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Looking for opinions - Rear axle.


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A friend of mine traded vehicles with a guy who turned out to be quite the jeep hoarder.  he has a 99 XJ 4dr that he has sitting around not running/driving and he offered to sell me the whole thing for $400 delivered to my house.  I've been wanting to get a non CAD front axle and do a 97+ doors and front end conversion so I'd get most everything I need right there.  I could probably sell the engine and trans/t-case for a bit to recover some money.

The question.  I want to get rid of the D35 behind my truck.  My plan was always to do an 8.8 swap, but this 99 would have the 29 spline 8.25 I believe.  I've read so many mixed reviews of how strong this axle is.  I am tempted to use it since I would have it right there, but I figured I could sell it and use that money toward an 8.8 as well.  I'm not going to be doing any sort of hardcore rock crawling or other extreme off-roading.  Just some trail running here and there and camping adventures. My plan here soon is to swap in a small diesel OR a 4.6 stroker depending on what kind of deals I can find, so I am worried about torque handling when coupled with 33" tires.  I plan to install a truetrac in either axle, so no lockers come into play.

Just trying to plan ahead and pick the best route.  Worth keeping/building the 8.25, or just skip it and go 8.8?  I appreciate any feedback given.

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It seems like there are quite a few keyboard warriors (and at least one respected magazine) who don't realize that the early 27-spline 8.25 is not the same as the '96+ 29-spline 8.25. The early one is not much better than a D35, the later is a significant improvement. It may not be quite as solid as a d44 or an 8.8, but it'll definitely be enough to stand up to 33's. I've got an 8.25 out of a 2003 4-cyl KJ waiting to go under my MJ. 4.10's disc brakes, and the correct width for an MJ. But if you're planning on using the XJ's front axle as-is, the rear will work great.

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Go with the XJ axle -- IF it's an 8.25. My understanding is that the late-model XJs used the 8.25 if they did NOT have ABS, but the ABS vehicles still used the Dana 35. I've never seen an XJ with ABS up close and personal, so I can't verify that.

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I've been beating the piss out of my stock (albeit regeared) 8.25 for years, last three on 35's. Never let me down. I know of others doing even heavier beatinhs and standing by the late model 8.25.

I just picked up one from a 2000xj to go into my MJ, I sought it out. I WANTED a 29 spline 8.25.

 

I would put it over an XJ/MJ D44, below a truck D44, and on par with an 8.8 strength wise.

 

They are a large 29 spline, no neck downs, larger 3" axle tube, stiff housing with no history of tubes leaving the housing (take that 8.8 guys!).

I get that an 8.8 is an upgrade if leaving a D35, granted. But I don't see it as a be all, end all holy grail axle. And the XJ/MJ D44 isn't the Holy Grail axle either, even though they are usually priced that way. If you already have one, great, keep it and sleep soundly at night. But I'm not paying D 60 prices to get one either. Even the 8.8's go for 450-500+ around here ... And a 29 spline 8.25 is equally as strong and can be found for $75-150 all day since the "experts" think it's weak.

 

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Go with the XJ axle -- IF it's an 8.25. My understanding is that the late-model XJs used the 8.25 if they did NOT have ABS, but the ABS vehicles still used the Dana 35. I've never seen an XJ with ABS up close and personal, so I can't verify that.

I will verify that, having owned a non ABS XJ, and being under a few of both varieties. The 8.25 was also the factory supplied towing package axle.

 

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My plan was to pull both axles and do work to them over time while I search for or building said engine.  All of your replies are making me want to keep it if it is an 8.25 axle.  As far as cost, I can get either axle around here for about the same price. 8.8's are a dime a dozen at the local pick a part, and they charge $165 for a complete axle end to end - brakes and all.  There are also usually a decent number of XJ's as well, in case this does turn out to be a D35 and not a 8.25 axle.  Thanks for the heads up on that too, btw, I will definitely double check that.

I figure if it ends up not being an 8.25 I will just use the money from scrapping what's left to buy an 8.8, otherwise I will keep it.  Parts between the two (axles and diffs) are about the same cost, so no real change in that regard.  About the only advantage of the 8.8 would be the disc brakes already installed, and being able to find one already geared the way I want (4.10).

Should I look into upgrading the stock axle shafts for the 8.25, or do you think the stock shafts would be ok?  I can always get spare shafts from the pull-a-part if I do manage to break one.

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About the only advantage of the 8.8 would be the disc brakes already installed, and being able to find one already geared the way I want (4.10).

Disk brakes are less of an advantage when crawling trails than they are when racing. I'm not crying my eyes out at night because none of my XJs or MJs have rear disk brakes.

 

Offsetting the possible advantage of the 8.8 having disk brakes is the fact that it's narrower than the XJ/MJ axles, so to run even stock tires on stock rims you need spacers. The XJ 8.25 is already the correct width, so just flip the perches to where you want them and you're done.

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About the only advantage of the 8.8 would be the disc brakes already installed, and being able to find one already geared the way I want (4.10).

Disk brakes are less of an advantage when crawling trails than they are when racing. I'm not crying my eyes out at night because none of my XJs or MJs have rear disk brakes.

 

Offsetting the possible advantage of the 8.8 having disk brakes is the fact that it's narrower than the XJ/MJ axles, so to run even stock tires on stock rims you need spacers. The XJ 8.25 is already the correct width, so just flip the perches to where you want them and you're done.

Rear discs do not pack up with mud like drums do

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Being C-clip axles in either case, I would prefer discs just for the potential need for axle retention. Otherwise, I have no real problem with drums out back.  If I really felt like it I could plunk the money down for a C-clip eliminator kit on the 8.8, which has the added bonus of widening the axle out to about the same width as the front Dana 30.  No matter what route I go I have a ZJ prop valve sitting around in case I decide disc brakes are in my future.  I'm pretty bad about hoarding parts that I will probably never use.  I am just hoping I can get enough cash back from parts to make this a nearly free venture, or at least a stupidly cheap one.

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Not familiar with it, nor do I want to be.  I would rather hear opinions of people that actually have said axles and use them in a manner similar to, or more aggressively than, I intend to.  I am pretty sold on the 8.25 if this XJ has one.  Just have to wait for the guy to get back from working in a week or so (works for one of the railroad companies), then I can buy it off of him.  

Then I just have to decide...SOA or SUA...

Proving to be a hard choice lol

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

I have not had any axle wrap issues on or off road with my SOA. I think that the "anti wrap" perches that I got from Barnes 4wd must be helping.

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

I have not had any axle wrap issues on or off road with my SOA. I think that the "anti wrap" perches that I got from Barnes 4wd must be helping.

 

Are those the ones in the kit linked in your $700 lift thread I found a couple of days ago?

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

Honestly, I was already wanting to do a 4" lift.  I can't imagine an extra inch or 1.5 inches making that big of a difference.  I would end up with drop brackets and aftermarket control arms either way.  The SOA keeps me from having to shell out $450-500 for rear leaf springs to match the lift as well. I already have pretty new leaf springs anyway, about 2 years old and not even 10k miles on them.

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See that's where we're different... I'm still running the 300,000 mile original springs and they need replacing. I was really only wanting around 3-4" lift, and not planning to do more than longer front arms. I also don't want anything bigger than 33x10.5's, 32 if I can find them in a severe-snow rated AT (want to keep the stock wheels), and at 5" that's getting a bit much.

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I toyed with the idea of 35" tires, but I would be plenty happy with 33x12.5 tires on a 15" wheel, or a metric equivalent.  I think as long as I try to keep the lift as close to 5.5" as possible it would look ok.  I've seen a couple of long bed MJ's with that combination, and I like how it looks.

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

I have not had any axle wrap issues on or off road with my SOA. I think that the "anti wrap" perches that I got from Barnes 4wd must be helping.

Are those the ones in the kit linked in your $700 lift thread I found a couple of days ago?

Yep. They appear to work as advertised

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I'm also in the SOA vs SUA conundrum.

I like the idea of lift vs ride quality of the soa. I'm just not quite sold on the axle wrap risk and 5-6" lift. Not sure I want to go that high in what is pretty much a daily driver, or go to tires large enough to warrant that much lift, or having to shell out for a front lift to match. At the same time though I don't want to limit myself for going higher in the future if I decide to...

 

Anything wrong with getting both sets of perches welded on at once? :dunno:

I have not had any axle wrap issues on or off road with my SOA. I think that the "anti wrap" perches that I got from Barnes 4wd must be helping.
Are those the ones in the kit linked in your $700 lift thread I found a couple of days ago?

Yep. They appear to work as advertised

 

Ok, cool I actually plan on following your list to the letter lol.  A bit more expensive than $700 now, but that happens with time.

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Well maybe I'll wait till you're done and see how it turns out. My eventual plan though is to use the MJ as a tow vehicle for whenever I finally get around to race-prepping my Lada, which is in part why I'm concerned about how much lift it gets, plus I'd be getting metric ton leaves, and other such things. I also don't think going to a 12.5" wide tire is the best idea on a factory 7" wide wheel, and for whatever reason I'm opposed to going to a different wheel.

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Two rules I live by that apply in this scenario.  Never lift a vehicle more than you need to for adequate tire clearance (and not until sheetmetal mods have been performed).  Never lift a vehicle you intend to use to tow with.

Both are good rules. The first, especially -- many other wise people also advise never lifting more than you absolutely need to. The corollary is that the price of lifting increases exponentially with the height of the lift (in other words, twice the height costs four times as much).

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Need is somewhat subjective in this case.   I want to run 33" tires.  This want changes my needs.  Technically, I could run said 33" tires with my trucks current ride height, and all I would need to do is run bump stops, do some trimming, Napier flares, and maybe 1 more inch of lift front and rear from where I am now, which would give me 3 inches front and then finding a way to match the rear like chevy shackles, so I don't end up with a Cali-lean.

I have considered this route as well.  It would definitely be cheaper up front,  and would be a good low COG approach to things.  To be an effective setup I would rather lift the front to 4" and run drop brackets or long arms to change the angle of attack on the control arms and improve said vehicles ability to climb.  I've done a lot of reading on low COG setups, and this was a factor that was brought up for consideration.  So to make it effective with minimal lift following those guidelines the front would still end up costing nearly the same.  Yes, I know it wouldn't really be a true low COG, but some of their ideas stuck with me.

Out back I would have to change leaf springs if I didn't go with a SOA setup.

The 3" lift is the minimum required in order to do a TDi conersion as well.  Which is a factor I am partially doing said lift for.

The rear lift staying SUA would require new leaf springs, but that is a $450 addition I would not have with a SOA swap.  In this case, the cost of my lift gets cheaper adding that extra height, as I can use the brand new leaf springs I already have mounted a different way.    In either lifts case, I will be running the same tires.   Yes, I would love to have a pair of the military wrapped MT springs out back from General Spring.  In that instance, I would probably keep it SUA and run a longer shackle, if necessary, to keep the truck with a bit of a forward rake.

My goal is more than simply going taller.  My goal is to build something truly effective and functional at the same time that suits my needs.   I would like the ability to tow with my truck, and I wouldn't have a problem towing with it lifted a bit.  Seeing as I don't tow things on a regular basis, it is not a high priority consideration for me.

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