Photo of the inside of a 231 t-case I worked on today

[Idaho08KK]

I was working on a 2006 KJ Renegade today with 19,000 miles on it. They had a pretty serious leak between the case halves of the t-case. I took this pic at the midway point of the job. I had separated the t-case halves and cleaned all the silicone off of the sealing surfaces.
I decided to try and do this job without completely removing the t-case. As you can see, it worked well. It took me about 45 minutes to get the t-case taken apart, and another 35 minutes to get it back together.
Anyways, here is a pretty cool view of the inside of a 231 t-case.

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[Idaho08KK]

No the 231 is simple. The full time 4WD transfer cases are more complex. They usually have clutch packs, magnetic clutches, viscous couplers, etc.

 

[LibertyFever]

Good job with the camera & the wrench (bowdown)
I've never seen somebody work on one on the Jeep. Typically I'd pull it off and work on it on the workbench. And usually when I pull one apart they don't look that clean inside.

I was thinking it would look more complicated on the inside. eek2.gif

That end of the transfer case looks pretty simple but there's a whole lot more to one than just the chain & sprocket assembly.

Here's an exploded view of an NP 241 transfer case;

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[ThunderbirdJunkie]

This picture makes ThunderbirdJunkie want a Dana 300 in his KJ

 

[eyehatetofu]

This picture makes ThunderbirdJunkie want a Dana 300 in his KJ

I want an ATLAS like in TJKJ's rig

 

[Idaho08KK]

No kidding, an ATLAS would be awesome.

 

[tjkj2002]

This picture makes ThunderbirdJunkie want a Dana 300 in his KJ

To bad you have to do a flip kit and has been causing issues,fluid leaks and shifting problems.

I want an ATLAS like in TJKJ's rig

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No chain to stretch,just don't complain about the price.

 

[LibertyTC]

Nice work and clear photo there Idaho08KK !
So what happens if that chain is too slack does it rattle or rub cutting into the case?
I suppose the chain only turns when engaged in a low or part time mode then?
Only RTV or what seals the 2 halves?

 

[tjkj2002]

So what happens if that chain is too slack does it rattle or rub cutting into the case?

Yep it will hit the case.

I suppose the chain only turns when engaged in a low or part time mode then?

With the 231 the chain turns all the time since your front driveshaft spins all the time,just no power being sent through.

Only RTV or what seals the 2 halves?

Yep,only RTV seals the 2 halfs.

 

[LibertyTC]

Interesting stuff that appears to be a magnet on bottom Left. I guess the only way to see it is to separate the case, or can it be seen from drain plug with cable camera?
Where does the ATF+4 level sit in there does it completely cover upper part of chain too?

 

[jnaut]

I was thinking it would look more complicated on the inside. eek2.gif

What Idahokk said. There's not much to them. It's just a really beefy set of gears with a chain drive around them. All you're trying to do is get the front wheels turning with the back wheels.

Which, unfortunately is why they're so easy to screw up on dry pavement.

 

[Idaho08KK]

Only RTV or what seals the 2 halves?

The service manual says that you can use either RTV or anaerobic sealant to seal the two case halves. I use the anaerobic sealant just because the two halves are aluminum. I think it seals better than RTV.

Where does the ATF+4 level sit in there does it completely cover upper part of chain too?

The ATF sits approximately halfway up the front output gear. The oil is slung all over by the chain to lubricate the upper half. Not pictured is the oil pump and pickup, which had to be removed to separate the halves. The pickup sits in the same slot as the magnet, at the lowest part of the case.

 

[ThunderbirdJunkie]

To bad you have to do a flip kit and has been causing issues,fluid leaks and shifting problems.

You ain't kiddin.

Plus, after the price of the flip kit and all the issues you'll have, an Atlas would be cheaper anyway.

 

[LibertyTC]

On the atlas site there does not appear to be one for the KJ, is it because tj used a SFA that he is able to utilize one? What is the cost of these units? $4k ?

 

[LibertyFever]

I've done a little bit of web research on transfer cases. I was surprised to find similarities between the different models of Jeeps. My YJ and KJ both have 231 transfer cases but slightly different flavors.

Basically when trying to chose a non-stock transfer case you need to concern yourself with how they mount to the transmission (an adapter ring may be needed), the input/output drive shaft spline count may be different and the stock drive shafts may need to be replaced. Then there's the shifter to be modified.

I'm still thinking of swapping out a 242 into my KJ for the Fulltime 4WD option. Or I can simply open my 231 transfer case and upgrade the sprockets & chains to heavier ones while installing a Slip Yoke Eliminator.

 

[Robsama]

The case behind the left gear make it look like it has huge spikes on it. Looks kinda steampunk.

 

[tjkj2002]

On the atlas site there does not appear to be one for the KJ, is it because tj used a SFA that he is able to utilize one? What is the cost of these units? $4k ?

Each AtlasII is custom built for you,your choice of low range(2:1,3:1,3.8:1,4.3:1,5:1,6:1 and 2 choices of 4 speeds),your choice of F/R rear outputs,passenger side or drivers side drop,and so on and so on.They can build one to fit either the 45RFE or the 42RLE(very easy,popular options for TJ guy's).The only draw back is is with the 45RFE/545RFE which you need to know the exact output shaft length as there are 3 different ones and no way of knowing which one you have unless you pull the t-case and measure,and you can not use the 4-speed Atlas behind the 45RFE/545RFE.Drive line mods are needed for any vehicle you install a AtlasII into.

Depending on your options and gear ratio a AtlasII starts at about $2000 and the 4-speeds can top $3000.My AtlasII 2 speed with 4.3:1 low,cable shifters,32 spline upgrade front output,1310 front CV yoke,and flange yoke in the rear ran $2500 shipped,then had to add 2 spacers at another $120.

 

[LibertyTC]

Thanks for the info! No doubt worth every penny. If ever my Cheapo case busts, first thing to order.
Just to gain a little more insight into this atlas jewelry, what happens to the stock shifter?
How does the "new"? shifter work with neutral and 4 speeds? I have a 42RLE so glad to hear about the choices and 4 speeds available. Might as well look at doing the diff while there too LOL.....What driveline mods are necessary to install this wonderful piece?

 

[tjkj2002]

Thanks for the info! No doubt worth every penny. If ever my Cheapo case busts, first thing to order.
Just to gain a little more insight into this atlas jewelry, what happens to the stock shifter?
How does the "new"? shifter work with neutral and 4 speeds? I have a 42RLE so glad to hear about the choices and 4 speeds available. Might as well look at doing the diff while there too LOL.....What driveline mods are necessary to install this wonderful piece?

The stock t-case shifter goes bye-bye and hello twin sticks!each lever independently controls the front and rear outputs of the t-case,don't worry it will not allow for one to be in high range and one in low range.The 4 speed version just adds another shifter that you can remotely mount just about anywhere or opt for the electric shifter for the reduction box.

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Oh and since you have the 42RLR you can get the RubiCrawler from Advance Adapters(who make the Atlas) that takes place of the trans to t-case adapter and gives you a extra 2.72:1 reduction via cable shifter so you can have a 4 speed t-case without the Atlas cost,no driveline mods needed,only works with the 42RLE trans with either the 231 t-case or a Atlas as far as I know.

http://advanceadapters.com/product/...ep-2003-2009-with-an-automatic-overdrive.html

 

[LibertyTC]

Wow. Ok this has me a bit confused. Two shifters for front rear outputs. SO this must be a split case gearing. So you have the two speed for low and high reduction. Can you explain how the right and left work work in simple terms? Does each shifter have high/low on each?
It looks like the Rubicrawler only works with stock transfer case which defeats the purpose of looking forward to no chain with a much better case, but cheaper.