
Driving the 6 spd might give me a slight increase in mileage because of the 2 extra speeds.

Extra 2 speeds compared to "what"?

All 8.1 engines were paired with the Allison transmission, which was either a 5 speed or 6 speed. 6 speed was 2006 and later I believe - at least that was the case on the Duramax / Allison combo.
2005 and earlier was 5 speed.

Correct. On the 8.1 gassers the 6th speed was introduced in 2006. Prior years had the 5 speed. The difference was rather inconsequential.

The Allison was the only transmission available if the 8.1 was selected on the order sheet.

Both the 8.1 and the Duramax were also available with the ZF-6 manual transmission.

trail-explorer wrote:

ramyankee wrote:
Driving the 6 spd might give me a slight increase in mileage because of the 2 extra speeds.

Extra 2 speeds compared to "what"?

All 8.1 engines were paired with the Allison transmission, which was either a 5 speed or 6 speed. 6 speed was 2006 and later I believe - at least that was the case on the Duramax / Allison combo.
2005 and earlier was 5 speed.

Correct. On the 8.1 gassers the 6th speed was introduced in 2006. Prior years had the 5 speed. The difference was rather inconsequential.

The Allison was the only transmission available if the 8.1 was selected on the order sheet.

ramyankee wrote:
Driving the 6 spd might give me a slight increase in mileage because of the 2 extra speeds.

Extra 2 speeds compared to "what"?

All 8.1 engines were paired with the Allison transmission, which was either a 5 speed or 6 speed. 6 speed was 2006 and later I believe - at least that was the case on the Duramax / Allison combo.
2005 and earlier was 5 speed.

It's a big block gasser. Mileage is going to s uck equally regardless of what slushbox is hooked to the back of it.
Only place you might pick up a smidge of gas mileage is haulin arse, bobtail, the 2nd OD of the 6 speed may give you a bit of a bump with a few less rpms, but at that speed you're burnin gas like it's free anyways.

Now, to get the Alli over the 4L80 whatever it is, is a big deal if you plan on keeping the truck. 5 or 6 speed. I would be more worried about the miles and condition of an old truck not whether it has the double OD.

Well I thought my Allison was a 4spd. Surely no expert so maybe mine is a 5spd.
No, mileage is not the biggest deal at all but just figured if I do upgrade may as well go with a truck combo I really like.
The diesel combo is at least $10000 more because for a diesel my pick would be the LBZ.

The reason for trading a truck with 14K miles was to get the Allison 5 speed, 410 rear and dually for towing the new 2001 35 ft alpenlite. Only auto and the 1st year for both engine and trannie. Traded in 05 for the duramax but the 2001 truck at 58K miles was the same as new. Only trip on a very windy day though El Central to Yuma was the only time the mileage was under 8 mpg but almost 8. I only traded it because of we could I guess.

chevman