There are many who have wondered what that advantage of the HP vs the LP dana 30 axle is. I will explain and show you what I did.
The Dana 30 axle that comes with the TJ Wrangler is a what is called a Low Pinion axle or LP. There is another axle that is the same in every way but has a high pinion. This axle is the Dana 30 High Pinion or HP. The low pinion is fine for most things but for those of us that are interested in getting the most out our Wranglers we can see the benefit of swapping in an HP axle.
The advantages to swapping in the HP is only a couple things:
First, the high pinion is higher. Instead of having the pinion on the bottom of the differential it is on the top. This is advantageous because it gives the drive shaft more clearance from the ground which will reduce the amount of times the drive shaft would come in contact with rocks. The other advantage is the drive shaft angle. With the drive shaft attaching to the differential in a higher location there is less of an angle coming off the transfer case. This helps to reduce wear on the u-joints and also helps to eliminate vibrations.
Second, moving the pinion to the top of the differential increases the strength of the gears. The gears are about 25% stronger as a result of them running on the drive side of the ring gear teeth. I am not an engineer and cannot explain the reason for this but this extra strength is enough to make me more secure when running 35's with a locker on a dana 30.
Here are the steps I took in acquiring a Dana 30 HP axle and swapping it out with my stock Dana 30 LP:
I just got a TSB letter in the mail today about the ODB light in my Jeep Wrangler.