Towing rpm range

mamumtsllc

Member
Sep 4, 2014
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I have a 06 3500 6 speed Allison. It's got 3.73 gears and 305 tires. I feel like the rpm is a little too low for that setup to tow very much or very far. The majority of my towing will be farm related here around home so I won't hardly ever get in 6th gear. But this winter I hauled some cattle a few hours. Jumped back and forth to 5th. I'm going to pull a 32' gooseneck to west Virginia from Arkansas here in a few weeks. Just wondered if anyone agrees or would suggest the gear change to 4.10 for my tire size to get me the rpm that I need. Rite now at 70 in 6th I'm a little over 1500 rpm.

Thanks

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Bdsankey

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Feb 1, 2018
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Larsen, Wisconsin
Why regear, just drop to 5th as its also an overdrive.


6spd Allisons have a double overdrive. I would assume you have the truck in tow-haul mode? Being a 5spd Allison owner I don't know the ins/outs of the 6spd and where it would shift into 6th with tow-haul engaged.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
296
83
Boise, ID, USA
X2, if the hunting bothers you, select M and restrict it to 5th. Way cheaper/easier than a re-gear.

If you are worried about the engine/transmission, lugging a diesel won't hurt it. The only reason to lock out 6th is if it hunts between 5 & 6 and that bothers you.
 

Bdsankey

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Feb 1, 2018
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Larsen, Wisconsin
X2, if the hunting bothers you, select M and restrict it to 5th. Way cheaper/easier than a re-gear.

If you are worried about the engine/transmission, lugging a diesel won't hurt it. The only reason to lock out 6th is if it hunts between 5 & 6 and that bothers you.

Not to mention the unnecessary wear on the trans constantly shifting.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,681
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Phoenix Az
I have a 06 3500 6 speed Allison. It's got 3.73 gears and 305 tires. I feel like the rpm is a little too low for that setup to tow very much or very far. The majority of my towing will be farm related here around home so I won't hardly ever get in 6th gear. But this winter I hauled some cattle a few hours. Jumped back and forth to 5th. I'm going to pull a 32' gooseneck to west Virginia from Arkansas here in a few weeks. Just wondered if anyone agrees or would suggest the gear change to 4.10 for my tire size to get me the rpm that I need. Rite now at 70 in 6th I'm a little over 1500 rpm.

Thanks

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use manual mode more like Dave suggested. most guys will only be pulling heavy loads in 5th gear unless you are making a damn good amount of power to hold 6th without egt's going through the roof. a re-gear will help get the low end grunt back but thats an expense i dont see favoring you at this time. i would try keeping it in 5th and let it downshift to 4th on hills.

Not to mention the unnecessary wear on the trans constantly shifting.

that will be a non-issue with how the allison shifts. specially if the truck is stock
 

mamumtsllc

Member
Sep 4, 2014
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Truck is mainly stock. Danville 2.5 drop in turbo. Built trans. Lift pump. Will more than likely soon habe 30-45% injectors. I'll give the dropping to 5th a try and see how it goes.

Thanks for the quick reply!


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Bdsankey

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Feb 1, 2018
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Larsen, Wisconsin
Truck is mainly stock. Danville 2.5 drop in turbo. Built trans. Lift pump. Will more than likely soon habe 30-45% injectors. I'll give the dropping to 5th a try and see how it goes.

Thanks for the quick reply!


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Dropping the rpm difference from 5th->6th is ~300-350rpm so you should be much better off.
 

Hambone

Always learning
Jan 24, 2016
572
0
16
Florida
I used to see about 1.5 mpg gain running M keeping it locked out in 5th running 70 pulling 8-10k
That put the truck around 2100 rpm with 285/75/16
So like everyone suggested
Try running in M before going for a regear :thumb:
 

mamumtsllc

Member
Sep 4, 2014
90
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Sounds like 5th it is. I just drove it and in 6th I'm just above 1500 then bumped it down to 5th and it's about 1900. So I'll give that a try.

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mamumtsllc

Member
Sep 4, 2014
90
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Just got home from a trip to west Virginia from Arkansas. About 1600 miles. Pulling 30 foot gooseneck with 1 ton truck on it. Ran mostly in 5th as 6th just wouldn't cut it. I planned on 10 mpg but I'm thinking it was closer to 9 maybe even a little less. Did find out that I need a new family hub as my ect got warm multiple times on long pulls. So I'm looking at options there. Egt might have reached 1000 a few times but mainly stayed at 850-900.

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Apr 15, 2015
419
2
18
dallas
How fast are you towing? Just curious b/c I like to tow around 75-80 lbz 7-8k 25' camper. Got 12 today but had a good tail wind and only did 65 in 6th.


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Pure Diesel

Active member
Apr 22, 2008
896
154
43
Ventura County
My last few trips of towing(9k 5th wheel) in 6th gear, on flat ground, was that the tranny temp started going up. It was maybe 20degrees. The EGTs would start to climb on any mild incline also. The truck really likes 5th gear when towing and at 65mph.
 

mamumtsllc

Member
Sep 4, 2014
90
1
8
36
My egt stays about 800 under throttle. Until I start climbing hard then it will almost hit 1000. If we ran under 70 she stayed cooled down for the most part. But the majority of the trip I ran 70-75 on cruise. I figure this trailer weighs around 8 or 9k. Going up I had a 2018 4 door duramax 1 ton. Coming back I had a 2012 Ford f350 ext cab.

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NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,201
363
83
At Da Beach
My last few trips of towing(9k 5th wheel) in 6th gear, on flat ground, was that the tranny temp started going up. It was maybe 20degrees. The EGTs would start to climb on any mild incline also. The truck really likes 5th gear when towing and at 65mph.

I used to pull in 5th with my LMM, it liked it, less shifting and temps stayed lower. Mpg seemed to stay the same with 6th locked out. My LML has a better shift strategy, it hardly ever shifts around, pretty sure the line pressure variation helps it do that...
 

Dozerboy

Well-known member
Jun 23, 2009
4,892
470
83
TX of course
All depends on the terrain, speed, and wind. I normally just let my truck do it’s own thing only locking out 6th when I’m in a rolling hills or a headwind. Maybe it’s the tune but I don’t understand you guys complaining about the transmission hunting. I had to make my Lbz down shift sooner it would take 70% throttle in 6th before it would down shift with the stock TCM tune.


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