re-gearing

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jk6672

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Diesel
I'd like to here from any 3500's with 6.7, Aisin transmission, and 37 inch tires on what ring and pinion set they went with and why. The reason I ask is I'm getting 37's mounted today and a Carli suspension installed next week. I don't plan on keeping the stock gearing, but I will be driving it home on stock gears. I've seen a few different setups in a few forums ranging from stock gears, 4.10, 4.30, and 4.56.
The shop I've talked to was very specific in telling me their opinion based on the gear calculator they use, my stock setup, and what tires I want to go to.
They said if I was going to be doing any large toy haulers, based on their gear calculations and 4th gear, I should re-gear with 4.10.
I don't have a toy hauler yet, but I want to gear accordingly, and I only want to do it once.
 

MADDOG

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I agree with the shop. My bro-in-law re-geared his old 12 valve and he says its a great option.

He tows an enclosed trailer 3 days per week and either a large boat or TT most weekends.
 

14RAM4X4

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Brandon Jansen hopefully chimes in. I believe he's running 4.56s & 37s with the cummins. IIRC he said that's too much gear for the 6.7. Not sure if anyone is running 4.30s with 37s. AEV offers 4.30s as an option on their prospector builds to turn 40s. I'm running 3.73 on the gas motor, so I can't really comment.

But from a gearing standpoint, going to 4.10s from 3.42s is a good jump gear wise. That'd be like me going from 3.73s to 4.44s.
 
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mtofell

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4.10s with the Cummins seems like a great setup. I don't have any experience as I'm in a Hemi with 3.73s. There are guys on RV message boards I frequent hauling some crazy big 5th wheels with the Cummins/Aisin and 4.10s and are extremely happy with the setup. I just can't imagine needing taller gears than 4.10 with that diesel and the extra 100lb ft of torque the Aisin gives you.
 

RainDesert

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4.10 for Ram and 3.73 in Ford due to tranny gearing differences. You will be happy with 4.10's.
 

Ratket

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I would research the cumins torque curve and figure out what gear set is going to put u right in that "Rpm sweet spot" in 4th gear for the appropriate speed you tow at. Weather it be 55/65/ or 75mph.- That's my opinion.

On ur drive home lock the truck out in 4th gear and see what ur Rpms are at the speed you will most likely tow at and post it here. we should be able to ball park the gearing as well.
 
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