I've read where some truck campers specify the ratio of gearing in the differential of their trucks used for truck camping. Would anyone out there be so kind so as to explain to me what the advantages/disadvantages are to these different configurations?Thanks in advance!

The higher the gear ratio numerically (3.55, 3.73, 4.10, 4.30, 4.44, 4.56) the more revolutions your driveshaft has to turn to make the tires go 1 Revolution. This increase in gear numerical gear ratio decrease effort required to turn the tires thus making it easier for a vehicle accelerate and pull a load. If you have a light vehicle that does not pull heavy loads you can use a numerically lower gear like 3.08 which decreases the rpm of an engine at speed and thereby increase fuel economy. On the other hand, if you have a heavy vehicle that frequently pulls heavy loads you’d want a higher numeric gear ratio to make it easier to accelerate and pull heavy loads.

Generally the modern 6 to 10 speed transmissions have made changing rear gears obsolete.Now if you have an old 3 or 4 speed and you feel like you are often in the wrong gear then consider a change.

time2roll wrote:Generally the modern 6 to 10 speed transmissions have made changing rear gears obsolete.Now if you have an old 3 or 4 speed and you feel like you are often in the wrong gear then consider a change.With 10 speeds perhaps but at least some 6 speeds aren’t that different than older 4 speeds when it comes to towing heavy. Our 6 speed Yukon will top 60 in 2nd gear so it would definitely need lower gears in the rear if I wanted to tow anything substantial with it. The 2 added gears allow for lower RPM when cruising in the 40-70mph range for better mileage.

Final gear ratio is always a balance between engine torque and differential gearing. For years I drive European vehicles, who I love for high differential ratio as they take most of the grades without downshifting. My family members on other hand drive Toyotas, who I get to drive occasionally. It gets really annoying when Toyota needs to downshift with each wind gust or freeway overpass. But then Toyotas get better mpg.Same with trucks, but here, on this forum you will find "conservative" members who drove trucks with high differential ratios for decades and can't comprehend changes combustion engines made in last years. Most of the members will advise you to get high differential ratio for camper. I educated myself and for my 440 HP dually - have chosen the lowest differential ratio Ford would install, yet still the truck takes all those 15-17 miles grades we have with 6000 lb camper never dropping from overdrive at 1600 rpm. Frankly I wish I could get even lower than 3.55 differential ratio for fuel economy. It doesn't make sense to gear truck for hauling 20,000lb rigs without downshifting.Transmissions have gears for a reason.

X2, Kayteg. My new Silverado with the eight speed transmission and 3.24 rear end pulls better than my 2015 Tahoe with the six speed and 3.42.

Rear end ratios | Good Sam Community

Grit_dog
Navigator
Dec 24, 2019
Kayteg1 wrote:
Right, but sounds like he likes the higher rpm engine whining.
I love when I don't hear my 6.7 at 1600 rpm with 3.55 differential.
Don't mind >12 mpg with big camper neither.
Side question. My 6.7 start delivering better mpg once it passed 20,000 miles mark. Did we get better fuels this year, or my engine finally broke-in?

Side question. Can I not be labeled a senior member here if I'm not actually a senior?
Lol
Grit_dog
Navigator
Dec 24, 2019
Kayteg1 wrote:
BradW wrote:
All me knows is me loves the 4.10 gears in our 2018 PSD Superdutuy when hauling our camper and towing our jeep.

That statement makes no sense without posting what engine (even better torque) you have?

What are you drinking tonight?
Kayteg1
Explorer II
Dec 23, 2019
Right, but sounds like he likes the higher rpm engine whining.
I love when I don't hear my 6.7 at 1600 rpm with 3.55 differential.
Don't mind >12 mpg with big camper neither.
Side question. My 6.7 start delivering better mpg once it passed 20,000 miles mark. Did we get better fuels this year, or my engine finally broke-in?
mbloof
Explorer
Dec 23, 2019
Kayteg1 wrote:
BradW wrote:
All me knows is me loves the 4.10 gears in our 2018 PSD Superdutuy when hauling our camper and towing our jeep.

That statement makes no sense without posting what engine (even better torque) you have?

He did: "PSD" = Power Stroke Diesel, 2018 would make it a 6.7L.

IMHO: not the best gears for fuel economy.

- Mark0.
Kayteg1
Explorer II
Dec 23, 2019
BradW wrote:
All me knows is me loves the 4.10 gears in our 2018 PSD Superdutuy when hauling our camper and towing our jeep.

That statement makes no sense without posting what engine (even better torque) you have?
BradW
Explorer II
Dec 23, 2019
All me knows is me loves the 4.10 gears in our 2018 PSD Superdutuy when hauling our camper and towing our jeep.
Grit_dog
Navigator
Dec 23, 2019
mt-ed wrote:
I've read where some truck campers specify the ratio of gearing in the differential of their trucks used for truck camping. Would anyone out there be so kind so as to explain to me what the advantages/disadvantages are to these different configurations?
Thanks in advance!

Bottom line, if you're "just" hauling a TC on any HD pickup from recent years, the highest gearing offered will haul it fine, even in the mountians.
But the same general gearing rules apply. Apples to apples, a lower final drive ratio will put more torque multiplication down and feel more powerful and typically downshift less in the hills. More so with gassers than diesels.
Grit_dog
Navigator
Dec 23, 2019
Kayteg1 wrote:
Darn. Dodge seems better as my Ford has governor at 85 mph.
Doing the speed at 1/2 way to redline.

Thats strange. None of the older or newer Powerstroke pickups I've been in are limited to 85.
Grit_dog
Navigator
Dec 23, 2019
specta wrote:
The older automatics had 3.0:1 first gears. My 2011 Chevy has a 6.0:1 first gear and 4th gear is still under driven instead of a 1.0:1 high gear.

The "granny" gear in the 4-speed in my '79 F-250 was 6.69:1.

5th is barely an overdrive, 6th gear is 0.67:1.

My pickup has 3:73 gears and with the transmission gearing I wouldn't care to have any lower gears in the differentials.

Besides the gearing the newer engines have way more power than the older trucks with 3&4 speed trans.

At 87 mph I'm still under 2500 RPM and that works good for me.

No, the 6L90 has a 4.0 first gear ratio and an overall 6.0 ratio spread from 1-6.
TxGearhead
Explorer II
Dec 23, 2019
Only ratio available on my 2016 Ram 3500 SRW was 3.42. Worked well with the Bigfoot and a 34ft 5th wheel. I went with 3.73 on the 2018 dually. It works well with both the Bigfoot and the 18,000 GVW Landmark.

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