Jeep Enthusiast Forums banner

hp dana 30 vs lp dana 30

58K views 50 replies 24 participants last post by  Wheelin98TJ 
#1 ·
just what the title says why is a hp dana 30 out of a cherokee better than a lp one out of a tj??
 
#8 ·
The coast side of the gear is the side that's beveled relative to the base of the gear. The drive side is the other side and it's face is perpindicular to the base of the gear.

A low pinion in the front drives on the coast or beveled side of the gear and under higher loads, the pinion teeth are forced out of the contact area into the higher thinner edges of the teeth and that's what tends to destroy the gear teeth.

A high pinion on the other hand drives on the flat side of the tooth and the contact pattern tends to remain static regardless of the loads placed on it.

High pinion= driven on the drive side of the ring gear teeth.

Low pinion= driven on the coast side of the ring gear teeth.
 
#5 ·
I would call it one of those swaps you do if you can get it cheap. It's not such a great thing that you would spend lots of money or time on it. As the previous poster noted the only real advantages are stronger R&P (actually the R&P is the same strength as the LP but it is running in "forward" instead of "reverse" so to speak) and getting the driveline a little higher. The weak point on a D30 and D44 is the axle ujoint and ears which remains the same. I have a HP in my TJ but it is because I was about to do a gear swap and was able to pick up an axle for about what the gear change was going to cost. I re used my TJ shafts due to the u joint (Mine was from an 89 model XJ).
 
#9 ·
ZJ's are low pinion. I had a ZJ axle in my rig for about two years. It is basically identical to the TJ axle. (The reason I did it was because it was free and I was trying to move from 3.07 to 3.73 gears). Most of the ZJ came with 3.73 from the factory.

V8 models have a heavy duty tie rod. Some models used CV's instead of u joints in the front axle. Also, a lot of them had antilock brakes (you can just ignore the sensors etc). Other than that it is identical to what you have in your TJ now.
 
#7 ·
zj's use some sort of funky pinion flange. i don't know anyone running one from a ZJ. Not sure that it is even a HP30.
 
#12 ·
another thing to keep in mind is that some ZJ axles have crappy CV joints instead of u-joints.

edit: see someone else already said that.
 
#13 ·
Another "advantage" of a HP 30 is it uses shims for pinion preload instead of a crush sleeve. The set-up is a bit more stable, and it makes changing out a pinion seal MUCH simpler.
 
#17 ·
Early on, when I was studying the internet chatter about TJ stuff, I read comments similar to the above about the XJ dana 30. I wanted a 4.10 gear set-up to match a rubicon rear axle I bought. I found a hp30 from a 4 cylinder '99 XJ for less than the price to regear my TJ 3.07 axle. I also got some usable spare parts which may pay off some day. And I agree about changing the pinion oil seal. It's pretty easy to do without the crush sleeve issue.

Since then, I've looked for discussion about why the TJ didn't come stock with a high pinion front axle. Imagine a conversation back around 1995 between a couple jeep design engineers.

"We're going to go with coil springs, round headlights and a low pinion dana 30 with 297x universal joints."

"But we've already got the high pinion design in the XJ and it's been doing great."

"Doesn't matter. The low pinion with a crush sleeve to set pinion bearing pre-load is going to be better because......"

So anyway, what do you think led to this decision? The YJ was high pinion on leaf springs and passenger axle disconnect. Did it have any other design flaws? Could it be they were thinking about a TJ on the trail in reverse gear, trying to back up a slope? Did they have a cost incentive from Dana/Spicer to change? Was the TJ design dana 30 already in production for some other vehicle? Just curious.
 
#18 ·
What year HP30

I know this is an old thread but, I'm about to do the axle swap and I found an HP out of an '89 cherokee. They have vaccume disconnects. I'm confused. Will it still work? I know our TJ diconnect from the T Case. The guy even said the Vaccume diaphram is not in good condition. 100 bucks. What do you guys think?

How can I tell if its really HP or not?

Will my current LP diff guard bolt right up?
 
#19 ·
Do a search, all of that is covered.

In short, it will work with slight modification, on a HP the pinion is at the top of the diff vs. the bottom, and yes, all parts except for the gears are the same.
 
#20 ·
Do a search, all of that is covered.

In short, it will work with slight modification, on a HP the pinion is at the top of the diff vs. the bottom, and yes, all parts except for the gears are the same.
not neccesarily. depending on the years (not sure off the top of my head) they had wider unit bearings that need a specific rotor or the breaks will not work properly, also the 89 has 267 ujoints in it as well. you can swap all your tj stuff into the hp 30 though from the axle shafts out and have a very stout axle. you just need to get a piece of steel plate to cover where the cad is at. you will need to add an inner axle seal as well.
 
#25 ·
Thanks for the info, mmy search brought me to this thread. It just was not the right criteria in the search. But thanks for bringing up the old "do a search"

Peace!
Peace...your question was answered here.

Swap over all your TJ stuff (shafts, brakes, hubs) and purchase a block off plate for the vaccuum disco. You'll be set.
 
#29 · (Edited)
Good Info

I have the links open now and am reading them. I found a few xj housings for $100, one from and '89 is in Lake Elsinor. I'll see if he will drop the price a bit, but I already told the guy I'm interested.

Also emailed Gerald from Savvy. I think my gas tank skid wont take another beating. I already had to patch up my tank with some Kevlar coating from my track bar bolt grinding into it.

BTW my name is Nima not Peace :tea:. I want to relax and not be pissed about stuff. I searched and searched but did not think to search for what you did. Were all good man.

Peace! haha

Edit: I was recommended to get the non disco. I'll look for that, but I guess its not a deal breaker.
 
#30 ·
Peace,

the non disco housing is a better bet but a disco housing is not a deal breaker by any means. If you get an older style (like the 89 you're looking at), just swap your TJ stuff over...you'll be happier.

Peace! :rofl:
 
#33 ·
Ive been looking for a 96-99 HP 30 for a while now with no luck but today I did find one from a 89 non disco
for basically free.(trade for my d35 which I swapped for a 44 out of an unlimited) What drawbacks would I be facing and What should I swap over from my 30 if I went with this axle. Thanks
 
#34 ·
Hp30

^ I have an '06 Unlimited with the dana44. It comes with 3.73 gears not 3.55 as on your profile. There is some info about the disco stuff (I think earlier in this thread). But, supposedly thats very minor if you need to do anything at all. But as far as I know, you don't. Other than that, the experts say its a direct bolt on. I bet your current brakes, even though they are stock are iin better condition. Maybe you want to upgrade to Vanco Brakes while your at it? I did and don't regret. Its a great bolt on solution!
 
#35 ·
If it is a non disco housing from 89, swap over your knuckles, shafts and unit bearings and be done with it.
 
#36 ·
Yeah I need to update my Prof I originally thought I had 3.55 but actually had 3.07. Now I haves d44 rear 3.73 with a 3.07 LP 30 up front and no 4wd. So ill go ahead and pick up that 89 and hopefully scrounge the money up for the 4.88s. Thanks guys. Side thought any chance that 89 could have 3.73s? Forgot to lookand that junkyard is a joke as far as the people go.
 
#37 ·
xj axles are almost always 3.54/3.55 with a 6 cyl and 4.11 with a 4 cyl.

Like Apex said, change the knuckles and out with your newer stuff. 89's had a 2 piece knuckle.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top