Good to know guys, thanks!
So would you say the power gained from 5.13's outweighs the weak link factor when thrown in a D30, or does the 4.88's have a better chance of survival?
..I think I'm wording this right...

 

Browse around a bit more and see how many posts you find about broken axles/housings, and compare that to the number you find about losing the R&P. You will find a lot of the first group, and very few of the second.

As noted several times in this thread, if you like to stand on the gas pedal and banzai through the rocks, you will be breaking D60 and 14bolt gears. For the rest of us, 5.13's are fine in a D30.

 

the 4.88 is as from what i found is a good way to go. I think the 5.13 are a very tall gear and i drive more highway so I went with the 4.88 if not then the 513 aren't bad just matter of choice.

 

Did you read what MJM said about 4.88 gears?!?

 

I have an unlimited auto with 315/70/R17 Duratracs, superchip, and 5.13's....I had your problem with 3.73 gears, now I can climb mountain passes at 75-80 mph at 3000+ rpm while passing other vehicles.

Stock, I was way over in the far right lane getting passes by 18-wheelers.

 

I have not said anything about 4.88s not sure what you are talking about? Please advise.

 

Personally, with all the talk about 5.13's being the 'best', I really don't see how the additional 100 rpms gained from switching to 5.13's from 4.88 is really that much of a benefit. 100 rpm is not a significant gain in the power curve or torque. I'll bet most who say they see massive differences really are just echoing what most others are saying.

 

While the 100rpm may or may not be a true value for most people (I'm assuming you're citing a gear ratio chart) the magnitude of change in a final drive ratio is pretty large. Rubi ratio ~91.5:1 w/5.13's vs. ~87:1 w/4.88's (%5 higher crawl ratio) over the stock 73.4:1 (+20% 5.13's, +15% 4.88's). The 5% increase would translate to all drives of the JK (not just 4lo crawling) standard drive in 5th gear would yield ~+150RPM @ 3000RPM over 4.88's...the higher the RPM load, the more effect it will have i.e. @4500RPM w/4.88's, 5.13's will be hitting 4725. If I'm paying a good hunk of cash to regear I'd rather shoot that 5% gap to squeeze all I can out of my investment-and it costs the same as 4.88's..... If the OP had smaller tires or wasn't an auto then yeah, 4.88's would be fine...But he's not considering 5.38's (which have other problems people can argue over) he's deciding between 4.88 and 5.13. I can't think of a single reason to take 4.88's over 5.13's in this situation.

 

All this talk about 4.88 vs 5.13 vs 5.38 is nice, but I think the important thing to remember is that pretty much any of these ratios is better than stock. Just yesterday I did a fifty mile interstate drive in my Rubi with 4.10 gears and 37" tires. The finishing point of the drive was 4000 feet higher in elevation than the starting point. My Jeep was able to maintain 80 mph, but most of the fifty miles was in second gear, at 4700 RPM, and my fuel mileage for that fifty miles was roughly 5 mpg.

Argue all you want about whether 4.88 gears are enough to prevent downshifts to third gear, vs needing 5.13 gears. The bigger thing to remember is preventing downshifts to second gear.

 

wow