Does anyone have any real data on what the real strength difference is between the 4:88 and 5:13? It looks like most of the information is empirical. It would seem to me that the difference wouldn't be that great, because of the small numeric difference. Or in comparison is the 4.10 really that much stronger than the 4.88, and the 4.10 that much weaker than 3.21!

 

x2 what tgrt said. In all the claims about the 5.13's being weaker than the 4.88's there has never been a documented case of failure on the 5.13's. At least none that I could find before I went with this choice.

 

The other reason I chose the 4.88's is for fuel economy. almost all of the charts that you look up show 4.88's as the best compromise for power and economy. here's one of them http://www.oly4x4.com/gearratios.htm

 

This is all very interesting. One thing to consider is everyones "stock" performance is different. 3.21s, 3,73s, and 4.10s.

Per the chart my 3.73s are at 2546rpm with stock 32's. If I go to 35's per the chart the closest to my "stock" performance would be 4.11s which gives me 2565 rpm. I know this isnt actual rpm with an OD auto but the final ratio's should be the same.

So by this chart my stock Sahara (3.73s) on 32's should have the same performance as a stock Rubicon (4.10s)with 35's. Is this true in real world?

 

Ok no one with 5.13s has stated they wished they went with 4.88s. Does any 4.88s wish they went with the 5.13s on 35s? And why.

 

Not me, I'm happy with my decision.

 

Nobody with 4.88's say they wish they went with 5.13's because they think they have it good and dont know what their missing!

I dont care what charts say about mpg, yeah 4.88's are closer to the stock ratio, but charts dont factor in the extra weight your hauling around.
The little extra that 5.13's give you over stock, just makes up for the extra weight of the 35's.

With 5.13's, my mpg went up over the stock 4.10's with 35's, and I still have to down shift up hill into the wind to maintain 70mph,
With 4.88's you'd be shifting even more, eating up more mpg.

 

And that the failure had to do with the smaller pinion in similar conditions where a 4.88 didn't have a failure. I don't doubt that the 5.13 are weaker, I just question that its substantially or notably weaker.

 

This will be my last post in this thread. Seems as though there are some getting emotional about it.

My buddy's mechanic said he thought it broke because of the pinion not having enough metal. Was there a controlled experiment showing a definite cause a effect relationship? No. That said, this guy wheels more agressively than anyone I know personally and I'm sure that has a lot to do with it too.

I'm glad to hear you 5.13 guys are happy, so am I, but I also have a sports car for speed and acceleration, I'll stick with the Wrangler for offroading.

 

Next question.....other than the ring and pinion if I am going from 3.73 to 5.13 do I need to worry about changing anything else like the carrier?