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Which Differential for Truck Camper

gregchambers
Explorer
Explorer
Looking to purchase a new 3500 Single rear wheel crew cab 4x4 standard bed truck and haul a Lance 855S (about 3,000 lbs) camper. Plan to get the 6.0L gas engine which comes with a 6 speed auto trans. My question is which differential I should get, the 3:73 or the 4:10? I don't plan to haul anything, just the camper and gear along with water, fuel, etc. so combined it should not exceed 4,000 lbs. total payload. Anyone have experience with either combination? Any big milage penalty with th 4:10? I live in California where we have some prety big hills. The camper if turned into a trailer could be pulled by any mini-van, I just need the 3500 for the payload capacity, not towing ability. Any milage experience on late model gassers would be appreciated. Sorry oil burners, not interested!
43 REPLIES 43

Oldtymeflyr
Explorer
Explorer
Really it comes down to the gear ratios in your transmission. What is a 6-7-8 speed? Compare those ratios with your experience and you will find that you have at least 2 overdrive ratios and maybe a very low, 1st gear.

Our 2006 GMC has an Allison 6 speed, 3.37 gears (an 8.1-the 8.2 was never an engine installed at the factory)and the GMC will not go into 6th gear with the camper unless its flat, very flat and with the slightest rise it will drop to 5th gear.

We have installed slightly larger tires and our adjusted axle ratio is now 3.42.

We had a diesel and some things I miss, but when we needed a new truck we went with a used, very low mileage and hard to find 8.1 GMC.

Good Luck!

EfonFred
Explorer
Explorer
I run an older truck, probably will till the day I croak. CTD with 4.10 or 4.11 ( sticker is fading). Not hauling the heaviest camper on earth but we spend a lot of time roaming around the Sierra. I hardly ever drive over 60 when loaded. I am happy with the performance. Average mileage I plan to attain is 15 on a typical jaunt.

Auto tranny.
2011 Ram 3500 Mega DRW
2015 Adventurer 86SBS

Redsky
Explorer
Explorer
I have had 4.10 gears on all my trucks until the current one which is a diesel with 3.73 gears. I had the same or better gas mileage as anyone using taller gears and that was with 4-speed transmissions. Current pickups have 6-speed transmissions and 5th and 6th are overdrive gears.

I would want the 4.10 to have the best possible acceleration when merging with traffic on a freeway and for passing slow moving semi's on steep grades. The 4.10 gears put the engine more readily into the peak torque area of 4200 RPM.

With a very heavy 8,000 lb. truck hauling a 4,000 lb. payload fuel economy is not worth talking about. It is what it is and the gears are not going to make a difference in the real world. The taller gears help with the EPA CAFE figures for the truck manufactures but that is about it.

BillL1356
Explorer
Explorer
Chevy 2013 HD 4.1 4x4 with snow plow package hauling a Northstar Arrow hardside. 10 mpg last 4k.
Bill

zman-az
Explorer
Explorer
Greg,

One other thing to factor in is wind resistance. That Lance is a pretty good darn sail. I have a jeep wrangler and when I mount the roof rack its a noticeable difference in power and fuel economy due to wind resistance. Being you said you were going to higher elevations and using that camper a lot I think you will be happy with the 4.10. It may actually give you better fuel economy due to that big sail up top. I also think the 3.73 gears are setup by the mfg to get the best fuel mileage with no load. You will have a load most of the time, granted not maxed out but 3-4,000lbs is not light either. Also, sometimes the 4.10 gears are combined with a tow package. Extra tranny cooler, heavy duty hitch, ect... Not sure if they play that game on the truck you are looking at.

Your comments regarding gas vs diesel are dead on. I like the part about high mileage and 45 years. You forgot to mention that the fuel pump, brakes, tranny and other things will give out long before that engine will. These parts are also a lot more expensive to replace than the gas counterparts. How many old diesel pickup trucks do you see on the road today. I would say its not much different that the gas ones. I went from a 1/2 ton for to a 2010 Ram Cummins. Both vehicles have their advantages.

BTW, several links out there on the web about gear ratio's and RPM's.
play with this one. Notice how they require the tranny to be involved. This is why one cannot compare different makes, model years and engines.

JumboJet
Explorer
Explorer
What is nice about a 6 speed transmission is that in 5th gear with a 3.73 you will still have a lot of pulling power, but at a few mph slower. I pull heavy loads in 5th gear.

Apples & Oranges? Ford 6.2L - 400 ft. Lbs. @ 4200 RPM. Cummins 6.7L - 800-850 ft. lbs. @ 1600 RPM. Ford 6.2L - 9.8 to 1 compression. Cummins 6.7L - 17.3 to 1 compression ratio. 360 ci vs. 402 ci. V8 vs. I6.

Of course the Ford & GM diesel's are V8s.

gregchambers
Explorer
Explorer
JumboJet, your chart is extremely helpful. Thanks for passing it along!

To those who keep suggesting that I consider diesel or keep comparing their diesel experiences to gas, please read the following edited statement that I posted on a Chevy owners forum in response to the same repeated suggestions. The apples and oranges comparison is closer than the 1% vs 2% milk. The engines are very different and although HP is about the same, torque is superior in a diesel and achieved at very different RPM's. Truely apples and oranges, both good fruit but from different trees with different nutritional values, just depents on what your individual body (personal truck hauling requirement) needs! I really enjoy this site and the information!

"Yes I have considered diesel and was planning to purchase one until I started studying owner blogs and interviewing people I work with in construction who drive large trucks. Many are going back to gas because the MPG on the newer diesel trucks is poorer than pre-DEF engines, add DEF, bi-annual smog, unplanned fuel filter changes, etc. At current fuel prices, diesel and gas are a wash. Gas fills up more often, diesel pays more when they fill up. Add the more than double cost of routine maintenance, the up-front $9,000 (before price negotiations)and you get diesel in a HD truck for two reasons, you want it and/or you need it for very heavy hauling. Yes the engine may last twice as long and the diesel truck will be worth more if you ever sell it but both are very weak rationalizations for going diesel. The diesel truck will be worth more at trade-in time because you paid a whole lot more in the first place and at 15,000 average annual miles, a engine lasting 600,000 miles will be 45 years old when it wears out, do you really want a 45 year old truck? I don't! With a 4,000 lb load, it doesn't make sense for my purposes. Yes, the steep grades would be more fun with diesel but with a truck camper, it's all about payload and diesel adds between 700 to 800 lbs to the truck. Yes the mfgr's add things to keep the payloads similar but most truck campers run over their GVWR. What you don't want to exceed is your axle and tire maximums which are the same between diesel and gas HD trucks. Gas allows you 700 to 800 lbs more payload safety factor. Any well researched article on truck campers will acknowledge that gas trucks have a cargo advantage over comparable diesel trucks. The diesel noise issue has been resolved in my opinion but not availability of fuel. Even if a station has diesel, it is often limited to one or two pumps. What I'm hoping to get from this post are people with similar gas rigs and their driving experience with both the 4:10 and the 3:73. I have read that the difference between the two is minimal with the six speed trans. Given my light load, is the 4:10 even worth exploring. Much like a diesel, it will be better in the mountains but is it really that necessary given the load. Towing is over 9,000 lbs with the 3:73 and up to 13,000 with the 4:10. At 4,000 lbs of payload and not towing anything, will the 3:73 be OK or with the new six speed trans, does the 4:10 work just as well with no noticeable loss of MPG at HWY speeds due to double overdrive?"

JumboJet
Explorer
Explorer
I checked my Ram 3500 on the drive home and at 1800 RPM in 5th gear I was at 56-57 mph. My chart calculations are correct.

BradW
Explorer II
Explorer II
zman-az wrote:
BradW wrote:
Back when we were shopping for our last truck in 2006, I was seriously considering a Ford V-10 gasser. I drove two, one with a manual / 4.30 and one with an auto / 3.73 (IIRC). The 4.30 was a rocket and the 3.73 was dog.


Again,

Apples and Oranges.

There is more involved than just gear ratios. To make a true evaluation about gears you need to have same motor and tranny. Gear ratio's are going to be different in the Auto vs Clutch not to mention the torque converter of the auto.


Nah, more like 1% milk and 2% milk.
Wake Up America
2019 Lance 1062 and 2018 F-350 CC PSD 4X4 DRW
Tembrens, Rear Roadmaster Sway Bar, Torklift 48" Extention and 30K Superhitch
Our New Lance 1062 Truck Camper Unloading at Dealer Photos

zman-az
Explorer
Explorer
BradW wrote:
Back when we were shopping for our last truck in 2006, I was seriously considering a Ford V-10 gasser. I drove two, one with a manual / 4.30 and one with an auto / 3.73 (IIRC). The 4.30 was a rocket and the 3.73 was dog.


Again,

Apples and Oranges.

There is more involved than just gear ratios. To make a true evaluation about gears you need to have same motor and tranny. Gear ratio's are going to be different in the Auto vs Clutch not to mention the torque converter of the auto.

zman-az
Explorer
Explorer
Sheriffdoug wrote:

I have had three diesels,

First, 2002 F250 4x4 Supercab Longbed 3.73 SRW, powerful, economical, but had
a Smaller Popup camper. Excellent.

Second, 2011 Chev Silverado DRW 2500hd Longbed supercab 3.73 with an
Adventurer 910fbs, heavy camper, would have been better with 4.10 and DRW.

Third, 2012 Ram 3500hd crew Longbed drw with 4.10 and 2013 Eagle Cap 1160,
extremely heavy camper, with sway bar, supersprings, Timbrens, despite extreme
weight, uses only 5-6% more fuel, but with 4.10 has incredible power at low & high
speeds with the added stability of dual rear wheel and other upgrades.


Apples and Oranges

You cannot make a judgment on gears with these trucks. They are all different years, makes, and models. The only way to make a statement about gears is to have the same drive train in a truck that has 4.10 gears vs 3.73 gears. Now if you go out and by a 2012 Ram with 3.73
with the same drive train then you can give real world experience about the gear ratio's.

Put 4.10 gears in that 2002 truck of yours and put 3.73 in the 2012 Ram. The 2012 Ram would still blow away that 2002 truck in towing.

JumboJet
Explorer
Explorer
Here is an approximate MPH chart for stock tires 31.8" tall


nycsteve
Explorer
Explorer
I have a 2011 F350 6.2 gas 6 speed auto tranny, with 4.3 rear( or 4.1 ,pretty sure though a .3) . Would do it again if buying again. Prior I had a F350 6.4 diesel with a 3.73 which had plenty of power. But comparing the diesel and gas as far as a 3.73 rear is comparing apples and oranges. With a gas there is a definite improvement going with the 4.1/4.3 . My mpg emty,close to 15 mpg, hauling a 4k# camper close to 11mpg. This is at 60mph highway driving , flat roads. My truck has no difficulty with hills etc.

On Edit; my rear is definitly 4.3

BradW
Explorer II
Explorer II
One time, at band camp; no wait, thatโ€™s a different story.

Back when we were shopping for our last truck in 2006, I was seriously considering a Ford V-10 gasser. I drove two, one with a manual / 4.30 and one with an auto / 3.73 (IIRC). The 4.30 was a rocket and the 3.73 was dog. I actually got out pulled by a 4-cyl Camry on the interstate in Birmingham in that 3.73. I couldnโ€™t imagine driving that 3.73 with 4,000 lbs in the bed and the wind drag of a TC.

Brad
Wake Up America
2019 Lance 1062 and 2018 F-350 CC PSD 4X4 DRW
Tembrens, Rear Roadmaster Sway Bar, Torklift 48" Extention and 30K Superhitch
Our New Lance 1062 Truck Camper Unloading at Dealer Photos