D30; Hp or Lp? How Can I Tell w/o BOM Number?

R

RAVC1

NAXJA Forum User

Location

Michigan

• Aug 25, 2007

• #1

My 1989 XJ is due for a lift, 33" tires, and 4.10 gears. However, I was not able to locate the "Bill of Material" number on my axle tube because of a thick layer of undercoating. So I'll be using the wire brush tomorrow to locate it.

However, I can state there is much more housing on the rear of the pig below the pinion entry point than above it. This suggests I have a Hp D30. The complication is my pinion is not much above the level of the axle tubes (If at all.). What does a Lp D30 of this vintage look like?

Can any of you Dana 30 experts help me here...in the absence of the Bill of Material #?

Thanks,

Rick

 

H

Hawk

NAXJA Forum User

Location

Union, Mo

• Aug 25, 2007

• #2

Your XJ should have a HP 30.
Here's a pic I found, for easy reference.

 

R

RAVC1

NAXJA Forum User

Location

Michigan

• Aug 25, 2007

• #3

Hawk,

You are correct! My D30 is identical to the one pictured at the right; with all the reinforcing webbing.

I must admit, it is very clear my 1997 has a Hp D30 front axle as the pinion is located at 12 o'clock and is well above the level of the axle tubes.

Thanks for your help. I'm off to the reverse rotation gear store!

Rick

 

H

Hawk

NAXJA Forum User

Location

Union, Mo

• Aug 25, 2007

• #4

The bonus, is that the gears themselves are actually stronger in your axle in the way that they mesh, but I've already hit the peak of my ability to explain, so if you do a little looking around you'll likely find out why, if you even want to know that bad.

 

R

RAVC1

NAXJA Forum User

Location

Michigan

• Aug 25, 2007

• #5

Hawk,

The reason for the strength of the HP or reverse rotation gears is these use the side of the gear tooth that is stronger than the side of the tooth used in the normal rotation gears.

Rick

 

lancey3

NAXJA Forum User

Location

Columbus Ohio

• Aug 25, 2007

• #6

get 4.56s not 4.10s

 

JeepFreak21

NAXJA Forum User

Location

Cameron Park, CA

• Aug 25, 2007

• #7

lancey3 said:

get 4.56s not 4.10s

Click to expand...

I'm sure that's great advice even if you don't have a clue what engine or transmission he's running or what kind of driving/wheeling he does.

Billy