1980 front differential in a 1985

[TEagle85]

Found a Front Differential from a 1980 full time 4x4 close by.  Looks like they started out with the 3.08:1 ratio in 1980 with a optional 3.54?
Still waiting to hear back from the guy about the ratio but I dont think he knows, looks like parts from a yard.

So I have a 1985 sedan with the 2.35 ratio and want to take it up a notch for a little more versatility off road. Not looking to rock climb but would be happy if I could tow a small alum boat and climb hills a little better then now and I assume Id have better acceleration as well. I do travel distance on the highway often so the 2.35 has been great there but no use when accelerating up hills or passing quickly. I run 65mph at about 2000 RPM so Im sure I have another 500 to comfortable work with on that motor. 3.08 might be perfect for me in the midwest.

This will be a slow swap so Im not too concerned about the rear right now , figure I could find one from a jeep which I have read on here and those are easier to come by then front eagle diffs. Or rebuild my rear 2.35 to match the front?

Is there anything major I need to know? will the 1980 bolt on to the 1985?
I plan to rebuild and swap the gearing  on that 1980 front diff over the winter. Are the parts hard to come by? Especially if I plan to swap in all new parts, so basically  just using it for the housing because from what I understand the 2.35 is the only housing that wont take any other gears.   

Any ratio I should swap to that would mate easier to some commonly used rear JEEP diff?

Thanks for any info.

[eaglefreek]

You will need the right side brackets from the 1980 vehicle. 3.07 rear axles can be found from Jeep Cherokees, but they were found in 5 speeds and not quite as common as the 3.55's. However, 3.54/5's would be too low with the stock 3 speed in my opinion.

[TEagle85]

Ah the brackets might be a problem. looks like the diffs are loose and already separated from the car. Probably be better off finding a front 3.08 off of a "newer" model with select drive. Guessing thats where the bracket comes in and out of play?

Having a hard time finding a Eagle in a yard let alone one with the right gearing.

So mixing a 3.07 with a 3.08 wont matter much?   3.07 would be the gear Id like.  Easiest thing woul be find both front and rear 3.07 from a eagle and rebuild.

The search continues

[TEagle85]

Would love to find a 5sp manual as well but I think Im getting a little too ambitious. Would it be better to gain that slight gearing edge by just swapping out the transfer case to a NP242? 
 

[eaglefreek]

No problem having 3.08 up front and 3.07 out back. The right side brackets are different on the 80-81 non disconnect axles than on the rest of the axles. I have a 3.08 ring and pinion for a front diff in my shed, but I've heard you can't swap them into a 2.35 disconnect axle because the housing is machined differently, but don't have first hand experience with that.
  I'm not understanding the question about the NP242. There would be no change in gearing in 2Hi, 4hi full time or 4 hi part time. It just sends the power through 1:1. There is a difference with 4 low, but you would only want to use that off road in a crawling situation.

[TEagle85]

I got ya on the NP242. Still would like one just for those tough spots eventually.
I might take you up on that ring and pinion if your willing to part with it. At least to get the ball rolling. Im going to look around a bit more for a complete front Diff that I can begin to rebuild. If anyone has any leads Id appreciate it. In the Chicago area and if not blowing the budget too much I could ship.

[macdude443]

I just did this swap to my 86.  I used the AMC 15 rear axle, as I don't do anything other than grandpa driving.  You'll need that longer pass side front bracket, as mentioned.  The man I bought my 3.08 axles from has a 3.54 front diff from an SX/4 for sale.  If I remember right, the 3.08 gears should swap into that.  I paid him $150 per axle, they were stored indoors.  I imagine the price would be similar for the 3.54 but don't quote me.  I'm in central PA and he is 10 minutes from me.

[TEagle85]

Definitely good to know. Any guesses on what something like that would cost to ship to Chicago? Also just wondering if a 3.08 would slide into the 2.35 rear. Its only the front housing? Does it matter for the ring and pinion if its front or rear. Seeing some R & P sets labeled as front or rear.

Ill look around for the longer bracket needed to mount a early 80s front diff. Guessing I could probably Fab something up too.

[macdude443]

The middle one is the early bracket you'll need.  The top is the bracket your '85 will have.  The bottom was a custom elongation for a lift and doesn't apply.  Something tells me he probably won't ship it.  Here is the ad for the parts he has.  If you call, get to the point fast.  He's pretty blunt on the phone but he knows his stuff.  https://altoona.craigslist.org/pts/5271127484.html

[carnuck]

If you have no O/D planned, I would just go 2.72 which is far more common. But then shipping a pair of axles is not cheap either.

The Dana 30 front gears can only be low pinion. XJ Cherokee won't work because until '00 they were all high pinion. On Grand Cherokees and TJ Wranglers, they have low pinion D30 front, but I'm not sure if it's the correct length/spline pinion.

[TEagle85]

would like to do the swap as easy as I can. not looking to match splines and all that. I know it all requires some degree of finagling. 
As for the longer bracket it looks like I can mod the shorter one to match the length I need just like that longest bracket in the photo above has been modded. That I can do and understand. I get so lost with yolk and spline talk.

The front diff I was looking at are only a couple hours away from me so that would be ideal.   I asked what the ratios were, he didnt know so I told him to check the tags. Here is his response   "numbers on the 83 are 3241220 2 35 47 20 the one off the 80 I cant read the numbers"     

So 83 is a no go since its 2.35 and the 80 looks like there is no bracket.

here is the listing:    http://www.ebay.com/itm/161881369587?item=161881369587&viewitem=&sspagename=ADME:X:RTQ:MOTORS:1123&vxp=mtr

I do really like the fact I can move on the highway pretty decently with the 2.35 so maybe a 2.72 would add that little bit of low end Im looking for when I get on the dirt roads.

I found a NP242 thats on its way to me. This will be my winter project to rebuild and figure out the headache it probably is to do that swap. At least with that I can pop it in low and get out of a rut. Had that problem last month in the Upper Peninsula of MI. Parked in a dip and from a dead stop the eagle had a bit of trouble getting out. Had to really punch it to get the wheels up and moving. To avoid over torquing the axles I want to get rid of the 2.35. felt like I was about to snap something but I bet all that stuff is a lot more durable then I expect.

[The Dark Side of Will]

www.car-parts.com

I'm sure you can find things in MI and the Chicagoland area.

The 2.35 actually has *LESS* axle torque than the 2.72 and higher.
You don't need to worry about breaking things.

[carnuck]

Unless you hve massive power going into it!