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Discussion Starter · #1 ·
2022 AT4 Duramax
I had read some threads about how it is "normal" for the 10-speed Allison to have a delayed upshift after a long downhill after it had downshifted due to the hill. In my experience and the routes I normally run the delayed upshift is not as pronounced when it only drops one gear going downhill. If it drops two gears for whatever reason the computer thinks it wants to it will rev well over 2k+ for no reason at the base of the hill for a fairly long time before it decides I am not going back up a hill and grab another gear. Very annoying to be spinning that high on the flat just because I WENT down a hill. From previous reading, this is "normal".

I had tried slipping into neutral at the bottom of the hill but when dropping it back to drive it would klunk (because gear it selected was too low for RPM once engine dropped RPM to properly sync up). I have found if it drops a gear or two and RPM are high just slip it to neutral and SLIGHTLY blip the throttle then back to D. It selects the gear that matches RPM and speeds just fine, very smooth return to Drive and normal upshift if you accelerate. My Mazda and BMW both downshift on same hill but immediately upshift smoothly and without delay. Apples to Bacon but the powertrain engineers think alike, it just so happens the DMax decided to delay the upshift for some reason.

Some may say I am overthinking this but certain hills just present a weird set of circumstances to the computer that delays the upshift for a ridiculous amount of time even though I am not towing, and transitioned to flat, and trying to accelerate. Neutral then blip ( I think only touching the throttle to vary idle RPM is enough) then back to D cures that. I still have no idea why the computer delays the upshift for so long after a descent. Perhaps that would go away after some miles and tranny learning? I have 3K on the truck and love the Allison except for that behavior as I hit these hills up and down several times each time I leave and return home.
 

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2022 GMC Sierra Denali 2500HD Duramax
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My 2022 does this. Coming back to the house, I have a mile long downhill. If I have the exhaust brake on, it will drop a couple of gears and run up to 2k revs. When i get to the flat run at the bottom, its another 3/4 of a mile, the truck will stay up around 2k revs for most of it before it shifts back up. When diesel was higher, I used to joke with my wife that that downhill just cost us $5.

I have 9k miles on mine, probably 80% of those towing 8K to 12K of trailers. Has not "learned" as of yet.
 

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2017 GMC Denali 2500HD, 3.5" Rough Country Lift, 305/55R20 Cooper Rugged Trek, Paragon Bed Cover
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Instead of going to Neutral, try going to Manual instead. If the new trucks are like the 2017-2019, the trans will go into M in the same gear that it's currently in. Then use the + button to tell it that it can have one more gear. See if that makes it shift sooner. I don't know if it will or won't, but it's something to try.
 

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2022 Chevrolet 3500 High Country CC
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Mine does the same. I let the truck do what it wants/needs to do. Personally I'm not going to mess with trying to force a gear change and with pressure against the truck prolly wouldn't mess with a neutral shift, computer should protect it but....

These trucks will determine the gear based on multiple factors and the algorithms that go with it. Angle, engine temp, tranny temp, trans pressures required for the task, engine torque requirement, etc etc...

I noticed I could be coming down a 5-6% grade with trailer, cruise set and engine break on and tranny may down shift to 2k rpm, the hit a short valley and up 2-4% grade but truck would stay in lower gear then finally up shift and finish the climb. I figured it's better than it hunting and shifting to quickly.

I also noticed that even unloaded turning on the engine brake does a great job maintaining the truck on a down hill slope at lower speeds, one of the valley roads in MD is a curvy 25-30 mph 7% down grade, playing around with the truck it seemed to do better with engine brake on and pressing the brake till the downshift occurred then manually downshifting to prevent riding the brakes down. Set the cruise at 25 and it's done and done.

This statement is not meant to be insulting in anyway, I've been in the industrial electrical/mechanical for years and educate operators at work that most likely they are not smarter then the computer running in auto, if the end result is achieved as programmed it will most likely happen quicker, smoother and more efficiently then chucking it in manual and trying to outsmart the computer. I've drove diesel for many years and it's hard for me to not monitor/control the truck like yester years. It's the abnormal occurrence that needs to be taken note of.

JMHO
 

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If the new trucks are like the 2017-2019, the trans will go into M in the same gear that it's currently in.
Melon, that's because the 2017-2019 trucks had real Allison designed 6spds instead of the Ford designed, Allison "branded", 10spd. You may find answers by searching PowerStroke forums under their transmission section. Follow the link if you're curious...


Flame away...
 

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Discussion Starter · #7 ·
No offense taken, just relaying an experience. I am also not saying I am smarter than the computer, just that they designed it for a set of circumstances that I am not in and the behavior is not what one would.d desire. I have had two different passengers in the vehicle when it has done the delayed upshift. Both thought something was wrong with the truck for the short duration it did not upshift. 2K plus for a 3/8 mile is not high RPM, just double what it would be if you had NOT just gone down a hill so the operation is way out of character. This would be great if there were another hill just past the base of the hill as it would avoid an upshift followed by a forced downshift.

If I recall if it only drops one gear it will upshift rather normally or as I would expect. When it drops two is when the delay is really bothersome.
 

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Melon, that's because the 2017-2019 trucks had real Allison designed 6spds instead of the Ford designed, Allison "branded", 10spd. You may find answers by searching PowerStroke forums under their transmission section. Follow the link if you're curious...


Flame away...
Still waiting for that list of interchangeable parts.
 
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Discussion Starter · #9 ·
Did not read many of the threads in Ford Forum. Did I not see them or have many GM "Allison" 10 speed had issues. Likely a different topic but curious if the Ford and GM 10 sp differ much. Aso curious if a Ford would exhibit the delayed upshift after a downhill initiated downshift. SW engineers don't always get it right, many things are done by committees or simply overlooked. I feel certain if the powertrain guys lived on my road they would have done it differently at least while not in tow mode.
 

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Melon, that's because the 2017-2019 trucks had real Allison designed 6spds instead of the Ford designed, Allison "branded", 10spd. You may find answers by searching PowerStroke forums under their transmission section. Follow the link if you're curious...


Flame away...
I still don't know what's true with this one. We have Mike L. who said they're the same, but everything else that one can find about it, including from GM and Allison says the HD transmissions are a GM product with the Allison brand. No mention of it being a Ford cooperation anywhere.
 

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Hi I have a thought here don't want to seem stupid but perhaps it's a design trait the turbo brake was just screaming down the hill holding back the truck / trailer as any idiot like myself knows this will build heat now then if we keep everything spinning at 2k were pumping more oil / coolant thus disapating the heat allowing your drivetrain to survive another round
 

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Hi I have a thought here don't want to seem stupid but perhaps it's a design trait the turbo brake was just screaming down the hill holding back the truck / trailer as any idiot like myself knows this will build heat now then if we keep everything spinning at 2k were pumping more oil / coolant thus disapating the heat allowing your drivetrain to survive another round
I think there's a lot of truth to this and that is what I was trying to allude to. I know Changing my dic to show truck angle if that's accurate I've seen hill where the truck would hunker in just under 2k rpm and climb no problem, then have a down hill followed by another up hill that felt similar and showed same angle but downshifted for higher rpm, makes no sense, after a few moments on the hill it upshifted and lowered the rpm, hunkered down and towed strong. Guessing it's for temps either trans or engine.
 

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Melon, that's because the 2017-2019 trucks had real Allison designed 6spds instead of the Ford designed, Allison "branded", 10spd. You may find answers by searching PowerStroke forums under their transmission section. Follow the link if you're curious...


Flame away...
not sure what parts are interchangeable or not or if metallurgically speaking the similar/same parts are actually the same. I do believe Mike L. knows his stuff or that shop would have folded along time ago and if he says there are same parts physically I believe that. How may ways can a 10spd are built? Ford declared that they made there super duty trans based off the 10 Spd f150 with less then 10% same parts, all other parts were beefed up. Since ford and gm collaborated on the 1/2 ton 10 Spd doesn't surprise me, makes me think Ford just like there hybrid beginnings said we don't know, and got help from someone else to get in the market, why not choose a company like GMC who owned Allison for decades and most likely learned a lot from them. GMC claims they designed there 10L1000 as a new transmission with Allison's involvement and certifications. Dunno??

However; my deciding factor was evident with the GMC/Allison running cooler, able to give full torque in 1st, and torque converter lock up in all gears including first which Ford electronics/mechanics couldn't do to me makes the 10L1000 superior to the Ford 10R140. Gear ratios are different in both, PTO is located on opposite sides if I'm not mistaken, and Ford doesn't have Allison's TCM and software which seems to be superior.

JMHO
 
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I still don't know what's true with this one. We have Mike L. who said they're the same, but everything else that one can find about it, including from GM and Allison says the HD transmissions are a GM product with the Allison brand. No mention of it being a Ford cooperation anywhere.
I have a friend that’s pretty high up at Ford, currently on the commercial trucks design team. I posed the question to him.

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My uncle worked at Allison for 40 years (retired a few years ago), knows the GM engineers (former Allison guys) who worked with Ford on the 10 speed, and knows the Allison guys who tested the transmissions to give their approval on the design. He told me this:

"Quite the story. In 2006 GM sold Allison. They transferred some of the engineers to a office on the north side of Indy. round 2015 GM assigned them to work with Ford on a line of 10 speed transmissions, for cars, and heavy duty trucks. GM sent 10 units to Allison in 2019 to be ran on durability test stands. All passed easily. I'm sure after that GM paid Allison to use the name. If you press your dealer , he is suppose to call it a "Allison Marketed Transmission". The difference between the Ford and GMs is converter housing, rear cover, and shift cycles. Inner workings are the same. Talking to the Allison people that did the testing, say it is a good transmission. I would get one no doubt."
 
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