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Gearing Q


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So, I hit the junkyard yesterday looking for an axle with better gearing for my 88 SWB.  I swapped the BA/10 trans for an AW4 a little over a year ago, but I still have the D44 with 3.07 gears in it.  Anyway, I found an 8.25 under an 88 MJ that is already set-up for SOA, with perches and a modified brake line set-up   I was looking for 4.10 gears, or even 3.73's but no luck yet. 

 

This 8.25 has 3.55 gears. Since I no longer do anything near "crawling" and the 4.0L/3.55/AW4 combo is a stock configuation, would it even be worth the time/money/effort to snag this axle and do the SOA I have been wanting to do (mostly to get rid of the shock mount set-up, and the doggy 3.07 gears).

 

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I run 32's with 3.55's gears in a  locked 29-spline SOA 8.25 but a 4.0/AW4. It does fine on and off road. Could it be better? Yep. But it is solid. I went 'wheeling both days last weekend: 120 miles @75 on the highway and did everything that any other 31/32/33" tired jeep of any model there could do. 

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OK, so I'm trying to snag this 8.25 this week, but I have another question.  The 8.25 is from an XJ, the perches have been cut off and new ones scooched over to the right position for an SOA (as this MJ is already SOA).  My question here is about the shock mounts.  It's got the regular XJ shock mounts, one behind the axle, one in front of the axle.  What is the advantage/disadvantage of having the shocks either way (normal MJ set-up vs. XJ set-up)?  If I do this should I use the spring plates from the MJ flipped over with the shock mount on it already??

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I'm no expert....that said-

 

You'll limit your shock travel with the mount on top.

He'll also NOT have to replace the shocks. And he said he does mostly street driving, with some light trail use.

 

Did I miss something? What tire size? That makes a lot of difference when choosing gears.

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You can cut those off and use the spring plate mounted MJ shock studs but it will limit your articulation some. Not an issue for a street truck but it might be for an off-roader. I bought two cheap weld-on shock mounts and put them behind my axle (stock location on a SWB...LWB is in front). I can run a longer shock and the shock is tucked up out of the way.

 

http://www.barnes4wd.com/Bent-Curved-Axle-Shock-Bracket-Pair_p_114.html

 

The plus is you can sell the D44 for huge money for those who just have to have one. You are giving up almost nothing to the 29-spline 8.25 as the MJ/XJ D44 is about the smallest tubed D44 made. 

 

BTW: the fore/aft shock mounting is supposed to help control axle wrap...

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Right now...235's because the 3.07 gears are so weak.

 

Want 32's

 

With 31's - 32's you will want 4.10 gears. I tried 3.55 gears with 31's for awhile - it sucked. 32's will be even worse. Why don't you just get a set of "thick" 4.10 gears for the D44 - no need for a new carrier.

 

Are you 2WD Charlie?

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No, I'm 4WD, easier to find a D30 with just about any gearing around here...up to 4.10.  Past that it gets harder.  But junkyards galore and junkyards with XJ's and even a few MJ's.

 

...and Cruiser...I responded to the e-mail.  I'm lazy. I do have a 44 though...never have done gears myself...looks too complicated, for me.

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Right now...235's because the 3.07 gears are so weak.

 

Want 32's

 

With 31's - 32's you will want 4.10 gears. I tried 3.55 gears with 31's for awhile - it sucked. 32's will be even worse. Why don't you just get a set of "thick" 4.10 gears for the D44 - no need for a new carrier.

 

Are you 2WD Charlie?

 

I agree with this as well.   You'd want at least 3.73's but 4.10's would probably be the best.  I used to run 4.56's with my 32's, with a 4.0/AW4 combo, seemed just fine to me.  2500rpm at 70 and lots of torque off road.

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Others have already said, 4.10's at least for 31's and above. If you can get that 8.25 SOA setup for a decent price, and you want to go that route do that. Gear it even. The nice thing about 8.25 is that any gears you would want to MJ/XJ doesn't need a new carrier, unless you want a full case locker. 

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You can cut those off and use the spring plate mounted MJ shock studs but it will limit your articulation some. Not an issue for a street truck but it might be for an off-roader.

 

BTW: the fore/aft shock mounting is supposed to help control axle wrap...

 

Yup.......if you flip the MJ plates you will need realllly short shocks.  This was mine, the shocks were for some kind of small pickup (bought them by size out of a book).  No real articulation, and I had moderate axle wrap as well.

 

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Right now...235's because the 3.07 gears are so weak.

 

Want 32's

 

With 31's - 32's you will want 4.10 gears. I tried 3.55 gears with 31's for awhile - it sucked. 32's will be even worse. Why don't you just get a set of "thick" 4.10 gears for the D44 - no need for a new carrier.

 

Are you 2WD Charlie?

 

I agree with this as well.   You'd want at least 3.73's but 4.10's would probably be the best.  I used to run 4.56's with my 32's, with a 4.0/AW4 combo, seemed just fine to me.  2500rpm at 70 and lots of torque off road.

 

A good friend ran his MJ on 31s with 3.55 gears and he claimed he was happy with it. But his speedometer didn't work and he has a very heavy right foot, so there's no way of knowing how it would have driven for normal people.

 

I second (or third) the motion for 4.10s. 3.73s are about right for 30" tires, 4.10s are right for 31s and not horrible for 32s. I used to run my '88 trail MJ on 31s with 3.73 gears. But the history was that I had bought the 3.73s with the idea that I was going to put them in my '88 XJ to run with 30" tires. Then I got the MJ. I already had the gears, so I used them in the MJ. What I found was that for 31s with 3.73 gears, the true overall final drive ratio (based on MPH per 1000 RPM) is exactly the same as a stock XJ or MJ on 225/75s with 3.55 gears. Okay for street, tolerable for trail ... but really not enough gear for those bigger tires.

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My first XJ had (still has) 3.55's and 31's.  I never really gave it much thought since it was stock and I just threw 31's on it after a 3.5" lift.

I had zero issues with power and "pep", I towed with it, loaded it up with gear and canoes, took hills with ease.  I never really thought I was under geared.

 

Fast forward to the MJ.  It came with a BA-10 and 3.07's...and 31" tires.  It was peppy, fun to drive for about 1,000 miles of dirt roads and around town.  Then the BA took a dump, so I swapped it with an AW4.  Kept the 3.07's. It still has plenty of power, pulling and acceleration wise, at speed.  But starting off from a stop I sometimes drop it into 1-2 just to get it going...faster.  I also have a manual lockout, so the torque converter doesn't go to OD

 

So, at this point I gotta put it on hold and hold out for an axle 4.10's.  I can easily (more easily than re-gearing it myself) set the thing up for SOA, and I don't want to have to do it twice.  It's just that the way SUA us set up - my diff is 8-9" off the ground, but the shocks and springs look to be about 4".  Lame...IMHO.

 

 So, guys, thanks for the input, I'll continue to scour the junkyard for the proper combo.

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