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Old 10-05-2012, 10:38 PM   #1
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4.0L swap from a 91 XJ into my 89 Yj

I need a little help I have taken a in line 6 cyl 4.0L and AX 15 from a 91 jeep cherokee (was told it was the original) and am putting it into my 89 yj that originally had a 2.5L and ax 5. I purchased a transmission mount for the 91 4.0 L but it doesnt line up to the transmission. my question is do i need a transmission mount bracket that hooks to the tranny and then the mount bolts to that? also is there a sight where i can plug in my tranny number and it verifies the year or type it is?the number on the bottom is 20101553 and the model number stamped on top is 53009528. any help would be appreciated. thanks

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Old 10-06-2012, 08:58 AM   #2
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Here's a basic list of parts you will need:

-New engine mounts (to weld onto the frame- old ones have to go)
-New transmission mounts (you have to modify the crossmember a bit)
-Strip entire wiring harness
-Transfer engine/transmission/transfercase to Jeep
-Transfer axles (the 2.5L's 4.10 gearing is too high for the 4.0)

That's about as basic as it gets. There's still LOTS more work than that though.

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Old 10-06-2012, 09:29 AM   #3
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Sounds like you need the bracket I needed.bracket bolts to the tranny and the tranny mount bolts to it.that bracket also holds the exhaust.i couldn't find one at the time and had to make one.also if you don't have the 4x4 shifter for a yj 4.0 it won't work either.I still haven't bought one yet.
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93 yj 2.5 swap to 4.0,ax15. 4 inch RC lift with 33s.410 gears
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Old 10-06-2012, 09:33 AM   #4
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Quote:
Originally Posted by Xpress View Post
Here's a basic list of parts you will need:

-New engine mounts (to weld onto the frame- old ones have to go)
-New transmission mounts (you have to modify the crossmember a bit)
-Strip entire wiring harness
-Transfer engine/transmission/transfercase to Jeep
-Transfer axles (the 2.5L's 4.10 gearing is too high for the 4.0)

That's about as basic as it gets. There's still LOTS more work than that though.
I didn't have to modify my cross member or swap my axles.the 4.10 gearing is not to ( I think you meant low) for the 4.0
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93 yj 2.5 swap to 4.0,ax15. 4 inch RC lift with 33s.410 gears
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Old 10-06-2012, 09:40 AM   #5
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Quote:
Originally Posted by psyco31 View Post
I need a little help I have taken a in line 6 cyl 4.0L and AX 15 from a 91 jeep cherokee (was told it was the original) and am putting it into my 89 yj that originally had a 2.5L and ax 5. I purchased a transmission mount for the 91 4.0 L but it doesnt line up to the transmission. my question is do i need a transmission mount bracket that hooks to the tranny and then the mount bolts to that? also is there a sight where i can plug in my tranny number and it verifies the year or type it is?the number on the bottom is 20101553 and the model number stamped on top is 53009528. The oany help would be appreciated. thanks
My stuff was from a 95 xj.the only things needed for the swap is that tranny bracket I told you about,or make one,4x4 shifter,driveshafts fr 4.0 yj.if you have that bracket and the driveshafts the tranny mount will bolt right up to your skid plate with the driveshafts in place.weld your engine mounts in place and splice you 2 injectors that you added.
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93 yj 2.5 swap to 4.0,ax15. 4 inch RC lift with 33s.410 gears
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Old 10-06-2012, 10:37 AM   #6
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Originally Posted by kdub View Post
I didn't have to modify my cross member or swap my axles.the 4.10 gearing is not to ( I think you meant low) for the 4.0
Depends on the tires, and what he wants to do with the jeep.

I like the 4.2 with 33" tires and the 4.10, but the 4.0 is a higher revving engine so it could be a bit high.

But I suspect with up to 31" tires it would be fine.
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Old 10-06-2012, 07:59 PM   #7
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Originally Posted by kdub View Post
I didn't have to modify my cross member or swap my axles.the 4.10 gearing is not to ( I think you meant low) for the 4.0
No, the 4.10 gearing will over-rev the engine without larger tires on board. You don't want to be running the 4.0 over 3000rpm while cruising, do you?
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Old 10-09-2012, 12:11 AM   #8
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Quote:
Originally Posted by kdub View Post
Sounds like you need the bracket I needed.bracket bolts to the tranny and the tranny mount bolts to it.that bracket also holds the exhaust.i couldn't find one at the time and had to make one.also if you don't have the 4x4 shifter for a yj 4.0 it won't work either.I still haven't bought one yet.
thanks for all of the input. i was able to find a tranny mount bracket taht was close from a salvage yard. still had to modify my pan though. I got a 4x4 shift lever from there also from a YJ with a 4.0 but was unsure of the year. i had to make minor modifications to the bolt patern on it. I still need the linkage though the one from the 2.5L is to short.
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Old 10-09-2012, 12:17 AM   #9
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i was thinking about 33" tires but not real sure about what size lift i would need with these tires. i don't want a jeep taht is rediculouse hight wise but i want it to be functional on and off road. I am new to the jeep world.

i got the 89 YJ from a friend for free because he blew the engine and i picked up the 4.0 with tranny and T-case for $275 so thought it would not be to much of a mod. was i wrong. I am learning alot along the way. I have the entire wiring harness and set up from the XJ i got the engine from. good thing since i burnt up the original wireing harness when i was grinding off the motor mounts (had a fuel line leak and didn't catch it before the flames came) got the fire out and only lost the wiring harness. live and learn.

thanks for all the insight
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Old 10-09-2012, 12:22 AM   #10
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i am going to start trying to figure out the wiring tomorrow. I have a Chiltons for both the YJ and the XJ and was going to use the wiring diagrams in those to try and figure it out. Does anyone have any better ideas on how to go about this?

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