Gear ratios and towing weight capacities

[stateofdade]

I've been searching a lot and still have yet to see real numbers for towing capacity using the ZF using different rear ends other than the 3.21 and the 3.92 that are factory options. I know the 3.92 effectively adds the ability to tow about 2k more than the 3.21. What does the 4.10 do for you? Another 700lbs or so? What about the 4.56? I see that Moe's offers these and I've been thinking about investing in a new rear-end since I like my truck and I don't want to lose money on it by trading in since I have such a good interest rate.

 

[Mike Murphy]

Here is the official dodge tow report for 2018. Select your truck on the right and all the gear ratio options and tow capacities will come up on the left.
https://www.ramtrucks.com/content/dam/fca-brands/na/ramtrucks/en_us/towing/2018 Ram 1500.pdf

 

[dhay13]

From a technical and legal standpoint it won't do anything for you. From a practical standpoint it would help but you will still be 'legally' restricted to what your truck is rated for

 

[Toddbigboytruck]

Thanks for the chart how ever I am more lost. I have a 18. 5.7 crew 6.4 box Laramie with a 3.21 could anyone help me figure this out been told 8000 to 8750

 

[Mike Murphy]

Thanks for the chart how ever I am more lost. I have a 18. 5.7 crew 6.4 box Laramie with a 3.21 could anyone help me figure this out been told 8000 to 8750

Here you go, looks like 7760 lbs.

 

[ThunderMug95]

Thanks for the chart how ever I am more lost. I have a 18. 5.7 crew 6.4 box Laramie with a 3.21 could anyone help me figure this out been told 8000 to 8750

7700lbs

 

[dhay13]

Thanks for the chart how ever I am more lost. I have a 18. 5.7 crew 6.4 box Laramie with a 3.21 could anyone help me figure this out been told 8000 to 8750

According to the Ram site it is 8040lbs if it is a 4x4. It won't let me select 4x2 with those options so I'm assuming it is a 4x4?
https://www.ramtrucks.com/towing-guide.html

 

[ThunderMug95]

Also to mention to the OP...if your truck is a 4x2, you can work different ratios if they are made for the ZF.
If you are a 4x4, you have only 2 choices in your model year, 3.21 or 3.92. The front diff is a welded in carrier and you must swap out the entire differential...even ti swap btw 3.21/3.92 or vice versa. There is a retrofit to put a 2010 era differential in that would allow you to go with gears other than the 3.21 or 3.92....

 

[Toddbigboytruck]

Sorry all yes 4x4. 2018 Laramie 4x4 rear is 3.21.

 

[mtofell]

I've often wondered a similar thing with my 2500 6.4 but you really can't find a concrete answer once you go above the factory gears. Basically, Ram only rates the trucks for factory gears so after that you are just guessing.

The real question is if/what is the weak link in the chain beyond gearing that would prevent you from pulling more weight?

My 3.73 gears rates me for a 12500# trailer but the 4.10s bump that up to 15,500#. So, if I were to go to 4.56 could I then pull a 17,000# trailer (not that I have any desire to)?

A little insight was offered with the new 8spd tranny on the 2500 6.4 gasser. I can't remember exactly what it is but the max towing was bumped up a bit for both gear ratios (still 3.73 & 4.10) which tells me the tranny probably is the weak link and going beyond the 15,500# with the 4.10s in the pre-2019 6.4 HDs probably isn't advised.

Of course, this is all a bit apples to oranges with OP's truck being a half-ton but it's the same concept.

 

[Mike Murphy]

I've often wondered a similar thing with my 2500 6.4 but you really can't find a concrete answer once you go above the factory gears. Basically, Ram only rates the trucks for factory gears so after that you are just guessing.

The real question is if/what is the weak link in the chain beyond gearing that would prevent you from pulling more weight?

My 3.73 gears rates me for a 12500# trailer but the 4.10s bump that up to 15,500#. So, if I were to go to 4.56 could I then pull a 17,000# trailer (not that I have any desire to).

A little insight was offered with the new 8spd tranny on the 2500 6.4 gasser. I can't remember exactly what it is but the max towing was bumped up a bit for both gear ratios (still 3.73 & 4.10) which tells me the tranny probably is the weak link and going beyond the 15,500# with the 4.10s in the pre-2019 6.4 HDs probably isn't advised.

Of course, this is all a bit apples to oranges with OP's truck being a half-ton but it's the same concept.

My initial thought is the final planetary gear set in the transmission. A five planet gear set will pull (have more torque) more than a four or three planet. They may be other factors such as suspension, etc.

 

[Longhorn1500]

My initial thought is the final planetary gear set in the transmission. A five planet gear set will pull (have more torque) more than a four or three planet. They may be other factors such as suspension, etc.

Looks to me like that one has six planets, even better!

 

[stateofdade]

I have a 4x2 with the 3.21 so I know I'm rather open regarding my options. I understand the "legal" issues in relation to how much you can tow, but I'm also looking at what kind of reasonable results I could expect to get from moving to a 4.10 rear-end as it appears to be cheaper than moving to a 3.92. Obviously, it will allow more potential towing capacity, but I'm not finding any real world figures for how to calculate this. The only answers I've seen stop at what the factory rates it with the 3.92 since that's the only factory option. What is the math that allows them to calculate towing capacity to gear ratio?

Alternately, I imagine that a 4x4 would technically (on paper) have less potential towing capacity due to added weight from the crank and 4x4 additions to the truck?

 

[mtofell]

I have a 4x2 with the 3.21 so I know I'm rather open regarding my options. I understand the "legal" issues in relation to how much you can tow, but I'm also looking at what kind of reasonable results I could expect to get from moving to a 4.10 rear-end as it appears to be cheaper than moving to a 3.92. Obviously, it will allow more potential towing capacity, but I'm not finding any real world figures for how to calculate this. The only answers I've seen stop at what the factory rates it with the 3.92 since that's the only factory option. What is the math that allows them to calculate towing capacity to gear ratio?

Alternately, I imagine that a 4x4 would technically (on paper) have less potential towing capacity due to added weight from the crank and 4x4 additions to the truck?

I think a 4.10 and 3.92 are so close that the difference would be very slight.... like a few hundred pounds. However, with the 3.92 (or 4.10) and a 2WD you would have quite a capable truck for sure.

You are correct about the 4X4 having less capacity due to weight. This is always a funny thing that surprises people - the most capable truck is the one that has the least stuff already in it. A somewhat extreme example of this is in HD trucks with regards to payload (NOT towing/pulling). A diesel usually has about 700# less payload than a similarly equipped gasser since the diesel weighs more. With pulling the diesel is superior by a mile but when the rating is weight on the truck it's actually not ideal.

 

[watajob]

I don't know about a specific capacity difference. What I can say for sure is I went from a 3.55 open for a 4.10 locker and not just towing but drivability in general improved markedly. The best way I can describe it is the truck feels much more "relaxed" now. And, there was no penalty in fuel mileage, which I found amazing.

 

[Ratket]

Bottom line. The truck has the power to pull the load regardless of gears. The 1/2 tons all have the same stopping power. The suspensions vary but that can be easily fixed/Manipulated. The biggest advantage to gears is the “ Drivability” and how well it pulls the load at the speed you “ want “ to pull at. If you are fine just taking your time and in no rush and don’t mind slowing down a little more on big hills then it’s a mute point. But if you want it to pull that grade at 70/80mph.. the motor will work a little easier with a better set of gears.

 

[stateofdade]

Bottom line. The truck has the power to pull the load regardless of gears. The 1/2 tons all have the same stopping power. The suspensions vary but that can be easily fixed/Manipulated. The biggest advantage to gears is the “ Drivability” and how well it pulls the load at the speed you “ want “ to pull at. If you are fine just taking your time and in no rush and don’t mind slowing down a little more on big hills then it’s a mute point. But if you want it to pull that grade at 70/80mph.. the motor will work a little easier with a better set of gears.

I tend to take it easy when pulling a large load simply for safety. It's not just my butt on the line but the drivers around me. I see people going 70-80 mph pulling big loads and it's just unsafe. If they have to hit the brakes, it's bone chilling. Also watching someone pulling a large load and seeing that joker swinging side to side is a scary proposition. I'm looking for easier transitions when pulling grades on the interstate which is why I'm thinking of swapping out the 3.21 for a 4.10. Does anyone have a round-about figure for the cost of labor on something like that? I know the gears will cost me about $300 from Moe's, which is a super reasonable price.

 

[ThunderMug95]

Theres just so many factors. Wheelbase, brakes, power, gears, trans, tires. If I was EVER going to tow near max weight in my 1500 on a regular basis it would get sold and Id buy a 2500. Just because you can get it up to speed doesnt mean you can control it in a turn or stop it safely. We all have seen crazy crap on the roads...use the proper tool for the job.

 

[Dan Lockwood]

Mike, didn't want to hi-jack this thread, but I couldn't find a button to PM you.

Where can I get a towing chart like the one you posted above, but for my '12 RAM, crewcab, 3500, 6.7L, 6-spd auto, 3.72 rear gear?

Again, sorry for slight diversion to my question.

Have a great day!

 

[crash68]

Where can I get a towing chart like the one you posted above, but for my '12 RAM, crewcab, 3500, 6.7L, 6-spd auto, 3.72 rear gear?

Let's see if this works for you:
http://www.rambodybuilder.com/2012/docs/ram/rammlup3500.pdf
It's a PDF download with all the towing infromation for the 2012 3500s