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Jeep 2.5 4 engine swap

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    Posted: 23 June 2018 at 1:19am
has anyone swapped in a 2.5 Jeep 4 cylinder, connected to original trans?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 3:54am
You mean like with an AX-5 tranny?  That's a pretty long setup.  Plus, the centered rear diff issue comes up.  I've wondered about that swap too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeeps3,4 Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 4:08am
I want to adapt the engine to the original T90 and drive train. cant find an adapter. Would keep it Jeep!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 4:19am
I would think that would be a more common swap than it apparently is.  "Keep it Jeep" is an excellent idea. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nivrat Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 4:31am
Been down that road already. No one makes an adapter for the T90 to mate up to the 2.5. They dont see enough profitability in making an adapter for what they consider a throw away engine.

I researched that very idea myself since I have a another flattie project and a free 2.5 laying around.
The only way you could  -possibly-  do it ( I haven't tried it) is to find a bellhousing from an S10 or Camaro with the V6 and use that to bolt to the engine, and then find an old Chevy to T90 adapter and bolt it to the bell to mate the T90 to. Clutch/PP would have to be figured out, as well as clutch linkage. In the end you're still going to have a tranny with 2.79 first gear (unless you have a T90C)
with way too much split between the gears for a 4cyl. to overcome.

Don't let me rain on your parade though...just about anything is possible. I will be going a very different route with mine.

Keep us posted...

Mike






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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeeps3,4 Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 3:41pm
I’m not really up for a science project right now - I will go a more established direction. Do the V6 swaps have the same ratio issue? How can you tell a T90 from a T90C? My parts Willys has a T90 adapted to a Ford straight 6, plate is between trans and bellhousing. Really don’t know what was done, need to pull it apart. Someone’s vision gone wrong. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64CJ5 Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2018 at 4:03pm
My 64 CJ 5 came with an F head engine and a T90C.  The four cylinder over comes the split in the gears just fine.  When I installed the 2.3 Pinto into our 52 M-38 I rebuilt the T90A into a T90C and here again the four cylinder overcomes the gear split with out difficulty.   First gear is lower in the T90C, 2nd & 3rd are the same as the T90A.
Novak built the bell housing to transmission adapter and new pilot bushing.  When I had problems they were only a phone call away and ready to help.
There are some really handy folks out there putting VW and Mercedes diesels into Jeeps.  So any thing is possible with enough time and money.  The Kobota diesel swap is more common.
Just my 2 cents. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 25 June 2018 at 7:07am
Originally posted by 64CJ5 64CJ5 wrote:

 First gear is lower in the T90C, 2nd & 3rd are the same as the T90A.    

Tom, actually 1st, 2nd, and Reverse are different between the T90A & T90C; 3rd is the same in both at 1.

        T90A                T90C
1st    2.79                  3.34
2nd.  1.55                  1.85
3rd    1.00                  1.00
Rev.   3.79.                4.53

Therein lies the issue with the T90C behind the L134 with stock axle ratios; much too big of a jump between 2nd and 3rd gear on the highway.  Pretty much dictates the use of an overdrive unit, which is what I installed this past week to counter this issue😉. I had T90C gears installed in Gus this whole time and didn’t even realize it (or remember it if I ever knew).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64CJ5 Quote  Post ReplyReply Direct Link To This Post Posted: 25 June 2018 at 1:48pm
With the Pinto engine I would like an overdrive to reduce the RPM's on the highway.  However the overhead cam is not bothered by high RPM's, I am.  But right now at 55 MPR and above there is a whole lot of shaking going on.  55 is plenty fast for the crowd I like to run with. 
This has gotten away from the question of putting a 2.5 Jeep engine into an older model.  I would think it would be doable, with some machine shop creativity.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 26 June 2018 at 3:01am
Originally posted by 64CJ5 64CJ5 wrote:

I would think it would be doable, with some machine shop creativity.  


I keep thinking that someone somewhere has done it but didn't bother to document it.  Darn it!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nivrat Quote  Post ReplyReply Direct Link To This Post Posted: 26 June 2018 at 5:55am
I'll be starting my project in the fall; I'll post some pics...
 Mike



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill2A Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2018 at 1:21am
If the 2.5 uses a GM bell housing, then an SM 420 can bolt in behind it, but then you'd need an adapter to the TC.
They exist.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote On Jeep About Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2018 at 10:12pm
The jeep 2.5 use the GM front wheel drive housing. It’s not the standard small block. This was because Jeep was using Chevy engines for sometime. When they switched to there own 4 cylinder is was simpler to just keep the GM front drive pattern.
Good news is lots of engines used the pattern from GM in lots of applications. Even the late Buick v-6s used that pattern.
I found a bell housing with front wheel drive pattern and standard GM tranny. There for can use t-90 with GM adapter.
I did have to drill and tap for a clutch pivot that is the same as GM not a bad job with nothing more the a hand drill and carefull measurements.
Sorry I don’t know what vehicle the bell housing came from. Nor have I finished the project so I haven’t sorted out the pilot bushing or clutch disc yet. I don’t except either of these problems to be much of a hurdle.
I even found a 904 Chrysler auto tranny with the GM pattern that will end up a couple inches shorter then a turbo 350 if you wanted to go auto route. The back of the 904 is the same as all the ax trannies which advanced adapters make a t-18 adapter for.
Anyway definitely a doable project.
Have fun.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2018 at 10:46pm
When I did my TDI - T90 swap there was no adapter. Dont let that stop you. Just get a plate of steel or aluminum and make one. Its not as hard as it seems. there are lots of write ups on how to do it. I just make the back of the block look just like the willys block then the t90 will bolt right up to it. I made mine out of aluminum but ive seen guys make them out of steel with an angle grinder and a cordless drill. 


You just have to make the back of whatever new engine you plan on using look like this and the transmission wont know the difference.




I made a plastic template and bolted the bellhousing to it then used the t-90 bearing retainer and an aluminum rod to locate the bellhousing. 


Adapter and crank spacer to keep the willys flywheel in the same location. 



Here is the adapter with the willys flywheel in there. The t90 doesnt know the difference. 


Here it is all together. TDI/T-90 no drivetrain mods needed. Stock trans mounts stock driveshafts. 


I would love you see you make an adapter and plop that 2.5 in there! 




Edited by Millennium falcon - 27 June 2018 at 10:50pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 02tj Quote  Post ReplyReply Direct Link To This Post Posted: 15 Nov. 2018 at 8:45am
Im doing a 2.5 yj engine, sm420, dana 300, dana 44 from a 76 cj5 and a dana 30 from a 80 cj in my 47 bubba willys. just got it running a few weeks ago.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64CJ5 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Nov. 2018 at 4:02pm
02tj,  Pictures and captions please.  The stories and pictures that people posted helped me with my Pinto transplant.  Novak helped me with hardware for the transplant and transmission rebuild.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote unkwally Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar. 2022 at 6:57pm
I'm working  on such a swap now. I tried this with the jeep bell housing but no one makes an adapter. I'm using the  2.5 Iron Duke/ Pontiac  engine/same as jeep 2.5 but with the GM bell housing.  Then you buy a GM/Buick v6 adapter to the stock transmission, problem solved.
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