This topic has been batted around here before. I'm hanging around Jeep guys lately (don't judge me) and I've stumbled on a new wrinkle.

The idea is how to cram a bigger, stronger gear into a HPD44. Yes, I know I want a 609 with a True Hi9. But money, time, etc won't allow for that yet.

Jantz engineering offers a kit to put D50 gears into the HPD44 housing. Pro: bigger ring gear, almost 9". Con: same pinion diameter as the D44.

I was at our club meeting a couple weeks ago and someone offered a HPD44 4.88 ring and pinion for cheap. I will need to regear when I get back on the road and I jumped on the chance. When I went to pick it up, I quickly realized this was a JK Rubicon HPD44 gear. I haven't bought it yet, but I started an internet search for any magic to install the gears into my axle.

Enter Jantz engineering's new kit: K4. This kit is made to install a rear JK Rubicon D44 ring and pinion into a regular D44 housing. Actually this would probably work for you guys with stock LP front axles. Pros: 8.9" ring gear vs 8.5" stock, larger pinion diameter than stock. Con: none except work and cost of the kit.

I've been emailing with Carl Jantz about using this in my HP axle. I'm not 100% sure it will work yet. Unfortunately, the JK Rubicon HP ring is still 8.5", not 8.9". It does have the larger, stronger pinion than the old D44 pinion.

So my questions is:

What is the weak point of the HPD44 ring and pinon with 37's, low t-case gears, and chromoly axles? The pinion or the gear?

Is it worth making the upgrade to the larger D50 ring?

Is it worth making the upgrade to the larger JK Rubicon pinon?

If only the JK Rubicon front gear upgraded to the 8.9" ring, it would make the decision easy. You would end up with a D60 pinion and a larger ring gear than the D44.

Below gen 1 D44 vs rear JKD44 vs D60
129-1007-15+dana-44-dana-60+ring-and-pinions.jpg

Pinion deflection is generally the weak point with a R&P set. Thus why the JK rear uses a bigger pinion shaft.

The JK HD44 upgrade seems worthwhile, the HP44 upgrade with the smaller pinion shaft doesn't gain you anything worthwhile.

Ya know I was pondering this myself. What I would do is get a dynatrac axle built. that is if they could work with factory outer knuckles. granted that would probably be $4k.

Interesting. I just got really happy about my doubler.

The bad news from Carl Jantz is that the ring and pinion I can buy will not fit. The pinion is too short in overall length.

This has confused me, Carl Jantz says there are 2 length of JK pinions. The one I have is a 'short' one at 7-1/2". I've looked at tons of JK ring & pinion sets on line and not one has mentioned short or long pinion. I even spoke to Currie, because this one is from a Currie axle, and they have never heard of different pinion lengths. Based on the part number on the pinion, my guess is it might be from Yukon.

Oh well it was worth a shot.

EDIT: It might be all JK Rubicon front diffs have the "short" pinion. I can't find any with longer pinion. Yukon's and Nitro's both mention short pinion.

Is Carl Jantz that dude that was on a tv show where they were on some adventure challenge 4x4 trip across Alaska ?

With the Atlas there is certainly the opportunity to wheel with more finesse, which is also my style. But when things break, the multiplied torque can really take out of lot of parts.

I had to be dragged out of Penrose (the easy trail) the one time I did it. Running stock HP44 shafts and u-joints I tried to crawl into one of the harder trails and broke the u-joint. So I gave up that idea. When we all started heading back out, I couldn't get a line I needed with 3WD. I maneuvered a little and got the dead wheel bound up against a tree. I could feel the torque was about to overpower my setup so I backed off. Spotter said it would come thru, so I tried again and BOOM, blew the rear atlas yoke and took out the CV. Sweet, 1WD now! That was not so fun.

But since I have upgraded to Chromoly shafts, I haven't had a breakage now that I know the limits of my system.

Then there are times were copious amounts of throttle need applied and I generally cringe in those scenarios.

I too am dreaming about the 609...but I have to get a lot more serious about my wheeling before I can justify that!