[Briancollins82]

Looking at a 2022 Silverado 3500 HD dual rear wheel and the only thing I'm hesitant on is the 3.42 rear axel. I will be towing my bumper pull 32' toy hauler (7,500 dry weight) and will be purchasing a new goose neck three horse trailer with living quarters in the near future (30-35 feet). Live in the flat part of Ohio but not wanting to limit myself with a crap rear axel. Should I keep looking or will the 3:42 rear end work?

 

[Hoser]

3.42 is the only axle ratio available for the Duramax. That is really light towing weight, even a gasser would pull that without any issue at all.

 

[Briancollins82]

I don't get why they put such a small rear axel in it. My old man has a 2022 2500HD with the 6.6 gas and it has a 3.73 in it. Doesn't make any sense to me. I don't want to be sitting on the side of the road with a blown up truck while hauling horses.

 

[Mmecsics]

I don't get why they put such a small rear axel in it. My old man has a 2022 2500HD with the 6.6 gas and it has a 3.73 in it. Doesn't make any sense to me. I don't want to be sitting on the side of the road with a blown up truck while hauling horses.

The gassers do not have the 10 speed transmission, nor the torque the diesels have. Heck, the truck doesn’t even start out in first gear, unless in tow haul. You will not have any problems.

 

[Briancollins82]

I would imagine there is a good reason why they put the 3.42 in the rear end, I just haven't come across a good reason on why.

 

[66436]

I would imagine there is a good reason why they put the 3.42 in the rear end, I just haven't come across a good reason on why.

Is there a difference in the wheel size? The Duramax was standard with the 3.73 until the 10 speed came out. The torque from the engine/ tranny would be more than enough but the 3.42 gear ratio will generate more heat. If the wheel size was a bit smaller that would help compensate for that but I doubt Chevy did that. I would much rather have more of a final gear ratio out of the tranny spinning the driveshaft more that applying more torque to the smaller gears. It would be interesting to see any data on the difference in diff heat between the older Duramax diff and the new set up pulling the same amount of load. Dean

 

[Hoser]

I don't get why they put such a small rear axel in it. My old man has a 2022 2500HD with the 6.6 gas and it has a 3.73 in it. Doesn't make any sense to me. I don't want to be sitting on the side of the road with a blown up truck while hauling horses.

You really think your truck is going to blow up towing 1/4 the rated capacity because it has 3.42 gears? Chevy actually has engineers that design and test this stuff before it’s put into production. And there’s many of us towing well over the rated weights for these trucks all over the country and no blown up trucks yet because of 3.42 gears.

Lots of old-timers relate towing ability based solely on rear gears, but you have to look at the whole package, not just a single aspect of it. And if you are interested, here’s the gears of the old vs new trannys and the final based on 3.42 gears.

1st 3.094 - 11.540
2nd 1.809 - 6.747
3rd 1.406 - 5.244
4th 1.00 - 3.730
5th .711 - 2.652
6th .614 - 2.290
R 4.48 - 16.710

1st 4.54 - 15.526
2nd 2.86 - 9.781
3rd 2.06 - 7.045
4th 1.72 - 5.882
5th 1.48 - 5.061
6th 1.26 - 4.309
7th 1.00 - 3.420
8th .85 - 2.907
9th .68 - 2.325
10th .63 2.154
R 4.54 - 15.526

 

[Nate Dmax]

The reason for the 3.42 is because the 10sp is geared different and makes up the difference. The axle is not any smaller just a different ratio. In fact it is a beefier axle.

 

[Hoser]

Is there a difference in the wheel size? The Duramax was standard with the 3.73 until the 10 speed came out. The torque from the engine/ tranny would be more than enough but the 3.42 gear ratio will generate more heat. If the wheel size was a bit smaller that would help compensate for that but I doubt Chevy did that. I would much rather have more of a final gear ratio out of the tranny spinning the driveshaft more that applying more torque to the smaller gears. It would be interesting to see any data on the difference in diff heat between the older Duramax diff and the new set up pulling the same amount of load. Dean

Tires are bigger on the new trucks.

I haven’t run the math, but it’s likely the drive shaft is spinning at pretty close to the same speed.

 

[66436]

Tires are bigger on the new trucks.

I haven’t run the math, but it’s likely the drive shaft is spinning at pretty close to the same speed.

You going the wrong way. For a taller tire you would need more gearing in the diff. A taller tire on the new truck with 3.42 is going to make the truck work harder to pull the load. D

 

[Hoser]

You going the wrong way. For a taller tire you would need more gearing in the diff. A taller tire on the new truck with 3.42 is going to make the truck work harder to pull the load. D

I didn’t say anything about whether it’s working the truck harder or not. I just said the tires on the new trucks are bigger and likely theDrive shaft is spinning at a similar speed.

Sometimes we base all that we “know” on what we know. We think that since basically all HD trucks used 3.73 or 4.54 gears in the past that we need at least that in order to tow efficiently and anything else is preposterous. But the fact is, we learn things, and the way things were done in the past often times was way overkill. Why do you think you need 3.73s, just because that’s what trucks had in the past?

And look at the ratios I posted, the truck is not actually working harder, it’s actually working less. Yes, the diff is “taking” more torque, but that’s why it’s bigger and improved. Personally I don’t care if the drive shaft is spinning faster, I’m more concerned with towing performance, less engine RPM, and getting the best mileage I can with the work I do, and the current drivetrain package delivers that, even with 3.42 gears.

 

[66436]

I didn’t say anything about whether it’s working the truck harder or not. I just said the tires on the new trucks are bigger and likely theDrive shaft is spinning at a similar speed.

"Sometimes we base all that we “know” on what we know."

Some here including myself refer to that as experience. I will completely agree that the 10 speed tranny will offset the gearing and the taller tires. Going down the highway will make little difference in that but I would be more concerned pulling a heavy load going thru some big hills. With a 3.73 diff and shorter tires the rest of the powertrain does not have to work as hard. With the new 10 speed tranny you are now shifting a bunch more to keep things going. Just a bunch more heat generated by the tranny and diff. The 3.42 gears would not concern me as much if the tire diameter stayed the same but taller tires effectively bring that torque multiplication down further meaning the tranny is now shifting more to keep the powertrain in the proper torque range of the engine. I can guaranty this was all done to help increase a bit of mileage but you are making the powertrain work harder going thru the big hills. It's no wonder the cooling system was beefed up so much (there are actually many reason why the cooling system was beefed up but this definitely adds to it). D

 

[Dave Brabec]

The 6 speeds have 3:73

 

[Hoser]

Some here including myself refer to that as experience. I will completely agree that the 10 speed tranny will offset the gearing and the taller tires. Going down the highway will make little difference in that but I would be more concerned pulling a heavy load going thru some big hills. With a 3.73 diff and shorter tires the rest of the powertrain does not have to work as hard. With the new 10 speed tranny you are now shifting a bunch more to keep things going. Just a bunch more heat generated by the tranny and diff. The 3.42 gears would not concern me as much if the tire diameter stayed the same but taller tires effectively bring that torque multiplication down further meaning the tranny is now shifting more to keep the powertrain in the proper torque range of the engine. I can guaranty this was all done to help increase a bit of mileage but you are making the powertrain work harder going thru the big hills. It's no wonder the cooling system was beefed up so much (there are actually many reason why the cooling system was beefed up but this definitely adds to it). D

Have you driven the new chassis or are you just speculating? I’ve owned new Duramax trucks since they came out, I’m a bit familiar and have a little experience with them myself.

Its physics my guy. It’s gears and ratios. Have you looked at the ratios and finals that I posted above? Show me where in that package the truck is working harder, even taking into consideration the 1/2” taller tire that rotates 10 less times per mile than the previous generation tire size. BTW, tire size was increased to meet the higher payload ratings.

Have you also looked at the tow ratings for the new chassis? They have increased DRAMATICALLY. do you think that maybe the cooling system was upgraded to allow towing of such heavy trailers? Do you think they could increase the ratings that much if the 3.42 gears were worse than 3.73s?

Again, speaking from experience, the truck does not work harder in big hills, or even mountains for that matter. The Tranny is not “shifting more”, it generally will drop a gear or two at once, pull the hill, then drop back into 10th, just like the older trucks, but now it has a much larger gearspread to choose from which makes it work more efficiently.

I can guarantee this was all done for towing, not mileage, however in the long run both are benefited. Why would they go to such great lengths solely to improve mileage on a vehicle that isn’t rated by the EPA?

 

[66436]

Have you driven the new chassis or are you just speculating? I’ve owned new Duramax trucks since they came out, I’m a bit familiar and have a little experience with them myself.

Its physics my guy. It’s gears and ratios. Have you looked at the ratios and finals that I posted above? Show me where in that package the truck is working harder, even taking into consideration the 1/2” taller tire that rotates 10 less times per mile than the previous generation tire size. BTW, tire size was increased to meet the higher payload ratings.

Have you also looked at the tow ratings for the new chassis? They have increased DRAMATICALLY. do you think that maybe the cooling system was upgraded to allow towing of such heavy trailers? Do you think they could increase the ratings that much if the 3.42 gears were worse than 3.73s?

Again, speaking from experience, the truck does not work harder in big hills, or even mountains for that matter. The Tranny is not “shifting more”, it generally will drop a gear or two at once, pull the hill, then drop back into 10th, just like the older trucks, but now it has a much larger gearspread to choose from which makes it work more efficiently.

I can guarantee this was all done for towing, not mileage, however in the long run both are benefited. Why would they go to such great lengths solely to improve mileage on a vehicle that isn’t rated by the EPA?

"I can guarantee this was all done for towing, not mileage, however in the long run both are benefited. Why would they go to such great lengths solely to improve mileage on a vehicle that isn’t rated by the EPA?" Bragging rights! The same reason you have these diesels cranked up more each year and bigger towing capacities.

I do not own one of the new trucks but I have rode with others that do, I like my LMM too much to dump that much money on the new ones. They are impressive though a bit too much on the gimmicks and looks for my taste. You are correct, it is physics. Make a simple comparison. Take a 10 speed bike. Would you want to go up the hill in 10th or in 5th? You can do this in 10th and offset some of that with changing the gears on the pedal side but the strain out back is still the same. The newer trucks can get away with it since they produce more power. Granted the gearing change between a 3.42 and a 3.73 is not that great but if you can offset that by the final overdrive ratio in the tranny I see no reason to go to the 3.42 except to get a bit more mileage. It was the whole premise for the overdrive transmission. With that said I am done with this thread. D

 

[Bow Tie]

The teeth on the 3.42 gears are larger than the 3.73, and should also be stronger. The 3.42 gears should also generate less heat in the rear differential because they are turning slower.

 

[Usmckenney]

Looking at a 2022 Silverado 3500 HD dual rear wheel and the only thing I'm hesitant on is the 3.42 rear axel. I will be towing my bumper pull 32' toy hauler (7,500 dry weight) and will be purchasing a new goose neck three horse trailer with living quarters in the near future (30-35 feet). Live in the flat part of Ohio but not wanting to limit myself with a crap rear axel. Should I keep looking or will the 3:42 rear end work?

I pull a 12,500 lb 5th wheel all over the place with my 2021 without missing a beat. The 10 speed trans makes up for the hearing in the rear end.

 

[silveradoboomer]

I traded my 2016 3500HD CC LB DW for a 2021 3500HD CC LB DW> Big difference. The 2021 pulls my 16,000 pound 5th wheel much easier than the 2016. 10 speed very smooth.

 

[Icutmetl]

You can get hung up on the rear axle ratio, or you can realize it’s one of many variables, like the number of speeds and ratio spread in a transmission for example…

 

[Twiggy]

Back in the days of 3 and 4 speed automatics rear end gearing was very important. The ratios of todays transmissions with 3 times the gears to work with changed the playing field completely. That weight towing you mentioned is gas truck material. I would not pay the extra money in initial purchase plus added maintenance cost of a diesel for that kind of towing.