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Topic: Allison shift speed into 6th (Read 1128 times) previous topic - next topic

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 how most of yours works?
Is it possible to have the shift point reset to 55 or so? Are there any reasons not to do that?

Dick
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

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?
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

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 is encountered.  If the terrain has become hilly (how much is up to your rig), I take the tranny out of mode resulting in doing what you described. . .5th most of the time until the grade increases.

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?
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

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 shift point so it doesn't do too much hunting on hills.  We also use the "mode" selection, which IIRC sets more economical shift points, but really will only make a difference on hills, not flat land.

On secondary roads we're probably staying in 5th, depending upon the road.  The terrain, the lanes, the shoulders, and our comfort level dictate this (as did interstates in Ohio, until they increased the truck speed limit from 60).

Michelle and Steve
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

Re: Allison shift speed into 6th

Reply #5 –
Quote from: Steve & Michelle –
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 shift point so it doesn't do too much hunting on hills. 

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
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Allison shift speed into 6th

Reply #6 –
Quote from: Barry Beam –
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 but our fuel economy suffers.  Call me crazy (Steve would - and does, on occasion,  :)) ) but I can feel a noticeable difference in the coach effort (much less) at 62 than 64.  Kind of like a sweet spot. 

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

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 mph.
116,797 miles @ 16,536 gallons & 2616 hours =
7.063 mpg &  44.69 mph average for the life of the coach.
I can't understand how it can be so low as every trip I take I get better MPG than that.
June 2008 I got 8.394 mpg http://beamalarm.com/travel/june_2008/june_22_2008.htm
June 2009 I got 7.538 mpg  http://beamalarm.com/travel/june_2009/june_2009.htm

The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

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 40' Alfa with a Cat 330.  I mentioned that I thought our RPMs at 60 were somewhere in the 1300s.  He assured me there had to be something worng with our tranny as his RPM at 60 were in the 1500 to 1600s.  Not being very mechanical I said I thought it might be due to our having 450 horses and they don't have to work as hard.  He thought I was being flippant.

Today on cruise control, flat road, no grades and no wind at 60 MPH our tach showed 1300 to about 1350 RPMs.  We were in Econ in 5th gear.
George Stoltz.  Retired from full-time living in a great Foretravel and now are back to living in a traditional sticks and bricks in Florida.

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, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

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, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: Allison shift speed into 6th

Reply #11 –
I will.
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

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 Replies were sent from MS Outlook 2007 and all were bounced back as "undeliverable". Yet here they are...
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: Allison shift speed into 6th

Reply #13 –
Quote from: Dick S –
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 Replies were sent from MS Outlook 2007 and all were bounced back as "undeliverable". Yet here they are...

Me, too.
George Stoltz.  Retired from full-time living in a great Foretravel and now are back to living in a traditional sticks and bricks in Florida.

Re: Allison shift speed into 6th

Reply #14 –
Quote from: Barry Beam –

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 first year of ULSD it was 7.8 when the lubricity wasn't the greatest.... and still isn't).

Any legs with non-ULSD diesel (which we can buy in a few states) will be around 9-9.5 mpg.  The first few years we made this trip our overall mileage for 4K+ miles was 9-9.5 mpg.  We're still surprised how much lower the fuel economy is with ULSD.

Any legs with B20 biodiesel will be 9.5-10 mpg.  And the engine runs noticeably cooler.  It has clogged the fuel filters more frequently, though, and it's usually more expensive and very hard to find for us.  But the engine clearly likes it.

Sadly, running from Texas to ABQ/SF New Mexico and back with the headwinds and the hills going westbound and only ULSD our fuel economy was 7.4.

Most of our driving is Interstate-centric. 

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

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 have to get back up to 61 to get to 6th again.
I think this is acceptable and thank you or the suggestion. I think 4 mph over the speed limit is probably ok, 6 or 7 over scares me.  ;D
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

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 when driving by.
You know the calif traffic.
At 55 you are having people wanting to to pass you & cut in front of you because they dont like how slow we are going.
I have a heck of a time trying to keep this coach at 55 on the freeway.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

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.
Audrey & Harvey Nelson
2000 U-320, 40' towing 2014 Jeep Grand Cherokee
nelsonah@ieee.org