RV.Net Open Roads Forum: Class A Motorhomes: Allison Mode Button

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Class A Motorhomes

Open Roads Forum  >  Class A Motorhomes  >  All

 > Allison Mode Button

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 
Page of 5  
Next
Sponsored By:
wolfe10

Texas

Senior Member

Joined: 10/08/2000

View Profile


Online
Posted: 12/23/06 09:07am Link  |  Print  |  Notify Moderator

I have had 2 PM's this week asking questions about the use of the Allison Mode (Economy Mode) button so I guess it is time to re-run that one.

ALLISON MODE:

There are TWO TOTALLY DIFFERENT "LET THE TRANSMISSION CHOOSE THE CORRECT GEAR" MODES/PROGRAMS in the Allison ECU which is the "electronic brain" controlling shifting and other functions.

In ECONOMY MODE, the transmission will not downshift even at WOT (Wide Open Throttle) until the engine pulls down to peak torque RPM in some application and 200 RPM lower that "regular mode" in others.

In REGULAR MODE, the transmission WILL downshift much earlier (to maintain higher engine RPM).

ONLY at higher throttle positions is there any difference, so on flat ground you will NOT notice any difference (except accelerating from a stop IF you are at or close to wide open throttle).

It can make a BIG difference in rolling hills. If you are in rolling hills and regular mode (particularly with the cruise control on), it is common for the transmission to shift down to 5th on the uphill and back to 6th on the downhill. Repeat this process hundreds of times. In economy mode, you will stay in 6th gear unless the hill is so steep or so long that the engine can not pull it without dropping below peak torque RPM. If you can pull a hill in a higher gear (lower engine RPM) AND the engine does not overheat, THAT IS WHAT CATERPILLAR AND CUMMINS RECOMMENDATION FOR THE MOST ECONOMICAL WAY TO CLIMB A HILL with a modern turbo, after-cooled diesel engine.

If you know you will need a lower gear because of the steepness of the grade and/or are engine temperature is rising higher than thermostatically controlled temperature, if driving in economy mode, use the down arrow to drop a gear (this is what I do) or switch out of economy mode. Be sure to switch back into economy mode when past the steep section, or agree to pump extra fuel in the tank.

IF your engine begins to overheat, your HP/weight ratio is low OR if it irritates you to loose a few mph on a hill in the name of saving fuel, in the hills, by all means drive in regular mode.

It confuses me to hear people advocate driving in economy mode only on flat ground, as there is not 1% difference in shift RPM's between regular and economy mode on flat ground, excepting accelerating from a stop if you use WOT.

Every time you start the coach, the transmission is in regular mode. This is the default setting. IF you push the mode button, it goes to "economy mode" AND the light illuminates.

There is no "absolute" on how much difference in fuel economy driving in economy mode will have. On flat ground where you will be in 6th gear irrespective of what mode you are in, there will be ZERO difference. The MOST difference in mileage will be in rolling hills, where in regular mode, particularly if on cruise control you will start up a hill in 6th gear, go to WOT in 6th gear, downshift of 5th gear still at WOT (WHERE IT IS USING A LOT MORE FUEL). After the hill is crested, the transmission will up-shift to 6th, then likely coast a little in 6th gear (unless you are driving with the exhaust brake on-- if you are it then applies the exhaust brake AND downshifts TOWARD the pre-select gear which is generally either 2nd or 4th).And so on 6-5-6-5-6-5-6-5.......

A modern turbo inter-cooled diesel is much more efficient at low RPM high throttle settings. This is NOT my opinion. It is stated in just those words in the Cat Owner's Manual and likely the Cummins manual as well.

Note: In either mode, you are free (and welcome) to use the up and down arrows to PRO-ACTIVELY choose the correct gear. You can not screw anything up-- even if you down-arrow to 1st gear at 70 mph, the transmission understands that you meant "please downshift to the next lower gear as soon as the engine RPM will not exceed the pre-set amount. Then downshift again when safe....."

By the same token, you can shift between regular and economy mode as often as you want with the transmission in any gear when you make the change.

OPINION: I drive in economy mode 99% of the time, including in REAL mountains, but use the up and down arrows to choose the proper gear. I use regular mode ONLY when I am willing to say, "I am willing to throw a lot of fuel away to gain a little performance." When passing on 2 lane roads, THIS IS the case.


Brett Wolfe
2003 Alpine 38'


FMCA Forum: www.community.fmca.com/index

Diesel RV Club:http://www.dieselrvclub.org/

Briteskys

Mesa, AZ

Senior Member

Joined: 09/21/2006

View Profile



Posted: 12/23/06 09:46am Link  |  Print  |  Notify Moderator

Thanks Brett - not only for this but all your posts. Great information.


'02 Beaver Patriot Thunder
Jeep Grand Cherokee
Ron & Jane's Travels


dav5942

Stuart, FL

Senior Member

Joined: 05/24/2004

View Profile



Posted: 12/23/06 11:02am Link  |  Print  |  Notify Moderator

Great post-been trying to figure it out since we got the new coach!

If you are in the economy mode and the downshifts are later than the regular mode, what effect does this have on your braking(break wear, etc.)? Or since there is little difference on flat ground(less than 1%) should we stay in the regular mode to help with braking on flat ground?


2007 Newmar 42' Mid Engine w/Fatboy,Grizzly 550s-in Garage,Rubicon w/4" lift,MotorMetal whls,MickeyT Baja tires-Cherokee w/4"lift in tow, Hog Valley FL(a diamond in the rough)
2010 Part2

Alaska Fishing Newmar Mid Engine 2010 Sportfishing


LanceMan

Sierra Vista, AZ

Senior Member

Joined: 10/29/2001

View Profile



Good Sam RV Club Member

Offline
Posted: 12/23/06 11:04am Link  |  Print  |  Notify Moderator

Ok, I'm still a little confused. I do not have a button but rather a rocker switch that has three positions, up, middle, and down. I fiddled with it while driving but didn't notice a difference and didn't know whether up was off or on, nor what the middle or down positions were. I was going to read the manual again before my next trip but stumbled upon this post. I have an '07 btw.

Ok -- I'm editing this post since I finally figured out why I felt so lost reading this thread. No one responded so I'll clear up my own confusion and perhaps it may help someone else.

I read the post because it was about the Allison transmission but somehow it escaped me that the post isn't about all Allison transmissions. Yes, I'm a noob to Class A's.

The post apparently refers to those Allison's used with Caterpillar and Cummins diesel engines. My WH W24 with Chevy 8.1 and 6-Speed Allison transmission does not have a selector for economy mode. It has a three position Overdrive rocker switch. Positions are Overdrive On, Overdrive Off -1, and Overdrive Off -2. The Overdrive Off positions basically limit the max gear available (5th or 4th). So there you have it...perhaps the subject of the post and or the content is obvious to most, for me it wasn't. Hopefully this additional information will help others. -Walt

* This post was edited 12/25/06 11:12am by LanceMan *


2010 Itasca Merdian 40L

v8q

Oviedo, FL

Senior Member

Joined: 04/11/2005

View Profile



Good Sam RV Club Member

Offline
Posted: 12/23/06 10:36am Link  |  Print  |  Notify Moderator

a. This should be a sticky/FAQ since it comes up so often.
b. Earlier models just say 'mode on' when you pushes de button...


Dave Head
Oviedo FL
95 Foretravel U320C SE
M11, HD4060

JohnnyT

On The Road

Senior Member

Joined: 07/15/2003

View Profile



Good Sam RV Club Member


Posted: 12/23/06 11:08am Link  |  Print  |  Notify Moderator

v8q wrote:

a. This should be a sticky/FAQ .


Done...

wolfe10

Texas

Senior Member

Joined: 10/08/2000

View Profile


Online
Posted: 12/23/06 11:16am Link  |  Print  |  Notify Moderator

dav5942 wrote:

Great post-been trying to figure it out since we got the new coach!

If you are in the economy mode and the downshifts are later than the regular mode, what effect does this have on your braking(break wear, etc.)? Or since there is little difference on flat ground(less than 1%) should we stay in the regular mode to help with braking on flat ground?



When you turn on your exhaust brake/compression brake, the transmission DOES downshift exactly the same in both modes.

When you just let off the throttle and coast to/toward a stop, the transmission DOES downshift exactly the same in both modes.

The DIFFERENCE is under WOT or close to WOT (when you certainly are not braking!)

wa8yxm

Wherever I happen to park

Senior Member

Joined: 07/04/2006

View Profile


Offline
Posted: 12/23/06 12:58pm Link  |  Print  |  Notify Moderator

Of course some rigs have "Economy mode" (mostly tow vehicles I suspect) and some (Like My Motor Home) Have Grade Brake, which is yet a 3rd Allison program as I understand it


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


dav5942

Stuart, FL

Senior Member

Joined: 05/24/2004

View Profile



Posted: 12/23/06 11:20am Link  |  Print  |  Notify Moderator

When you turn on your exhaust brake/compression brake, the transmission DOES downshift exactly the same in both modes. When you just let off the throttle and coast to/toward a stop, the transmission DOES downshift exactly the same in both modes. The DIFFERENCE is under WOT or close to WOT (when you certainly are not braking!)[/quote] Understand but with our limited experience it did seem to be down shifting later(w/o exhaust/compression brake on) in the Economy mode-will watch it on next trip, thanks!

Note: Due to invalid formatting, all formatting has been ignored.

wolfe10

Texas

Senior Member

Joined: 10/08/2000

View Profile


Online
Posted: 12/23/06 02:26pm Link  |  Print  |  Notify Moderator

wa8yxm wrote:

Of course some rigs have "Economy mode" (mostly tow vehicles I suspect) and some (Like My Motor Home) Have Grade Brake, which is yet a 3rd Allison program as I understand it


This discussion concerns Allison 3000 and 4000's as found on all but the smallest DP's.

PERHAPS, it also applies to 1000 and 2000 series. I have no first hand knowledge with these. Perhaps someone very familiar with the 1000 and/or 2000 can tell you.

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 
Page of 5  
Next

Open Roads Forum  >  Class A Motorhomes  >  All

 > Allison Mode Button
Search:   Advanced Search

Search only in Class A Motorhomes


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2018 CWI, Inc. © 2018 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS