2023 L8T 10 Speed

C/K Man · December 5, 2021

Some pretty reliable sources are reporting that the 2023 Silverado/Sierra HD's with the L8T 6.6L gas engine will be available with a 10 speed automatic transmission. I have been wondering which 10 speed it will be, either the 10L80 or the 10L1000. Anyone know for sure? My best guess is it will be the 10L1000. Reason is the 10L80 is the transmission co-developed with Ford, and Ford does not use their version in the Super Duty. Even with their 6.2L gas V-8, the Super Duty gets the 10R140 TorqShift.

SWDoodle · December 7, 2021

On 12/5/2021 at 5:05 PM, C/K Man said:

Some pretty reliable sources are reporting that the 2023 Silverado/Sierra HD's with the L8T 6.6L gas engine will be available with a 10 speed automatic transmission. I have been wondering which 10 speed it will be, either the 10L80 or the 10L1000. Anyone know for sure? My best guess is it will be the 10L1000. Reason is the 10L80 is the transmission co-developed with Ford, and Ford does not use their version in the Super Duty. Even with their 6.2L gas V-8, the Super Duty gets the 10R140 TorqShift.

That's the rumor I've been hearing too. I have a 22 on order but they tell me it's likely I won't get it and will have to order a 2023. I don't mind waiting if there are some upgrades, but part of me feels like what's gonna happen is the 22's that don't get built will be labeled 23's and then mid model year they'll launch say a 2023.5 with the new upgraded Duramax and "potential" new 10 speed gas. That would piss me off. Problem is there is just now way of knowing what's gonna happen.

ShotgunZ71 · December 10, 2021

They need more rear gear options. A 4.10 gearing choice, along with the 10-speed, would really wake things up.

Epsilon Plus · December 10, 2021

I wouldn't be surprised to see it in LTZ or higher trims, or maybe even a stand alone option for LT, perhaps included with LT. Reason being is the 6L90E is the bulletproof fleet trans on the market. I had time to wait for this truck but pushed on this year specifically to get the 6L90. Probably sounds silly to those who want the latest and greatest, but I only see the 10-speed increasing city MPG and that's about it.

This L8T is great but it's not a 1,000lb/ft @ 2,000RPM monster. Being a traditional pushrod SBC it gets its torque meat and potatoes up at 3-4k with the HP starting to jam in good around 5k. I can't see shifting it out a bazillion times as its hooked to a heavy load really being beneficial. The 6L90E is perfectly matched to this combo to keep it where it needs to be (maybe some 4.10s for those that really want to sweeten the pot). It's ridiculously butter smooth and damn near indestructible (with a stock truck). Yeah, I don't really need/want the added complexity of the 10-speed just to keep up with the multi-gear Jones' and get another city MPG...

Stand By · December 11, 2021

I concur. My only interest in it would be if it offered an under drive, which would only be used for towing, and a higher overdrive to save fuel. That's not gonna happen. The current 6 gears allow engine to wind up through each gear. The 7.3 has to make 30 more horsepower to get a hair better torque. But with a narrower power band between 10 gears, is it getting there efficiently? Maybe that had something to do with the overheating issue that got ignored in that video where it supposedly outperformed Chevy towing up the mountain? As mentioned, all that shifting induces heat and wear. Add all the extra moving parts and servos. I don't like buying transmissions as it is. There are other things I'd rather be improved before worrying about this transmission.

SWDoodle · December 11, 2021

12 hours ago, Epsilon Plus said:

I wouldn't be surprised to see it in LTZ or higher trims, or maybe even a stand alone option for LT, perhaps included with LT. Reason being is the 6L90E is the bulletproof fleet trans on the market. I had time to wait for this truck but pushed on this year specifically to get the 6L90. Probably sounds silly to those who want the latest and greatest, but I only see the 10-speed increasing city MPG and that's about it.

This L8T is great but it's not a 1,000lb/ft @ 2,000RPM monster. Being a traditional pushrod SBC it gets its torque meat and potatoes up at 3-4k with the HP starting to jam in good around 5k. I can't see shifting it out a bazillion times as its hooked to a heavy load really being beneficial. The 6L90E is perfectly matched to this combo to keep it where it needs to be (maybe some 4.10s for those that really want to sweeten the pot). It's ridiculously butter smooth and damn near indestructible (with a stock truck). Yeah, I don't really need/want the added complexity of the 10-speed just to keep up with the multi-gear Jones' and get another city MPG...

I would be fine with 4.10/4.30’s with the 6-speed. I just don’t understand why GM won’t give some options for Max payload with the gas. I would agree the 10 speed may shift a ton if towing. You’d almost have to manually lock it out OD gears which I used to do with my old 6.0.

ShotgunZ71 · December 11, 2021

The current setup is easy go get speed/RPM figured out, I will say. When I had mine, I knew that at 70 mph, 4th gear was 3000 RPM. At 70 mph in 3rd gear, that was 4000 RPM. It would keep pace up inclines as well, but you needed to let the engine rev. Many are afraid to do so or simply don't like the noise. I had no issues with mine pulling my 5er. Probably still have it if not for the trade value for it and pricing I got on the Denali. I wouldn't hesitate to go back to that setup, but I do wish for at least a lower rear end choice, such as 4.10 option.

C/K Man · December 11, 2021

18 hours ago, Stand By said:

....Maybe that had something to do with the overheating issue that got ignored in that video where it supposedly outperformed Chevy towing up the mountain?...

I missed that! I hear you can't get air brakes on the 7.3L F-650 because they run so hot it damages the brake lines.

sheath · December 15, 2021

I thought pretty hard on this, and decided the weight savings, simple servicing (that any transmission shop has seen), and cheap replacement parts are worth a few less gears. Currently pulling a 15K 5th wheel behind a 5.9L Ram with a 4 speed auto, so six gears is 50% more better... lol

6L90E has a great rep, and I don't want a transmission that has more gears than I have teeth... :cheers:

Epsilon Plus · December 16, 2021

On the big 2019+ T1 FB group someone posted a thread asking about who's had problems with the 6.2/10 combo in the 1500s. I was surprised to see so many transmission complaints. The common ones seemed to be 1) Back window leaks (unrelated but still reported). 2) Lifters (well known issue) and 3) 10 speed trans issues with quite a few replacements.

Careful what you wish for.

MORSNO · December 17, 2021

20 hours ago, Epsilon Plus said:

Careful what you wish for.

Isn't that the truth! The current transmission has been proven over time and just plain works, the 10 speed has much more to fail, weighs much more, and will be nonstop shifting under heavy loads.

vucelick · December 18, 2021

On 12/16/2021 at 8:53 AM, Epsilon Plus said:

On the big 2019+ T1 FB group someone posted a thread asking about who's had problems with the 6.2/10 combo in the 1500s. I was surprised to see so many transmission complaints. The common ones seemed to be 1) Back window leaks (unrelated but still reported). 2) Lifters (well known issue) and 3) 10 speed trans issues with quite a few replacements.

Careful what you wish for.

The 10 speed in the 1/2 ton is a completely different and light duty transmission compared to the heavy duty 10 speed in the diesel 3/4 and 1 ton trucks.

CRApex · December 18, 2021

It will be interesting to look back at this thread once the 10spd is in use and new owners provide real world feedback.

newdude · December 18, 2021

On 12/5/2021 at 6:05 PM, C/K Man said:

Some pretty reliable sources are reporting that the 2023 Silverado/Sierra HD's with the L8T 6.6L gas engine will be available with a 10 speed automatic transmission. I have been wondering which 10 speed it will be, either the 10L80 or the 10L1000. Anyone know for sure? My best guess is it will be the 10L1000. Reason is the 10L80 is the transmission co-developed with Ford, and Ford does not use their version in the Super Duty. Even with their 6.2L gas V-8, the Super Duty gets the 10R140 TorqShift.

10L90 from the ZL1 is the most likely candidate. 10L1000 would be overkill and un-necessary behind the 6.6 gas. Much larger and heavier, needs more input power (duramax) to spin everything.

ZL1 2012-2015 used the 6L90 from the HD so to me it only makes sense.

Edited December 18, 2021 by newdude

newdude · December 18, 2021

On 12/17/2021 at 7:53 AM, MORSNO said:

Isn't that the truth! The current transmission has been proven over time and just plain works, the 10 speed has much more to fail, weighs much more, and will be nonstop shifting under heavy loads.

Shifting is good, keeps the engine in the power. Gas engines don't want to lug, they need RPMs to get to that sweet spot in the torque band and HP.

Having driven a bunch of 8s and 10s at work, I will never get another 6-speed truck if I buy new.

6L90 is a tank, don't get me wrong, but a 10 speed is NEEDED in these, especially with the 3.73 GM decided to put in the axles.

10L90 is only 32 lbs heavier dry weight so I wouldn't say is weighs "much more".

Its also not any more complicated than the 6 or 8 speeds inside.

Camaro ZL1’s Lightning-Fast Transmission is a Perfect 10 (gm.com)

Quote

Creative packaging
Creative packaging solutions, which had to accommodate another clutch in comparison to the eight-speed, allow the 10-speed to be the approximate size of Camaro’s other eight-speed transmission. It uses four simple gearsets and six clutches: two brake clutches and four rotating clutches. That’s only one more clutch than the eight-speed, despite having two more forward gears.

It is also the latest transmission with an all-new, proprietary electronic control system and performance calibrations. The calibration is unique for the ZL1’s high-performance-oriented driving experience, while additional applications will feature calibrations matched to their respective performance ranges.

Hell, even the 8 speed is no heavier than the 6L80:

2015 Chevrolet and GMC Pickups, SUVs to Offer Eight-Speed Transmission

Quote

The GM-developed Hydra-Matic 8L90 eight-speed is approximately the same size and weight as the Hydra-Matic 6L80 six-speed automatic. Its 7.0 overall gear ratio spread is wider than GM’s six-speed automatic transmissions, providing a numerically higher first gear ratio to help drivers start off more confidently with a heavy load or when trailering. The 8L90 also enables numerically lower rear axle ratios, which reduce engine rpm on the highway.

I will always bring up TFLTruck's Ike video on the 2020 HD as the clearest and best reason these HD's are neutered. I know, its an extreme towing example, but even 14000lbs at sea level, its gotta work a lot harder with 6 gears instead of 10. GM should have kept the 4.10's being they kept the 6 speed, however they threw 3.73s in for "fuel economy". If they want to keep those, it NEEDS a 10 speed.

Edited December 18, 2021 by newdude