Front diff swap?

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Axel-ander92

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Hey all I just registered today. So! Next week I plan on buying a lifted kj 2006 limited with 31 inch tires. Only issue is that it needs to be regeared. I really wanna do 4.10 but every thread I've seen on here kind of beats around the bush getting to the answer. I can find the 4.10 for the rear but from what I've read that won't fit in the dana 30a for the front. So I guess what are my options? Can I just swap a front differential from a 2.5 with the 4.10 already in it? Or is there more to it then that. I'm on a budget so I'm looking for the cheapest most reliable way to do this. It would be my daily but still something I'd take off road and from what I've read that gearing would be preferable. I know 13 mpg isn't horrible but I'd like to see better being as I will use it for road trips in the winter. So what are my options?!
 

tommudd

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Hey all I just registered today. So! Next week I plan on buying a lifted kj 2006 limited with 31 inch tires. Only issue is that it needs to be regeared. I really wanna do 4.10 but every thread I've seen on here kind of beats around the bush getting to the answer. I can find the 4.10 for the rear but from what I've read that won't fit in the dana 30a for the front. So I guess what are my options? Can I just swap a front differential from a 2.5 with the 4.10 already in it? Or is there more to it then that. I'm on a budget so I'm looking for the cheapest most reliable way to do this. It would be my daily but still something I'd take off road and from what I've read that gearing would be preferable. I know 13 mpg isn't horrible but I'd like to see better being as I will use it for road trips in the winter. So what are my options?!

Like tjkj has already mentioned one fro a 4 cylinder gasser will work, direct bolt in have done it a few times here at my place.
Not sure about beating around the bush, been mentioned/ talked about/ described many times on here in the past .
Also like he mentioned gearsets are still available .
JBA still has them listed and can buy from them.
Next thing is ...what lift is on it, hopefully a full spring lift like OME or JBA coilover, if not pass on it
Oh and 13 is horrible if thats on road MPG with only 31s
 

Axel-ander92

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Like tjkj has already mentioned one fro a 4 cylinder gasser will work, direct bolt in have done it a few times here at my place.
Not sure about beating around the bush, been mentioned/ talked about/ described many times on here in the past .
Also like he mentioned gearsets are still available .
JBA still has them listed and can buy from them.
Next thing is ...what lift is on it, hopefully a full spring lift like OME or JBA coilover, if not pass on it
Oh and 13 is horrible if thats on road MPG with only 31s
Yeah its just got a spacer lift but that'll go bye-bye and ill do it right. And yeah its actually closer to like 14.5 15 mpg in city. But still id like to regear before I switch to larger tires and lift too
 

Axel-ander92

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You can get the correct 4.10's still for the front,only Dana/Spicer(OEM sets).

And yes you can direct swap in a front diff from a 2.4 gas KJ with 4.10's already installed.
What year 2.4 would you recommend? We have quite a few junkyard here and around these parts kjs aren't missed much so I could probably score a low mileage whole 2.4 depending on year and just use the front and rear both
 

HoosierJeeper

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Any of them would be fine. Go for the one with lower miles.
 

tjkj2002

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Somewhere between being sane and insane!
What year 2.4 would you recommend? We have quite a few junkyard here and around these parts kjs aren't missed much so I could probably score a low mileage whole 2.4 depending on year and just use the front and rear both

If your SOL for the rear for having a '06.The 2.4 gas KJ's only are 2002-2005 model years and in 2006 they changed the rear 8.25 for 4 channel ABS so a '02-'05 rear diff will not work if you want your ABS to work.

And no just switching the backing plates and axles will not work since the axles themselves are different between '02/'05 and '06/'07 and can not be interchanged.
 

Axel-ander92

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If your SOL for the rear for having a '06.The 2.4 gas KJ's only are 2002-2005 model years and in 2006 they changed the rear 8.25 for 4 channel ABS so a '02-'05 rear diff will not work if you want your ABS to work.

And no just switching the backing plates and axles will not work since the axles themselves are different between '02/'05 and '06/'07 and can not be interchanged.
Ok good to know!
 

tommudd

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Yeah its just got a spacer lift but that'll go bye-bye and ill do it right. And yeah its actually closer to like 14.5 15 mpg in city. But still id like to regear before I switch to larger tires and lift too

4.10s and 265-70-16s work perfect, if going larger tires than that then 4.10s of course will help but you'll be wishing for even lower.
Over 100,000 miles of experience with 4.10 / 4 inches of JBA lift and 32s on the 04
over 30,000 miles with 2.5 inches of JBA lift / 4.10s and 31 s on the 03
 

Axel-ander92

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Upon an inquiry at local junkyard I can only get a front diff with 4.10 shipped here for around $545 total completely tested and checked and with 110k miles. Does this sound like a decent deal?
 

tommudd

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Upon an inquiry at local junkyard I can only get a front diff with 4.10 shipped here for around $545 total completely tested and checked and with 110k miles. Does this sound like a decent deal?

Not really from what I have been finding but maybe right for your area.
I just bought front and rear 4.10s for less than that, and less than 70,000 miles
One front 4.10 diff I paid 75 bucks for with 10,000 miles
Last set we installed in a friends I think he may of had 700 in front and rear, can't remember for sure
I found another whole KJ for 750 here close by yesterday
so keep checking Craigslist etc they are out there but getting harder to find
 

Axel-ander92

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Not really from what I have been finding but maybe right for your area.
I just bought front and rear 4.10s for less than that, and less than 70,000 miles
One front 4.10 diff I paid 75 bucks for with 10,000 miles
Last set we installed in a friends I think he may of had 700 in front and rear, can't remember for sure
I found another whole KJ for 750 here close by yesterday
so keep checking Craigslist etc they are out there but getting harder to find

Yeah that's true. Ill keep looking every week or so. I plan on getting this jeep hopefully by Wednesday next week. Anything particular I should be looking out for? I'm mainly gonna check for alignment, ball joints, wear and tear on the motor, spark plugs, seals on differentials all that good stuff. Anything else?
 

Axel-ander92

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4.10s and 265-70-16s work perfect, if going larger tires than that then 4.10s of course will help but you'll be wishing for even lower.
Over 100,000 miles of experience with 4.10 / 4 inches of JBA lift and 32s on the 04
over 30,000 miles with 2.5 inches of JBA lift / 4.10s and 31 s on the 03

Tommudd what was your fuel economy like with those setups??
 

tommudd

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Tommudd what was your fuel economy like with those setups??

04, OVER 4 INCHES OF LIFT, AFTERMARKET BUMPERS, HEAVY SKIDS 265-75-16S AND 4.10S EASILY GOT 21-22, EVEN GOT OVER 23 ONCE RUNNING ACROSS PENNSYLVANIA . THATS ALL AT 75 PLUS ON THE HIGHWAY

03 with 2.5 inches of lift, 265-70-16, heavy skids etc I get about 22 at 75 plus. But I can tell it has more power on hills etc, doesn't shift as often . But honestly haven't checked it lately . Have to next week, another Ohio to North Carolina and back down through WVa and Va

05 stock doesn't do as well maybe 19 and its all stock but then it needs to have the snot ran out of it for a bit, been a while
By the way mine gets ran hard, rev limiter is my friend, I find it daily, don't bog these KJs down they like to be revved
 

tommudd

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Upon an inquiry at local junkyard I can only get a front diff with 4.10 shipped here for around $545 total completely tested and checked and with 110k miles. Does this sound like a decent deal?

You may have to run with that one unless you can find cheaper
but like has been mentioned , new gears in the rear since you can not use what we do with 02-05s
 

Axel-ander92

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You may have to run with that one unless you can find cheaper
but like has been mentioned , new gears in the rear since you can not use what we do with 02-05s

Yeah I think I may. Ill probably have my uncle show me the right way to put a different ring and pinion in so I can learn to do it myself if need be!
 

tommudd

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Yeah I think I may. Ill probably have my uncle show me the right way to put a different ring and pinion in so I can learn to do it myself if need be!

If he has all of the proper tools to sit one up, thats cool.
If I have any I just let someone who does it daily do mine. Easier, cheaper and faster than for me to, although I've done a lot of them. BUT been 20 years ago LOL
 

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