2020 hd

LikeABoss

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Nov 18, 2018
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Here’s the ratios,



First number is the 6 speed the second number is the 10 speed.

1st 3.094 4.54

2nd 1.809 2.86

3rd 1.406 2.06

4th 1.00 1.72

5th 0.711 1.48

6th 0.614 1.26

7th 1

8th 0.85

9th 0.68

10th 0.63



R 4.48 4.54



Cool. Thanks. Those look nice.
 

Hoser

Active member
Jun 19, 2016
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9th and 10th sure are close

That should be a good thing, instead of the larger drop from 6 to 5 in the current trans, when you get on it just a bit it can downshift that nice little step and give you the go you need, hopefully it’s almost unnoticeable.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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if you can get into the TCM and develop a skip gear tune (assuming it can happen on this trans), it may not be an issue. it would actually give you alot of possibilities to keep the truck in a good power band down the track but skipping useless gears due to the upped power.

skipping will depend on the internal design and how clutches are applied though.
Everything I've read says it can skip shifts. I forget where I seen it, but I read where it said it can jump multiple gears at once during downshifts to cut down on the lag currently experienced. As to swaps, I'm sure it will be possible, but it appears this trans is quite complicated internally, and finding a suitable controller may be an issue. But most of the info I can find is on the 10l80, not the new big boy.
 

Hoser

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Jun 19, 2016
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. . . . . . it can jump multiple gears at once during downshifts to cut down on the lag currently experienced.

This is what I am hoping for. When I floor it, I have to write a sweet little love letter and mail some roses, hoping my dear sweet Allison gets them before they die and she decides to downshift. . . .
 

Hambone

Always learning
Jan 24, 2016
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https://youtu.be/Z35ZThqcg6k
Banks did a comparison of the upcoming L5p
Two things I took away from it
1. Can we fit the new oil cooler on the 17-19?
2. He took a stab at aftermarket intakes that get rid of pcv and run direct into the turbo
Yet at the end of his video the dyno motor had the same 3.5” piping lol
 

kiwilml

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Nov 4, 2015
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This is what I am hoping for. When I floor it, I have to write a sweet little love letter and mail some roses, hoping my dear sweet Allison gets them before they die and she decides to downshift. . . .
You need the tcm tuning that I'm running then or something.. Mine shifts as soon as I stomp it, matter of fact it down shifts when I don't even want it to sometimes..
 

Hoser

Active member
Jun 19, 2016
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You need the tcm tuning that I'm running then or something.. Mine shifts as soon as I stomp it, matter of fact it down shifts when I don't even want it to sometimes..

That’s what makes me a bit apprehensive, I don’t want to roll into the throttle a bit and have it downshift when it doesn’t have to. That’s one of the main things I like about the D/A combo, I can be pulling a pretty good sized trailer and roll into the throttle on a hill and it will maintain speed and not downshift. Basically I’d like the exact same shift parameters but when it does need to downshift it does it right now. Maybe that tuning is available, and I’d be interested in it.
 

2004LB7

Well-known member
Dec 15, 2010
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That’s what makes me a bit apprehensive, I don’t want to roll into the throttle a bit and have it downshift when it doesn’t have to. That’s one of the main things I like about the D/A combo, I can be pulling a pretty good sized trailer and roll into the throttle on a hill and it will maintain speed and not downshift. Basically I’d like the exact same shift parameters but when it does need to downshift it does it right now. Maybe that tuning is available, and I’d be interested in it.

It can be done. Used to have what you describe but ultimately liked it better when it did downshift when rolling into it enough. Takes a bit more fine tuning with the shift tables. I found that even a 1/2 mph adjustment could change the way it feels and reacts

Mine will hold 6th at 65mph and up pretty good but if I get into it it will downshift in a hurry. In lower gears will downshift more often even with lighter throttle input

Took me many revisions to get where I am now
 

Mike L.

Got Sheep?
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Aug 12, 2006
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I think this is going to be a busy trans and that's not a good thing. From the cut out, it looks like a chain driven pump. If so, that means it's going to be a quick shifter and I assume it will be in 10th gear by 45-55 MPH for better mileage. Hopefully they get the software right for decent shifts. For street driving I would think 2nd gear would be a better start off gear.
 

PureHybrid

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Feb 15, 2012
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I think this is going to be a busy trans and that's not a good thing. From the cut out, it looks like a chain driven pump. If so, that means it's going to be a quick shifter and I assume it will be in 10th gear by 45-55 MPH for better mileage. Hopefully they get the software right for decent shifts. For street driving I would think 2nd gear would be a better start off gear.

The picture I looked at had a clutch assembly attached to it. Almost made me wonder if it was for electric drive input
 

beach_33

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Feb 18, 2008
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Maybe 1st gear start in T/H only. Assuming it has the ability like the current trans if a completely different shift strategy for T/H VS just drive
 

beach_33

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Feb 18, 2008
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In the video interview that I watched with one of the transmission engineers for gm he said that it was a chain driven PTO. Take that for what it’s worth
 

kheims

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Oct 7, 2012
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Just got back from the Chicago auto show. Gotta say that Chevy looks much better in person then in the photos without and with the bow tie grille. They had a high country and an ltz up on stage. They even had a work truck version with a v-plow hooked up. That one even looked good paint match front grille and Chevrolet across the front. I like it. The gmc looked really good too. I talked to a guy that works for Allison about the trans he says nothing on the inside looks like an Allison design. They had a cut open one on display at the gmc booth. It literally is just tested by Allison to get the branding. I hope gm did their homework a trans can make or break a really good truck in my opinion.
 

Hoser

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Jun 19, 2016
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The chain is for the PTO. I really don’t like hearing the words “busy tranny”. For some reason the constant shifting of these 8-speeds in the half tons drive me bonkers, I don’t want that in an HD truck pulling trailers.
 

THEFERMANATOR

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Feb 16, 2009
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Here's a video I found on another site. The pto is chain driven. From what I could find on the lighter duty version 10 speed, I believe they said it uses a variable displacement pump in the trans to control pressure. It also has the option of installing an electric pump to hold it in gear for the engine start stop technology. There's alot going on inside the trans, and it looks nothing like the allison in the 4500/5500 trucks.

https://youtu.be/RdAn1byqQOg
 

TheBac

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Apr 19, 2008
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They arent adding that annoying start/stop to the Dmax trucks, are they? That would absolutely suck.