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2.5L Transmission Swap


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Just wondering how difficult it would be to swap in like a manual transmission into my '86 Comanche. I have a torqueflite 904 3 speed auto and it's awfully slow and maybe an AX4 swap would work, or is it just a waste of money. Plus I practically have to floor it everywhere I go just to get up to speed. So is it worth the effort for better gas mileage, etc. or should I just keep it stock and deal with it. Thanks.

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Just wondering how difficult it would be to swap in like a manual transmission into my '86 Comanche. I have a torqueflite 904 3 speed auto and it's awfully slow and maybe an AX4 swap would work, or is it just a waste of money. Plus I practically have to floor it everywhere I go just to get up to speed. So is it worth the effort for better gas mileage, etc. or should I just keep it stock and deal with it. Thanks.


Depending where you’re at, a deal could be made. I have the AX4 in my ‘87 MJ that I’m going to auto 4x4 to swap. But it’s 2wd and I know my 4 speed came with 3.55 gears. (I have 3.07 in my 4.0L 5 speed 2wd and 3.55s to go in)


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I think it's easier to go from automatic to manual than the other way. If you're going to do it, though, don't bother with the AX-4. Do an AX-5. You don't have to use 5th gear, but it's there if you want it, and you might decide to change axle ratios down the road.

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Ax5 are very common, just a ax4 with a fifth gear.

about any year ax5 from a XJ or mj will work. It’s the same transmission in 2.5 wranglers too but the rear housing is clocked differently so the transfercase does not hit the body.

 

I’m assuming you have 4 wheel drive, 2 wheel drive there is no problem with clocking.

 

 

 

 

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Please enlighten me (us) on this statement?

It’s a common complaint from those who have done the swap especially if they travel a lot on the highway.

 

The ax5 is geared to work better with the 2.5 power bands, with the AX15 on the hwy in fifth the engine rpm isn’t at the right place to maintain speed on a hill or pass in 5th, even crawling using first and reverse the ax5 gear has some advantage.

Ax5 1st 3.93 2nd 2.33 3rd 1.45 4th 1.00 5th .85 Rev 4.74

Ax15. 1st 3.83 2nd 2.33 3rd 1.44 4th 1.00 5th .79 Rev 4.22

 

For a street car you probably wouldn’t notice the difference, on a under powered jeep that is struggling with automatic transmission it might be a issue. I guess it Depends on how they drive and where.

 

Ax15 is strong enough a 2.5 or 2.8 shouldn’t be able to kill it. On paper the ax5 should be able to cope with the power as well but many have trouble with it.

 

 

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If you go with an ax4/ax5, all you need is flywheel, clutch, trans, shifter plate and boot, and pedal assembly.  You may also need the crossmember and drives hats for the manual.

 

The tf904 is a manual valve body.  Harness should be pretty close to the same as

 There is no computer involved.

 

Ax15 and ax5 have the same/similar final drive, and won't effect speed or final drive.

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T case may swap, I'm not sure what output the 904 used.

Personally I would swap the t case anyway, a 231 would be a nice upgrade from a 207.

Also make sure that you get a 86-90 flywheel for your swap , any year trans will work but the flywheel needs to match the Renix system on your engine.

 

I see you're in Sandy, you might get ahold of Jeeps West, David may have everything you need laying around the shop.

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Those 207 for the automatics were 21 spline or 23 spline? I’m thinking automatics were 23 spline.

Something is probably different since the parts look up has the np207 automatic and manual different. I’ve got an automatic 207 I bought for parts but no way to compare it to the manual 207 right now.

The ax5 needs 21 spline, 231 would be a nice upgrade. I’ve not had a bad experience with the 207, it’s low range is pretty good but sounds funny as hell. Thing I hate about it is the speedometer gear is a reverse cut gm deal and impossible to find as are most 207 parts. 231 has a world of support and many options. Just a great choice. And plenty of years to get the parts from.

 

 

 

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AX15 didn't slow my 2.5l down at all, i can spin 37s on pavement in first and cruise in 5th on the highway.
 
Never tried the AX15 on a stock 2.5l though.
 
 
 
 

I have no idea what gears and tires they were running. It’s just a complaint some 2.5 guys had about the ax15 swap. The 2.8/3.4 guys never mention anything like it. But we’ve got 3.73 axels for the most part.

I’m going to be doing the ax15 231 swap on my 2.8 XJ, the ax5 207 lasted over 300k miles but it’s tired. Ax15 is a great transmission for these jeeps. To me it depends on what the owner needs, if it’s a KISS swap grabbing the ax5 with transfer case is the way to go, more ambitious plans then the ax15 with all the tweaking and fabrication would be the better for the long term.



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Unless someone is handing you the parts for free............?

 

That's a two day swap and minimum $1000. 

 

And you'll be even more disappointed than you are now. 

 

Park a 3.4 in front of that 904 and be happy. 

 

You are blaming the transmission for what a tired 32 year old 2.5 no longer has to offer. 

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I will have to check mnkyboy's build thread bet its close to what i have been dreaming up the past couple weeks for my 86 minus the bed, caged, no doors fenders and metric 34's no interior 6" long arm and a ton of room for flex. I have the ax 15's stored in the garage and I'm not buying the ditch the 2.5 jargon. The little 4 bangers got some grunt when set up with good gearing.

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9 hours ago, saveevryjp1998 said:

I will have to check mnkyboy's build thread bet its close to what i have been dreaming up the past couple weeks for my 86 minus the bed, caged, no doors fenders and metric 34's no interior 6" long arm and a ton of room for flex. I have the ax 15's stored in the garage and I'm not buying the ditch the 2.5 jargon. The little 4 bangers got some grunt when set up with good gearing.

I assume  you are referring to me?

 

I don't speak in jargon. 

 

I take it you have not built one yet?

 

My statement stands, his engine is worn out. He's asking what is the best bang for his dollar? 

Putting another transmission behind a worn out 2.5 will net him a loss, not a gain, this has yet to be addressed but by me. Stock rebuilt will run him a minimum of $2000, you have other expenses which no one ever mentions, fluids, gaskets, clutch, starter, water pump........etc.......

Going beyond stock, as I have, you will be well above the $3000 mark. 

I am successful, I suppose, but I'm not happy. 

mnkboy is the ONLY ONE that claims success. Of all the Jeep sites, of all the 2.5 builds, of all the effort, all the money...........he is the ONE, apparently. 

 

Some of us have chased the rabbit down the hole.......you don't want to buy into my 'jargon', that's up to you. You mentioned regearing, if you can do it yourself, $500, if you take to a shop, $1200+, every dollar spent is a work around to low power up front. 

 

And no one mentioned that he'll likely lose his front and rear DS with this swap..........another $400++

 

OP, find a good XJ donor with a 2.5 and a AX5 for around $800 and swap it all over, that's the best for your dollars spent. 

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You took all that out of context friend. I was not in any way shape or form mentionioning doing anything to the motor or implying that it was a race engine or could be. It is far better than what people give it credit for is all and does the job if its maintained. I own 2. Both get excellent gas mileage and are far more capable than other trucks of its class in that time frame. The answer to the 2.5 is not swap in a 4.0 every time. Thats rediculious, nor cost effective, or even practical, or logical to tell someone who probabably doesn't have the experience, tools, and capability to do so. The ax 15 would be a great swap I have 2 in my garage. It took 4 hrs to pull 1 in a junkyard without impacts and I think I'm slow the cost was $150 with core out door bellhousing, clutch included. Yes it would take someone new 2 days and around 500 to 700 depending on how much new parts they sourced going junkyard route. Either way you forget he doesnt have a working trans and there is going to b a cost to fix bottom line. The ax15 would be an excellent investment since its sought after by many including wrangler and cherokee guys. If he finds one in a yard cheap doesnt like it he will easily double to triple his money. Trust me i have sold them for the core bad to people for 300 bucks who did not have one and needed a core to save 50 on a rebuilt. Regardless he has a great transmission for any xj mj. No where in this post does it mention his motor is bad. Your telling this poor guy to gut his mj change wirring harnesses motor transmission? If he is gonna do that buy a new mj with it in it. I'm done I wish you good luck NCardwell. A fool and his money go separate ways. If you have questions and if I can help I will. Feal free to pm me.

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A manual swap even on a worn out engine is going to be night and day.

 

An auto already saps more power than a manual but then on top of it the A904s gear ratios aren't all that great.

A904

1st 2.74,2nd 1.54,3rd 1.00

AX5 

1st 3.93,2nd 2.33,3rd 1.45,4th 1.00,5th .85

Kinda like driving around using only 2nd,3rd,and 4th gears.

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As far as 2.5l builds, I've come across several other built 2.5ls, pretty much all are MPFI and most are running forced induction or a stroker.

 

You can make a 2.5l perform pretty well, it's not really cost effective though, for whats gone into mine i could have easily swapped in a V8 or something.

I just have a thing for being different and wanted to see what i could do with the 4banger.

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2 minutes ago, mnkyboy said:

As far as 2.5l builds, I've come across several other built 2.5ls, pretty much all are MPFI and most are running forced induction or a stroker.

 

You can make a 2.5l perform pretty well, it's not really cost effective though, for whats gone into mine i could have easily swapped in a V8 or something.

I just have a thing for being different and wanted to see what i could do with the 4banger.

This. 

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20 minutes ago, saveevryjp1998 said:

You took all that out of context friend. I was not in any way shape or form mentionioning doing anything to the motor or implying that it was a race engine or could be. It is far better than what people give it credit for is all and does the job if its maintained. I own 2. Both get excellent gas mileage and are far more capable than other trucks of its class in that time frame. The answer to the 2.5 is not swap in a 4.0 every time. Thats rediculious, nor cost effective, or even practical, or logical to tell someone who probabably doesn't have the experience, tools, and capability to do so. The ax 15 would be a great swap I have 2 in my garage. It took 4 hrs to pull 1 in a junkyard without impacts and I think I'm slow the cost was $150 with core out door bellhousing, clutch included. Yes it would take someone new 2 days and around 500 to 700 depending on how much new parts they sourced going junkyard route. Either way you forget he doesnt have a working trans and there is going to b a cost to fix bottom line. The ax15 would be an excellent investment since its sought after by many including wrangler and cherokee guys. If he finds one in a yard cheap doesnt like it he will easily double to triple his money. Trust me i have sold them for the core bad to people for 300 bucks who did not have one and needed a core to save 50 on a rebuilt. Regardless he has a great transmission for any xj mj. No where in this post does it mention his motor is bad. Your telling this poor guy to gut his mj change wirring harnesses motor transmission? If he is gonna do that buy a new mj with it in it. I'm done I wish you good luck NCardwell. A fool and his money go separate ways. If you have questions and if I can help I will. Feal free to pm me.

I didnt' suggest a 4.0, I suggested a 3.4. 

 

Engine mounts and exhaust would be his greatest expense outside of the donor itself. 

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