My next project is going to be re-gearing. Looking at different Ring/Pinion/Master overhaul kits with 5.13 ratio and wondering if anyone that has them can share their opinion. I don't mind the lost fuel economy for increased torque and performance. I was between 4.88 and 5.13's. Also, I know i'll need a new carrier for the different gears, I want to confirm that these carriers usually are included in vendors "Master Overhaul" kits or if its a separate buy.


And if you can suggest your preferred brand to help my search.


Thank!


-Matt

 

I have 5.13s on my '13 JKU 3.6L with 37" Nittos inflated to 28psi cold (With 28k miles of wear on em and inflated to 27/28spi, they measure just a tad over 35"). I think that combo is probably a bit aggressive for most people. You didn't mention what size tires you were running, and that is going to make a big difference in your question. My fuel economy is pretty sucky....typically ~13.5mpg with most of my driving a mix of 50/50 city/highway. 75mpg puts me right at/above 3k rpm's, and the fuel gauge drops fast around there. I'd say there's a considerable drop over 65mph. Engine revving that high gets to me sometimes.....I'd prefer to see interstate speeds around 2700 rpm, but I don't have a Rubi TC, and I appreciate the offroad benefits of my gearing. I think most people with a similar build would prefer 4.88's for a daily driver.

My brand of choice is Yukon.

 

I've had 5.13's and 5.38's...running both 37" and 40". IMO either tire needs 5.38's.

 

You had those on a 3.8L though right? I can't even imagine 5.38's with 37s the '12+ 3.6L and tranny.

 

Ah yes, let me add that I have 35's. 315/75/16 Yokohama Geolanders

 

I have a buddy with 35" Ridge Grapplers and 4.88's on a '15. His set up is very comparable to mine with 37's and 5.13s in regards to speed/rpm's. I really don't think you'd want to consider 5.13's. You might even be happier with 4.56's for a nice all around daily driver. If you don't mind revving a bit higher on the highway, 4.88's would be bearable. If you every THINK you might move to a 37, 4.88's would probably be better choice considering the long term. The gearing charts are pretty accurate. I'd suggest downshifting at highway speeds and forcing the engine to run around 3k rpm's for an extended period and see if that bothers you or not. Low end, around town, you'll love the lower gearing. It's longer trips that it can be a bit of a drag.

 

another question, Im reading that since my stock gearing is 3.21 that the front Dana30 differential won't fit something like a 4.88 gear. Is this correct? And would I just need to replace the front case or front and back?

 

It will need a new carrier to regear, not a case.

 

No, if you have factory 3.21 gearing, your carrier itself won't accommodate the lower gearing. You can purchase a new carrier that will for fairly cheap, or you could throw a locker in there (acting as the carrier) should you choose to go down that path.....which is getting in to a whole new debate. I'm presuming you don't have factory upgraded 3.73 gearing.....otherwise that carrier would be fine to use with the lower gearing you're looking at. Think new carrier probably runs $100-$125 give or take....but I haven't looked.

edit....duh, you say your stock gearing is 3.21. Disregard my line about presuming you don't have 3.73s .

 

Ah ok, thanks for clearing that up. Would the correct carrier bearing be included in the master overhaul kits?