Hello everyone. I am looking for advice on what gears to run with 37's, a Dynatrac XD 60 in the rear, and a stock Dana 44 up front. It is a 2014 JKU and has a RIPP supercharger on it. I can't decide between 4.88s and 5.13s. Any advice would be much appreciated, thanks.

 

With the 3.6L and the RIPP, I would go 4.88. 5.13 is just a touch low for 37s with the 3.6L IMO. With the SC I'd be most concerned with the most ideal gearing for pavement so the transmission stays happy (assuming auto tranny but you don't mention). You don't mention how you use this jeep or if you have the rubi TC or not, so take my opinion with a grain of salt. I have run non-supercharged 3.6L with 37" Nitto and Toyo tires with both 5.13 and 4.88 gears. The 5.13s are a touch low for high-end interstate driving IMO, though there are also times I wish my current 4.88s were my old 5.13s (I got shifted back due to an axle swap).

 

Ok got it, thanks. It is a automatic with a rubicon t-case. With the added weight of a dana 60 in the rear, I wonder if that extra weight in the back would make up for the slightly overpowered gearing of 5.13's in your situation. Anyhow, thanks for the response.

 

It's all about engine and transmission. Regardless of weight, 70+ mph would still be up at 3k RPMs and up with 5.13 gearing. I currently have 37x13.5 Toyo Open Coutnry MTs, full float rear Dynatrac 60 and a PR44 front with a spyntec hub conversion, so a very similar set up to what you got cept no extra HP. I have a friend with a RIPP and another friend that has had RIPP, Sprintex and a Prodigy turbo. Others out there that have forced injection themselves could probably speak better to it, but my understanding is it is really best to have optimal gearing for the pavement for the auto tranny to not be stressed given the extra HP. I'd say that the 4.88s are probably a bit more optimal since you have that 4:1 TC for offroad. That is all just my opinion though....sure not the end all be all. Have fun with the upgrades