simoniz

Well here is my weekend experience. I took my son with me to North Fork WV from Greensboro NC to ride in our Polaris RZRS on some great WV trails! 398 miles round trip with quite a few 6 to 8 percent incline's!

Short towing history, I borrowed my dads Toyhauler (5th wheel XLR) . 12,860 dry weight. With the RZRS and gear it has to be close to 15,000lbs.. I've pulled this trailer with my dads Ford F450 DRW (4.56 gear) several times. Pulling with his truck, it pulls like a dream. No swaying, no rough shifting up or down, truck does not slow down! MPG's pulling this camper with his truck, 7.9 to 8.1.

Now for my weekend towing experience with my dads camper (5th wheel) with my 2012 Dodge 6.7 3500 DRW, 3.73.

I tried to stay bwtween 62 and 68mph. So I learned real quick I had to lock out in 5th. That was putting me RPM wise around 2100 to 2300. I had to drop down to 4th and to 3rd a couple of times because of temps! I was constantly pushing 221 degree's engine temps except for flats and down hill runs. I was told to keep it below 225 degrees. My tranny temps stayed between 167 and 186 degrees except for about 30 miles of the trip. That 30 miles the tranny temps got up to 220 degree's.

Here were my 2 fill up's fuel mileage wise. 167.9 miles, 22.964 gallons equals 7.31mpg! Next fill up, 167.4 miles, 22.62 gallons, equals 7.40mpg. So needless to say I'm a little on the not so happy side. This info. might not sound bad to others because of the weight but I have a Cyclone 4100 King Toy Hauler (5th wheel) on order that weighs almost another 2000lbs dry. So I'm really worried about my choice now! My dads F450 Ford just pulled this same trailer like a dream and got better fuel mileage. I know his has 50 more HP and the 4.56 gears so am I left with buying 4.10 or 4.56gears for my new truck?

Last note, I had some swaying action! Pretty bad coming down the mountains when passing 18 wheelers or getting passed by them! My truck just fealt to soft! (I also have Firestone air bags) had them at 40lbs.. I really feel if my dad or my wife would have been driving, I would not be sitting here typing this up.

Anyway, I'm just looking to here if others have had similiar experiences to mine with a 4th Gen Dually.

Thanks

Spooler

Pulling heavy, 4.10's are the best way to go. The 3.73's killed your mileage. You never said if it was a bumper pull or a 5th wheel.

C Schomer

I went from a 97 ctd w/3.54 5 spd to the 03 w/4.10 6 spd. The 97 had more power mods and would run circles around the 03 empty but the 03, overall, towed easier and went just as fast towing up hills. If I load a tune in the 03 so it has the same engine power the 97 had, the 03 would easily win every contest. Gearing really matters! I think you just proved the same difference between 3.73 and 4.56. Craig

j_martin

A sticky fifth wheel will make the rig wander and sway.

Hvytrkmech

I pull my 15k 5ver with the truck in my sig. Hauls it like a dream. Engine temp hovers from 190-210 dependent on the terrain. Tranny stays 180 or less as long as its in lockup. From a standing start the tranny will go to 200-210 but once in 3rd and locked it quickly falls back. I had an 03 F350 6.0 and torque shift with 373 rear haul the same trailer, the tranny made a huge difference but the engine was always on top of the governor, it did not pull as good as the Dodge. Honestly I wish I had the torque shift in my Dodge, it would be the perfect combo, but all in all I am pleased with how it performs across the board. I also average 12 mpg while towing on moderate terrain. I was 23k and change on a cat scale.

simoniz

Sorry, made the correction. It was a 5th wheel. I agree on the 4.10. I just really didn't think it would make much difference on a Diesel but I was wrong.

simoniz

Any other 4th gen guys out there have similar experiences? Anyone made a gear change on a 4th Gen.?

Thanks again guys, I thought I new a little bit and I do but every experiance you learn something new lol... I admit the ride home went alot better then the ride up. I was just not really expecting to have to do so much manual shifting and watching temps. My dads Ford F450 spoiled me I guess. I hope to make the right changes/adjustments to give me a better experience sooner than later. My HEAVY camper will be here in a week or 2 and I will be burning up the rode in it!

j_martin

After all, the 450 is a heavier class truck. Your 3500 properly set up should be more than ample for the task.

My first gen without lockup never gets over 200° on the tranny, usually running about 150° with a heavy load at 90° ambient. Do ya think the frame mounted electric fan transmission cooler might have something to do with that?

bnold

Gearing.... Forget the motor and trans differences between the f450 and your 3500. 4.56 to 3.73 towing anything of weight will show the difference in a hurry!


Why they offer a DRW 3500 in a 3.73 makes little sense to me. I wish my SRW 3500 was a 4.10.


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signature600

Boy I'm glad I don't own a camper.

I hauled a load of antique tractors this weekend, trailer and load was about 21K lbs, so gross weight with the truck should have been roughly 29K lbs. My 3500 SRW Auto w/3.42 gears did just fine, at about 10mpg for the trip.

Those campers are light, but maybe the wind is what hurts you. I know I've had better than 45K lbs gross with my 3.42's, and other than getting moving, it tows like a dream. Getting moving takes a little pedal as you'd expect, but the torque of the 6.7L does a fine job.

Chris

409CI

Your mileage was most likely killed by your high RPM's. If your locking out 5th you should slow it down. These engines run the best between 1600-2000. I had an 06 that would take a dive on the mileage anytime I ran over 2k on the tach. I always tried to set my cruise by an rpm rather than a speed...

Ahlkey

I am new to the forum but already this thread makes me feel that I made the right decision to buy the heavy tow package RAM 4500 (4.88) over the 3500. I went back and forth numerous times but given I will be pulling close to 20,000 lbs at times I liked the larger 4.88 axle, brakes, tires, and transmission. MPG will suffer with the larger truck weight and the 4.88 ratio but I would rather have the right truck to do the job rather than pushing its limits. I think it would be better comparing the F450 to the 4500 with the standard 4.44 axle.

simoniz

It's hard to hold back my disappointment. I will probably be re-gearing to 4.10, then deleting the EGR and DPF and a H&S mini mag, and a S&B intake.

zulusafari

As has been stated, it really is a big gap comparing a 4.56 geared truck to a 3.73 setup! I have never been settled on the issue, myself. Running in 5th, with higher RPMs and associated noise is not what I want to do, and it seems counter intuitive that the mileage would be better. But then again, I have first knowledge of two very heavy vehicles with different engines in them, one 272 Cu In, the other 354 cu in, and the 354 gets MUCH better mileage than the 272. Same transmissions, though I don't know what the rear gearing is. The bottom line is the power to weight ratio, and the loading on the engine vs. driveline. I see tractors working all day long, pulling deep and heavy, running on 190 hp, or less. They don't go fast, but they go all day and on little fuel. It is all in their gearing.

zulusafari

Its also difficult based on user posts on the boards --

I had 4.10's in my 2001.5, and mileage sucked. Towing was easier though, and I had the 47RE auto. At the time, everyone seemed somewhat condescending, relating great tales of hauling very heavy loads with 3.54's, if I remember, and 35's, auto or manual, 20k lbs, etc., getting fantastic mileage all the time. The consensus then was that the 4.10's were an unnecessary $50 option that you kept paying for at the pump every single time you drove the truck. For the times I haul, I think that running the truck in 5th at a lower speed will be fine, and keeping the better gearing for running around unloaded (my wife gets to use the truck as her daily driver -- she doesn't have a commute, so it is for whatever errands and trips she and the boys do. any decent shopping is at least 30 minutes away, so the truck warms up well and all.) should gain me some mileage for the vast majority of the trucks life. EVerything is a compromise.

If you are going to be running the truck towing your new heavy load, and mostly that purpose only, I encourage you to regear the truck. Look to see if anyone with the 4.10's wants to swap to 3.73's. I was working on a deal with a guy to do that, but he had almost 180k miles on stock brake calipers and rotors, while I had all new brakes installed all around. We were going to swap axles complete - hub to hub, front and rear, even steven trade. He wasn't interested in upgrading his brakes or swapping mine and his out, so we didn't complete the deal.

If you are going to regear, are there any other ratios available for the AAM1150 that you could use? 4.30's or anything similar? Chevy uses the same axle, and might have different options available, too! That would bring you even closer to the 4.56 you are used to.