DIRTDOGXJ

I searched and didn't come up with a clear answer. I know I have a D30 up front and D44 out back....my question....how do I know if the D30 is hp or lp? Also, how do I determine what gear set I have into each? PO said they weren't stock but wasn't sure because he didn't change them. He thought the front had a lunchbox of some sort too. Other than checking the stamps on the axles, how do I got about figuring this out ? Thanks in advance......

Agent_Oragnge

there should be steel tags that are placed within the bolt pattern of the differnatial cover on each axle. those tags (if they are still there) will say what the gear ratio is. short of that the only way to be sure it to crack open the diff and count the number of teeth on the ring and divide by the number of teeth on the pinion. the number will be a gear ration 3:55 3:77... 3 teeth on the pinion for every 77 teeth on the ring.

DIRTDOGXJ

Any idea on hp versus lp?

xjmarc

Unless the front came out of a 00-01 XJ, TJ or ZJ it's high pinion. You'll need to pull the diff cover to check for a locker to be positive. An easy way to check gear ratio is to block the wheels and jack up one of the rears. With the transmission in neutral spin a tire one complete turn and count how many turns the pinion yoke turns. 3 and a half would be roughly 3.55, 3 and 3/4 would be 3.73 and so on. Lucky you getting a rear 44. Kind of rare since they only came in XJs for 3 years and your year isn't one of those.

SeriousOffroad

Hp= The pinion is above the centerline of the ring gear.

DIRTDOGXJ

I believe the rear axle isn't factory but its all hearsay. The rig was pretty cobbled together by the PO. I knew there was an easy way to determine the gear ratio, just didn't know the formula. Thanks for the info.....

Agent_Oragnge

BRILLIANT !!.

blue_on_blackXJ

Not quite. If there were 3 teeth on the pinion for every 77 ring gear teeth it would end up as like a 20" ring gear. The 3.55 3.73 etc indicates 3.55 pinion gear rotations for every one ring gear rotation. Ring gear tooth count is usually around 40 giver or take 5 ish

Agent_Oragnge

Yeah i caught myself over thinking it then when the wheel rotation vs shaft rotation was pointed out... needless to say i'm not the guy to listen to. ever. haha

blue_on_blackXJ

Ill keep that in mind!

89eliminator

take a pic of the rear axle...

DIRTDOGXJ

I did a little digging and im pretty sure its not a D44. Looks more like a D35 or a 8.25.......bummer......

Rock Toy

Well, the C/8.25 is as strong as a D/44 if you upgrade to 29 spline shafts.

Plus you can check the gear ratio without jacking the axle.
Mark a line on a rear tire and one on the drive shaft, then have someone lay on the driveway and count
the drive shaft revolutions as you move it forward one revolution of the tire. Same as
you would if you jacked it, just makes it easier and faster.