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another question, what are the spline counts and would it matter which spline count i got as long as gear ratio match?

 

if you are changing carriers or shafts yes, the splines must match.

 

the splines are located on the ends of the axle shafts they are ridges. they are what "grips" the carrier. 

 

45553-2-Axle-Shaft-Dana-80-35-Spline-3.j

 

 

Stock spline counts

Front:

Dana 30 = 27 Spline

 

Rear:

Dana 35 = 27 Spline

Dana 44 = 30 spline 

96 & older 8.25 = 27 Spline

97 & newer 8.25 = 29 spline

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splne count doesnt matter as long as gear ratio match,

 

but did they use different spline count for different gear ratios, or for just heavier duty axles?

 

what years of the xj rear end will fit on my 87 comanche other than 92, an 01 wouldnt fit would it,  and will everything hook the same like brake lines

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so ive done some research and i believe i could go both ways, i could set the d-44 to 3.55 to match the front or make the d-30 a 4.11 to match the d-44, assuming those are the ratios seeing they are the most common IIRC (don't write it in stone)

4.11 is NOT the most common ratio for an XJ or MJ Dana 44. The Dana 44 was found mostly behind the 6-cylinder engines (although AMC would allow you to order it with a 4-cylinder), and the ratios for the 6-cylinder were 3.07 for 5-speeds and 3.55 for automatics.

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disregard last post was writing it when u posted that.

 

say say my rear end was a 29 spline and the front wasa 27. if the gear ration matched would that affect it

 

thanks Eagle, like i said i was just reading around and allot of them were about the 3.55 and 4.1, i was just assuming they were common. never just assume lol

 

ASSUME

Makes an @$$ out of U and ME

lol

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Updated:

 

splne count doesnt matter as long as gear ratio match,

 

but did they use different spline count for different gear ratios, or for just heavier duty axles?

 

what years of the xj rear end will fit on my 87 comanche other than 92, an 01 wouldnt fit would it,  and will everything hook the same like brake lines

 

1. spline count does not matter unless you are changing carriers to use stronger larger aftermarket shafts.  as long as the Front and Rear gears match it does not matter if the front axke is 27 spline and the rear is 30 spline.

 

2. the different spline counts where usually the construction of certain axles. the only stock axle for XJ that changed was the Chrylser 8.25 when it was upgraded from 27 to 29.

 

3. any rear XJ axle will fit under your MJ with modification.

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i know, but if i were to buy a dana 44 axle and say the gear ratio didnt match my front, could i buy a d-44 ring and pinion that could match my front gear ratio depending on what it is.

Yes, you can. But, depending on what ratio the axle has and what ratio you want to change to, you might also have to buy a new carrier. (Of course, if you convert to a limited slip you have to buy a new carrier anyway.) You'll also need new carrier bearings, new shims, and a new pinion crush sleeve. And then somebody has to set up the new ring and pinion gear. They don't just drop in -- since you don't have either the tools or the experience to do it, just the installation will cost you a few hundred dollars in labor.

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awesome, and all axles will bolt up the same and brake lines the same too?

No.

 

XJ axles are set up with the spring perches on the top of the axle, MJs are set up with the spring perches under the axle. Also, the distance between the perches is different for the XJ than for the MJ. To use an XJ axle in an MJ somebody has to cut the spring perches off and weld new ones in the correct location.

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3. any rear XJ axle will fit under your MJ with modification.

 

That modification being new spring perches. You will need to shorten your driveshaft for both the 8.25 AND the D44.

 

Now finding a D44 ... that is bolt in .... can you say hens teeth?

You will most likely be using an XJ axle when you find one ... unless you start passing horseshoes.

 

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r. (Of course, if you convert to a limited slip you have to buy a new carrier anyway.) You'll also need new carrier bearings, new shims, and a new pinion crush sleeve. And then somebody has to set up the new ring and pinion gear. They don't just drop in -- since you don't have either the tools or the experience to do it, just the installation will cost you a few hundred dollars in labor.

 

No experience, but do have an associate degree in diesel mechanics so i know how to set backlash, preload and wear pattern. Some automotive background form high school and mainly my jeep. you right i don't have the tools to do that, but ill get em eventually.

 

why would i have to remove the pinion? i thought when you bought the truetack Dana 30 or 35 you bolt up your original ring gear?

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3. any rear XJ axle will fit under your MJ with modification.

That modification being new spring perches. You will need to shorten your driveshaft for both the 8.25 AND the D44.

 

Now finding a D44 ... that is bolt in .... can you say hens teeth?

You will most likely be using an XJ axle when you find one ... unless you start passing horseshoes.

 

why, the axle didnt get closer? 

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why would i have to remove the pinion? i thought when you bought the truetack Dana 30 or 35 you bolt up your original ring gear?

If you are ONLY converting from an open diff to a limited slip, you don't need to touch the pinion. You do still have to set/adjust carrier bearing preload and backlash.

 

But ... you were talking about buying a new ring AND PINION in order to change the ratio.

 

how would i go about shorten the shaft? cutting mine, buying new one? and xj are to short to use right

You take your driveshaft to a driveshaft shop and tell them to make it ___ inches shorter.

 

and the for the perches do i cut mine off to weld on the other axle or can u buy new ones

You can do it either way. But I wouldn't cut the perches off the old axle to put onto the "new" axle. First, if you go from a Dana 35 to a Dana 44 or an 8.25, the tubes will be larger and the perches from the Dana 35 won't fit. The factory perches are only welded along the outside -- if you're half decent with an angle grinder you can cut the welds without damaging the perches, and just relocate them.

 

And you'll want the factory MJ perches on the original MJ axle so you have a template from which to match dimensions and angles.

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why would i have to remove the pinion? i thought when you bought the truetack Dana 30 or 35 you bolt up your original ring gear?

If you are ONLY converting from an open diff to a limited slip, you don't need to touch the pinion. You do still have to set/adjust carrier bearing preload and backlash.

 

But ... you were talking about buying a new ring AND PINION in order to change the ratio.

true true. only if they didnt match, 

 

so whats cheaper and easier,  axle swap or buying a truetrack and would they send instructions on what the new backlash should be and preload.

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ah thats right, probably what I was thinking at time when i wrote that srry. saw that and i figured that will be something for the future. and where online should i buy new axle perches?

 

is it hard to do, its seems once you re-locate the perches and shock \brackets, all you have to do is extend that flexible brake line.

 

and how would i know what to put the drive angles at, could i tip the yoke side of the differential up a tid bit to be safe? so the angles wouldn't be so hard

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would i need to fabricate new shock mounts as well?

Have you even looked at the suspension under your truck? The rear shock mounts are welded to the axle on XJs. On MJs the shock mounts are part of the spring retainer plates.

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would i need to fabricate new shock mounts as well?

Have you even looked at the suspension under your truck? The rear shock mounts are welded to the axle on XJs. On MJs the shock mounts are part of the spring retainer plates.

 

seeings i converted it to 4wd, yea ive seen my suspension.

 

 

So this all started with the front diff, but the thread has migrated to the rear diff. Just to clarify do you want to swap the front or rear? XJ front axles are bolt in. TJ and ZJ axles will also bolt in but are low pinion.

it did, might swap both idk yet. depending on what you all say is whether or not I'm swapping axles or buying a truetrack. either way i am eventually going to do that SOA, just wanted to know if i needed to fabricate my own shock mount to weld on the axle or if i could buy them. And what should the drive line angles be at?

 

also found spring perches a Rusty's offroad, anyone used them?

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would i need to fabricate new shock mounts as well?

Have you even looked at the suspension under your truck? The rear shock mounts are welded to the axle on XJs. On MJs the shock mounts are part of the spring retainer plates.

 

seeings i converted it to 4wd, yea ive seen my suspension.

 

 

So this all started with the front diff, but the thread has migrated to the rear diff. Just to clarify do you want to swap the front or rear? XJ front axles are bolt in. TJ and ZJ axles will also bolt in but are low pinion.

it did, might swap both idk yet. depending on what you all say is whether or not I'm swapping axles or buying a truetrack. either way i am eventually going to do that SOA, just wanted to know if i needed to fabricate my own shock mount to weld on the axle or if i could buy them. 

 

 

 

what is your current setup? engine, trans, and what not.

 

It will all depend on what gears you want to go to.  for example if you have the 4.0 and a manual transmission then odds are you have 3.07 gears.  if you wanted to step up to say 3.55 gears then it would be cheaper to find a XJ in the junk yard that had the 4.0 and auto trans, odds are it had 3.55 gears.  the front axle will be a direct swap (if you hace a CAD on the current axle the vac lines will need to be capped), the rear axle will need the spring perches cut off and relocated and the xj shock mounts will also need to be cut off.  my local Pick and pull sells jeep axles for $90 out the door per axle, and a shop may charge about $100-$150 for the perch relocation.  so for about $280 to $330 i could have gone from 3.07 gears to 3.55 and for the most part i can do all the work.

 

The other option is to buy the gears (and carrier if needed) and have some one install and set up the gears.  I just had this done in my MJ and the total cost was about $2,100 for 2 sets of 4.11 gears, master rebuild kits for both axles, Dana 30 E-locker, Dana 44 open diff carrier ( I have an aussie locker), and labor.   :ack: Just realized how much i spent....

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