Good Sam Club Open Roads Forum: Truck Campers: 3.42 gears for TC
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 > 3.42 gears for TC

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mellow

Salisbury, MD

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Posted: 05/26/22 07:30am Link  |  Quote  |  Print  |  Notify Moderator

I know on the Ford side the new 10 speeds made the 7.3 gasser a very viable puller with either 3.73 or 4.30 (better suited for heavy).

I always direct people to this very long thread on gearing on the 7.3: https://www.ford-trucks.com/forums/16656........ers-dont-lie-3-73-vs-4-30-explained.html


2002 F-350 7.3 Lariat 4x4 DRW ZF6
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Grit dog

Black Diamond, WA

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Posted: 05/26/22 07:45am Link  |  Quote  |  Print  |  Notify Moderator

mellow wrote:

I know on the Ford side the new 10 speeds made the 7.3 gasser a very viable puller with either 3.73 or 4.30 (better suited for heavy).

I always direct people to this very long thread on gearing on the 7.3: https://www.ford-trucks.com/forums/16656........ers-dont-lie-3-73-vs-4-30-explained.html


Lol, that guys an id10t in his explanation. And basically sounds like he lost a bar bet and is trying to talk his way out of it!
Too many people acting like they know what they’re talking about, when they don’t….
No wonder people like the OP who (obviously) don’t know jack about vehicles can get confused so easily….


2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
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Grit dog

Black Diamond, WA

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Posted: 05/26/22 07:50am Link  |  Quote  |  Print  |  Notify Moderator

LL8 wrote:

Thanks, the 18” wheels are standard and the 20” are a add on option. If I go with the 20’s it’s only for looks. I know I’ll sacrifice some MPG and some of the gear ratio. I’d love to have them if it’s not a huge trade off.


What are you even talking about? Too much internet reading? Do you know that is the size of the rim, not the diameter of the tire?

Hope the do gooders here who don’t know what they’re talking about don’t confuse you any more than you’ve already been confused.

mkirsch

Rochester, NY

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Posted: 05/26/22 08:12am Link  |  Quote  |  Print  |  Notify Moderator

If the truck is rated to tow something like 16,000+lbs with a 3.42 ratio it can surely haul a <4000lb truck camper.

Gas engines need to run at higher RPMs to produce their power. It would not be unusual for a gas engine to be turning at 3500RPM, and they can run up to 5000RPM to produce maximum power.

A diesel is redlining at 3500RPM. Plus they produce their power at lower RPMs. This makes it practical to run a taller differential ratio like a 3.42, especially with the 10-speed transmission.


Putting 10-ply tires on half ton trucks since aught-four.

Grit dog

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Posted: 05/26/22 08:14am Link  |  Quote  |  Print  |  Notify Moderator

…..

* This post was edited 05/26/22 11:44am by Grit dog *

valhalla360

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Posted: 05/26/22 08:23am Link  |  Quote  |  Print  |  Notify Moderator

BurbMan wrote:

I wouldn't sweat it, my truck also has 3.42 rear with 6 speed transmission and handled the Lance fine, also pulls the new 13k 5er fine too. Rear axle is more critical with gas engines and older 4 speed transmissions that had wider gear spacing.


Mostly about the transmission (I pulled some info on Ford transmissions. Different models may vary a bit but the general pattern will hold).

In the OP's truck dropping down 1 gear from 10 to 9 will bump up RPM by about 9%.
6 speed transmission would bump RPM by about 20%.
4 speed transmission would bump RPM by about 30%.
3 speed transmission would bump RPM by about 32%.

Additionally, when pushing really hard, 1st gear in the newer transmissions has been able to go deeper the more gears the transmission has. So when pulling a really heavy load up a steep hill, you will be more likely get to the top:
10speed: 4.70-1
6 speed: 4.17-1
4 speed: 2.84-1
3 speed: 2.46-1

With the 3 or 4 speed transmissions, once the truck can't hold top gear, the engine has to run at drastically higher RPM to maintain the same speed.
- If you did significant and heavy towing, a higher (numerical) rear end to hold top gear more of the time and would get you up steeper hills...but running empty, you would be running higher RPM with a loss of efficiency.
- If you rarely do any heavy towing, the lower rear end would give you better efficiency running empty but expect it to rarely hold top gear when towing heavy and on the steepest hills, it might not get to the top.

With the 10speed, it can dial in very close to the ideal RPM to maximize efficiency and power to match load/road conditions regardless of the rear end. Only for the very heaviest loads on the steepest hills might it run out of enough oomph to make it...but that's not even close to happening with a truck camper on a diesel drivetrain.


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Lwiddis

Cambria, California area

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Posted: 05/26/22 09:10am Link  |  Quote  |  Print  |  Notify Moderator

Seems you are "over trucked" for the load you will be toting. You won't have any issues IMO.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, WindyNation 300 watt solar-Lossigy 200 AH Lithium battery. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist. 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad


kirkl

Washington

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Posted: 05/26/22 10:32am Link  |  Quote  |  Print  |  Notify Moderator

Im pulling a 9500 pound camp trailer with my ram that has 3.42 rear end. No issues. And a 2000lb camper.


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ppine

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Posted: 05/26/22 10:47am Link  |  Quote  |  Print  |  Notify Moderator

New diesels have a lot of power. The 3.42 is designed to match up with the 10 speed. You can haul 15,000 pounds easily.

LL8

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Posted: 05/26/22 04:29pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for all the replies folks. Learned a lot

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