So David at Northridge offered me a good deal if I upgraded both differentials/axles the works...to a pair of dynatrac's

So I'm getting pro rock 44's with arb's and RCV axles and the same in back in a pro rock 60

I'm also replacing both drive shafts...

I'm trying to goto 37's from 33's

What gear ratio is best for semi dd?

Someone suggested 4:56 but I thought it might be more like 5:13's?

Should I stick with 16" rims as I had planned, or 17"?

Do I absolutely have to chop up my fenders?

I know I have to fix the pinch seam in the back

Also I have a 3" suspension lift

Matthew

 

Can't answer everything but with 3" of lift you will most likely need flats (or trim stockers) to stuff 37's. 17" rims have a much wider range of tire choices in 37's over 16's. You can find some in 16's but the picking is definitely slimmer. The pinch seam doesn;t have to be cut if you push your axle back a bit. But doing that requires a few other adjustements as well to make sure you have nothing hitting stuff (i.e. sway bar relocate). I'd just cut the seam.

Why a dana 60 in the rear? Tons of people run the stock 44 with 37's. That's a lot of money to drop on an axle so just asking...if you had plans to go to 40's or bigger than have at it but don;t see the need for it if only running 37's.

 

Good call on the 60 rear, I assume you got a semi float. Are you going to re-use your brakes ore are you getting after market units? Most after market brakes require 17" wheels.

Are you getting wider then factory width on the axles? I would get at least a wms of 68.5" It will give you extra clearance for your steering and will take some of the stress off the ball joints. I hope you got the unlimited model as well that is caster corrected for you lift.

4.56 seems to be the choice on gearing for 37" tires

 

The 37" choices I found for 16" rims:
Falken WildPeak/RockyMountain - ($265-ish)
BFG KM2 - ($365-ish)
SuperSwamper M-16 ($400+, didn't find many reviews)
Pitbull Rocker (bias, not radial. Backordered, no data on next production run)
Maxxis Trepador (directional, $400+)

Toyo - (if you want to move up to a 38x14)

As noted, much better selection with a 17.

If you don't want to chop or go to flats, look into taller bumpstops and/or a body lift.

 

I disagree. First off, you didn't say what year. If you have a 2011 w/ automatic trans, I'd suggest at least 5.13's, if not 5.38's. I have 5.13s myself and if I had it to do over again, I would've geared deeper to 5.38's.

if you have a 2012+ (3.6L), then I'd go 4.88's, as that seems to be the ratio where the new engine & trans (assuming auto) are happy. If you have a manual 2011 or older, then 4.88s are good, too, at least for a 2DR.

As for the other stuff, you'll likely want at least chopped factory flares, or some other form of flats. Just kinda the way it goes. Also, you may not have to trim the pinch seams, but it's a good idea to ensure your tires don't get into them and get gouged up like mine did the first I wheeled after my lift install. My pinch seams were trimmed, but I wasn't running any additional bump stop in the rear. So make sure you add bump stop accordingly. I added 2" in the rear and nothing in the front and do just fine now.

As for wheels....well...it's already been mentioned that there are many more tire choices versus 16's, so I'd say bump up to 17's. Otherwise, though, personal preference.

 

5.13's or 5.38's
17"
Congrats! David and his crew are great!
Enjoy!

 

X2

congrats on the step up

 

2012 auto with 37 . I would do 4:88
I run 5:38's on my 07 and wish I had more motor still. Wouldnt even think of running 40's on mine now.

 

Guys. I think the most important question is what kinda deal did you get? I mean is this something we should all get in on?

 

OP has a 2012 it is in his sig. Says daily driver, nothing about wheeling. I have no experience with the new motor so I was just pulling from chart. 4.88 on the chart puts it in the performance range. If lots of wheeling or live/driving with lots of steep hill then I would agree to go to 4.88 on the 3.6
Tires weight will have an affect as well and the fact the op has 2 door may make a difference with the power to weight ratio.

Mb try and find someone that is running 37's on the 36 and take it for a drive to see how you like it.