Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Michael & Jackie on April 27, 2017, 03:25:07 pm
Title: Manual Shifting Allison
Post by: Michael & Jackie on April 27, 2017, 03:25:07 pm
I hesitate asking such a simple question, it just runs up my post count with no contribution to the technicalities or gee whiz of FT ownership. But this is important to me.....!
Do you frequently shift gears manually? We talk about changing the rpm to help with cooling or braking, easing up on the Retarder.
I know that if I shift on the fly and it does not want to, it will not (thankfully!). So it seems ok.....but the other option is to stop and shift and set the top gear at some level.
Is that what you all are doing... manually shifting frequently to hit the cooling and braking optimum points rather than awaiting automatic shifts? What I have been doing is shifting on the fly.....is that what all do, it is okay?
example, a mountain pass grade, I need to drop into 3 or 4 on way up or down. As I am moving, and tach looks a good range to do so, I push an up or down arrow. As it can, the rpm changes as does the gear. In this I am having to trust the governor whatever will not let it make a move that over-revs the engine even if i asked for a gear that would be wrong at that speed......my interpretation
And in another question, I read in some thread to not shift out of D into N at a red light. I forget the reason but seemed logical so I quit doing that though I did like to shift to N at a long light. I think the concern was it may wear out the shift pad? (bet I got that wrong!) But even more, and really scary, it avoids accidentally shifting into R as leave the light (oh my!).
And while I have your attention, I do not turn off the engine when taking on diesel.
Title: Re: Manual Shifting Allison
Post by: craneman on April 27, 2017, 03:29:47 pm
I let ours do all the downshifting on the upside of a grade, but sometimes will lock a lower gear going down to aid the retarder.
Title: Re: Manual Shifting Allison
Post by: speedbird1 on April 27, 2017, 03:49:19 pm
I will sometimes help it by downshifting going UP if it sounds like it is laboring and often downshift coming down the mountains to ease the load on the retarder and to keep the temperatures down. I learned the hard way when I first got this one and ran down a L O N G mountain in 6th with the retarder all the way!! By the time I reached the bottom it was giving the chime, and then shut down before it got too hot!!!!!!!!!!!!!!!! Then no power steering etc. but I was almost on the level and got it stopped. A quick call to FT enlightened me to whichever gear it needs to go UP the hill is the one to use coming DOWN!! Speedbird 1.
Title: Re: Manual Shifting Allison
Post by: Michael & Jackie on April 27, 2017, 04:04:31 pm
Dear Craneman
For whatever reason, when we first got ours and tried a particular pass, it was very slow to downshift on the way up. Seemed climbing on 1100 rpm. Then a hard shift. I was new to this, not familiar with what it going to do or needed from me.
Then, after that, a friend told me to be sure to shift into third before began the climb, that otherwise the coach would be slow to shift to where it needed to be . So now I shift before get very far into the climb
This is not a very high altitude climb by mountain standards but it is steep going up, and down, for its 1000 ft to top at about 9800 ft
thanks
Title: Re: Manual Shifting Allison
Post by: craneman on April 27, 2017, 04:19:19 pm
Mike, I only have driven up the Bishop grade for my information. we do this twice a year with me pulling '01 Grand Cherokee. This June I will be pulling the boat and my brother will tow his Tahoe. The boat is 2000 lbs. lighter but maybe the downshifting might match what you have. I watch the tach. and it seems to shift before lugging down. I drive a '81 International that weighs 32,000 lbs. and has a 210 HP 605 lbs. torque @ 1400 rpm. motor with a RT13 trans. Possibly the motorhome has me fooled as I am not used to the torque of it.
Title: Re: Manual Shifting Allison
Post by: Roland Begin on April 27, 2017, 04:22:30 pm
And while I have your attention, I do not turn off the engine when taking on diesel.
I no longer turn my engine off when refueling thirty plus hours stuck on a fuel isle will do that to you and I do not turn off the engine when dumping the tanks either for the same reason.
Roland
Title: Re: Manual Shifting Allison
Post by: Andy 2 on April 27, 2017, 04:24:40 pm
Mike here in the West and all mountains we drive up and down.i always watch my RPMs.with my Detroit it may differ then your Cummins and only having a 4 speed I manually down shift all the time. Driving by my temp gauge.. and as you know what ever gear you go up a steep grade that is the gear you can safely go down. You can go down a hill fast and burn up you brakes or tranny with a retarded or go down slow and never have a problem. Anyway that's what I do good luck. 8)
Title: Re: Manual Shifting Allison
Post by: Roland Begin on April 27, 2017, 04:32:18 pm
As to manually shifting going uphill I do that always when I know I am going up a long grade. I shift before the rpm's get low enough to kick in the next gear I like to keep my rpm's up when climbing. Once you lose the rpm's you never get them back. I don't know about anyone else's tranny but mine will go real low on rpm's before it shifts so I take control after all I know I'm climbing a hill the tranny does not.
Roland
Title: Re: Manual Shifting Allison
Post by: sk320 on April 27, 2017, 04:38:25 pm
I set my maximum gear up or down and let the tranny do the rest. If fourth or fifth is all it can pull going up, I will limit it to that gear, that stops the up shift if you have to lift for a few seconds.
I see what gear the coach is happy with going up and then limit the tranny to the same gear going down. Fourth gear up = fourth gear down.
I also use the retarder going down any steep hill.
I am always towing a 10,000lb trailer as well.
Steve
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 27, 2017, 05:04:55 pm
Yes, I treat the Allison 3000/4000 like a manual transmission. I "overrule" the automatic, particularly in the mountains. Why? Because, I can be PROactive. The transmission is only REactive-- because of momentum, only seeing what happened well behind you. It has no idea that you only have 100' left to the top of the grade, or about to tackle (i.e. in front of you) an 8% grade.
As Mike observed, the Allison is what I call "idiot-proof". If you select a gear that would endanger the engine, the Allison ECM "translates" your request into "I will do what you ask as soon as I can SAFELY do so. Basically, you are selecting what Allison refers to as a "pre-select" gear. So, you could down arrow to 2 at 60 MPH and it will downshift a gear at a time until it reaches 2nd gear. It will NOT overspeed the engine.
So, feel comfortable leaving it D if you like. But, also feel comfortable being proactive with the up/down arrows and/or the mode button.
Title: Re: Manual Shifting Allison
Post by: Michael & Jackie on April 27, 2017, 05:15:25 pm
Thanks to each of you.....I feel more secure in my driving with shifting
I know Mr. Wolfe has reported on such before, and I think others of you have made educational comments before.
My filing system is not so good as Roger whom I think has it all electronic. I have a three ring with tabs, such as Allison. I need to make a copy of these and put in that tab.
Now if I can just find the three ring next time I get to thinking on this.....
Thanks again, and I bet some readers will like the refresher on these couple of topics....shifting and cooling and fueling
Title: Re: Manual Shifting Allison
Post by: speedbird1 on April 27, 2017, 05:29:06 pm
Never hesitate to ask. Look what came out of this one!!
In my case I knew nothing about the fact that too much use of the retarder would cause the engine to shut down and FT said nothing about it when I bought it from them.
Always easier to ask than to find out the hard way and no question is a silly one!! Speedbird 1.
Title: Re: Manual Shifting Allison
Post by: Texas Guy on April 27, 2017, 06:08:43 pm
Great refresher, all. I never knew or had forgotten that no matter
where you selected for the Allison it would not go directly there
but would stair step down, thus not going to sling itself apart.
Thanks,
Carter-
Title: Re: Manual Shifting Allison
Post by: AC7880 on April 27, 2017, 07:51:35 pm
On my previous coach, Cummins 8.3 and Allison 3060, I manually downshifted on climbs to keep it cooler and because the coach shifted late on it's own.
On our new to us 2003 U320, I find the auto shift points for climbs satisfactory except for one case today. On a hard mountain climb in Montana today the right lane was closed, and all traffic was in the left lane. Heavy semi trucks were bogged down, and the coach wanted to stay in 4th at what I felt too low of an rpm, so I manually downshifted into 3rd.
I always manually downshift on the downgrades. One advantage to manually downshifting on the climb is that you will already be in a gear correct or close to correct for the downgrade.
Title: Re: Manual Shifting Allison
Post by: Barry & Cindy on April 27, 2017, 08:08:54 pm
Shift anytime you want going up or down. Drive by tach, not spedo. Don't shift under hard throttle, but it probably won't change gears anyways. Tranny almost ALWAYS protects itself, it is very smart. Don't let tranny 'hunt' between two gears back and forth, shift down to stop it. Can't hurt this baby. Never shift to neutral, that is unless you want to sit at that spot for the rest of the day. Never turn engine off at fuel up (for the same reason). Often better to manually downshift before the computer makes the decision to down shift. Always downshift and go slower up hills to prevent overheating. Get used to driving slow and letting others pass when necessary. Get a pyrometer and also drive by exhaust gas temp, along with tachometer, no better way to protect engine and components and get to the top safely.
Title: Re: Manual Shifting Allison
Post by: SteveB on April 27, 2017, 08:34:25 pm
Another great reason to run the Silverleaf software as it will show you your retarder temperature. Use too much retarder and watch the temp quickly head towards 300 degrees while the analog dash gauge barely starts to move up from around 170 degrees. Really gets your attention going down a 6% grade while grossing out at around 50K#!
Gearing down and a little judicious use of the brakes and retarder seems to be the best way to go for me.
Steve
Title: Re: Manual Shifting Allison
Post by: Pierce & Gaylie Stewart on April 27, 2017, 09:04:34 pm
. Never shift to neutral, that is unless you want to sit at that spot for the rest of the day. Never turn engine off at fuel up (for the same reason).
Don't see any reason not to turn off the engine at a fuel stop. I wouldn't drive the coach if I didn't think it was going to start (and instantly) every time I shut it off. If your engine ever hesitates or fails to start, it's time to find the problem so you don't worry every time the key is turned off. The only time to idle it is if it's been pulling hard and you want to bring down the oil temperature so you don't get any coking in the turbo.
I turn off our cars when fueling and do the same with the coach.
Pierce
Title: Re: Manual Shifting Allison
Post by: bbeane on April 27, 2017, 09:24:53 pm
I manually shift when going up or down big hills, I like to keep RPMs up 17-1800 seems to keep things happy. I will also set the max top gear when Im in lower speed zones no need trying to run 6th gear at 55.
I also don't turn the engine off at dumps and fuel stops, only where it's going to be parked out of everyone's way.
Title: Re: Manual Shifting Allison
Post by: jcus on April 27, 2017, 09:36:38 pm
Not for motorhomes yet, but can see it coming. https://www.arb.ca.gov/msprog/truck-idling/factsheet.pdf
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 27, 2017, 09:44:01 pm
I live like wolfe10 does. Turn off the "mode" and shift it as needed.
Or wanted. Slightly faster up grade. Why not? Half the fun to outwit the Mechanical simple brain.
As far as the idling standard we are neither a truck or bus.
Yosemite no gen Rv campground is full of high idling Mercedes diesel class "b" vans generating 110.
Thought "where's the noise from?"
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 27, 2017, 10:17:37 pm
I live like wolfe10 does. Turn off the "mode" and shift it as needed.
Perhaps I misunderstand or we are just saying the same thing differently. I drive in economy mode 99% of the time and then I, repeat I decide if I need to downshift. So, each time I start the engine, I hit the mode button to select economy mode.
Said another way, my "default" when driving is to have the Allison drive for economy (upshifting when it can grab the next gear at peak torque RPM rather than winding up to peak HP RPM before shifting). If I want more performance, I use the down arrow. The only time I drive in power mode is in situations like passing on two lane roads where I am willing to pay for extra fuel for a little better performance.
BTW, any Allison dealer can reprogram the ECM so that economy mode is the standard and you would have to push the mode button to get to performance mode. I'm too cheap to spend the money to have it reprogrammed. Easy enough to just push the button.
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 27, 2017, 10:33:57 pm
Some are type b and some are type a drivers.
My foolproof test selling new Foretravels was to diagram a two lane on each side interesection.
I showed a car in the curb lane and the inside lane open.
Then I asked the customer if they were coming up behind the curb lane car would they pull up behind the car or move over and take the inside open lane?
Lots of laughs and interspection.
If you move to the empty lane turn off the mode and see what's faster up the hills. Shortshifting torque or downshifting hp.
Only testing will show.
And whether it's important to you?
Where would you be in my diagram, behind the car or move over to the open lane in a car.
You are really bad if you would pull over in your coach towing...
Title: Re: Manual Shifting Allison
Post by: TheBrays on April 28, 2017, 08:41:34 am
Yes, I treat the Allison 3000/4000 like a manual transmission. I "overrule" the automatic, particularly in the mountains. Why? Because, I can be PROactive. The transmission is only REactive-- because of momentum, only seeing what happened well behind you. It has no idea that you only have 100' left to the top of the grade, or about to tackle (i.e. in front of you) an 8% grade.
As Mike observed, the Allison is what I call "idiot-proof". If you select a gear that would endanger the engine, the Allison ECM "translates" your request into "I will do what you ask as soon as I can SAFELY do so. Basically, you are selecting what Allison refers to as a "pre-select" gear. So, you could down arrow to 2 at 60 MPH and it will downshift a gear at a time until it reaches 2nd gear. It will NOT overspeed the engine.
So, feel comfortable leaving it D if you like. But, also feel comfortable being proactive with the up/down arrows and/or the mode button.
But what happens when you are in ,say, 3rd and the momentum (and gravity) increases the rpms toward the danger point? (As I understand it,something like 2,700 should be the max for the 8.3) The Allison is not going to UPSHIFT is it?
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 28, 2017, 09:31:47 am
But what happens when you are in ,say, 3rd and the momentum (and gravity) increases the rpms toward the danger point? (As I understand it,something like 2,700 should be the max for the 8.3) The Allison is not going to UPSHIFT is it?
YES, it will upshift! It's primary job is to protect the engine.
So, if you find your speed creeping up toward where that would occur, step on the brakes firmly and long enough to allow you to drop to the next lower gear (that down arrow).
Title: Re: Manual Shifting Allison
Post by: gootie on April 28, 2017, 05:03:10 pm
In the mountains getting coolant flow increase with a selection of a lower gear on the uphill will aid in keeping temps reasonable. Coming down intermittent app of retard will run tranny temp up but if already in a lower gear will also expedite tranny temp reduction. I miss my coach
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 28, 2017, 06:05:40 pm
In the mountains getting coolant flow increase with a selection of a lower gear on the uphill will aid in keeping temps reasonable. Coming down intermittent app of retard will run tranny temp up but if already in a lower gear will also expedite tranny temp reduction. I miss my coach
Excellent point. When descending long grades with a transmission retarder, you will keep transmission temps in check by staying at the high end of engine RPM, as that spins the water pump faster.
A LONG time ago, I was in Skagway, AK when a Foretravel Caravan came into town. A couple of extremely overheated transmission. Evidently, the wagon master did not review this before the incredible descent of the Chilkoot pass.
Title: Re: Manual Shifting Allison
Post by: Mike Leary (RIP) on April 28, 2017, 06:09:57 pm
Quote from: gootie link=msg=269851 date=1493413390 I miss my coach[/quote
And well you should! :)) Every year, with SOB coaches, pulling I-17 from Phoenix to Flagstaff (prolly 6k pull) was daunting. With this coach, she just does what she wants to do, I don't fool with the Allison at all, and once the retarder is engaged on drops, I don't do much either. I do keep a close eye on the gauges, though.
Title: Re: Manual Shifting Allison
Post by: amos.harrison on April 28, 2017, 08:30:54 pm
I know the peak torque on my M-11 is 1500rpm. If the tach drops below 1300 climbing I start downshifting. Coming downhill, if I see a sign for 6% or steeper grade, I downshift to 4th at the top. If my retarder is not keeping my speed in check, I brake firmly and shift to 3rd, repeating as needed.
Title: Re: Manual Shifting Allison
Post by: craneman on April 28, 2017, 08:48:21 pm
I know the peak torque on my M-11 is 1500rpm. If the tach drops below 1300 climbing I start downshifting. Coming downhill, if I see a sign for 6% or steeper grade, I downshift to 4th at the top. If my retarder is not keeping my speed in check, I brake firmly and shift to 3rd, repeating as needed.
I believe our peak torque is at 1200 rpm.
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 28, 2017, 11:45:43 pm
1350-1400 if memory serves me. Fat torque curve about there. Hp going up at that point.
Title: Re: Manual Shifting Allison
Post by: craneman on April 29, 2017, 12:57:59 am
1200 across the board Cummins M Series engine - Wikipedia (https://en.wikipedia.org/wiki/Cummins_M_Series_engine)
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 29, 2017, 01:54:55 am
We have all noticed the ability to pull grades seems to be as good or better at 1400-1500 rpm.
Flite10(bob) and I talked about this today. We both noticed it on our 97 m11 celect plus engines.
If that'past the torque peak on a chart which is fairly flat at those rpms then the rising hp curve must work with the torque at those rpms.
The additional power seems to allow somewhat higher road speeds without a mpg loss.
That being said we both have the dynamatic 199 degree hydraulic fan controllers and aero 5050xl resonators.
He showed me on his glass dash his run into Orange County towing a dolly at 63-64 mph and the VPMS showed 10.2 mpg.
That's when he mentioned the better hill climbing over the nominal 1200 rpm rating.
Amos Harrison is saying the same thing.
Running hard in wind to Vegas and back at 37,000 pounds I averaged 8.2 mpg at 70 minimum and downshifting on all grades and revving the motor up.
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 29, 2017, 02:03:45 am
For the Alaska pass I actually thought about a Jake brake for my m11.
I think both the retarder and Jake could be on at the same time if wired that way.
I had to try hard to get the trans buzzer to come for testing purposes.
Full speed downhill at grapevine ca. And again at monarch pass.
Trans Buzzer on at 250. Bottom of grade and two miles with retarder off the buzzer ceased.
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 29, 2017, 09:34:12 am
For extreme grades (length as well as steepness) like descending into Skagway Alaska, down arrow to a low gear--perhaps even second gear and use the least amount of retarder that you can. Keep engine RPM near the high-end of the RPM range so the water pump turns faster.
If transmission temperature becomes excessive use a pull-out (there are several on that particular road-- we have driven it several times).
Title: Re: Manual Shifting Allison
Post by: Caflashbob on April 29, 2017, 10:16:54 am
Yes on what Wolfe10 said. Definitely lowered the trans temp from less load and higher coolant speed
Title: Re: Manual Shifting Allison
Post by: amos.harrison on April 29, 2017, 05:04:16 pm
When climbing, the rule is: if the coach will not accelerate with more go pedal, you are in too high a gear-downshift. My engine will bog down at 1200rpm.
Title: Re: Manual Shifting Allison
Post by: wolfe10 on April 29, 2017, 05:39:03 pm
When climbing, the rule is: if the coach will not accelerate with more go pedal, you are in too high a gear-downshift.
Good rule-- I agree.
Title: Re: Manual Shifting Allison
Post by: Barry & Cindy on April 29, 2017, 07:11:01 pm
To add to Brett, it seems like pressing accelerator without increased RPM, indicates fuel being added could cause engine to run hotter with no gain in power. We never have throttle pedal to the floor. It take patience to let up on throttle when the heart says press harder on throttle.
Title: Re: Manual Shifting Allison
Post by: Pierce & Gaylie Stewart on April 30, 2017, 01:24:36 pm
To add to Brett, it seems like pressing accelerator without increased RPM, indicates fuel being added could cause engine to run hotter with no gain in power. We never have throttle pedal to the floor. It take patience to let up on throttle when the heart says press harder on throttle.
The electronic engines control the fuel with sensors so there is no worry about EGTs as the Allison will downshift on it's own. Still a good idea to keep RPMs up to circulate coolant. That's why you don't see any black smoke out the exhaust. With the mechanical engines, back off the throttle when you see smoke in the mirror as that can raise EGTs especially up at altitude plus is rude to cars behind.
I am almost always throttle to the floor off stop signs, on ramps, hills, etc. When I reach the speed I want to drive at, then I back off. Sensors/ECU keep it smoke free. On grades, if it won't accelerate or starts slowing down, it's time to manually shift down a gear. 200 degrees makes me ease up on the throttle and drop a gear. Back roads with a lot of turns also make me treat the tranny like a manual so I do most of the shifting. Heading steep downgrades on two lane roads also sees me using the touch pad, service brakes and Jake. Interstate downgrades are usually high gear, Jake only with few exceptions.
Pierce
Title: Re: Manual Shifting Allison
Post by: bigdog on April 30, 2017, 07:09:56 pm
I've always heard this: Torque gets you up to speed, HP helps keep you at that speed.
Title: Re: Manual Shifting Allison
Post by: FourTravelers on May 01, 2017, 05:30:28 am
I always thought it was the other way around................ HP to accelerate and torque to keep you at speed...................
Title: Re: Manual Shifting Allison
Post by: Michael & Jackie on May 01, 2017, 10:28:18 am
You are probably both right....I knew I liked more of each! 😀
Title: Re: Manual Shifting Allison
Post by: craneman on May 01, 2017, 11:34:06 am
Bigdog has it correct, the horsepower rating does not come in until much higher rpm. When driving up a grade engines like to be at or above the max torque rpm. Think of torque, launches you, and HP keeps the acceleration going after you pass the peak torque rpm.
Title: Re: Manual Shifting Allison
Post by: Caflashbob on May 01, 2017, 11:53:09 am
Some engines are mph faster up grades short shifted using the torque. Most are slightly faster using the hp at high rpms.
Our m11 is around five mph faster up grades revved hard than upshifted to use the torque.
I have driven coaches where the torque is faster than the revved hp.