mj to xj axle housings question

[mjdoa]

I don't mean to waste anyone's time by not searching first,

I did ,didn't find what I'm needing.

Mine is an '88 mj.

I have a chance to pickup 2 complete '90 xj axles cheap

with a better gear ratio.

Question is,rear axle is complete,springs and all,even brakes,

will it bolt in directly?Do realize I'm going SOA,

which is good for me.Need to know if housing

is the same width.and are the spring perches the same distance

apart mj and xj?Getting drive shafts,so those can be

changed if necessary.

Thanks,guys,as always.

I'm far away from you all,So Florida,

my project is coming along nicely,I'll put up some pics.

[Motion Offroad]

A XJ axle will NOT bolt into a MJ (and vice versa). The width of the spring perches are different.

 

To make it work you'll need to weld on new spring perches on the XJ axle.

[Pete M]

Please refer to rule #2. :D

http://comancheclub.com/forums/viewtopic.php?t=1239

 

And as Motion said, the perches don't quite line up and will need to be moved. Aside from that, the axle itself is pretty much the same.

 

 

Oh, and we have several members in Florida. 8)

[Backdraft]

You're wasting everyones time. Search.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

just kidding......what they said :D

 

Mike

[mjdoa]

As always,you guys are awesome.

I think I'll get them,mine's got 3.08's,these are 3.55's,

I'm running 32x11.50's,4.0,5 spd,4.5"lift.As you can

imagine,5th gear is useless,and I'm sure it's straining the

drivetrain tremendously.I'd like to go 3.73 or 4.10,but

this guy has both axles complete,brakes,springs,and both

driveshafts,$200.00.For that price,I can afford to do a little

fabbing on spring perches and still be able to afford lockers,

and live with 3.55's for a while. 8)

I will put some pics up this weekend,so you all can laugh

at my ugly truck.Body work and paint to follow.

I'm a member of a Jeep club down here,and it's nice to

have something different from a Wrangler,ugly or not.

Thanks very much for your help,ya'll are the best.

[mjdoa]

BTW,thanks for pointing out Rule#2.

You guys are

[MiNi Beast]

I wanna be

 

 

:D

[mjdoa]

For a price,we'll include you.

[Geonovast]

so you all can laugh

at my ugly truck.

 

Without even seeing it, I can guarantee we've all seen worse, and most of us have owned worse.

 

If it's originally from FL, how bad could is possibly be? :nuts:

[MiNi Beast]

For a price,we'll include you.

 

 

:cheers:

[mjdoa]

It was bought new in Plant City,Fl.=no rust. :D

It has however,been rode hard and put up wet

for 20 years.And I haven't helped by wheeling it.

It's banged off a couple cypress trees in the Everglades.

I've upgraded both bumpers,have rock sliders being

built by TomkenInd,so we'll get her there.

I'll get off my butt this weekend and post a pic.

Thanks again.

[Eagle]

You are wasting money and effort going from 3.08s to 3.55s.

 

I was running 31" tires through 3.73 gears. The overall final drive ratio was exactly the same as stock tires and 3.55 gears. With 32" tires, all you're going to do is get back to approximately the equivalent of your stock 3.08 gearing with stock tires. But ... your tires are much heavier and harder to start turning. You really need at least 4.10 gears, or preferably 4.56s.

[mjdoa]

But... my other vehicle is a 2500 Chev diesel,with fuel prices as they sre,I'd like to be able to take the 32's off after wheeling,put the streets on

and use for d/d.Would 3.55's not be a good compromise under those circumstances?

Or should I keep looking?

[mjdoa]

btw,Eagle,I had done the math,you are absolutely correct.

:cheers:

So shall I go back on the hunt?Would 4.11's be streetable,

and halfway economical?

And as I read this,I realize I want my cake and eat it too.

:nuts:

[mvusse]

If I were you, I'd check local restaurants to get some contacts for free used french fry oil, and invest in a setup to make your own biodiesel.

 

Then drive your Chevy more for about $1 a gallon.

[JeepcoMJ]

ok, a few problems with what you're getting.

 

rear axle you'll need to switch spring perches in the rear.

 

xj rear springs DON'T work. they're far shorter and your axle will not center in the wheel well

 

xj rear driveshaft WON'T work and will need be retubed.

 

everything up front is the same.

 

switching from 3.07's to 3.55's is a marginal upgrade, but you need 4.10's for your tire size.

[mjdoa]

Alright,I'm convinced.

Back to craigslist. :roll:

Thanks for your sage advice,gentlemen.

[pingpong]

4.10's or 4.56's would work great for you. Both ratio's came stock in jeeps so you should be able to find them at your local Pick and pull but they only come up once in a while. Your other option is to buy gears and install kits. Not exactly a cheap option, but a feasible one if you can find used gears. Install kits are right around 100 bucks an axle. Labor is what gets you, and add up quick. This is where a local Jeep or Offroad club comes in handy.. befriend the local gear installer, and work a deal. I just had some gear work done, and got a smoking deal from the installer cause I took him to Tellico a few yrs ago as my winch Biatch.

[mjdoa]

pingpong,I do believe that's the direction I'll go,

but I still think I'll buy the axles I'm looking at.They're

complete,brakes and all,and driveshafts,just for the

spare parts aspect.And the front axle at least,is the same.

And just throw them in the corner for the time being.

Looking at motion offroad as we speak,I think you've called the

way to go.And guys,I'll go at least 4.11's.

I work at a Dodge dealership,labor is pretty cheap. ;)

They installed my 4.5'' lift for $150.For that price,why do it

in the driveway?

Also member of our local jeep club,Caloosa Jeepers,

a few shops in the group.

Motion offroad has inexpensive Aussie lockers,anyone

had any experience with them?

:cheers:

[Guest vzehler]

You are wasting money and effort going from 3.08s to 3.55s.

 

I was running 31" tires through 3.73 gears. The overall final drive ratio was exactly the same as stock tires and 3.55 gears. With 32" tires, all you're going to do is get back to approximately the equivalent of your stock 3.08 gearing with stock tires. But ... your tires are much heavier and harder to start turning. You really need at least 4.10 gears, or preferably 4.56s.

 

I hate to say it, but, 4.56's are total overkill for 32" tires. They'd be great for offroading, but, would suck for highway driving. 4.10's are about perfect for 33's in my honest opinion. And I don't think he would overly disappointed with 3.55's and 32's.

 

However, I don't disagree that if your going to go to the trouble of swapping axles, you might at well make it worth your while and just re-gear to 4.10's

[pingpong]

Having spare axles around only take up space :brows: If you want them for spare parts pull the shafts ( only if they are the later 297 joints, the 260 style joints will break under mild wheeling with a locker), pull the wheel bearings (only if you are sure they are useble, or keep for trail spares), pull the steering if you are running stock style steering (it will bend), the rest of it will do you no good.

 

You might wanty to take the spare knuckles and have them drilled/reamed for 1 ton steering, you never know when you might do that mod :nuts:

[Eagle]

You are wasting money and effort going from 3.08s to 3.55s.

 

I was running 31" tires through 3.73 gears. The overall final drive ratio was exactly the same as stock tires and 3.55 gears. With 32" tires, all you're going to do is get back to approximately the equivalent of your stock 3.08 gearing with stock tires. But ... your tires are much heavier and harder to start turning. You really need at least 4.10 gears, or preferably 4.56s.

 

I hate to say it, but, 4.56's are total overkill for 32" tires. They'd be great for offroading, but, would suck for highway driving. 4.10's are about perfect for 33's in my honest opinion. And I don't think he would overly disappointed with 3.55's and 32's.

I beg to differ.

 

With 32" tires and 4.56 gears, the RPMs at 70 MPH would be 2640 RPM. That's right at the sweet spot of the torque curve for the 4.0L engine, which is also the engine speed that provides the best economy. In the "good old days," AMC geared the predecessors of this engine to run 2500 RPM at 60 MPH. I had a Rambler American set up like that (no overdrive, 3.08 gears) that delivered an honest 28 MPG on the highway.

 

It's not overkill at all. It's setting the engine up to run in the usable part of the RPM range.

 

With 3.55s, at 70 MPH he'll only be turning 2050 RPM, and at 55 MPH he'll be at 1610 RPM. That's so low he won't be able to use 5th gear except downhill with a tailwind.