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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