Hi,

I'm new here in the forum. My wife and I are planning on semi retiring and take to the road as professional nomands. We sorta have 5th wheel picked out and we are specing out our Ram to pull it. The trailer is rated at 20,000 pounds and we are looking at obviously a 3500 Ram deully, Cummins 6.7l, crew cab, new or slightly used.

My questions are in regards to the appropriate gear ratio to go with. According to building my Dodge, I have 3 options. 4.1, 3.73, and 3.42. While the 4.1 gives me ample pulling power, the 3.42 gives me fuel economy and still have just enough trailer capacity for my 5th wheel. However, there's no performance data.

Anyone out there with similar setups can give me some real world experiences? What ratio do you have and would you have gone differently? How was your mileage under load and cruising dead head? Is there more data out there or calculators I can plug in data to get a better picture? What ratio gives me optimum hp and torque under load on the highway? And other insight be helpful.

I avoid dealerships because they are there to sell trucks. I want to buy the right one for me. I like to find a happy balance of performance under load and fuel economy once I get there. Thanx beforehand

 

3.73 are a good gear. I have them in my 2500. 3.42 are good for fuel, truck will struggle pulling a hill. 4.10 you will pay for in fuel. Your other option would be to look at a lighter rv. You will enjoy the nomad life style. We started in 2010.

 

What kind of mileage do you get without the camper?

 

That's a heck of a heavy trailer.

I had 3.73's in my 08 2500 and towed about 15000 pounds around for a while, got a good solid 12.5 mpg and never had any issues with getting up to speed or pulling hills.

The biggest problem was dragging that thing up to Rushmore - the steep grade and iirc 25 mph limit had me heating the trans up pretty good (68rfe).

I had a Black Maxx programmer and egr/dpf deletes at the time, but ran the lowest tune while towing.

What's the pin weight on that camper? Make sure you factor that into your truck purchase.



Edit: When I moved back, I towed the trailer behind my current truck, 98 12 valve with the 47re and 3.55 gears. Again, not really any problems pulling hills or maintaining speed, but it wasn't really happy with stop and go traffic (trans temps again).

 

We don't have the camper yet but the over all rated weight will be in 20,000 lbs range. once loaded, it will not be far from its max rated weight. Now we know what we want, we are planning to get the truck first and get it broken in before we really work it. We are planning to getting the AISIN 6 speed mainly for the Mrs. Need to research that tranny more. It will also have a transmission cooler. Although with building a truck on Dodge's website which I can go with the 3.42, im leaning towards the 3.73. Sort of the middle of the road Per say. With the 6.7 Cummins and the AISIN transmission, I'll have ample torque so I have not given up on the 3.42 just yet.

What kind of mileage do you get when you are not pulling your camper?

 

Before the deletes 8 after 12. We are a little over 13K.

 

My 08 was 10 before, 15 after. But I drove it like it ran 13s in the 1/4 mile (which it did).

 

I pull a 38.5 ft. 5th wheel with my 08 2500 w/6 speed manual tranny. Wasn't happy with gear selection and so installed a "Gear Vendor" underdrive/overdrive and can split my shifts between most gears. Now I have 11 forward gears instead of 6 (can't use the overdrive in granny first gear). Improved my MPG and can pick my RPM on the hills.

 

3.73 with Aisin transmission is all you need to consider...