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Discussion Starter · #1 ·
On the Chev & GMC sites, it lists the axle ratio as 3:42. Seem odd that they would go numerically lower, especially when I believe Ram offers 4:10.

Does anyone have a comparison chart of final drive ratios with the 3:73 axle and Allison 6spd comapared to the 3:42 and trhe Allison 10 spd?

The engine is already turning such low RPMs at reasonable interstate speeds, where will it run with this new combination? Does the computer lock out some of the gears in the trans when in tow-haul mode?

I got to see a GMC 2500 up close at my local dealership over the weekend. Looks like a beast of a truck!
 

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Thread relocated over to "Drivetrain - 2011+"

:thumb:
 

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Seriously? The final drive ratio is only part of the reduction in gearing from the engine output. When you factor in the ratios of the new transmission, it all works out.
 

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I already posted a chart that I made of the final drive ratios in another thread. As stated, the 3.42 ratio is part of an entire driveline package with a wider gearspread. It’s not like they added 4 overdrives and then also dropped the rear gearing. . . . . . .
 

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Discussion Starter · #5 ·
I already posted a chart that I made of the final drive ratios in another thread. As stated, the 3.42 ratio is part of an entire driveline package with a wider gearspread. It’s not like they added 4 overdrives and then also dropped the rear gearing. . . . . . .

Do you have a link to that thread?
 

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capacity.html#post9817504https://www.dieselplace.com/forum/63-gm-diesel-engines/8-upcoming-gm-diesels/973578-2020-l5p-up-35-500-towing-capacity.html#post9817504

For those that want math...

With this you basically get better than 4.3 gear final,
AND you also get better than 3.73 gear final,

All in one transmission + it handles more torque...

Even lower first final of my MYD @3.73
4.03 1st
15.0319 final


So, what are we complaining about?
Attached Thumbnails
2020 L5P up to 35,500 towing capacity-capture.gif



https://www.dieselplace.com/forum/63-gm-diesel-engines/8-upcoming-gm-diesels/973578-2020-l5p-up-35-500-towing-capacity.html
 

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I think one of the unmentioned reasons is that a 3.42 is physically stronger than a 4.11.
 

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Torque may indicate behavior, but not performance. It's overuse as a metric of comparison is what annoys me. I've seen article after article of puzzled auto journalists wondering why their vehicle is so slow despite being able to "feel the torque!".Ican make 1000 ft-lbs of torque, but I doubt many people would want me in their engine bay. My guess is that when a new HD powertrain is developed, a trade study is commissioned. This study could analyze the actual required performance vs required marketing output. The appropriate levers to tweak become the engine geometry itself. Need more torque? Upsize the stroke, or perhaps downsize the turbine wheel and trade some power out on the topside. If the engine was a black box, and I said I had one that made 1000 ft-lbs of torque, and one that made 2000 ft-lbs of torque, are those engines any different? Or did I just slap a 2:1 gear reducer on the back of one of the two identical engines? Which is the better choice?
 

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Well, seeing as how torque on a diesel is rated at the flywheel, the above seems moot.
 

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Cruising at 75 in 10th gear my RPM is at 1500.
 

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I find it interesting that the ten speed trans uses second gear from a stop unless in tow/haul mode. In tow/haul they use first gear. Good to know if you're loaded heavy, not towing, and want a little more boost to get things rolling.
 

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I find it interesting that the ten speed trans uses second gear from a stop unless in tow/haul mode. In tow/haul they use first gear. Good to know if you're loaded heavy, not towing, and want a little more boost to get things rolling.
I did not know this, thanks for the heads up!
 
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