Allison 6sp: Is 6 spd. Allison really 6 spd. or overdrives ?

2012 DMAX

Member
Nov 4, 2012
41
0
6
Southwest IA
Just took delivery last week of our new 2012 Chevy 2500HD Duramax/Allison. Is the Allison really a 6 speed or does it have overdrives ?

Does it also have an electric torque converter that locks up ?
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,701
756
113
Texas!!!
Just took delivery last week of our new 2012 Chevy 2500HD Duramax/Allison. Is the Allison really a 6 speed or does it have overdrives ?

Does it also have an electric torque converter that locks up ?
Yes, it is a 6 speed. Yes, it has 2 overdrives. Yes, it has a lockup torque converter that is electronically controlled.
 

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
Its actually a 2-speed Powerglide, with 4 overdrive units bolted onto the back. :D

Just kidding of course.

the ratios are as follows.

1st gear - 3.10
2nd gear - 1.81
3rd gear - 1.41
4th gear - 1.00
5th gear - .71
6th gear - .61
 

2012 DMAX

Member
Nov 4, 2012
41
0
6
Southwest IA
OK, thanks for the replies.

Our towing plans include:

28' travel trailer aprox 7500#

goose neck trailer hauling farm tractors, possibly up to 14,000#

The travel trailer may go to Yellowstone in the future so flat ground and mountains.

The goose neck trailer hauling tractors will encounter rolling hills and flat ground.

This is our first diesel/allison pickup. Any advice for pulling these loads, or just put it in D and monitor the tranny temp. ?
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
232
63
Fullerton CA
OK, thanks for the replies.

Our towing plans include:

28' travel trailer aprox 7500#

goose neck trailer hauling farm tractors, possibly up to 14,000#

The travel trailer may go to Yellowstone in the future so flat ground and mountains.

The goose neck trailer hauling tractors will encounter rolling hills and flat ground.

This is our first diesel/allison pickup. Any advice for pulling these loads, or just put it in D and monitor the tranny temp. ?

Trans will run cool.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,701
756
113
Texas!!!
I would recommend using Tow/Haul mode when hooked up to either trailer.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,724
292
83
Boise, ID, USA
I would recommend using Tow/Haul mode when hooked up to either trailer.
Aah, yes. Been running my Duramax so long I forget to mention the obvious stuff like that, which wasn't so obvious when I was new to it.

I think the manual says use tow/haul when the GCVW is over 10,000 lbs. At least for my year. I recommend at least scanning through the Diesel Supplement to the manual. Should of come with the truck, if not you can download it from GM for free.

Sent from my Galaxy Nexus using Tapatalk 2
 

LWATSON

future trans limpers
Jul 30, 2008
2,587
1
36
55
Scotland Neck NC
I use tow haul with almost every trailer no matter how light. Its nice to have the grade braking even though it still performs fine without it.
 

jc1843

New member
Sep 27, 2009
228
0
0
86
So Calf
When in Tow/Haul mode-- it will also help hold the truck and trailer while going down a steep grade. Don't be alarmed when the engine increases the RPM over 4,000-- it knows how to do this and will protect everything. Sure makes it safer and saves the brakes.
 

trashygasman

Slowly but Surely
Dec 18, 2008
637
1
18
49
Washington, OK
Also, since yours is a 2012, it has the exhaust brake which increases your stopping power that much more. Using it and tow/haul, you hardly have to use the brakes.:thumb: