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4.1 vs 3.73


masterdrago
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New to 5th Wheeling. Got a fix on two new 5rs. GVWR ~ 16,500-16,800. Hitch weight ~2.900. Have a line on two tow vehicles. Dodge 3500 Crew Cab DRW long bed 6.7 liter Cummins diesel. Both have AISIN 6 speed auto tranny. One has axle ratio of 3.73, the other 4.10. I'm sure we will be doing travel to hilly and mountainous worlds. Leaning towards the 3.73 due to cost savings and rebates on 2017 in stock. One is 2018 = more $$$. What say you guys?

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Depends. How often are you towing? What size of tires? How much of a savings? Cash or financed should be considered as well on what you might be paying on top of the "up price".

If you consider resale at all... you'll get more back out of a 4.10 on a dually, but savings is savings if it's going to be a long time driver/TV for you.

If your towing is occassional the 6.7 Cummins with a 3.73 is likely to get you to where you're going and possibly save a little on fuel on top of the intial purchase savings.

I "would" say... if you're full time... you can never have too much truck and I would go with the 4.10. But that's just me. I consider longevity, ease and control under tow the ultimate deciding factor over price tags.

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How often? Wild guess, 20% of year or a tad less. Tires? Both trucks are 17" E rated, both 5rs 16" G rated tires 8 lug. Savings, not sure of exact $ but 4.1 is a 2017 200 miles away. The 2018 will be received by dealer on Sept. 21 and will have about $3,000 less savings than the 2017 with 3.7 gear. The 4.1 gear has about 5,000# more headroom than the 3.7 gear - 30,000# vs 25,000.

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Actually... you would want to be looking at tire diameter vs. wheel size when calculating gear ratios, however, it looks like you really could go either way. That's not much towing so as long as you don't push it too hard and watch your temps you could get away with a 3.73 with the weights you are talking about.

Just a quick search pulled up this chart that might be helpful with your wheel diameter to gear ratios.

That being said... if you're only talking $3k more to go with a 2018 and a 4.1 GR... all things considered... IMHO, that's a "drop in the bucket". With the 2017, 80% of the time you'll likely get a little better gas mileage... not so much around town, but if you drive long distances at higher speeds it would. However, under tow you're likely to get a little more "wear and tear". How will that translate into dollars over the life of your rig... who knows.

I wouldn't look too much at the extra 5k lbs when you're getting into published ratings that high. Mathematically it works, but at some point you have to just say, "that's an INSANE amount of weight to have pushing my little 7,000lb rig around with". They are marketing "higher ratings make our truck better than their's". At some point, as the one behind the wheel, common sense needs to prevail.

In a nutshell, with the 2017, it seems to come down to upfront $ savings and potentially better mileage as a daily driver. It's very "doable" with the weights you're talking about. With the 2018 you're looking at a "more capable" (aka. safer) rig under tow and a bit higher "curb appeal" for resale that would help off-set the cost on the back-end. It would also allow you a bit more "growing room" if you were to go with a heavier 5er at some point.

I already said which one I would take, but it's your money and your choice. You certainly won't suffer no matter which side of the coin you choose to go with.

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We drove a 3rd duelly today. that was in stock. Different transmission (68RFE) 3.42 axle ratio the upcharge to 3.73?? I remember it having power adjustable pedals but nowhere on the sticker does it show them. Turns out, the other two appear to not have them listed either. If they do not have them, it would be a deal breaker since my wife is 5 ft tall. I'm leaning toward the one in central Texas that has the Aisin transmission and the 4.1 but it needs  a cargo camera, tubular side step and power adj pedals if they are not included in the Laramie Package 28H. I'll make some calls in the morning.

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Go with the Aisin for sure.  I optioned the 410 rear when I ordered my truck.  The fuel difference is really not that much. But the pulling and breaking power is much better on the 410 rear.  

 

Check out the Cummins forum on this.  There are a couple of threads on the 373 and 410 rear debate.

Edited by rynosback
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"Inquiring Minds Want To Know"  I "need" the cargo camera so that I can "see" the hitch in the bed of the truck while I'm trying to hook up the hitch thingy. I'm a complete noob to the 5th wheel world. I've trailered a boat for over 10 years and the backup camera is a huge time saver. Maybe liking/wanting might be a better way to describe my thirst for the extra gizmo.

It's just a shame that right now, I'm having an issue finding the truck that has all the right goodies on it. Some, clearly can be installed aftermarket easily - side step, and maybe a cargo camera. It's just another gizmo that might make life simpler. We are paying cash for the truck and it would be nice to have the "stuff" already installed by the "Dodge Boys".

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8 hours ago, masterdrago said:

"Inquiring Minds Want To Know"  I "need" the cargo camera so that I can "see" the hitch in the bed of the truck while I'm trying to hook up the hitch thingy. I'm a complete noob to the 5th wheel world. I've trailered a boat for over 10 years and the backup camera is a huge time saver. Maybe liking/wanting might be a better way to describe my thirst for the extra gizmo.

It's just a shame that right now, I'm having an issue finding the truck that has all the right goodies on it. Some, clearly can be installed aftermarket easily - side step, and maybe a cargo camera. It's just another gizmo that might make life simpler. We are paying cash for the truck and it would be nice to have the "stuff" already installed by the "Dodge Boys".

Why not just order a truck to your exact spec?  That way there is no compromise.

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I have no experience with the Rams but our 2014 F350 dually with the 3.73 rear end and the 6 speed tranny does a fine job towing our 17.2K fifth wheel, mountains included.  On level ground we get over 10mpg.  The loaded weight of your selected fifth wheels and the Rams excellent exhaust brake should be great with the 3.73 rear end.     Greg

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16 hours ago, masterdrago said:

"Inquiring Minds Want To Know"  I "need" the cargo camera so that I can "see" the hitch in the bed of the truck while I'm trying to hook up the hitch thingy. I'm a complete noob to the 5th wheel world. I've trailered a boat for over 10 years and the backup camera is a huge time saver. Maybe liking/wanting might be a better way to describe my thirst for the extra gizmo.

It's just a shame that right now, I'm having an issue finding the truck that has all the right goodies on it. Some, clearly can be installed aftermarket easily - side step, and maybe a cargo camera. It's just another gizmo that might make life simpler. We are paying cash for the truck and it would be nice to have the "stuff" already installed by the "Dodge Boys".

Don't overlook that many (maybe most) newer fifth wheel RVs have a mirror on the front cap that in combination with the rear view mirror lets you see your hitch. Also I have found that fifth wheels are far easier to hook up than a regular hitch since you do not have to be quite as precise since the hitch will "grab" the kingpin and align itself as long as you are close.

 

8 hours ago, rynosback said:

Why not just order a truck to your exact spec?  That way there is no compromise.

And then there is this.

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My 2 cents worth.

I towed a Mobile Suites 38TKSB3 at 18,000# with a 2015 Ram 3500 CCLB dually with a 68RFE and 3.73 gears.  It pulled the trailer great but I tow at 62-65 mph and I could never find a happy spot with that combo.  I either had to drive too fast in 6th or run the engine at too much rpm at 65 in 5th.  I was always fighting the thing to get the engine at 1700-1900 at 65mph.

My last truck was a CCLB SRW with a 15,000# Arctic Fox.  The truck had a 68RFE and 3.42s.  I towed that trailer in 5th gear at 1750-1800 RPM at 65 mph.  It towed great.....and we would still be using that combo if we hadn't gone to a much longer trailer.  The advantage of the 3.42 is you  run in 5th in the moutains and 6th on the flat at about 1500 rpm and pick up a little fuel economy.  The other advantage is you will get 20 mpg empty on the highway....about 16 around town.  It gave outstanding fuel economy.

My current truck is another dually but this one has 4.10 gears and an Aisin.  I had planned on buying another Mobile Suites with a 22,000-24,000# GW, hence the 4.10s.  It would have been perfect.  However, we ended up buying a slightly lighter RiverStone 39FL by Forest River.  It has a 19,000# GW...

I bought the truck first and had I known our new "new home" was going to be lighter, I would have purchased one with 3.42s.  Don't get me wrong, with the 4.10s, I put the truck in 6th and let the computer do what it wants....it is a flawless towing machine.  It runs at 1900 rpm at 65 mph and gets the same fuel economy towing as the 3.42s.  The downside is about 4 mpg less on the highway.

In my world the 3.42s are the thinking man's gears if towing medium weights.  The 4.10s are great for heavy loads up to Gross.  And in my world, the 3.73s are useless.....I'll never buy another truck with 3.73s.  They just don't work for the way I drive.

I hope this helps a little.

Edited by hutchman
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On 9/6/2017 at 4:59 PM, masterdrago said:

"Inquiring Minds Want To Know"  I "need" the cargo camera so that I can "see" the hitch in the bed of the truck while I'm trying to hook up the hitch thingy. I'm a complete noob to the 5th wheel world. I've trailered a boat for over 10 years and the backup camera is a huge time saver. Maybe liking/wanting might be a better way to describe my thirst for the extra gizmo.

It's just a shame that right now, I'm having an issue finding the truck that has all the right goodies on it. Some, clearly can be installed aftermarket easily - side step, and maybe a cargo camera. It's just another gizmo that might make life simpler. We are paying cash for the truck and it would be nice to have the "stuff" already installed by the "Dodge Boys".

Why not just order a truck to your exact spec?  That way there is no compromise.

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My son had a 4.11 in his 02 Chevy dually and switched to a 3.73 which gained about 1 mpg (it's what happens when you don't check diff oil levels). I tow with a 06 Chevy dually that has 300k+ miles of heavy tow on it and the 3.73 has worked fine for me. I just replaced it's first pinion seal last week and the gears don't show any wear.

Greg

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Ordering the 2018 would have a $6-8K penalty. We found one that had everything except the 4.1 axle (has 3.73 with a ventilated aluminum cover on diff) about 300 miles away. They had several with the 4.1 but they either had no adjustable pedals or were interior Tradesman-like (wife needs adj pedals and would not go for cloth interior). She also likes all the other bells and whistles. It's a Limited with the Kitchen Sink and all my boxes got checked except the 4.1. I think the only thing missing is an exhaust header temperature readout. I'm sure I'll learn to drive it. We got it near $16K below MSRP and finally negotiated the minimum I would take for my 180k miles '09 F250 4x4 diesel crew cab.

I was perusing the user guide found this.....   "Because of the construction of the Cummins turbo-charged diesel engine, engine run-in is enhanced by loaded operating conditions which allow the engine parts to achieve final finish and fit during the first 6,000 miles". I'm thinking, do I pull my boat (5k) everywhere I go during break-in???

I think I'm going to be a happy ex Ford owner even though I have nothing whatsoever against Ford. I've been in Fords all my life until I've started this 5r quest.

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6 minutes ago, masterdrago said:

 

I was perusing the user guide found this.....   "Because of the construction of the Cummins turbo-charged diesel engine, engine run-in is enhanced by loaded operating conditions which allow the engine parts to achieve final finish and fit during the first 6,000 miles". I'm thinking, do I pull my boat (5k) everywhere I go during break-in???

 

1

Just drive it like you stole it...literally.  Cummins diesels love to have a load on them.  When I had my Dodge, it always ran better with a load than empty.  Even the Volvo with the 1998 M-11 Cummins runs quieter and smoother after a long haul.  

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On 9/9/2017 at 10:12 AM, masterdrago said:

Ordering the 2018 would have a $6-8K penalty. We found one that had everything except the 4.1 axle (has 3.73 with a ventilated aluminum cover on diff) about 300 miles away. They had several with the 4.1 but they either had no adjustable pedals or were interior Tradesman-like (wife needs adj pedals and would not go for cloth interior). She also likes all the other bells and whistles. It's a Limited with the Kitchen Sink and all my boxes got checked except the 4.1. I think the only thing missing is an exhaust header temperature readout. I'm sure I'll learn to drive it. We got it near $16K below MSRP and finally negotiated the minimum I would take for my 180k miles '09 F250 4x4 diesel crew cab.

I was perusing the user guide found this.....   "Because of the construction of the Cummins turbo-charged diesel engine, engine run-in is enhanced by loaded operating conditions which allow the engine parts to achieve final finish and fit during the first 6,000 miles". I'm thinking, do I pull my boat (5k) everywhere I go during break-in???

I think I'm going to be a happy ex Ford owner even though I have nothing whatsoever against Ford. I've been in Fords all my life until I've started this 5r quest.

I think you bought a great truck!

Short story about "break-in". I bought a 3/4T Dodge CTD, drove and towed with it for ~80,000 miles and it still used a quart of oil per 1,000 miles. One August trip, between Bakersfield and Las Vegas we got stuck in a rolling traffic jam. Truck temp was nudging the red mark, I'd pull off until temp reduced to normal then resume the crawling traffic. When we got home the truck had stopped using oil. I asked my SIL/diesel mechanic and he said the Cummins finally got hot enough to fully-seat the rings. That truck never again used oil between changes.

So yes, pull heavy loads occasionally; however do not use it for short trips, <20 miles in cold weather, as the engine will not fully reach operating temperature.

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Thanks Ray. I've always been aware of the "need to heat up" in diesel engines. I've had the 6.0 & 6.4 Ford. We do some short trips but I think I've finally convinced my Better Half that we need to only use the car (4.6 liter) for that. We traded trucks due to the coming need to pull a 17k# 5r in the next few months. I think I might, for the good of this truck, yank the 5k# boat around town when I go out next time.

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