3.92 with the Ecodiesel

[DieselFuelOnly]

Obviously 3.92 is preferred for towing but most of the talk about gearing is regarding gas engine trucks.

Any reason to avoid the 3.92 in the diesel?
Does anyone have experience with both the 3.21 and 3.92 in the diesel 1500?

Thanks.
Oh and I am new here, nice forum!

 

[Rockman]

Get the 3.92...... will have no regrets

 

[Keezer]

If you do a build on the Ram site it looks like with the diesel you have no other choice but 3.92

 

[Firebird]

My buddy just loves the 3.92 gears in his 2020 EcoDiesel

 

[Hrspwr88]

You can only get the 3.92 with the ecodiesel. I tried getting the 3.21 as I dont tow heavy and wanted to stretch the fuel mileage, but it wasn't an option. I assume it's to help the ecodiesel get out of the hole a bit better.

 

[Danny_TheHouseCook]

You can only get the 3.92 with the ecodiesel. I tried getting the 3.21 as I dont tow heavy and wanted to stretch the fuel mileage, but it wasn't an option. I assume it's to help the ecodiesel get out of the hole a bit better.

My dealer said I could get the other gears offered when we were configuring my build. I figured RAM must have made the 3.92 a default for a reason so I just stuck with that reason, whatever it is.

 

[Willwork4truck]

Nothing wrong with those gears ever. I'd have taken them with my hemi but couldn't get the colors she wanted.
With an ecodiesel the extra gearing (for not towing) won't be any advantage but won't be any disadvantage either. You never know, you might tow something someday.

 

[Danny_TheHouseCook]

Nothing wrong with those gears ever. I'd have taken them with my hemi but couldn't get the colors she wanted.
With an ecodiesel the extra gearing (for not towing) won't be any advantage but won't be any disadvantage either. You never know, you might tow something someday.

Yes, I already tow a boat, just not often.

 

[WXman]

My dealers have lots of EcoDiesels, but most are 3.21s. I specifically wanted a 3.92 axle and found one at a dealer in Frankfort, KY. The deeper gearing actually improves mileage in the city, as well as tows trailers better. I love it.

 

[DieselFuelOnly]

My dealers have lots of EcoDiesels, but most are 3.21s. I specifically wanted a 3.92 axle and found one at a dealer in Frankfort, KY. The deeper gearing actually improves mileage in the city, as well as tows trailers better. I love it.

Same boat!

The dealers around me had very few diesel's with the 3.92, and I also noticed that you cannot select the other gearing when building an ED on the RAM web site. Odd. They must have ordered a bunch of diesel's with out the 3.92 and most were just sitting on the lot.

I did end up going with the diesel and the 3.92 in a white Laramie trim. I drove it to work today for the first time, so far so good with 157 miles on the odo.

I have read / heard the horror stories with the previous gen and actually owned a 2005 Jeep Liberty with the WM 4 cylinder diesel. The liberty diesel was decent to me, the Jeep Liberty it self had some "quirks" to say the least. One thing I like about the gen 3 ED is the timing chain, the Liberty had a belt and that was a fun service to do at 100,000 miles.

Let's hope this new diesel is a winner!!

 

[Danny_TheHouseCook]

Same boat!

The dealers around me had very few diesel's with the 3.92, and I also noticed that you cannot select the other gearing when building an ED on the RAM web site. Odd. They must have ordered a bunch of diesel's with out the 3.92 and most were just sitting on the lot.

I did end up going with the diesel and the 3.92 in a white Laramie trim. I drove it to work today for the first time, so far so good with 157 miles on the odo.

I have read / heard the horror stories with the previous gen and actually owned a 2005 Jeep Liberty with the WM 4 cylinder diesel. The liberty diesel was decent to me, the Jeep Liberty it self had some "quirks" to say the least. One thing I like about the gen 3 ED is the timing chain, the Liberty had a belt and that was a fun service to do at 100,000 miles.

Let's hope this new diesel is a winner!!

Better be a winner is all I can say. I had no problems with my Gen 1 so hopefully this Gen 3 will be even better.

 

[tyresmoker]

Are the 3.21's out there 4x4 or 4x2?

 

[WXman]

Are the 3.21's out there 4x4 or 4x2?

All the ones I've seen are 4x4.

 

[StuartV]

If there is one thing I wish was different on my truck it is that I wish I had 3.21 gearing instead of 3.92.

I drive a lot of highway miles. I work from home so no commuting. I've had my truck 8 months now and have over 16,000 miles.

I generally run around 80 MPH when on the Interstate on a road trip. The RPMs I'm turning with 3.92 gearing means my truck is in the "fuel guzzling" zone. For what I do, the 3.21 gears would have me turning something like 300 or a bit better RPMs less and that would (I believe) make for a nice improvement in fuel economy.

The ONLY time 3.92 gearing is better is if you're towing or hauling, and then it's only at take-off. When the truck is unloaded, it makes more than enough torque to spin the tires off the line, so it's traction control that limits your takeoff, no matter which gears you have. Unless you're towing/loaded and the extra weight gives you enough traction to make a difference.

Once you're rolling, it doesn't matter. You might be in 3rd gear with 3.92 gears or 2nd gear with 3.21. Either way, the tranny is going keep itself in the same RPM range, regardless, so your roll-on acceleration is going to be a wash between the 2.

And, as I said before, while 3.92 is better from a standing start when loaded or towing, the tradeoff is high RPMs at highway speeds (and thus, worse mileage, which means shorter range).

I don't generally tow a trailer or haul much. A motorcycle in the back or a bed full of scuba tanks and other gear. Enough that a smaller truck wouldn't work for me. But, not enough that I need 3.92 gears to be able to take off from a stop.

 

[Zoompastu]

About the only thing you can do other than swapping the front diff and rear axle out is to install a taller tire that is still lightweight. Best option would be the 275/65/20 NItto Terra grappler G2. That tire weighs 47 pounds as long as you get the P rated tire. It is 11 inches wide same as factory but 34 inches tall. Going from a 32” to a 34” tire Would effectively bring your gear ratio down to around a 3.55 which is a happy medium between the two. You’re not adding a bunch of weight with that tire or width for rolling resistance. The only negative is the truck will be 1 inch higher off the ground and at 80 miles an hour that will have an effect. I still suspect you will show an increase in mpg at that speed by having your RPMs drop from about 2100 to 1850ish

 

[Aseras]

I was able to begin a factory order with the ecodiesel and a 3.21. Had to be a custom override. Then we found one with 95% of what I wanted a couple hours away. Good enough or I'd still be waiting on a truck.

Still stupid that tow mirrors kill surround view. Def considering having a lawyer send a nasty gram to FCA threatening class action for nuking 2,000 of option on the Monroney with a tow package that everyone is obviously going to get.

 

[WXman]

The ONLY time 3.92 gearing is better is if you're towing or hauling, and then it's only at take-off. When the truck is unloaded, it makes more than enough torque to spin the tires off the line, so it's traction control that limits your takeoff, no matter which gears you have. Unless you're towing/loaded and the extra weight gives you enough traction to make a difference.

Once you're rolling, it doesn't matter. You might be in 3rd gear with 3.92 gears or 2nd gear with 3.21. Either way, the tranny is going keep itself in the same RPM range, regardless, so your roll-on acceleration is going to be a wash between the 2.

And, as I said before, while 3.92 is better from a standing start when loaded or towing, the tradeoff is high RPMs at highway speeds (and thus, worse mileage, which means shorter range).

I don't generally tow a trailer or haul much. A motorcycle in the back or a bed full of scuba tanks and other gear. Enough that a smaller truck wouldn't work for me. But, not enough that I need 3.92 gears to be able to take off from a stop.

Which requires more fuel: maintaining speed on the interstate, or getting a 5,500 lb. vehicle moving from a stop?

I posted this in another thread which took some time, so I won't do it here, but there are NO points in any gear where the RPM overlaps between 3.21 and 3.92 axle gears in these trucks. The RPMs are different at any speed between the two, and not only does the 3.92 have to work less to get the truck moving which improves mileage around town, or with a trailer, or without a trailer, but it also responds better in the middle gears and it has an 8th gear RPM that's actually more comfortable on the highway, where the 3.21s would either put you at higher RPM in 7th or lower RPM in 8th and cause more downshifting.

There's a reason the 3.92 gears are an option that you pay for, and it's because they know it's the most desirable ratio.

 

[Neurobit]

Looks like a 4 MPG advantage for the 3.21, which is a lot.

 

[silver billet]

Which requires more fuel: maintaining speed on the interstate, or getting a 5,500 lb. vehicle moving from a stop?

I posted this in another thread which took some time, so I won't do it here, but there are NO points in any gear where the RPM overlaps between 3.21 and 3.92 axle gears in these trucks. The RPMs are different at any speed between the two, and not only does the 3.92 have to work less to get the truck moving which improves mileage around town, or with a trailer, or without a trailer, but it also responds better in the middle gears and it has an 8th gear RPM that's actually more comfortable on the highway, where the 3.21s would either put you at higher RPM in 7th or lower RPM in 8th and cause more downshifting.

There's a reason the 3.92 gears are an option that you pay for, and it's because they know it's the most desirable ratio.

WXman, you keep posting this same misinformation. It's wrong in the other threads, and it's wrong in this thread. Read this chart, look at the numbers, and please stop posting bad data. You're confusing other people as well and possibly causing them to purchase the wrong gear (costing them mpg).

The shaded cells are where the 3.21 and 3.92 are pretty much equal, just offset by 1 gear. You can see the difference is minimal.

You only benefit from the 3.92 if you're pulling a very heavy load (to get off the line; while towing at city or highway speeds, both will have the same final ratio available, just offset by a gear). Or, if you plan on offroading like the rebel, where the 3.92's extra torque in first is a benefit for rock crawling.

 

[Roaminglost]

I have 3.92 and it runs great. added 35s lift and camper shell (weight) and the truck runs no different than stock.