Axle ratio

[c_l_phillips72]

Ok, probably the craziest question ever asked on the internet...

Can I change my truck’s axle ratio from 3.21 to 3.92?

I literally have no idea if that’s even possible, or how feasible it would be.

I’m asking because I’d like to buy a larger camper (didn’t ever think about one until now) and not be so close to the limits of my truck.

I’m looking at a camper with:
dry weight - 7,162
Carrying capacity - 2,518
GVWR - 9,780

My truck’s GVWR is 7,100, based on the placard inside the door. The GCVWR is 13,900, so my towing capacity is 6,800 so even if I towed the camper at its dry weight I’d still be over the max by 362 lbs..

If my truck had a 3.92 axle ratio, my GCVWR goes up by around 3,000 lbs.

Is it even feasible to change axle ratio’s for this purpose, and if so what’s the approximate cost?

***EDIT***
I saw a similar post where it sounded like changing the gear ratio was feasible, so I called my dealer and they quoted $5k for both front and rear.

For that cost, I think I’d just trade in my brand new truck and take a 5 - 8k loss and buy a new one with the axle ratio I wanted.

I was hoping I could get it done for around 2k, and I would have done that in a heartbeat.

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[Neurobit]

You've answered your own question. It will prob be cheaper to get a new truck. That being said, I believe you should be fine with the rear end you have now. Perhaps others with more towing experience can chime in.

Cheers,

 

[Jordan2929]

There was a thread a few weeks ago showing the differences of a 3.21 truck and a 3.92 truck. They tested 0-60 loaded and unloaded and the restuls were incredibly similar, like within a couple tenths of a second. This is most likely due to the 8 speed transmission being able to stay in the power band much better than a 6 speed could.

Edit: I found the thread- https://5thgenrams.com/community/threads/3-92-vs-3-21-who-wins-trucktrend-data-shows.5750/

 

[Gondul]

There was a thread a few weeks ago showing the differences of a 3.21 truck and a 3.92 truck. They tested 0-60 loaded and unloaded and the restuls were incredibly similar, like within a couple tenths of a second. This is most likely due to the 8 speed transmission being able to stay in the power band much better than a 6 speed could.

Edit: I found the thread- https://5thgenrams.com/community/threads/3-92-vs-3-21-who-wins-trucktrend-data-shows.5750/

A better test would have been identically equipped trucks with only the gearing being the difference... this 'test' is useless.

 

[Jordan2929]

A better test would have been identically equipped trucks with only the gearing being the difference... this 'test' is useless.

I don’t see how this could be useless information?

 

[Adrianp89]

The test is useless for the OP. It's not about speed, its about towing.

Anyways if you are going to be towing close to 10k - a 1500 is not the right truck for you. You really should go to 2500. Just because it "can" doesn't mean you should for long and often trips.

 

[2wd]

Your truck with 3.21 may be within the limits to handle this trailer. We need your actual Payload (door jam sticker) of the truck, and the tongue weight of the trailer.

Your towing weight limit should be around 8300 lbs for the trailer assuming you are not over the payload limits of the truck.

 

[NDanecker]

Yes it is possible, and judging by the fact you are asking the question you would need someone to do the work for you. Total job would be 2 - 3k depending on who you go to, OEM parts, reusing carrier / pinion bearings, etc.

Is it worth it? That is something only you can answer.

I changed a SRW to a DRW because I thought it was cheaper than getting a new truck. In the end it was not and resale was effected. Also didn't 'legally' increase my payload or tow capacity but it certainly handled like a DRW truck, and I was happy at the time.

So - from a legal aspect you may not increase your suggested GCVW as that is done by the mfg, but then again that number is just a suggested number and not enforced by DOT. But - something to think about in your decision making process.

 

[c_l_phillips72]

The test is useless for the OP. It's not about speed, its about towing.

Anyways if you are going to be towing close to 10k - a 1500 is not the right truck for you. You really should go to 2500. Just because it "can" doesn't mean you should for long and often trips.

I believe you’re right, but I’d like to hear your opinion on this if 90% of my towing was done within 100 miles, with one or two annual trips from Eastern Nebraska to the mountains in Colorado.


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[Dontra]

A 2500 with that weight would be the way to go

 

[c_l_phillips72]

Your truck with 3.21 may be within the limits to handle this trailer. We need your actual Payload (door jam sticker) of the truck, and the tongue weight of the trailer.

Your towing weight limit should be around 8300 lbs for the trailer assuming you are not over the payload limits of the truck.

From the sticker, payload is 1,667, with a GVWR of 7,100. Evidently that makes my curb weight 5,433.

Wouldn’t the tongue weight of the trailer be a percent of the trailer’s GWVR? I’ve read it could be between 9 and 15%, so 9,780 * .09 = 880.20, or 9,780 * .15 = 1,467.

If I understand things correctly, I’d need to add the tongue weight (880.2 or 1,467) to my weight, my passenger’s weight, the weight distribution hitch weight, and anything else I have in the cabin or bed if my truck to calculate the payload. If the tongue weight is truly 1,467, then there’s barely enough payload left for just me.

How would I know if the tongue weight should be 9%, 10%, or any up to 15%? Is there a selector switch?


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[lambone]

I agree that with close to a 10,000lb trailer you will be happier towing with a 2500.

I just downsized from a 2500/10,000 pound 5th wheel combo (which I will miss).

You also have consider your payload capacity. Check your load sticker on your door frame. Payload doesn’t change by switching gearing ratio.

With that camper fully loaded you will be pushing close to 1,000lb tounge weight. That will leave you very little to tow with your family and/or anything in the truck.

 

[Adrianp89]

I believe you’re right, but I’d like to hear your opinion on this if 90% of my towing was done within 100 miles, with one or two annual trips from Eastern Nebraska to the mountains in Colorado.


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I am probably not the best person to give an opinion on this, as my towing experience is pretty limited to 5k and under.

From what I have read, and I am sure others can chime in, even at 100 miles, a 2500 is still much safer and better choice, especially in mountains. I have no doubts the 1500 could perform the task, but the risk is significantly higher in a 1500.

If you were looking to trade in anyways because of axle ratio - I would def go 2500 at that point just to play it safe. Of course I am the type of person that is always over prepared and ready for anything that comes by way.

 

[lambone]

How would I know if the tongue weight should be 9%, 10%, or any up to 15%? Is there a selector switch?


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%10 is a general rule of thumb on how you want to set up your weight distrobution hitch. That doesn’t mean tounge weight will actually be %10 of the trailer GVWR.

There is no way to know the actual tounge weight of the trailer withought putting on the scale fully loaded. There are a lot of variables depending on what you have on board, and how you pack it, and the design of the trailer frame itself.

You could go to the dealership and the should have a scale. Have them put batteries and propane in it and fill all the the tanks with water. That will give you an idea.

You could also go onto the RV manufacturer forums and ask other owners with a similar model what their real world tounge weight is. A lot of RV enthusiats (that are smart) know their numbers.

Don’t believe the listed tounge weights in the brochures.

You also have to consider the experience of towing a heavy RV with a half ton truck. Trust me I’ve towed a 7,500lb trailer with a Tundra and a 10,000lb 5th Wheel with a 2500. The experience is night and day different.

Sure you can do it and your numbers may even be legal. But on a long haul you will either be wishing you had a smaller trailer, or a bigger truck. Been there, done that. Very expensive path to go down.

Now I’m back to a smaller truck and a smaller trailer. Mine is 4,500 dry, 23ft total length.

 

[RonH]

As others have said, you should probably be towing that trailer with a 2500. Or switch to a lighter trailer. Don't trust an RV dealer when he says your truck can pull it.

 

[Gondul]

I don’t see how this could be useless information?

If the intent was test the difference between axle ratios, the trucks should have been equipped exactly the same... they were not and this adds too many variables to make an apple to apple comparison.

 

[Zinger]

I'd buy a camper that is online with your current capacity before sinking money into a new axle or truck. You're looking at a major loss upgrading the truck. It's not like they don't make ultra light campers.

 

[lambone]

Just based on what you said:

“(didn’t ever think about one until now) “

It sounds like you have just started looking at trailers. Before you start considering redoing your gears or trading in the truck...

Let me give you a piece of advice. Don’t rush into buying a trailer. There are a lot to choose from. Buying one, especially new is a huge commitment because they depreciate a ton. Way more then a new truck. And they can be hard to sell. Ask me how I know...

You might consider finding a RV rental place and rent a small one for a weekend. Get a feel for what it’s like to tow it, then you will know better what you are comfortable with in your current truck.

When you start looking at RVs it’s easy to start getting sucked into wanting larger and larger units. But a small camper has a lot of advantages. Lighter, easier and cheaper to tow, easier to store, easier to reverse and easier to find suitable campsites.

It really depends on what your (and your families if that applies) needs are. Start with the bare minimum. Are you just going weekend camping? Are the kids old enough to want to be out in a tent?

What I did, which is a common mistake....

1. Bought a Tundra and decided I wanted an RV

2. Bought an RV that was nice but kinda big and heavy for the Tundra

3. Decided to upgrade the truck to a Ram 2500

4. Once I had the 2500 decided I wanted a 5th wheel. Which was a great setup btw, just now all of the sudden I was in a $100k rig just to take the fam camping a handful times a year. And the rest of the time I hated driving the 2500 around town.

5. Traded the 2500 for the 1500

6. Bought an 18ft trailer that I plan to cram the family into.

7. Selling the 5th wheel.

Way underwater on all of it. Don’t be like me...

 

[Neurobit]

Just based on what you said:

“(didn’t ever think about one until now) “

It sounds like you have just started looking at trailers. Before you start considering redoing your gears or trading in the truck...

Let me give you a piece of advice. Don’t rush into buying a trailer. There are a lot to choose from. Buying one, especially new is a huge commitment because they depreciate a ton. Way more then a new truck. And they can be hard to sell. Ask me how I know...

You might consider finding a RV rental place and rent a small one for a weekend. Get a feel for what it’s like to tow it, then you will know better what you are comfortable with in your current truck.

When you start looking at RVs it’s easy to start getting sucked into wanting larger and larger units. But a small camper has a lot of advantages. Lighter, easier and cheaper to tow, easier to store, easier to reverse and easier to find suitable campsites.

It really depends on what your (and your families if that applies) needs are. Start with the bare minimum. Are you just going weekend camping? Are the kids old enough to want to be out in a tent?

What I did, which is a common mistake....

1. Bought a Tundra and decided I wanted an RV

2. Bought an RV that was nice but kinda big and heavy for the Tundra

3. Decided to upgrade the truck to a Ram 2500

4. Once I had the 2500 decided I wanted a 5th wheel. Which was a great setup btw, just now all of the sudden I was in a $100k rig just to take the fam camping a handful times a year. And the rest of the time I hated driving the 2500 around town.

5. Traded the 2500 for the 1500

6. Bought an 18ft trailer that I plan to cram the family into.

7. Selling the 5th wheel.

Way underwater on all of it. Don’t be like me...

Great advice sir. Lots of things to consider.

 

[2wd]

Just based on what you said:

“(didn’t ever think about one until now) “

It sounds like you have just started looking at trailers. Before you start considering redoing your gears or trading in the truck...

Let me give you a piece of advice. Don’t rush into buying a trailer. There are a lot to choose from. Buying one, especially new is a huge commitment because they depreciate a ton. Way more then a new truck. And they can be hard to sell. Ask me how I know...

You might consider finding a RV rental place and rent a small one for a weekend. Get a feel for what it’s like to tow it, then you will know better what you are comfortable with in your current truck.

When you start looking at RVs it’s easy to start getting sucked into wanting larger and larger units. But a small camper has a lot of advantages. Lighter, easier and cheaper to tow, easier to store, easier to reverse and easier to find suitable campsites.

It really depends on what your (and your families if that applies) needs are. Start with the bare minimum. Are you just going weekend camping? Are the kids old enough to want to be out in a tent?

What I did, which is a common mistake....

1. Bought a Tundra and decided I wanted an RV

2. Bought an RV that was nice but kinda big and heavy for the Tundra

3. Decided to upgrade the truck to a Ram 2500

4. Once I had the 2500 decided I wanted a 5th wheel. Which was a great setup btw, just now all of the sudden I was in a $100k rig just to take the fam camping a handful times a year. And the rest of the time I hated driving the 2500 around town.

5. Traded the 2500 for the 1500

6. Bought an 18ft trailer that I plan to cram the family into.

7. Selling the 5th wheel.

Way underwater on all of it. Don’t be like me...

This is excellent advice. Right now I just rent the RV's and am able to try out lots of different sizes/configurations.