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  • Dick S
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Allison shift speed into 6th
After about 3 weeks of driving on secondary roads (I haven't driven on any freeways yet), I discovered I was never getting to 6th gear. With posted speeds of 55, I like to drive at 57 to 58. My tranny doesn't shift into 6th until 61 mph. Is this...

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Re: Allison shift speed into 6th
Reply #1
Others who know more will likely amplify...but, have you trie using the Allison in MODE selection?

Re: Allison shift speed into 6th
Reply #2
Don't know about newer FTs; and I am not particularly mechanical minded;  but with "The Burrow" when cruising on relatively level roads, I push the button marked "Mode".  It seems to be an overdrive and the "Ally" rides in 6th gear until a hill...

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Re: Allison shift speed into 6th
Reply #3
Do you know the weight of the coach as loaded for travel?  Do you have a tag axle?

Re: Allison shift speed into 6th
Reply #4
For our '03 U320 40' with tag, our top shift into 6th is around 61 mph.  We then use the fine adjustment on the cruise to get to around 1350 rpm in 6th for optimum fuel economy.  This results in about 62 mph, give or take.  Just a bump above the...

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Re: Allison shift speed into 6th
Reply #5

For our '03 U320 40' with tag, our top shift into 6th is around 61 mph.  We then use the fine adjustment on the cruise to get to around 1350 rpm in 6th for optimum fuel economy.  This...


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Re: Allison shift speed into 6th
Reply #6

Ours is identical. I get to 6th gear at 62mph at 1350 rpm.
They said 1500 rpm is optimal but that takes me over 70mph


Hmm....  is that "optimal" from the torque/hp curves?

We've tried 64-65 mph...

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Re: Allison shift speed into 6th
Reply #7
Steve,
What MPG do you get with your sweet spot.

Being on the west coast where there does not seem to be long stretches of flat land,
I have not found a definitive sweet spot.
When I get a level stretch, I get head wind, side winds etc. to skew the...

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Re: Allison shift speed into 6th
Reply #8
This is a great topic.  I posted a question elsewhere on this forum aobut the 5th 6th gear quandry and you folks have answered my question.  Here is another question/observation.

Couple of weeks ago I was talking to a Lucent engineer who owns a...

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  • Dick S
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Re: Allison shift speed into 6th
Reply #9
We just weighed coming into Idaho with 1/2 tank fuel and fresh water. GVW is
36,900 and yes we do have a tag.

  • Dick S
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Re: Allison shift speed into 6th
Reply #10
Thanks for the suggestion. No, I haven't tried traveling using the Mode
selection. I'll try that tomorrow to see if it will shift to 6th at a lower
speed.

  • Dick S
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Re: Allison shift speed into 6th
Reply #11
I will.

  • Dick S
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Re: Allison shift speed into 6th
Reply #12
In Oregon & California the speed limit on freeways is 55 for trucks and vehicles towing. I would like to stay within 4 or5 mph of that limit and still run at the lower rpm's of 6th gear. Would Allison be te appropriate resource?
BTW, my previous...

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Re: Allison shift speed into 6th
Reply #13

In Oregon & California the speed limit on freeways is 55 for trucks and vehicles towing. I would like to stay within 4 or5 mph of that limit and still run at the lower rpm's of 6th gear. Would...


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Re: Allison shift speed into 6th
Reply #14


What MPG do you get with your sweet spot.



Barry,

It depends on terrain and a lot on the type of diesel.

At 1350 rpm in 6th our round trip from Texas to Maine and back with ULSD is 8 to 8.2 mpg (the...

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  • Dick S
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Re: Allison shift speed into 6th
Reply #15
Today I drove using the Mode selection. I still have to hit 61 mph to shift to 6th, but then I can set the cruise control for 59 mph and it will hold there until I come to a hill with enough grade to force a downshift. After I crest the hill I...

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Re: Allison shift speed into 6th
Reply #16
I have had the highway patrol pass me by when I was doing 65 mph.
Everyone else is doing 75 mph.
I was told they dont look at you until you are over 10 mph speed limit.
As long as you are going with the flow of traffic I have not had one look at me...

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Re: Allison shift speed into 6th
Reply #17
Likewise, mine shifts at 61.  This is a problem in California, when towing as the speed limit for anything towing is 55.  I find I can get it to shift up at 61 and then decrease it to 60 and it holds in Economy Mode.