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rynoshark

4x4 D35 non-C/3.55 to D44/4.10/LSD?

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The D35 non-clip on my 87 4x4 4.0 was replaced by a previous owner with the incorrect unit (one from a later Wrangler), so does not lock.  I was thinking of tracking the correct one down, but then though it might be nice to swap to a D44 to get 4.10 gears and find one with a limited-slip differential.  It has a 21-spline rear NP231, was considering NP242 so I could use 4x4 even at higher speeds. Given I run the BFG T/A Mud Terrain 30x9 50R15LT tires, it seems like changing from 3.55 to 4.10 would improve drivability as well.  I do a lot of highway miles and occasional light offroad/gravel driving.  In snow right now, the Comanche is useless since with open diff, one tire spins...and it won't shift into 4x4 mode.

 

What is the best "original style" setup in this case?  Am I going down the right track here?  Thanks!

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snow tires will change your life :D    the 242 will too.  my liberty has been in AWD mode for 12 years now.  :driving:

 

the original dana 44s are getting harder and harder to find in any condition, but one with 4.10s and posi would be a rare bird indeed.  the 4.10s would only have come behind a 2.5L MJ with the Metric Ton package and they didn't build a lot of those.  :(  And then the first owner would also needed to have checked the posi box because it was a separate choice.  I'm not saying it's impossible, but the odds are stacked against you. :(  

 

now, if originality isn't the main goal, you can find Explorer 8.8s, Liberty 8.25s and 97+ XJ 8.25s in the junkyards all day long.  :D  giving a decent budget, I would grab a Liberty 8.25 with disks and have it regeared to my needs.  :comanche:

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Fix your transfer case first. 

 

If you are going to regear the rear  you'll  have to match it in the front. 

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10 hours ago, rynoshark said:

The D35 non-clip on my 87 4x4 4.0 was replaced by a previous owner with the incorrect unit (one from a later Wrangler), so does not lock.

 

What does this mean? There was nothing "locking" about the D35 differential in a 1987 Comanche.

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1 hour ago, Eagle said:

 

What does this mean? There was nothing "locking" about the D35 differential in a 1987 Comanche.

 

I think he means the current D35 is an open differential, and he'd prefer it to be locked, or at least limited slip.  That's what I'm reading anyway.  Adding a locker or limited slip and upgrading to the NP242 would all be nice-to-haves, but if the requirement is just to drive in the snow, a working stock NP231 with an open D35 will do just fine.  The regear sounds unnecessary - it's 3.55 now running 30x9.5x15 tires.  They should spin just fine.  I'd say all terrain tires and a working transfer case gets it around in the snow.  Those mud tires don't do well in snow at all, in my experience.

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58 minutes ago, kryptronic said:

 

I think he means the current D35 is an open differential, and he'd prefer it to be locked, or at least limited slip.  That's what I'm reading anyway.  Adding a locker or limited slip and upgrading to the NP242 would all be nice-to-haves, but if the requirement is just to drive in the snow, a working stock NP231 with an open D35 will do just fine.  The regear sounds unnecessary - it's 3.55 now running 30x9.5x15 tires.  They should spin just fine.  I'd say all terrain tires and a working transfer case gets it around in the snow.  Those mud tires don't do well in snow at all, in my experience.

 

I agree with your recommendations, but the way the OP phrased his post very much suggests that he thinks the original D35 in this MJ was locked. My question stands: What did the statement mean?

 

As to gear ratio, 3.55 is just fine with 30x9.50s. That tire size is basically the same diameter is 235/75-15s, but with slightly wider tread width. 4.10s is overkill with that tire size. I know from first-hand experience that 3.73 gears with 31x10.50-15 tires works out to exactly the same final drive ratio (MPH per 1,000 RPM) as stock tires with 3.55 gears. For the type of driving described by the OP, 4.10s would not be a good choice.

 

I also agree on tread design. Mud tires are designed to throw stuff OUT of the tread. Snow tires are designed to keep snow IN the tread, because snow sticks to snow, improving traction. Mud tires are lousy snow tires.

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Great points everyone, thanks for the ideas.  The MT definitely are not great in the snow...or ice...or even rain, though that was solved mostly by siping them.  I love the look of the MT though...the big knobby tires just fit the look of my truck perfectly.  Realistically, we only get snow here 3-4 days a year...this year being a rare exception.  So I don't have to worry about it too much.  The other benefit of an all terrain tire would be quieter road noise.  I will start investigating what tires to buy...I have a brand new spare set of 10 spoke aluminum wheels, so will fit to those.

 

So, based on kryptoronic/Eagle/Pete M's suggestions...I will give up on trying to find the D44/NP242/LSD unicorn ;). Perhaps a D44 Posi + NP242 with 3.55 (so nothing else has to change) would be ok.

 

A NP242 would be nice to be able to run AWD all the time, even on highway, during inclement weather.

 

 

 

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no, no.  you should definitely still hunt down that t-case. :L:  

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A local guy has a Dana 35 w/factory limited slip, with new drum brakes & wheel cylinders, for $300 and a NP242 for $250.  All from 1989 Jeep.  That might be the simplest and most cost effect swap...including replacing my wrong transfer case *AND* getting limited-slip added.  For my 1987, do I need anything special to fit the NP242 regarding the shifting mechanism?

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From what '89 Jeep? an XJ?

 

You'll have to do just as much work to fit the D35 as  you will an 8.25. 

 

And you can get discs for the 8.25........bolt on. 

 

Find a good LS 8.25 with discs in 3.55...........should still be plentiful for about $150. This is a no-brainer. 

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Yes, 1989 XJ.  Reminder: this doesn't see off road use...mostly pavement and gravel roads, occasional very light trail.

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Mine doesn't see off road abuse either. 

 

Still, I would not bother installing a POS D35 in it.

 

s2a8xUE.jpg

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Thanks everyone for the suggestions.  I just want the best highway / light off road use combination that is "original" to Jeeps of that era.  The LS 8.25 would be a great option if I was trying to get better performance (braking), but with new shoes, the drums on my truck in the rear have been totally fine. I'm not towing much other than a 10-12' Livingston boat with this thing..and occasional dump runs.

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24 minutes ago, rynoshark said:

Thanks everyone for the suggestions.  I just want the best highway / light off road use combination that is "original" to Jeeps of that era.  The LS 8.25 would be a great option if I was trying to get better performance (braking), but with new shoes, the drums on my truck in the rear have been totally fine. I'm not towing much other than a 10-12' Livingston boat with this thing..and occasional dump runs.

I understand your wanting to keep it with "original" era parts. I am in that same mind set. I will continue to look for the purple Unicron with rainbow stripes (factory Dana 44). 

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the Liberty 8.25 is also a couple inches wider which helps the rear tires to look less "tucked in".  MJs have a wide butt compared to XJs (which have the same axle, but the tires normal like the fronts).  :D 

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IMG_20190210_171609984.jpg.0bbf993ac8fc10e1cf42e187fa64967d.jpg

These do suck on ice and light snow. They are awesome in deep snow though. I sure do love the look though! The joys of Iowa. Mud tires are one of my week spots.

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I just put a set of General Grabber ATx in a 31x10.5x15 on my 4.0/ax15 ZJ, with 3.55's. It's not awful, but it was a noticeable change as far as acceleration is concerned. I think 4.10's would be a bit much, but I did briefly consider a set of 3.73 axles from a 5.2. I just haven't been able to find a set for under $300 each without just buying a second ZJ... And I don't really want to do that, haha. And I'm sorta enjoying not having to shift out of first until the other side of the intersection now. But I digress. 

I was already convinced in the power of the winter tire, but after going from the non-winter ATs I had to the winter-rated Grabbers, I now have about the same traction on snow and ice in 2wd as I did before in 4x4, possibly more, open diff and all. I really wasn't expecting such a huge difference either as I saw. 

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If you go with a 242, the shift bezel is different, it has the additional "full time" setting.  This part is obvious, what is not obvious is that the metal shift gate below the bezel, bolted to the floor, is different from a 231 to a 242.  From what I have researched, the shift handle and shift linkage below the body is the same, but that gate is definitely different.  

 

I have a D44 rear and 242 case that will be going into mine as I convert it to 4wd.  Hope to start the work this summer.

 

First pic is a 242 gate and bezel, second pic is a 231 gate.

gate_only_1.jpg

s-l225.jpg

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and if you're up for it, you can likely swap out the input gear for a 21 spline.  don't quote me on that though.  when it comes to Jeeps, things you never thought would swap will swap, and things that sound like they should swap, don't.  :roflmao:

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Re: the 242 vs 231 shifter. It's correct that it's the same parts apart from the bezel and gate. I didn't initially swap the gate because the donor I was pulling parts from was super hantavirusy, and I didn't want to spend more time in there than necessary. There are people who will tell you you don't need the shift gate, and I've even had someone laugh at me for suggesting the two were different parts (despite showing them photos and parts manuals... stupid gonna stupe) and yes I was able to get all the 242's positions with the 231 gate, but it was a major pain in the @$$. Basically to get full-time in the 231 gate you had to pull it all the way to the 4hi stop, then move over and pull it back just a hair and half the time pull too far and end up in neutral, and going the other way, you'd hit the gate again before making the shift from neutral back to full-time. Ending up with your transfer case in neutral at highway speeds (I.e when I'd be most likely to use full-time) is something that you need to essentially stop to correct, hence it being a PITA. Sorta defeats the point of shift-on-the-fly if you have to slow to under 3mph. With the 242 shift gate, pulling it straight back till it stops gets you in full-time, as does pushing it forwards from neutral. 

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