Driving with the Allison Automatic Transmission

[BIGBIRD130]

We are renting a 2008 42' Tiffin Allegro Bus with the Allison Automatic Transmission
Is there anything special you need to know about using it?
I've driven a tractor trailer but that was a 10 speed standard
Thanks for any help

[BIGBIRD130]

Thanks again for all the information
Learned a lot:)

[RVUSA]

One other thing that I didnt see in the list...

When it's cold out the tranny will hold in 1st gear for what can seem like a really long time. I cant tell you how many times I have heard the rv's leaving in the mornings driving thru the park at 2000 rpms trying to get the thing to shift up.

The newer ones may have changed that but just in case you experience it...

[rolling_rhoda]

Good discussion! Thanks so much posters!

[frankdamp]

I drove transit coaches with Allison 5-speed and 6-speed boxes for nearly three years. I never tried to out-guess Allison's computer - it seemed to be a lot smarter than me, even though I'm a B.S. (Mech. Eng) guy.

If you're renting and not familiar with either diesels or Allison transmissions, my advice would be to put it "D" and let the computer take care of things. You could screw things up trying to out-guess the Allison computer.

[wolfe10]

Brett here.

The only reason NOT to use economy mode is if at least two of three things are happening at the same time-- engine coolant temperature is rising AND/OR you don't want to have to manually downshift (down arrow) AND/OR speed is dropping more than you want (and are willing to pay a lot more fuel for a few more MPH). Sorry, I know that is a mouthful.

But, we are back to the root question-- are you (and are you interested in being) smarter than something that can only see what has happened BEHIND you.

There is no right or wrong answer. I drive a manual transmission car (has have been the vast majority of my vehicles over the last 40 years) and am used to being proactive. Can I beat most others in MPG AND, repeat AND shortest drive time-- YES.

But, there is nothing wrong with saying "I bought an automatic, let it do its own thing".

The only time EVERYONE should use the down arrow is if you are climbing a grade and the transmission is "hunting". That is shifting between gears-- can't quite make it in the higher gear, so downshifts, then upshifts, then downshifts.......... Bad for any transmission. Use the down arrow to lock the transmission in the lower gear until the grade eases.

The beauty of the Allison is that you can drive it as an automatic, or you can use the shift pad to make it work like a manual.

[prstlk]

This is probably another question for Brett, how does the economy mode work while towing. We tow a 20 enclosed trailer with a small car I was told never to use economy mode while towing. Your thoughts and thanks in Advance

[Smitty77]

Two more quick additions, that may or may not apply to the OP.

1) The gear that the trans will shift to when engaging the Jake Compression or Exhaust Brake assist, may vary. (I saw 2nd gear was mentioned in one post. In contrast, our 2004 Country Coach with the 30XX series trans - down shifts to 4th gear.) This is also something that can be changed, along with a few other setting related to how things behave with cruise control.)

2) I LOL at myself, after about 18 months of driving our coach, when I learned that on our rig (as it was programmed), that in order to down shift below 4th gear while in Jake Brake mode - you had to hit the down arrow button multiple times. (The trans still feel it is in 6th gear (or whatever gear you were in before activating the Jake). So to get down to 3rd gear, you need to tap the down arrow three times (5th, 4th and land in 3rd). And if on a real steep hill, one more down arrow will get you into 2nd:)!

For a short term usage, just get in and drive. If this is a rig you will own for along time, or put many, many thousand miles on - then do learn to read the road ahead, and use down shifts to keep the RPM's in the best power range for hill climbing. (CAT or Cummins can tell you the best RPM range for peak power, with a simple call.)

And after reading Wolfe's article back when he wrote it, and from other posts, we default drive in Economy - and manually intervene when we feel it is needed.

Best to all,
Smitty

[retiredtraveler]

Thank you so much,
As always you guys rule.
And Merry Christmas to everyone.

[wolfe10]

retiredtravelers2013 wrote:
Thanks so much. I maybe a little dim, but from what I gathered you just hit the mode button and it goes into economy mode? Hit it again and all is as it was?

Correct. Hitting the mode button toggles between power and economy mode. Each time the ignition is started, it starts in power mode.

Most shift pads have a light that illuminates when in economy mode, goes out when in power mode.

Brett

[retiredtraveler]

Thanks so much. I maybe a little dim, but from what I gathered you just hit the mode button and it goes into economy mode? Hit it again and all is as it was?

[Valkyriebush]

wolfe10 wrote:

retiredtravelers2013 wrote:
I have been curious about the economy mode but have been afraid of pushing the mode button since the manual says nothing about it. Can someone explain exactly how it works?

Keld

From an article I wrote a couple of years ago for the FMCA Magazine:

ALLISON TRANSMISSION MODE BUTTON

BY BRETT WOLFE, F252125

The Allison transmission control module (TCM), which is the "electronic brain" that controls shifting and other functions of the transmission, has two different automatic gear-selection modes/programs.

In Economy Mode, the transmission will not downshift even at wide-open throttle until the engine pulls down to peak torque rpm in some applications and 200 rpm lower than Performance Mode in others. In Performance 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 variation between the two modes, except when accelerating from a stop if you are at or close to wide-open throttle.

However, mode selection can make a big difference when traveling over rolling hills. If you drive in such areas while in Performance Mode (particularly with the cruise control on), it is common for the transmission to shift down to fifth gear on the uphill and back to sixth gear on the downhill, repeating this process hundreds of times.

In Economy Mode, the transmission will stay in sixth gear unless the hill is so steep or so long that the engine cannot pull it without dropping below peak torque rpm. According to engine manufacturers, the most economical way to climb a hill with a modern turbocharged diesel engine is in a higher gear (lower engine rpm), provided the engine doesn’t overheat.

If, while driving in Economy Mode, you know you will need a lower gear because of the steepness of the grade and/or the engine temperature is rising higher than the thermostatically controlled temperature, 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 you will be stopping at a service station for fuel sooner than you expected.

While you are driving in hilly terrain, if your engine begins to overheat, the engine’s horsepower-to-weight ratio is low, or it irritates you to lose a few mph in the name of saving fuel, by all means drive in Performance Mode.

It confuses me to hear people advocate driving in Economy Mode only on flat ground, as there is not 1 percent difference in shift rpm between Performance and Economy modes on flat ground, except when accelerating from a stop if you use wide-open throttle.

Every time you start the motorhome, the transmission is in Performance 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 number that can be given to illustrate the difference in fuel economy that will result when driving in Economy Mode. On flat ground where you will be in sixth gear no matter what mode you are in, there will be zero difference. The most significant difference in mileage will occur in rolling hills, where in Performance Mode, particularly if on cruise control, you will start up a hill in sixth gear, go to wide-open throttle in that gear, and downshift to fifth gear still at wide-open throttle, where it is using a lot more fuel. After the hill is crested, the transmission will upshift to sixth, then likely coast a little in that gear unless you are driving with the exhaust brake on. If you are, the exhaust brake will be applied and the transmission will downshift toward the preselected gear, which is generally either second gear or fourth gear. And so the process will continue, with the transmission shifting up to sixth gear on the downhill, back down to fifth gear on the uphill, etc. The problem with this is that a modern turbocharged diesel engine is much more efficient at low rpm with high throttle settings.

Note: In either mode, you are free to use the up and down arrows to proactively choose the correct gear. You cannot screw anything up, even if you downshift to first gear at 70 mph. The transmission circuitry understands that you want to downshift to the next lower gear as soon as the engine rpm will not exceed the preset amount. Then it will downshift again when safe.

By the same token, you can shift between Performance and Economy modes as often as you want with the transmission in any gear when you make the change.

I drive in Economy Mode 99 percent of the time, including in the mountains. I use the up and down shifting arrows to choose the proper gear. I use Performance Mode only to pass another vehicle on a two-lane road, when I am willing to sacrifice a little fuel economy to gain a short-term burst of speed.

X-2 Thanks for explaining that. I always thought E mode was flat lands only.

[wolfe10]

retiredtravelers2013 wrote:
I have been curious about the economy mode but have been afraid of pushing the mode button since the manual says nothing about it. Can someone explain exactly how it works?

Keld

From an article I wrote a couple of years ago for the FMCA Magazine:

ALLISON TRANSMISSION MODE BUTTON

BY BRETT WOLFE, F252125

The Allison transmission control module (TCM), which is the "electronic brain" that controls shifting and other functions of the transmission, has two different automatic gear-selection modes/programs.

In Economy Mode, the transmission will not downshift even at wide-open throttle until the engine pulls down to peak torque rpm in some applications and 200 rpm lower than Performance Mode in others. In Performance 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 variation between the two modes, except when accelerating from a stop if you are at or close to wide-open throttle.

However, mode selection can make a big difference when traveling over rolling hills. If you drive in such areas while in Performance Mode (particularly with the cruise control on), it is common for the transmission to shift down to fifth gear on the uphill and back to sixth gear on the downhill, repeating this process hundreds of times.

In Economy Mode, the transmission will stay in sixth gear unless the hill is so steep or so long that the engine cannot pull it without dropping below peak torque rpm. According to engine manufacturers, the most economical way to climb a hill with a modern turbocharged diesel engine is in a higher gear (lower engine rpm), provided the engine doesn’t overheat.

If, while driving in Economy Mode, you know you will need a lower gear because of the steepness of the grade and/or the engine temperature is rising higher than the thermostatically controlled temperature, 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 you will be stopping at a service station for fuel sooner than you expected.

While you are driving in hilly terrain, if your engine begins to overheat, the engine’s horsepower-to-weight ratio is low, or it irritates you to lose a few mph in the name of saving fuel, by all means drive in Performance Mode.

It confuses me to hear people advocate driving in Economy Mode only on flat ground, as there is not 1 percent difference in shift rpm between Performance and Economy modes on flat ground, except when accelerating from a stop if you use wide-open throttle.

Every time you start the motorhome, the transmission is in Performance 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 number that can be given to illustrate the difference in fuel economy that will result when driving in Economy Mode. On flat ground where you will be in sixth gear no matter what mode you are in, there will be zero difference. The most significant difference in mileage will occur in rolling hills, where in Performance Mode, particularly if on cruise control, you will start up a hill in sixth gear, go to wide-open throttle in that gear, and downshift to fifth gear still at wide-open throttle, where it is using a lot more fuel. After the hill is crested, the transmission will upshift to sixth, then likely coast a little in that gear unless you are driving with the exhaust brake on. If you are, the exhaust brake will be applied and the transmission will downshift toward the preselected gear, which is generally either second gear or fourth gear. And so the process will continue, with the transmission shifting up to sixth gear on the downhill, back down to fifth gear on the uphill, etc. The problem with this is that a modern turbocharged diesel engine is much more efficient at low rpm with high throttle settings.

Note: In either mode, you are free to use the up and down arrows to proactively choose the correct gear. You cannot screw anything up, even if you downshift to first gear at 70 mph. The transmission circuitry understands that you want to downshift to the next lower gear as soon as the engine rpm will not exceed the preset amount. Then it will downshift again when safe.

By the same token, you can shift between Performance and Economy modes as often as you want with the transmission in any gear when you make the change.

I drive in Economy Mode 99 percent of the time, including in the mountains. I use the up and down shifting arrows to choose the proper gear. I use Performance Mode only to pass another vehicle on a two-lane road, when I am willing to sacrifice a little fuel economy to gain a short-term burst of speed.

[retiredtraveler]

We have a 98 HR with the 5.9L Cummins and 6 speed Allison. During the 4000 miles we have driven it I have just kept it in D. It has performed fine. I have been curious about the economy mode but have been afraid of pushing the mode button since the manual says nothing about it. Can someone explain exactly how it works?
And I have used the exhaust brake quite a bit It surely helps keeping things under control. Especially on long grades.
Thanks in advance for any clarifications.
Keld

[bycrackey]

CA Traveler wrote:
No reason to switch to N for stop lights. It takes a much more extended time in grid lock before the tranny temp starts any significant rise.

absolutely agree.there is no problem what so ever sitting at a stop with trans in gear on this unit,Lite brake peddel application is more than adaquete to hold unit at a stop with zero effort