I've read several comments regarding the improvement that 513 gears can make on the JK with 35" tires. That seems to be the accepted combination. For those of you that have this setup, do you use it hard offroad? My XJ and ZJ builds have the HP30 with 488s and the pinion gets kind of small. I know the 44 in my 2010 Unlimited with auto is better than the hp30, but 513s are probable to the 44 that 488s are to the hp30. Am I wrong or do these gears make the R&P the weak link? I'm waiting for 34" MTRs to add to the OME 3" lift from Northridge. I doubt (should never say that) that I will ever go bigger with the tires, as it will be my DD 90% of the time and my wife and I are approaching 70 and don't need something higher to get into. I have a fairly light and cautious right foot. Are 513's still right for me??

 

There are about a billion threads asking this, and the general consensus is that:
auto + 35's = 5.13 (or 5.38 for rubi's)
manual + 35's = 4.88 (or 5.13 if you want a bit more oomph)

Back a year or two ago, pinion size on the D30 was talked about quite often as the 'weak link'. But it just hasn't turned out that way. People are losing axle shafts before the 5.13s/5.38's...

 

OK, that sounds good. Although mpg's aren't a big issue, I imagine there is very little difference between the 513's and 538's. It's a whole new concept for me to accept those high ratios for a DD and expect decent economy. I've read many of the related threads, but I'm from the old school and it's hard to change ones logic. Maybe it's time to accept what I've read and just do it.

Thanks

 

The higher (numerically) gears will keep you in a better power band without the transmission constantly having to downshift. The end result is better power and mpg's.

If you want to take it a step further, plug in a Flashpaq...


And what he said

 

I dunno about the axles vs the R&P. I got stuck in some mud and my 5.13 R&P grenaded itself. Could've just been installed incorrectly though, wouldn't put it past a certain parts dealer/shop...

 

I programed it with the Flashpaq a few days ago. Just waiting for the wheels & tires to get here from 4wheelparts. Should have been here by now, but haven't shipped yet. I think they Hooked me with the "It's in stock and will ship out in the morning" line, when they really didn't have it. With David at Northridge, the lift came in a few days like he promised. Guess where I'll order next time?

 

Is another possibility that you were putting a lot of stress on the gears because you were hammering it in reverse? A lot of people don't know that that can be catastrophic.