yannick

I currently have an 02' HO 2500 with the 6 speed tranny and 3.53 rear. I tow a large (14,000) Lb fifth wheel trailer.

I am considering a new 04.5 or 05. I am really torn on choosing the rear axle ratio btwn 3.73 and 4.10.

Legally, I can't tow my trailer without a 4.10 rear but realistically, the 3.73 is bound to be adequate If I am currently doing well with a 3.53. What do you guys recommend? Is there a large difference in fuel economy from the 3.73 to the 4.10? My preferred cruising speed while towing on highways is 70 mph with bursts up to 75mph. I am curious as to engine revs at 70 mph. I fear the 4.10 will force me to drive at a much lower speed to get reasonable fuel economy. Then again, the 3rd generation trucks have larger diameter tires so that's bound to help the picture with a 4.10 rear right?

Does anyone have an opinion on short box vs. long box for towing? I am assuming that the longer wheelbase will give a better ride and negate the need for a sliding fifth wheel hitch.

Any comments or opinions are welcome

Thanks in advance for your help

Yannick

Mcmopar

IMHO,

4.10:1 and the short box!!

PapaPerk

I pull an 8000 lbs trailer with 3.73. No problems what so ever. Of course that is not 14,000 lbs like you. But at 70 mph the RPM is right at 2000. This is where the fuel mileage really tanks. So with 4.10 gears I would say 70 mph will be excessive.

Also if I was pulling 14,000 lbs. I would most certainly get a dually!

RustyJC

Check my signature for the rig that pulls our 16,000 lb GVWR 5th wheel. With the NV-5600 and 4.10 gears, 70 MPH in 6th is 2350 RPM, 75 MPH in 6th is about 2500 RPM. I've pulled the 5th wheel all day on the Interstate at 75 MPH and the engine likes it just fine - no oil consumption, good coolant temperatures, etc.

As you said, the 3rd gen will have taller tires than my 2002, but I believe the new G56 6-speed has a shorter 6th gear.

Rusty

HOHN

Don't be afraid to wind up the Cummins. It can handle the rpm just fine. You're far more likely to hurt the engine from lugging it with a heavy load than from winding it up a bit.

That said, I'd go with the 3.73 gears. This will deliver marginally better fuel economy when empty. You aren't likely to put significantly larger tires on a dually that tows heavy, so the taller gearing is fine.

Keep in mind that the G56's shorter OD ratio will partially negate the taller gears.

I've been of the mindset that you can always downshift if you gears are a little too tall, but if they are too short, there's nothing you can do once you're in OD.

Thus, to me, gear selection is about initial launch and legality. If you need a certain gear to be legal at a certain weight, then you have no choice if you value legality (Like RustyJC's situation). If you can launch your truck without excessive clutch slippage, then you have plenty of axle gear reduction, and going shorter on gears (numerically higher) will only hurt fuel economy.

yannick

Thanks for the help guys.

Is anyone running the stock 17" wheels and a 4.10 rear? Any idea on fuel mileage at 70 mph either empty or towing?

MedicShawn

I started out at about 14-15mpg new. I'm now getting about 17.25 after all the flashes and on winter fuel. I am about to turn 20K for milage. I drive about 75%on the highway. I try to run about 69 with the cruise on to help my mileage as much as possible. Thats turning about 2250 rpm wise. I don't really tow anything with weight so I can't really speak to that.

Blessed

I would go with the 3.73 rearend because more than likely you will be putting more miles on your truck NOT pulling then pulling. And it is more fun to drive a 3.73 than a 4.10. The 3.73 will get better fuel economy. I know for a fact that a 3.73 can handle 14,000 lbs. My RV weighs 12,000lbs (weighed on truck scales) and I have never had a problem pulling ANY hill.

As HOHN said you can always downshift a 3.73, but you cannot "add a 7th gear" to the 4.10. I would say a 4.10 would only be needed if you CONTINOUSLY pull extremly heavy loads >17,000 lbs (i.e hotshot pulling, 4 car hauler, etc)

Also, if your pulling a large 5th wheel- get long box- only way to go. Because if you trade RV's at some point in the future- you will probably get a RV than is as big or bigger then the one you have now. For example, you very, very seldom see someone with a 35 foot 5th wheel to trade and go back to a 30 footer, etc.....

just my .02

Mcmopar

I really don't think the gearing will make that much difference. Case in point, My 98.5 3.54 4X4 2500 gets about 19.5 Highway only unloaded, my Dad's 96 4X4 4.10 dually gets 20 empty same speed, my work truck 96 2500 4X4 4.10 gets about 21 empty.

redneckonthenet

Ya 70 mph it runs about 17.5 give or take a point or two (empty). Towing 8000 lbs. travel trailer it will run 70 mph at 14 or so. If ya can keep it down that far, I have a hard time not running it at 75 or 80! They said it would happen. "The power will go to your head" it did!
Towed the same trailer with 1/2 ton 318 never saw 70. Not ever downhill

pquestad

i would reccomend getting a long bed....and running 3:73 gears..there is not a big difference in rpm's, however, it does make a big difference in fuel economy..even 200-300 rpms at 70 mph is huge on a road trip...also.. i agree with "Blessed"..you will be putting more miles on your truck unloaded than loaded...3:73 is much nicer to drive...

yannick

O.k. Guys your feedback is greatly appreciated. I'm pretty convinced that the 3.73 and long box is the way to go for a recreational hauler.

Now for the big one: I'm getting a 3500. Single rear wheel or dual?

I'm leaning towards the single rear wheel as it costs less to operate (i.e. tire costs and slightly better fuel economy due to fewer tires on the ground)

Currently, I have no issues with my SRW 2500 pulling my fifth wheel . I did have a scare in a freak wind storm once where the trailer almost flipped on me on the highway just as I was entering a mountain pass. The crosswind gust came out of nowhere at about 80 mph and I was sure i'd lose it - the trailer rocked side to side a few times and scared the living crap out of me.

I think that a dually gives you a lot more security in a situation like that. But I'm not sure that's enough to warrant the extra long term cost.

What do you guys think?

Thanks again ya'll are really helping me out here

RustyJC

14K trailer = dually.

Rusty

yannick

Rusty,

Could you elaborate a little on your opinion?

The 2005 Dodge towing guide shows that a SRW 3500 with a 3.73 rear can have a max trailer size of 13,600 LB while the DRW is 13,450 Lbs

With a 4.10 the max trailer weight is:

DRW = 15,450
SRW = 15,600


So then my question becomes, why should I get a dually if a single rear wheel has the capacity to handle the loads?

I'm not being smart just trying to clear up my ignorance and reconcile the fact that according to Dodge, 14K trailer does not equal dually

boarbuster

A dually isn't necessary even though some people swear to it.

The 3.73 ratio will do just fine for pulling anywhere up to around 30,000, anywhere above that the load should probably be on a semi.