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High pinion D30 vs. low

Okay, but I guess I'm looking for the engineering reason. Quite a few Grand Cherokee owners (with LP) seem to be doing well with moderate lifts and tires. I'm not questioning the answer, just trying to find what it's based on. Also, what are the advantages?
 
Last edited:
gator_grabber said:
Okay, but I guess I'm looking for the engineering reason. Quite a few Grand Cherokee owners (with LP) seem to be doing well with moderate lifts and tires. I'm not questioning the answer, just trying to find what it's based on. Also, what are the advantages?
Click to expand...
I'm no engineer, but here goes...
The HP axle has two big advantages. The first is strength of the R&P setup. The HP axle is a reverse-cut gear, and uses the strong side of the ring gear. The set-up is also more precise, as it uses shims for the pinion depth and preload, instead of a crush sleeve like the LP axle.
The other advantage is driveshaft angle. With the driveshaft coming into the diff above the axle tube instead of below, the u-joint operates at less of an angle. This is VERY helpful at lifted heights.
 
Thanks, that's the kind of info that's helpful. I knew that there had to be something other than the driveline angle at play, so this really helps. Are there any other issues with the axles, U-joints, etc.?
 
gator_grabber said:
Thanks, that's the kind of info that's helpful. I knew that there had to be something other than the driveline angle at play, so this really helps. Are there any other issues with the axles, U-joints, etc.?
Click to expand...
I'm glad it helped. I'm not sure what other "issues" you were looking for...?
I used a HP housing from a '94, and swapped over my axle shafts and everything else from my 2001. (except the gearset) I get the HP advantages, and the 297 u-joints from the newer model. Everything fits fine.
HTH.
 
You covered it with your last post. Manufacturers have a maddening habit of building a sound piece of equipment with some kind of "got ya" built in (the LP D44 comes to mind). Behavior like that often answers the question of what happened to all of those 80's "crack babies"...:rolleyes:
 
A high pinion is always stroger in front applications as it "pushes" the ring gear and does not "pull" to turn the carrier. As the inner pinion bearing is always stronger than the outer this is a significant advantage in strength and for longeivitiy of the pinion bearings.
 
So pull the tubes from a WJ and use a HP casting - same spline counts - best of both worlds... :roll:

And after your done you will have the experiance to put D60 stuff on a 9", 14b, whatever center or retube a pull-a-part 60 so it is the correct driver side drop.... It's not rocket science!
 
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