3.55 vs 4.10 gears

**CBF1955** · 03-20-2021, 03:32 PM

We just ordered a new Solitude 310GK, about 15K pounds loaded. We also will be ordering a new F350 diesel dually. I ordered the 3.55 gears, but I still have time to change that to 4.10.
Curious whether I am really sacrificing pulling power and will I get better mileage?

**TheLexx** · 03-20-2021, 03:39 PM

With 1050 ft/lb of torque I don't think you'll be lacking for pulling power. If you're pulling big hills all the time, maybe the 4.10 gears might be better, but you'll be saving a lot of fuel with the 3.55 gears otherwise.

**orbsah** · 03-20-2021, 03:40 PM

I feel like I have plenty of pull with 3:55. That said, I’ve never tried 4:10 so I can’t compare.

**cfowler55** · 03-20-2021, 03:40 PM

I’m towing a 310 with a RAM & 3.73 gears. Plenty of power , and we tow in the Rockies at least once a year. The new Ford will probably have a smidge more torque , I’m at 1000 , and the new 10 speed transmission. You should be good with 3.55 with that weight.
Charlie

**sirtate** · 03-21-2021, 08:40 AM

The 10speed makes all the difference..

Do the math of all of the gears' final drive ratio. (3.55 x gear ratio)...
I bet you find the starting gear calculate out as the same as the 6spd with 4.3 rear end... (Gear ratio x rear end ratio)

The lower rear ends of days gone by were needed to provide torque multiplication to get the heavy rig rolling with only 3 or 4 gears to choose from.

Now with a 16.4 starting overall ratio, they aren't needed...(6 speed had 15.99 overall in first, BTW)

You get the same grunt when heavy with much taller, quieter, economically better when light, top gears...

It's a win/win

Sent from my LM-G900 using Tapatalk

**210craig** · 03-21-2021, 04:31 PM

I have a 2020 dually with 4.10. I pull a 20k 397th like it was on rails. I buzz down the freeway at 65 and rarely fall out of 10th.in tow mode. I was plesantly shocked at how well it pulls the beast. I know alot do tow with 3.55 but most tow the big boys with f450 with 4.30. With the virus I was not able to get one so i went with the f350 with 4.10 and that was not easy to find. The milege hit was not that bad. I added a 50 gal aux tank to give me plenty of distance.

**RobWNY** · 03-21-2021, 04:52 PM

This is apples and oranges to this discussion but my 2020 Silverado diesel with the 10 speed has a 3.42 rear end and there are no options to get anything different. The 10 speed does make all the difference.

**huntindog** · 03-21-2021, 05:07 PM

Originally Posted by RobWNY

This is apples and oranges to this discussion but my 2020 Silverado diesel with the 10 speed has a 3.42 rear end and there are no options to get anything different. The 10 speed does make all the difference.

True, but for a few reasons. The GMs were late to the party with the high tow ratings in the 30K + range. When this first occured I had a conversation with a long time GM employee and asked him why GM wasn't going along and just lowering the rear end ratio as the others had. I thought his reply was B. S. at the time. He said "We cannot get the pinion gears at lower ratios to live behind the Duramax, and we will not raise the rating with the 3.73, as we do not think our customers would be happy with it" Fast forward to 2020 and the new 10 speed tranny. Because of the ratios in the tranny, they can actually make the rear end gears taller and stronger, while lowering the final over all ratio.. Anyone that knows differentials knows that a 3.42 is stronger than a 3.73. And to make it even stronger, the duallys went from a 11.5 ring gear to a 12.0. Those two changes are consistant with what my friend told me some years ago.
Now I no longer think my old friend was talking B. S. back then.

**zinman** · 03-22-2021, 11:04 PM

Originally Posted by CBF1955

We just ordered a new Solitude 310GK, about 15K pounds loaded. We also will be ordering a new F350 diesel dually. I ordered the 3.55 gears, but I still have time to change that to 4.10.
Curious whether I am really sacrificing pulling power and will I get better mileage?

@CBF1955 you will be fine. I tow our Solitude 375WB which is close to your rv weight with my F350 and do not have any pulling issues with the same gearing and less torque than your new truck will have. I'll take the 3.55 particularly for the everyday driving and fuel mileage. Safe travels!!

**That 1 Ron** · 03-23-2021, 08:46 PM

Originally Posted by huntindog

True, but for a few reasons. The GMs were late to the party with the high tow ratings in the 30K + range. When this first occured I had a conversation with a long time GM employee and asked him why GM wasn't going along and just lowering the rear end ratio as the others had. I thought his reply was B. S. at the time. He said "We cannot get the pinion gears at lower ratios to live behind the Duramax, and we will not raise the rating with the 3.73, as we do not think our customers would be happy with it" Fast forward to 2020 and the new 10 speed tranny. Because of the ratios in the tranny, they can actually make the rear end gears taller and stronger, while lowering the final over all ratio.. Anyone that knows differentials knows that a 3.42 is stronger than a 3.73. And to make it even stronger, the duallys went from a 11.5 ring gear to a 12.0. Those two changes are consistant with what my friend told me some years ago.
Now I no longer think my old friend was talking B. S. back then.

There’s definitely some truth to that. Having built a few high HP/torque D-max trucks over the years and having some friends with them as well, I saw a few snap the rear pinion yoke right off. I’ve also seen a couple snap the rear aluminum driveshaft as well. Then there’s the IFS front that has it’s own weaknesses. The new GM’s are supposedly stronger though.