Axle Ratios
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Tuned
Joined: Jun 2023
Posts: 348
Likes: 146
From: Houston
Axle Ratios
I'm trying to figure out all the details for a 350 to serve as a new tow vehicle. This will be wayyy too much truck for my current needs but I'd like to be able to tow a shorter, lighter 5th wheel in the future. The largest trailers I've been looking at for reference are in the 10-11k GVWR range. All of the weight numbers work out but I cannot figure out if the 3.31 axle would be enough with the 6.7L standard diesel. The current configuration I've saved is using the 3.31, but how much would this struggle on hills and steeper inclines to accelerate and maintain travel speeds? For reference, we're on pace for around 60-70 days this year in the camper and will only grow in future years. Want to start visiting national/state parks and general travel in North America. Would I be disappointed with 3.31 performance with heavier trailers or should I swap around options so we can upgrade to the 3.55?
ETA The FX4 package is what is currently "restricting" me to 3.31 but I don't see much that can't be added or enabled after delivery.
- Hill Descent Control - can this be enabled with FORSCAN? At first I thought this was the engine brake but this looks different. I doubt it would be needed ever but still curious if it could be enabled.
- Shock upgrades - can be upgraded later if necessary
- Skid plates - can be added later if necessary
- FX4 decal - outraged I'd miss out
ETA The FX4 package is what is currently "restricting" me to 3.31 but I don't see much that can't be added or enabled after delivery.
- Hill Descent Control - can this be enabled with FORSCAN? At first I thought this was the engine brake but this looks different. I doubt it would be needed ever but still curious if it could be enabled.
- Shock upgrades - can be upgraded later if necessary
- Skid plates - can be added later if necessary
- FX4 decal - outraged I'd miss out
Cargo Master
Joined: Jul 2003
Posts: 3,360
Likes: 250
IMO the FX4 package is a waste of money for what you get.
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
Cargo Master
Joined: Jul 2021
Posts: 2,970
Likes: 2,407
From: Ridgway, CO
The standard 6.7 has a claimed 1000 lb/ft of torque. They do not offer a gear ratio that motor can't pull. The 3.31 is probably rated to tow over double what you heavier trailer will weigh. With the ten speed trans there is almost no performance difference between 3.31 and 3.55. You are concerning yourself over something that is absolutely not a problem.
Cargo Master
Joined: Jul 2021
Posts: 2,970
Likes: 2,407
From: Ridgway, CO
IMO the FX4 package is a waste of money for what you get.
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
Thread Starter
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Tuned
Joined: Jun 2023
Posts: 348
Likes: 146
From: Houston
IMO the FX4 package is a waste of money for what you get.
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good
Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it
Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality
FX4 Decal- buy one if you want the look.
If it was me I'd skip the FX4 and get the 3.55 gears
The standard 6.7 has a claimed 1000 lb/ft of torque. They do not offer a gear ratio that motor can't pull. The 3.31 is probably rated to tow over double what you heavier trailer will weigh. With the ten speed trans there is almost no performance difference between 3.31 and 3.55. You are concerning yourself over something that is absolutely not a problem.
Cross-Country
Joined: Oct 2022
Posts: 78
Likes: 33
Based on the tow guide for a ‘23 SRW both the 3.31 and 3.55 are more than capable for your listed weights. I don’t see a need one way or the other, and unless someone has both a 3.31 and a 3.55 to do a comparison you may just need to order based on the features that come with the truck. What I mean by this is, I would order based on if the need for the items you listed, skid plate, shocks, hill descent and so on. I don’t think a gear as close in ratio as the 3.31 and 3.55 would be my deciding factor. Not that I could get a 3.31 in my case (DRW) but I prefer the 3.55.
Thread Starter
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Tuned
Joined: Jun 2023
Posts: 348
Likes: 146
From: Houston
Based on the tow guide for a ‘23 SRW both the 3.31 and 3.55 are more than capable for your listed weights. I don’t see a need one way or the other, and unless someone has both a 3.31 and a 3.55 to do a comparison you may just need to order based on the features that come with the truck. What I mean by this is, I would order based on if the need for the items you listed, skid plate, shocks, hill descent and so on. I don’t think a gear as close in ratio as the 3.31 and 3.55 would be my deciding factor. Not that I could get a 3.31 in my case (DRW) but I prefer the 3.55.
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Tuned
Joined: Jun 2023
Posts: 348
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From: Houston
That's what it seems like. The online configurator prompts me to add the FX4 package if it's not selected and I try to add on skid-plates. Looking at the order guide, it appears they are only available with the XL offroad, FX4, and Tremor packages
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With the ratios in the 10 speed trans, the 3.31's will pull ANYTHING you hook the truck to over the tallest mountains without breaking a sweat.
And, there is so little difference in ratio between 3.31 and 3.55 you would never feel the difference.
So, if some package you want, restricts you to the 3.31's, don't worry about it at all, get the package and move on.
And, there is so little difference in ratio between 3.31 and 3.55 you would never feel the difference.
So, if some package you want, restricts you to the 3.31's, don't worry about it at all, get the package and move on.
Fleet Mechanic
Joined: Oct 2006
Posts: 1,351
Likes: 242
From: North Florida
I am towing over 15,000 pounds with 3.31s. It handles it just fine. The 10 speed transmission makes the difference. My 2016 6.7 6 speed had 3.55s. I didn’t notice any drop off with the 3.31s on the 2022. When you look at the actual final drive ratio between the two, it is the same in 1st gear and 6th gear in the 6 speed 3.55 is the same as 9th in the 10 speed 3.31.
Fleet Mechanic
Joined: Aug 2022
Posts: 1,590
Likes: 1,117
What they said; it doesn't matter for the weights you are talking about. Mileage won't be any different either. That said, I'd choose the 3.55's especially if you plan on bigger tires which, it seems, 90% do (not me). I don't think the FX4 is really worth ordering and IIRC, skidplates were still a separate option on the Canadian configurator when we ordered our 2023 but we didn't order them. I'd pick the 3.55's over the FX4 but you'll be just fine either way. I tow my 10,000 lb load up any hill at the speed limit.
Cargo Master
Joined: Mar 2021
Posts: 2,044
Likes: 1,336
if what you’re saying is true then this is a good reminder to not believe everything you read on here. The post was made sounding like he had the utmost certainty yet every last bit of it could be incorrect.
Thread Starter
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Tuned
Joined: Jun 2023
Posts: 348
Likes: 146
From: Houston
5th wheels are not, which is what I'd like the capability to do. They weigh too much.