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I'm looking into ordering a new 2020 hd and was wondering how the new 10 speed trans is. It feels good on a test drive but being so new I wasn't sure how the reliability is. Anyone with higher mileage on their trucks care to share their opinion on the trans?
 

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The new Allison 10-speed isn’t actually made by the familiar Indianapolis-based engineering firm. It will be built in-house by General Motors and simply features Allison branding.
General Motors describing the Allison-branded unit as “all-new.”

Mike L. Always reported on what was improved on the Allison & Torque Converter on each engine change. I highly doubt he will do this on here. Usually with more hp there’s transmission and torque converter changes and I don’t remember him giving us a update on the new 2017 L5P Trans/TC.
His last post on here was 09-26-2017
 

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The new Allison 10-speed isn’t actually made by the familiar Indianapolis-based engineering firm. It will be built in-house by General Motors and simply features Allison branding.
General Motors describing the Allison-branded unit as “all-new.”

Mike L. Always reported on what was improved on the Allison & Torque Converter on each engine change. I highly doubt he will do this on here. Usually with more hp there’s transmission and torque converter changes and I don’t remember him giving us a update on the new 2017 L5P Trans/TC.
His last post on here was 09-26-2017
The “Allison” transmissions haven’t been made be Allison for a while now, the 10-speed isn’t unique in that regard.
 

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The “Allison” transmissions haven’t been made be Allison for a while now, the 10-speed isn’t unique in that regard.
The Allison that is in the GM trucks were never actually built by Allison aside from maybe the first year I believe. They were built at a GM transmission facility and after GM sold Allison in 2007 the design started to differ slightly as GM typically had new requirements that required upgrades. The overall transmission design never differed to much from what the transmission started as.
 

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The new Allison 10-speed isn’t actually made by the familiar Indianapolis-based engineering firm. It will be built in-house by General Motors and simply features Allison branding.
General Motors describing the Allison-branded unit as “all-new.”

Mike L. Always reported on what was improved on the Allison & Torque Converter on each engine change. I highly doubt he will do this on here. Usually with more hp there’s transmission and torque converter changes and I don’t remember him giving us a update on the new 2017 L5P Trans/TC.
His last post on here was 09-26-2017
Correct the 10-spd was not designed by Allison but I will say that the lead group in the development of the new 10 speed were a lot of the same people that were involved with the original 5/6 speed Allison that were still there from when GM sold off Allison.

As far as the upgrades on the L5P trans, I will have to go by some memory but I believe the TC has the clutch springs increase and the TC pressure from the Valve body increased to allow for more holding pressure. The rest of the transmission did not see much of a change. Input (turbine) and stator shaft (ground sleeve) spline changes for more strength.

I believe that was it but I am just going off memory. It has been a few years since I left GM but that was where we were at when I left GM 3 years ago. It's pretty bad that I don't remember it all since I was the Lead Engineer on the Allison which was the only reason I joined this site back in the day.
 

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Our new 2020 GMC 3500hd SRW isn’t here yet.
Just joined Facebook (2020 DURAMAX GMC & Chevrolet)
It’s a completely sealed transmission. This is why some people won’t even buy because of this.
Lots of blown transmissions from new owners.
Few dislikes, but that’s normal.
 

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So sorry to hear of the reported problems. There are better ways of spending nearly $80K than to buy a truck where you are not assured of a trouble free service life. Just think how much of a benefit it would be for GM to gain a rock solid reputation of having trucks that run good, take only normal maintenance, and dealership service that is well trained to fix what problems come to them. I thought I would buy a '19, then after reports, I changed to maybe buying a '20, and now it will be 2021 or later, when HOPEFULLY they become reliable.
 

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I don't know much about it, but from what I have seen I am very skeptical.

While I haven't driven one personally, from everything I have seen, heard or saw they are going to be too shift happy for me. One of the biggest reasons I love driving my diesel truck is the lack of shifting at highway speed. I can roll into the throttle at 55MPH and stay in top gear all the way up to 80 without any trouble. I am not an overly aggressive driver, so I don't mash the pedal to get a downshift, I use my turbo to scoot me along. This truck wants to be in its optimum range so badly it's going to want to shift all the time.

I am waiting to see, but I am very nervous about the drivability of this new 10 speed. From everything I've seen it looks like it drives like a gasser, which is something I have no interest in. Not to mention the serviceability is crap. I don't understand how you can build a heavy duty truck without serviceable components - that is something I'd expect on a 1/2 ton.
 

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Everybody I’ve talked to loves the new transmission


Sent from my iPad using Tapatalk
 

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sad it has no spin-on outside filter
It doesn’t?
I was wondering about this since it’s a sealed transmission now.
You have a 2020?
In Service and Maintenance
Change automatic transmission fluid and filter. 45k, 90k, 135k
Seems there are no 2020 Owners on this site. Looks like I need to crawl under one.
Will be getting our 2020 GMC 3500hd SRW soon to confirm.

2020 6.6L Duramax Diesel Engine Supplement
Page 84
https://my.chevrolet.com/content/dam/gmownercenter/gmna/dynamic/manuals/2020/chevrolet/multimodel/2020-6.6-duramax-diesel-supplement.pdf
 

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Drain plug is in the pan on the 2020 but haven't seen any procedures to fill it back up. Looking for this lately.
 

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Stupid, inept GM management. The two things their trucks had over their competition was the Duramax engine and the Allison transmission, and they gave away 50% of that advantage when they sold off Allison, before the recession. Stupid bean-counters squandered their reputation and market advantage in exchange for cash, that only delayed the inevitable bankruptcy by less than a year. What really pisses me off is that they refer to the transmission as Allison branded, like we are too stupid to notice. Eff you, GM.
 
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It doesn’t?
I was wondering about this since it’s a sealed transmission now.
You have a 2020?
In Service and Maintenance
Change automatic transmission fluid and filter. 45k, 90k, 135k
Seems there are no 2020 Owners on this site. Looks like I need to crawl under one.
Will be getting our 2020 GMC 3500hd SRW soon to confirm.

2020 6.6L Duramax Diesel Engine Supplement
Page 84
https://my.chevrolet.com/content/dam/gmownercenter/gmna/dynamic/manuals/2020/chevrolet/multimodel/2020-6.6-duramax-diesel-supplement.pdf
Check this: Where do I add trans fluid in 2020 2500 hd
 

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Stupid, inept GM management. The two things their trucks had over their competition was the Duramax engine and the Allison transmission, and they gave away 50% of that advantage when they sold off Allison, before the recession. Stupid bean-counters squandered their reputation and market advantage in exchange for cash, that only delayed the inevitable bankruptcy by less than a year. What really pisses me off is that they refer to the transmission as Allison branded, like we are too stupid to notice. Eff you, GM.
The federal court forced GM to sell Allison. Not their choice.
 

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The federal court forced GM to sell Allison. Not their choice.
Not quite. The Allison division was sold in 2007, nearly 2 years before the government bailout. Here's the lowdown:
 

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Not quite. The Allison division was sold in 2007, nearly 2 years before the government bailout. Here's the lowdown:
Why would they sell Allison when it was bringing in almost 3 billion a year for 5 billion? Sounds stupid.
 

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Going only on memory, IIRC, GM only sold off the Allison component making large transmissions and kept a hand in the LT transmission manufacturing.
 
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