Gear Swap?

[steadly2004]

Some members have done so.

I would look at 4.30, maybe even 4.56.

I have 3.73 and will go to 4.11, but I have 35's.

If I had 37's, I would go 4.30 or 4.56.

Sent from my Pixel 5 using Tapatalk

Looks like the ol’ gear calculator puts 4.1 as my “return to stock ratio, coming from 33.8” to 37” tires.

That would put the RPM range back to where it was with stock tires.

However, it doesn’t consider the extra weight of the tire.

So maybe 4.3 is a decent choice.

I would kinda be stuck staying on 37’s, as 35” would make the RPM’s a bit higher on the freeway if I ever wanted to revert.

Decisions decisions.

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[steadly2004]

What do you actually drive?

A regular diesel 2500 or a power wagon? is this switch you're talking about the 4 wheel drive switch in the cab? what year is your truck?

I didn’t realize I never put it all in my signature/profile.

I have a 2015 2500 crew cab Cummins, with a 2nd gen swap.

Still have the stock 68RFE.

Yes, the 4wd switch says 4 lock and 4 low.

My old 1500 had it labeled as 4hi and 4 low.

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[AK Bob]

I didn’t realize I never put it all in my signature/profile.

I have a 2015 2500 crew cab Cummins, with a 2nd gen swap. Still have the stock 68RFE.


yes the 4wd switch says 4 lock and 4 low. My old 1500 had it labeled as 4hi and 4 low.

4wd lock simply means locked in full time 4wd as apposed to 4wd auto.

Agree you will want to look into adding the limited slip rear differential or lockers in place of the conventional.

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[scs210]

I went back and forth for a while with the same debate.

I went from stock to 37s with the stock of 3.42.

I drove for about a month in this configuration and couldn't stand it.

Eventually, I settled on the 4.10s, mainly in case I ever wanted to drop back to 35s.

I geeked out on the topic and made a few charts to compare.

Here's links to the posts I made on some other threads.

Gears For 37s? - Page 4 (igotacummins.com)

and another one with good discussions - Changing Gears - Page 2 (igotacummins.com)

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[steadly2004]

I just set up the gear change at a local offroad shop.

It will cost $5.5k, with an Eaton Trutrac LSD added to the rear.

That option was like $1200.00.

I could have done the gears for that much less.

The parts are on order; hopefully, they will arrive quickly, and I can drop off the truck this weekend.

Also, I just installed a 37” x 12.5 Toyo RT trail.

They are rubbing on the fender liner when turning.

I will trim up the necessary plastic maybe this evening.

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[sootmaster]

Hello, I presently have a hybrid-style personal build.

Front AAM-9.25 with Power Wagon Electronic carrier and wired-in switch (it can be done).

Rear AAM-11.5 Yukon Detroit Locker Rear

I had the factory worm gear, a non-clam shell style carrier for the rear axle, and got stuck on green grass with a 4x4.

Only one wheel turned front, and one wheel turned rear.

The rear carrier failed or was worn out—just trash.

With the New Rear Locker, it takes effort to get the Detroit locking lugs to release on misty days; the truck does fishtail tail a little and also has light tire wear from scuffing.

All Normal from Detroit lockers.

The Front Axle was an open Carrier from the factory.

With the front AAM Ecteronic(power wagon) carrier, make the front unit a spool, so turning on the pavement will destroy the carrier lug pins.

The carrier is only an off-road locking setup.

Without purchasing the unit, I could not confirm the worm gear carrier from the power wagon's front 9.25 carrier axle spline counts.

It is unknown if it would have worked.

As well as axle housing bearing spacing.

Next is to rewire the front axle to only lock when in 4x4 Low and speed limit and disengagement so as not to damage the unit; the electronic, magnetic coil is activated like an AC clutch, but pins have to align with holes in the carrier housing to spline into.

I would never go to factory-style carriers, as they suck.

Detroit locker rear and an air shifter style front are most desirable, but I wouldn't say I liked the price, so I added an air compressor.

https://www.motortrend.com/how-to/19...wagon-lockers/

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