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Old 07-20-2016, 08:32 PM   #1
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Mountain driving

Hi All,
We are planning an out west trip this year which will include extensive mountain driving. Yellowstone, Tetons, Glacier are just a few of our planned visits.

My main concern is weather to manually shift the Allison or let her do as she wishes. I do know to use the exhaust break, go down the mountain no faster than I went up and to pump the breaks as opposed to riding them to help keep them cool.

Most of my research indicates to let the transmission decide.

So all you experienced mountaineers I would love to hear your input.

On a side note, any suggestions or must sees would be appreciated. Lastly, should I bring a dehumidifier? I was in NC over the summer and had a tremendous amount of moisture in the coach and do not want a repeat of that.

thank you in advance!
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Old 07-20-2016, 09:07 PM   #2
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Having just spent over 5 months out west I can answer two of your questions.


1) Let the transmission shift for itself.


2) You definitely will not need a dehumidifier, you will be in a dessert with humidity readings in the low to mid teens. The average rainfall in the west is less than 15 inches per year till you get along the west coast.
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Old 07-20-2016, 09:28 PM   #3
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I agree. your transmission will do a better job of shifting than you can do. I've been out west with 2 different coaches, one gas, one diesel up to 10,000 feet and just let the tranny handle the shifting with no issues
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Old 07-20-2016, 09:28 PM   #4
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You will do a lot better manual shifting to keep your RPM's up while climbing. Engine will run cooler.
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Old 07-20-2016, 09:35 PM   #5
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We did that trip in 2009 right after we bought the coach, went all the way to Alaska then dropped down to Napa Valley before heading back east. Saw lots of mountain. We didn't have a clue as to mountain driving so we relied on the transmission to select the gears and it performed great.

As to sites to see, you will be visiting some of the nicest NP's in the country. Just take your time and see all that is available. When we left Yellowstone my wife decided we needed to go to Billings so we decided to go across Beartooth Pass, what a drive. Wife took +40 pictures going up but only 3 going down, she cursed me holding onto the passenger seat armrests saying "she would haunt me if we crashed and injured any of the 4 dogs we had in the coach". Needless to say we survived.

If you have passports it would be worth a days drive across the Ca border into Waterton the sister Canadian NP of Glacier.
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Old 07-20-2016, 10:55 PM   #6
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Quote:
Originally Posted by lenny-shawna View Post
Hi All,
We are planning an out west trip this year which will include extensive mountain driving. Yellowstone, Tetons, Glacier are just a few of our planned visits.

My main concern is weather to manually shift the Allison or let her do as she wishes. I do know to use the exhaust break, go down the mountain no faster than I went up and to pump the breaks as opposed to riding them to help keep them cool.

Most of my research indicates to let the transmission decide.

So all you experienced mountaineers I would love to hear your input.

On a side note, any suggestions or must sees would be appreciated. Lastly, should I bring a dehumidifier? I was in NC over the summer and had a tremendous amount of moisture in the coach and do not want a repeat of that.

thank you in advance!
lenny-shawna,
Well, yes, you can let the Allison think for itself and it will do its job and survive. But, in true practical reality, based on just what kind of weight you will be hauling, the grades you will encounter, your ability to "out think" that programming of it and, the engines requirements, how crowded the roadways will be (just in case you decide to pickup speed for a grade and use a faster lane etc.) and a few more parameters, the "human" brain can, in most cases, be of more benefit to that engine and it's available HP than waiting for the trans to decide.

Our coach, an '04 Itasca Horizon, 36GD with the C-7 330HP CAT, is moderatly powered for many of the grades you will encounter. It is seriously more advantageous for me to think ahead of time and do what manual shifting is needed to keep that coach and engine, at peak efficiency.

Now, not only is it advantageous to drive in that manor to "help" your engine but, in many cases, based on the outside temps, you will keep your engines heat down at a lower operating temp by downshifting for a grade, within reason, to keep your RPMs up which, will keep the fan speed up, which will pull max air through both the CAC and Radiator.

Some folks will simply push the pedal to the floor, let things operate as the electronics have planned, and go for broke, so to speak. That's OK, it's their coach/engine. I prefer to ASSIST ours to help preserve its life span.

As for descending grades, and the use of the exhaust brake, well, that subject's been covered a few zillion times on this and other forums. The "Standard" is, if at all possible, descend the hill as fast as you would climb it. Well, that's all well and good if, IF, the circumstances allow for it. But, quite often, you may crest a grade or, all of a sudden, you're descending a grade before you realize it and, you're about to gain speed.

So, in that case, you let the E-brake take over and, watch and listen to both your engine and tach, AND WHERE YOU'RE GOING! Depending on the grade, your present speed etc. your e-brake may or may not, begin to slow you down. Yes, based on it's operation and, the programming with both the Allison and the engines ECM, your coach will automatically down shift to the next lower gear than you're presently in. If you begin a grade in 6th, and, you're at say, 65 or so mph, you may not feel the actual down shift due to the fact that a 6-5 down shift, at 65, the ebrake is too over powered by inertia and, 5th gear is not low enough to make a difference at that speed. Never the less, it will do it automatically.

And, what you'll see on you shift pad is "2". Not to be alarmed, your trans is not in SECOND gear at 65 mph. That's only a target gear for the operation. If your trans were to actually downshift to second at 65, you'd find engine and trans parts spread all over a couple of zip codes.

So, take your time, learn as you drive, learn your coach, engine and transmission. There's lots of USA to see and feel while you travel. So taking care of your coach, WHILE you're driving it, will help you accomplish your trip/vacation.
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Old 07-20-2016, 11:23 PM   #7
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A motor home is NOT a car. You cannot just put it in D and drive, especially in the mountains!

The fatal flaw in the philosophy that says, "Let the transmission shift itself." is that the transmission cannot anticipate anything. It can only react to something that has already happened! By then, it's usually too late.

You can anticipate the grade that's coming. You can shift down a gear just BEFORE the grade starts, so you can get the revs up on the horsepower peak at the bottom of the grade and keep the engine cool all the way up the climb. You can then climb the grade with confidence that your engine is operating at its horsepower peak and you're operating it the way the manufacturer intended.

Some will say that you should run at the peak torque RPM on a hard climb. That is just plain wrong and reading a Cummins or CAT manual will prove it. The peak torque RPM is far below the peak horsepower RPM. On my ISL peak torque is 1,400 RPM but the horsepower peaks up at 2,000. If I attempted to climb a grade at 1,400 RPM the engine would overheat and my speed would drop drastically. It is not torque that gets you up a grade, it is horsepower.
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Old 07-20-2016, 11:23 PM   #8
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When I first bought my Monaco Diplomat in 2005, I tried shifting the coach and did a terrible job. The problem was......I was trying to shift like it was a gasser. As time went on and I got more comfortable, I found dropping into 5th on 6% grades or steeper, at the base of the grade, made a huge difference. The Allison does a good job, but sometimes by the time it downshifts, you've lost too much power. This worked well because my Diplomat had gobs of power and could climb any grade out west at 55+, while towing my Silverado.

Now my new coach is a different story. It has the 450HP engine, but is a dog compared to my Diplomat. I've tried the dropping to 5th at the base of the grades, but it hasn't really helped. If I allow the Allison to do the shifting, I'm bogged down before it downshifts. With my new coach, 5th gear is useless, once I start to climb, I quickly drop to about 48 mph - 50 mph, which is 4th gear range. So.......I watch the speed and as soon as I hit 50 mph, I shift to 4th gear and leave it alone. In 4th, it will climb most grades without issues.

So the moral of the story.....try different things with your coach. You'll soon learn what works best for your weight and HP.
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Old 07-21-2016, 12:28 AM   #9
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Quote:
Originally Posted by lenny-shawna View Post
Hi All,
We are planning an out west trip this year which will include extensive mountain driving. Yellowstone, Tetons, Glacier are just a few of our planned visits.

My main concern is weather to manually shift the Allison or let her do as she wishes. I do know to use the exhaust break, go down the mountain no faster than I went up and to pump the breaks as opposed to riding them to help keep them cool.

Most of my research indicates to let the transmission decide.

So all you experienced mountaineers I would love to hear your input.

On a side note, any suggestions or must sees would be appreciated. Lastly, should I bring a dehumidifier? I was in NC over the summer and had a tremendous amount of moisture in the coach and do not want a repeat of that.

thank you in advance!
Going UP HILL you will need to manually down shift to keep RPM's in the 1700-2000 range, otherwise you're engine temp will start going up considerably, to the point you'll overheat.

Going down hill, use your engine brake. Don't manually downshift. (I believe you have an engine brake, not an exhaust brake). That will tell the Allison to downshift when able without exceeding the engine's rpm. Tap the brakes, or slow down aggressively for a short period to help the Allison down shift, but you're right, don't ride the brakes.

Someone once told me, "Going UP or DOWN, take your time".
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Old 07-21-2016, 12:42 AM   #10
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Originally Posted by lllkrob View Post
Having just spent over 5 months out west I can answer two of your questions.


1) Let the transmission shift for itself.


2) You definitely will not need a dehumidifier, you will be in a dessert with humidity readings in the low to mid teens. The average rainfall in the west is less than 15 inches per year till you get along the west coast.
I respectfully disagree. If you let your diesel coach transmission shift itself going up a long 6-7% grade, it's going to overheat. There is too much torque for it to automatically downshift to keep the rpm's up. You need to manually downshift.

Now maybe you can get away with that in a gasser, but OP has a diesel, per his signature.
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Old 07-21-2016, 06:19 AM   #11
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You will do a lot better manual shifting to keep your RPM's up while climbing. Engine will run cooler.
Anticipate the grades - My 6 speed Allison functioned much better when I would down shift manually keeping the RPMs between 2000 & 2500. Especially when I approached an uphill grade at 1,750 RPM and the speed started dropping off. RPMs dropped off too quickly.

On minor uphill grades the Allison did OK.

I maintained 55 mph up most of the steep uphill grades on I-90 through Montana and Idaho.

My drive train is a 2003 325HP 5.9L Cummins with the 6 speed Allison. Your setup may be different. More HP & Torque and the Allison might handle the shifts automatically much better.
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Old 07-21-2016, 07:56 AM   #12
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I am in the camp of manual shifting. More likely to be able to keep the rpms up and not fall behind on momentum. Also going down steep grades it makes it easier to enforce the slower speeds (coach will speed up too much if I let it do its own thing
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Old 07-21-2016, 08:08 AM   #13
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Originally Posted by jacwjames View Post
We did that trip in 2009 right after we bought the coach, went all the way to Alaska then dropped down to Napa Valley before heading back east. Saw lots of mountain. We didn't have a clue as to mountain driving so we relied on the transmission to select the gears and it performed great.

As to sites to see, you will be visiting some of the nicest NP's in the country. Just take your time and see all that is available. When we left Yellowstone my wife decided we needed to go to Billings so we decided to go across Beartooth Pass, what a drive. Wife took +40 pictures going up but only 3 going down, she cursed me holding onto the passenger seat armrests saying "she would haunt me if we crashed and injured any of the 4 dogs we had in the coach". Needless to say we survived.

If you have passports it would be worth a days drive across the Ca border into Waterton the sister Canadian NP of Glacier.
Wow, you drove the Beartooth from Yellowstone to Red Lodge.... down those switchbacks??

We drove from Red Lodge, MT up the switchbacks and over to Cooke City then into Yellowstone in a 2002 Journey pulling a Ford Explorer. It was a thrill and beautiful for sure. I would certainly not want to go down into Red Lodge however. There is a cut off to the Chief Joseph Highway that avoids that steep incline on the northeastern end.
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Old 07-21-2016, 08:11 AM   #14
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Anticipate the grades - My 6 speed Allison functioned much better when I would down shift manually keeping the RPMs between 2000 & 2500. Especially when I approached an uphill grade at 1,750 RPM and the speed started dropping off. RPMs dropped off too quickly.

On minor uphill grades the Allison did OK.

I maintained 55 mph up most of the steep uphill grades on I-90 through Montana and Idaho.

My drive train is a 2003 325HP 5.9L Cummins with the 6 speed Allison. Your setup may be different. More HP & Torque and the Allison might handle the shifts automatically much better.
Agree with the manual downshifting. My coach is heavy and my 425 ISL has its hands full on steeper grades. I've found the Allison lets rpm's fall a bit too much so I anticipate and downshift early to keep those rpm's up.

Ask any trucker.... gotta keep those rpm's up to climb the hills.
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