junkyard trip for MJ

[case5412]

I've settled on what I want and hopefully yall can educate me on what to get. I need a few things at the junk yard but I'm not sure exactly. This jy has nearly 20 XJs and about 1 MJ.

 

1. My rear axle is at 3.07 gear ratio and I need a matching front strait axle. OR I can grab the D44 rear from the Isuzu Rodeo and grab a matching gear ratio front from the XJs or MJ (hopefully a little better than sluggish 3.07); I would only do this if the Isuzu was an easy swap, because I want easy and I want a daily driver by next Friday. My drive shaft doesn't fit right now anyway because the truck was 2WD.

 

2. I'm also grabbing the gear nob and the hook ups down to the transfer case for the 4WD shifter nob. I currently don't have one.

 

So that's 3 things I want. Hopefully matching XJ/MJ axles for an easy swap or XJ front and the Isuzu rear, which I hope is also an easy swap.

 

I also have another question. I keep getting lectured on getting a high pinion D30 and forgetting my low pinion D44. I don't actually understand the term completely. But I can look that up, please answer the questions that are impossible to look up.

 

Thanks in advance for the info...

Casey

[HOrnbrod]

Are you aware that the Isuzu rear diff axle shaft size is 5 on 5" centers? Not a showstopper as the width is okay, but not that bolt-in "easy". I'm like easy too. :D

[case5412]

Are you aware that the Isuzu rear diff axle shaft size is 5 on 5" centers? Not a showstopper as the width is okay, but not that bolt-in "easy". I'm like easy too. :D

 

The Isuzu also has 6 lugs. I'm just sleepy, been up too long, haha, what was I thinking.

 

How can you tell high pinion and low pinion apart?

[case5412]

Are you aware that the Isuzu rear diff axle shaft size is 5 on 5" centers? Not a showstopper as the width is okay, but not that bolt-in "easy". I'm like easy too. :D

 

The Isuzu also has 6 lugs. I'm just sleepy, been up too long, haha, what was I thinking.

 

How can you tell high pinion and low pinion apart?

 

I also do not know what "5 on 5" centers" means, so the answer to your question is: No, I am no aware of this

[Geonovast]

Whoever's lecturing you about the high pinion D30 vs a low pinion D44 must be confused... either that, or I am.

 

You're not looking for a D44 front, are you? They're trying to get you to avoid a low pinion FRONT axle, a low pinion rear is fine, I don't think I've ever even seen a high pinion rear..

 

High pinion Dana 30s can be had from 84-99 XJs, and all MJs. Shouldn't be too hard to find one in 3.07. Most of us can't even give them away.

[Geonovast]

How can you tell high pinion and low pinion apart?

 

 

High pinion on the right, low pinion on the left.

[Eagle]

I also do not know what "5 on 5" centers" means, so the answer to your question is: No, I am no aware of this

"5 on 5" means the wheels (and hubs) have 5 bolts, arranged on a circle with a diameter of 5 inches. The XJ and MJ (Cherokee and Comanche) are "5 on 4-1/2", meaning they use 5 lugs but the bolt circle is 4-1/2".

 

The Rodeo uses a 6-bolt hub, so finding a front axle to match AND be a bolt in for an MJ is not possible.

[case5412]

Whoever's lecturing you about the high pinion D30 vs a low pinion D44 must be confused... either that, or I am.

 

You're not looking for a D44 front, are you? They're trying to get you to avoid a low pinion FRONT axle, a low pinion rear is fine, I don't think I've ever even seen a high pinion rear..

 

High pinion Dana 30s can be had from 84-99 XJs, and all MJs. Shouldn't be too hard to find one in 3.07. Most of us can't even give them away.

 

It seems you are confused and I'd blame me. They said the low pinion D44 isn't worth the trouble, so go with a high pinion D30, which is what I'll look for tomorrow. I see in your picture that the high pinion has a different shape pumpkin, maybe that's all I see, but I should be able to tell them apart from that picture. Thank you.

 

Can someone post a picture of the bolt in axle I'm looking for? So I can compare it to the one at the JY, or, post the XJ years that had the easy swaping axles, would be very helpful and ensure that I don't waste my time pulling off the wrong axles again.

[Eagle]

Can someone post a picture of the bolt in axle I'm looking for? So I can compare it to the one at the JY, or, post the XJ years that had the easy swaping axles, would be very helpful and ensure that I don't waste my time pulling off the wrong axles again.

For a truly bolt-in rear axle, it has to come from an MJ (Comanche). The spring perches will be located on the underside of the axle tubes.

 

XJ (Cherokee) axles are the exact same axles as MJ axles, bbut the spring perches are located on the top of the axle tubes. All that's necessary to put an XJ axle into an MJ is to grind the welds holding the perches to the tubes, relocate the perches to the correct location AND ANGLE as an MJ axles, and reweld.

 

There are four possible axles you might find under an XJ: In early ones, you will usually find a dana 35 but you might find a Dana 44. In XJs 1991 through 1996, you may find a Dana 35 or maybe a Chrysler 8-1/4" with 27-spline (small) axle shafts. From 1997 through 2001 you might find a Dana 35 or a Chrysler 8-1/4" with 29-spline (larger/better) axle shafts.

[case5412]

Can someone post a picture of the bolt in axle I'm looking for? So I can compare it to the one at the JY, or, post the XJ years that had the easy swaping axles, would be very helpful and ensure that I don't waste my time pulling off the wrong axles again.

For a truly bolt-in rear axle, it has to come from an MJ (Comanche). The spring perches will be located on the underside of the axle tubes.

 

XJ (Cherokee) axles are the exact same axles as MJ axles, bbut the spring perches are located on the top of the axle tubes. All that's necessary to put an XJ axle into an MJ is to grind the welds holding the perches to the tubes, relocate the perches to the correct location AND ANGLE as an MJ axles, and reweld.

 

There are four possible axles you might find under an XJ: In early ones, you will usually find a dana 35 but you might find a Dana 44. In XJs 1991 through 1996, you may find a Dana 35 or maybe a Chrysler 8-1/4" with 27-spline (small) axle shafts. From 1997 through 2001 you might find a Dana 35 or a Chrysler 8-1/4" with 29-spline (larger/better) axle shafts.

 

Thanks for explaining what is under an XJ. Which one would be the best option and I'll look for that. Any drive sfaht complications that I might run into? Or other rear end options that may exist at the JY to try and match my gear ratio.

 

Thanks again,

[akamcbird]

Rear axle id

not mentioned is the amc20 (or m20) found in 86 mj's, very round diff cover

 

you will need a 4x4 mj drive shaft... but which one..?..

 

comanche rear drive shaft lengths-eye to eye (couple blank spots in there)

 

lwb,_2.8,____tf 3speed,____np207,_amc20= 53"_____d35= 54"

lwb,_2.8,____ax5-ax4,______np207,_amc20= 53.75"__d35= 54.75"

lwb,_2.8,____ax5-ax4,______2wd,___amc20= 63.75"__d35= 64.75"

 

lwb,_4.0,____aw4,__________np231,___d44= 47.5"___d35= 48.25"

lwb,_4.0,____aw4,__________2wd,_____d44= ________d35= #

lwb,_4.0,____ax15-ba10/5,__np231,___d44= 49"_____d35= 50"

lwb,_4.0,____ax15-ba10/5,__2wd,_____d44= ________d35= #

swb,_4.0,____aw4,__________np231,___d44= 41.25"__d35= 42.35"

swb,_4.0,____aw4,__________2wd,_____d44= 52.125"_d35= 53.125" *

swb,_4.o,____ax15-ba10/5,__np231,___d44= 42.25"__d35= 43.25"

swb,_4.0,____ax15-ba10/5,__2wd,_____d44= 52.125"_d35= 53.125" *

 

lwb,_2.5,____ax5-ax4,______2wd,_____d44= 63.75"__d35= 64.75"

swb,_2.5,____ax5-ax4,______2wd,_____d44= 57.5"___d35= 58.5"

lwb,_2.5,____ax5-ax4,______np231,___d44= ________d35= #

swb,_2.5,____ax5-ax4,______np231,___d44= ________d35= #

lwb,_2.5,____tf 3speed,____np207,_amc20= 53"_____d35= 54"

 

ax15-ba10/5 (same length) are 1" shorter than aw4

d44, chr8.25, amc20 have a 1" longer snout than d35

 

 

 

best option... mj d44... good luck finding one

second best, bolt in...mj amc20

third best, bolt in...mj d35

if you have to get perches welded mite as well look into a broader selection

 

when buying jy axles always pull the cover, also ratios are stamped on the ring gear

[TrailReadyMJ]

I'll try to help clear some things up, but may end up adding to the confusion :D

 

There are really only 3 bolt in front axles:

HP Dana 30 found in all MJs and pre 00 XJs (most older models have 2 piece passenger shafts with vac disconnect)

LP Dana 30 found in 00-01 XJs and most TJs, and ZJs.

LP "Dana 44" found in Rubicon TJs.

 

The Rubicon D44 is not a true D44. It still uses D30 outers, and retains the unit bearings. They gave it a D44 center so they can advertise it as a D44. IMHO this axle is not worth it unless you can get it cheap! IIRC these all had 4.10s and a factory locker.

 

The LP30 isn't even worth looking at.

 

The HP 30 will by far be the most common, and your best choice. Gearing ranged from 3.07 to 4.56 (although 4.56s are extremely rare. I am pretty sure they only came on 4cyl autos with tow package). 3.55s are almost standard in 4.0 auto XJs and MJs.

 

A LP44 will be slightly stronger than a HP30, with emphasis on "slight", and really not worth the effort in most cases.

 

The rear axle has been covered, but to add to the non-bolt in list, don't forget the explorer 8.8s. This is a relatively easy swap, and if from a 96+, you get disc brakes in addition to the 31 spline axles. If you have any questions on this swap, I have done several and would be happy to provide any info you need.

 

As far as high pinion vs. low pinion, here's the breakdown. If you look at the teeth on a ring gear, you will notice a flat side, and an angled side like this |\ . The flat side is the "drive" side of the gear, while the angled side is the "coast" side.

 

When a low pinion axle is used in the front, you will be driving on the coast side of the gear while moving forward. The coast side is roughly 30% weaker than the drive side due to the deflection created by the angle of the tooth.

 

With a HP axle in front, the reverse cut gear pattern allows for proper rotation, and uses the drive side while moving forward. There really aren't many HP rear axles for these reasons, although a hi9 conversion for a ford 9" is HP and variations of HP Dana 60s have appeared in the aftermarket.

[Incommando]

I hope that you are not planing on using that shop from your other threads that couldn't tell a pass. drop front from a driver's.

 

You have several posts asking for advice. That is fine and dandy. But are you willing to listen to advice, or read the advice posts?

 

Buy a matching axle set from an MJ ( probably scarce). Avoid the D35 if you want to hit it hard. You can find these sets in 3.55 all day for cheap, and some 4.10's. Other ratio's are out there but the 3.55 seems most common.

 

The same rules apply for an XJ axle set, except you will need to swap your spring perches, a very easy operation for anyone but a shop that can't tell a LP from a HP. I would not let them tighten my lug nuts.

 

Buying a match axle set is BY FAR the cheapest and easiest way to do this.

 

There is no cheap/easy D44 front. This swap is probably not the best for someone without some solid experience. This is not for you.

 

The 8.8 rear is an easy swap with just the right driveshaft and a spring perch movement needed. But finding the matching front that is an easy and/or cheap bolt in is the issue. Paying to have gears swapped is usually fairly expensive.

 

YOU NEED TO FIND A MATCHING SET OF MJ/XJ AXLES IN A BETTER RATIO OR BUY AN MJ/XJ FRONT TO MATCH YOUR EXISTING REAR. You probably ought to hook up with some local wheelers who know something about jeeps to keep from screwing yourself over, which will lead to frustration and an abandoned project. That happens all of the time. Getting in over your head is a huge but common mistake, so befriend someone local who can help you with the swap, help you weed BS from good info, help you tell which direction shocks point on an axle, and keep the fact that swapping a 6-lug rear Rodeo axle without a matching lug pattern front leads to more expense/work to make them match or two carrying two spares or going without in mind.

 

Good luck on your build.

[case5412]

thank you, I've printed out everyones advice and I'm bringing it with me to the JY now. I'll post later.

[Pete M]

brakes changed over the years. try to get an axle that's as complete as possible.

 

and please please get something better than 3.07s :no: