Let's talk axle ratios...

HaydenHunter · Apr 15, 2017

Going to be buying a new RAM in the next 3 months when I retire and have to turn in the keys to the company truck. I am going to go Hemi. When I tow it will be my hunting/fishing boat (somewhat light by boat standards) and possibly a small, lightweight bumper pull camper.

I am looking for the axle ratio that will provide the best balance between gas mileage city / highway and yet provide power to tow the above-mentioned items through the mountain west.

3.21? 3.55? 3.92? This will be on a 4WD RAM.

Thanks in advance for your input.

AtomicDog · Apr 15, 2017

tgged for interest. I had the 3.92 rear end in my '12, my latest has the 3.21 but with the new 8 speed transmission I wonder if 3.92 is that necessary now.

Pull Ya · Apr 15, 2017

If you get the 8 speed trans then I would recommend either the 3.21 or the 3.55, if you're not going to do any heavy towing. Usually the 3.21's are best for fuel economy and the 3.92's are best for acceleration and towing heavy. I'd test drive a couple of different ratios first before making a decision. If you do a lot of mountain driving then maybe either the 3.55 or the 3.92 would be best.
Jay

Buddy · Apr 15, 2017

If your going new truck it will have the 8 speed trans, so your choices are 3:21 and 3:92. With your towing needs you can easily get away with the 3:21, it can tow 8000.

Burla · Apr 15, 2017

The 8 speed flipped the script when it came to talking about gears, it is less important then ever before. My truck year, anything less then a 3.92 will make you fkin puke. But just from what I hear on the board, the 3.21's will work fine. Me personally, I would still go with 3.92's, more power and less stress for long term. But if you value gas mileage, especially on freeway, go the other way.

Enjoy your retirement.

69GWC · Apr 15, 2017

The 8sp and 3:21s work real nice together, with that said I would get the 3,92s if you can.

karjar · Apr 15, 2017

ordered my 2017 1500 with the 3.92 and LSD. Trailer will only be 6000# but will be going through the Rockies a bit.. firm believer that I would rather have it and not need it, than not have and wish I did!

shane1981 · Apr 15, 2017

get the 3.92 fuel milage wont be much different than the 3.21 and it will tow more . 3.21 is fine if you drive downhill everywhere

tuned by Jay Greene

6.7CumminsDrvr · Apr 15, 2017

3.92's FTW! They do pretty well on the HWY.......my best tank was 19.4 mpg handcalculted (when truck was bone stock) and I don't exactly drive slow.

69GWC · Apr 15, 2017

shane1981 said:
get the 3.92 fuel milage wont be much different than the 3.21 and it will tow more . 3.21 is fine if you drive downhill everywhere

tuned by Jay Greene

Really ? down hill Pss...........

shane1981 · Apr 15, 2017

in all reality if you just uze a truck to drive like a car and do very light towing 3.21 is fine but if you're towing regularly up and down hills putting bigger tires and so on then 3.92 is great for that. i personally think that nothing less than a 3.73 should be in any truck. people today are using trucks like cars and thats why they have the 3.21

tuned by Jay Greene

yillbs · Apr 15, 2017

the 8 speed fixes the old myth about gear ratios, heavily. The 3.92's will net you close to 20MPG, so it's certainly good. The only time those 3.92 gears will hurt you, is when you go bigger / heavier tires. If you throw on some 70~ pound tires, and 35's, your 3.92's will make you wish you wen't 3.21, but if you're just doing stock towing on a small boat / TT, then 3.92 will be fine. I tow 7600 pounds with 3.21 gears, and it does an amazing job.

yillbs · Apr 15, 2017

shane1981 said:
in all reality if you just uze a truck to drive like a car and do very light towing 3.21 is fine but if you're towing regularly up and down hills putting bigger tires and so on then 3.92 is great for that. i personally think that nothing less than a 3.73 should be in any truck. people today are using trucks like cars and thats why they have the 3.21

tuned by Jay Greene

That's not at all why they are using 3.21 gears in a truck. They are using 3.21 gears in a truck because the 8 speed final drive ratio is better than that of a jeep with 4.10's from 5 years ago. The 3.21 is equal to, or better than super low geared jeeps / trucks, and SUVS of 2010. Why not throw in good gas mileage while we're at it, seeing as how we can already match the performance. It has nothing to do with the way people drive, and everything to do with the amazing 8 speed.

Wild one · Apr 15, 2017

yillbs said:
That's not at all why they are using 3.21 gears in a truck. They are using 3.21 gears in a truck because the 8 speed final drive ratio is better than that of a jeep with 4.10's from 5 years ago. The 3.21 is equal to, or better than super low geared jeeps / trucks, and SUVS of 2010. Why not throw in good gas mileage while we're at it, seeing as how we can already match the performance. It has nothing to do with the way people drive, and everything to do with the amazing 8 speed.

Has nothing to do with the way people drive or what people want or the 8 speed,the reason they're using as tall a gear as they can in the trucks is for CAFE standards. The big 3 are selling more trucks then ever,and the CAFE standards are getting harder to meet,so the gear ratio's are going down to bring the corporate milege up.
The Café target for 2018 is 25mpg ,in 2022 that number rises to 26 mpg and rises again each year till it hits 30 mpg in 2025. That's why Ford is going to aluminium bodies and smaller engines in their trucks,and also why the Hemi demise is probably gonna happen fairly soon,and we'll see some version of a turbo'd Pentstar to replace it.

shane1981 · Apr 15, 2017

i traded my 3.21 for a 3.92 because it was such a huge difference all the way around and still get the same mpg with alot more grunt so my advice is spend your money the way you want because there is always a disagreement between people on everything . id drive bith and se for yourself

tuned by Jay Greene

jljbtm · Apr 15, 2017

I have the 3.92 in my 2011 mpg's is between 14-17

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huntergreen · Apr 15, 2017

Had ,3:55 in my 11 sport, now have 3:92 in my 16 big Horn. Getting the same mpg.

Punishher7 · Apr 16, 2017

yillbs said:
the 8 speed fixes the old myth about gear ratios, heavily. The 3.92's will net you close to 20MPG, so it's certainly good. The only time those 3.92 gears will hurt you, is when you go bigger / heavier tires. If you throw on some 70~ pound tires, and 35's, your 3.92's will make you wish you wen't 3.21, but if you're just doing stock towing on a small boat / TT, then 3.92 will be fine. I tow 7600 pounds with 3.21 gears, and it does an amazing job.

Why would you rather have 3.21 if putting larger/heavier tires on? The lower ratio would make the added weight less noticeable wouldn't it?

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Jwithing · Apr 16, 2017

Wild one said:
Has nothing to do with the way people drive or what people want or the 8 speed,the reason they're using as tall a gear as they can in the trucks is for CAFE standards. The big 3 are selling more trucks then ever,and the CAFE standards are getting harder to meet,so the gear ratio's are going down to bring the corporate milege up.
The Café target for 2018 is 25mpg ,in 2022 that number rises to 26 mpg and rises again each year till it hits 30 mpg in 2025. That's why Ford is going to aluminium bodies and smaller engines in their trucks,and also why the Hemi demise is probably gonna happen fairly soon,and we'll see some version of a turbo'd Pentstar to replace it.

Very interesting.... Never thought about that portion, your analysis and predictions make sense... Would love to hear more detail/ thoughts.

Jwithing · Apr 16, 2017

Wild one said:
Has nothing to do with the way people drive or what people want or the 8 speed,the reason they're using as tall a gear as they can in the trucks is for CAFE standards. The big 3 are selling more trucks then ever,and the CAFE standards are getting harder to meet,so the gear ratio's are going down to bring the corporate milege up.
The Café target for 2018 is 25mpg ,in 2022 that number rises to 26 mpg and rises again each year till it hits 30 mpg in 2025. That's why Ford is going to aluminium bodies and smaller engines in their trucks,and also why the Hemi demise is probably gonna happen fairly soon,and we'll see some version of a turbo'd Pentstar to replace it.

They're already doing it with diesel. Hell, Cummins are now in Nissans due to this exact reason. Curious as to why they started with the diesels... Guess it was easier and could still put up necessary tq #s, but would have thought high risk with that type of target market.

Let's talk axle ratios...

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