Quote Originally Posted by dalearyous View Post
timmy, can you break down in percent time spent on driving in the city, highway, trails? i think that is also important when making this decision. also, please post back your impressions once the gears are in (i am sure you will).

did the dana 30 have any weight in your decision (as far as pinion size concerns etc ...)?
Oh yeah, sorry, I put this in my "37" tire upgrade" thread and forgot to repost it over here.

Here's my percentage driving
40% - 0mph-40mph
40% - 40mph-60mph
10% - 60mph-80mph (my sedan makes up any other highway driving as needed)
10% - Off-Road (hopefully this number will increase as I learn the area a bit more)

Great question on the Dana 30! Yep, the Dana 30 did actually weigh into the decision slightly. I've read that 4.88 is really the highest gear you can safely go on a Dana 30 from a strength standpoint. There are people running 5.13's on the Dana 30 front without any issue, but I've seen pictures and the pinion gear suuuuuuure looks small. Knowing that I want to put a supercharger on at some point (if I can stop forking out money for other upgrades first!) I wanted to make sure I had a ring/pinion that could handle the added power. If 4.88 is supposedly the highest recommended, I figured backing off to a 4.56 would give me a nice safe margin if/when the engine has a nice big power bump. The gears and labor are expensive enough that I would be pretty pissed off if I went with 4.88's and then put an SC on and found that I broke the pinion due to too much torque. I purchased Yukon gears, which are supposed to be pretty good, but then I read that basically every "good" gear you purchase for a Jeep these days is all manufactured from the same main supplier (whoever that is, and most likely made in China.) So with that information in mind, it also swayed me to 4.56 to make sure the pinion gear was a little larger.

I'm having a hard time finding a pic I've seen of the difference between 4.56, 4.88 and 5.13 pinions. Here is one though that shows the difference between a 3.07 next to a 4.56 Dana 30 pinion, which certainly shows the dramatic difference in size. You can imagine how much smaller a 4.88 and 5.13 would be.



Here's a pic of a Dana 44 vs Dana 30 of the same gear gear sizing to see how much smaller a Dana 30 is.


Here's a Dana 30 destroyed by 37" tires (not sure what pinion size it was.) The caption of the post was "Yeah, D30 rings and pinions are virtually bullet proof..." (said jokingly in response to someone saying most people don't break D30's.)