The 5.2/5.9 swap guide for YJs - JeepForum.com
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post #1 of 167 Old 11-06-2013, 11:36 PM Thread Starter
SunDevilJeeper
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Be forewarned that some of the information below might need to be corrected, I intend to correct it as people inform me of the errors.




Notes:

This is intended to be a basic guide to those who have questions about this swap. The questions that are most commonly asked about this particular project are mostly answered here.

This is not intended to be an all inclusive guide, it covers the basics for those that are interested in doing the swap. There are several write ups here, and on other sites that give a very in depth guide on what to do.



Manual Transmissions:

AX15:

Easy to find, and capable of withstanding a decent amount of abuse behind a 4.0. The input torque rating is 300lb-ft at max GVW. That means the AX15 will live behind a stock 5.2 or 5.9 in a YJ, however it's a medium duty transmission and putting it behind either of these engines is still putting it in its upper limit of what it can handle. Basically you don't want to be doing massive burnouts, bang shifting, or clutch dumps with an AX15 behind a Magnum engine. In order to mate one of these up to a Magnum, you'll need a Dakota 3.9 bellhousing.

[EDIT]: The Dakota 3.9 bellhousing has become harder to find in recent times (as of mid 2018), and people have severely jacked up the price on them as well because they allow you to adapt the Magnum engines to the AX15, so buyer beware. They can still be found for cheap like a while back, but it won't be as easy these days.


AX5:

The AX5 that came behind the 2.5L engine can't even hold up to the 4 cylinder, it sure as hell won't hold up to a V8. It can't even be adapted to a V8 anyway, nobody makes an adapter and the Dakota bellhousing doesn't fit.


NV3500/NV3550:

The NV3500 that came in the Dodge Dakota and Dodge Ram came behind the 5.2 from the factory. It bolts right up to the back of the engine without any need for adaptation. The NV3550 is simply a later version of the 3500 that has a removable bellhousing. Torque rating for the 3500/3550 is identical to the AX15, which is why it was never offered behind a 5.9 in Rams or Dakotas.

NV4500:

In order to use the NV4500 behind the 5.2 or 5.9, you will need to find a NV4500 out of a 2nd gen Dodge Ram 2500 with the 5.9 V8, not the 5.9L I6 Cummins. The 4500 will also hang down below the frame rails by quite a bit, so beware if you're doing an LCOG build. The only way to get it further up between the frame rails is either a body lift, or cutting a hole in the floor to fit the transmission and transfer case through it. How big that hole ends up being depends on how far through the floor you're trying to lift the drivetrain. You'll more than likely need to do a MML (Motor Mount Lift) as well to keep the drivetrain level. The NV4500 is a really tall transmission, but will handle a stroked 5.9 (408 cid) easily... and still last a long time.

NP435

The NP435 came behind 1st Gen Rams, or W model trucks (W150, W250, etc). It's a 4 speed transmission with no overdrive, so 4th gear is 1:1. There are two versions, one has a 6.69 first gear, the other has a 4.78 first gear. The 4.78 first gear version will have a 23 tooth third gear, so if you're wanting to know which version you have, count the teeth on the third gear. It was offered behind the LA 318 and 360 engines so it'll bolt up to the 5.2 and 5.9 Magnum. The NP435 is well known for being very strong, and cheap and easy to rebuild. Since it doesn't have a overdrive gear, you'll want to consider using taller axle gears if you go this route, otherwise you'll be spinning the engine something fierce going down the highway. Nobody likes cruising at 4000 RPM for however long when you're going down the highway headed to your favorite trail.


Clutch and Flywheel

The 5.2 and 5.9 are balanced differently. The 5.2 is balanced internally in the rotating assembly, while the 5.9 is balanced externally on the flywheel. What that means is the flywheels are different so use the correct one for the engine. When using a manual transmission behind a 5.2, you'll want to use a flywheel from a 2nd gen Ram 1500, and a 2nd gen Ram 2500 for the 5.9.

For clutch kits, if you're using an AX15 from a YJ or TJ, you can use the pilot bearing that comes with the clutch kit, the OD of the pilot shaft needs to be .750" for it to work. If you are using an AX15 from a different vehicle, you'll need to do some handy work with the pilot bearing.

mike_breaker_5 explains in post #37
https://www.jeepforum.com/forum/f12/5...l#post18254466

Do not use the stock I4 or I6 clutch with this swap, it will not work, and if you make it work, it still won't work.

For the NV3500/NV3550 or AX15 transmissions, the clutch kit you'll want to buy would be for the 2nd gen Ram 1500, or 94-01.
And in case the question arises, the 5.9 clutch kit will fit inside either bellhousing, it's the same dimensions as the 5.2 kit.


Automatic Transmissions:

Torqueflite 727 aka 36RH/37RH

This transmission is commonly found behind the older LA blocks, not the Magnum blocks we're discussing here. It's not really a transmission you'd want to pursue, but it'd work.

The 727 bolts up to both the D300 and NP231 transfer cases without adaptation. However, due to the clocking of the transfer case, you may or may not experience clearance issues with the drive shaft and skid plate in a YJ.



Dodge 46RE

The 46RE is what's used behind both the 5.2 and 5.9 in Dodge and Jeep vehicles. There are plenty of documented problems with these transmissions, but there are also just as many well documented fixes for these defects as well upgrades to make them quite strong and reliable.

As to whether or not they fit in a YJ without any major headaches, that information is quite hard to come by since not many people have used it in a YJ. Those that have, haven't been very vocal about it on the forums.



Transfer Cases:

NP231:

The NP231 is the most common transfer case used in this swap, and it bolts up without adaptation to most, if not all of the transmissions listed.

D300:

The D300 transfer case is a sought after upgrade that requires an adapter kit, and needs to be flipped if it is being used with driver side drop axles, or the stock front axle.


More transfer cases will be added to the list as people utilize different ones, and information on them becomes more available.

Engine Mounts:

Novak and Advanced Adapters make engine mounts for this specific swap. The 5.2 and 5.9 Magnum engines have the exact same mounting points and locations, since the blocks are the same. What that means is, if you swap in a 5.2 and later on decide you want to bump up to a 5.9, the 5.9 will simply bolt right in to the motor mounts you installed for the 5.2 without any issues. Just beware of the fact that the crankshafts won't swap between the engines if for some reason you need to swap out engines and want to use parts from both engines to create a complete working engine. The main differences internally besides the way they're balanced, is the 5.2 crank journals are smaller and uses flat top pistons, while the 5.9 has dished pistons. The camshafts are also different, the 5.2 has a slightly more aggressive cam.


Electronics:


PCM:

There are many choices out there for the PCM (computer) for these engines. For the 5.2, the vehicles that have the proper computer would be the ZJ Grand Cherokee, Dodge Ram, Dodge Dakota, Dodge Ram Van, and a few more, but the vehicles mentioned are the easiest ones to source a computer from.

Because of the intended purpose of the vehicles mentioned, they have different fuel maps, but one does not outperform the others. They are simply factory tunes for where the torque and horsepower is concentrated.

If you want to utilize a manual transmission, it is best to find a computer from a Dodge Ram or Dakota that had the 5.2 or 5.9 with a manual transmission. The PCMs that came with the automatic transmissions can be used as well, but you have to bypass the Neutral Safety Switch in order for it to work.

One question that has been asked many times before in various build threads for this swap, is security programs written into the PCM. Dodge Ram and Dakota PCMs don't have one, however ZJs and Durangos do. So if you're using a PCM out of a ZJ or Durango, be advised. That'll be an issue you'll have to address before you can start the vehicle.


EDIT: Apparently some of the PCMs (for the 5.9 at least) will have a two plug port, and some will only be a single plug. Make sure you do your homework if you're buying parts separately. If you're getting all your parts from a single donor vehicle, chances are you won't have anything to worry about. If you're swapping a 5.2, you might want to do the same homework in case the PCMs have the same situation.

EDIT: OBDI computers have 3 plugs, and OBDII have a single plug.

Wiring Harness:

Having the wiring harness that was attached to the engine would be a big plus, but if you do not have it, any wiring harness for a 5.2 or 5.9 that isn't cut or hacked up will do just fine. You need the ENGINE wiring harness. You splice that harness into your factory harness and you use the PCM from the donor vehicle with your now modified harness. All of the Chrysler PCMs from the mentioned donor vehicles are the exact same computer as the stock PCM in your YJ, same ports, same shape, they just have a different program written in them.

One of the benefits of this swap is that the donor computer speaks the same language as your stock gauges, so they communicate perfectly. You have no need to go out and buy aftermarket gauges with this swap.

CPS:

For the CPS, the manual and automatic sensors are different. The automatic CPS is longer and will make contact with the tone ring on the flywheel if you use it with a manual flywheel. You can use washers as spacers for the automatic sensor.

Cooling:

With a little craftsmanship, you can use the stock 4.0L radiator with the 5.2 and 5.9 engines. Based on the information available at this moment in time, the stock 4.0 radiator does fine cooling both engines. It does however require some craftsmanship with the radiator house routing.

Those who go with an aftermarket radiator should look for a radiator made either specifically for a Chrysler small block conversion, or a Chevy conversion radiator since the inlet and outlet are on the same sides.

Aluminum radiators are almost always, if not always, recommended when going to an aftermarket radiator. As to the amount of cores and rows, that is up to the owner to decide. Electric fans are also ideal.


Exhaust:

The stock 5.2 and 5.9 exhaust manifolds from later model 2nd gen Ram 1500s can be used. The other common solution is aftermarket block hugger shorty headers. Long tube headers will not work with this swap, and neither will a true dual exhaust. If you're using the NV4500, you'll more than likely run into clearance issues with the catalytic converter.







Last update: 01MAY2020


00 Ram 1500 Sport
98 Ram 1500 Sport
91 YJ 4.0
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post #2 of 167 Old 11-07-2013, 09:44 AM
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Sub'd to read later. Thanks for writing it up!

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post #3 of 167 Old 11-07-2013, 02:45 PM
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Sub'd thanks sundevil.

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YJ 5.2 magnum MPI, AX15, NP231 SYE, Dana 30 4.56 open/ 8.8 4.56 detriot locker. 1" shackles
2" BL, 4" stretch all on saggy waggy springs.
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post #4 of 167 Old 11-07-2013, 04:14 PM Thread Starter
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You are most certainly welcome, I'm researching the 727 transmission and updating the info right now. Information about that transmission is all over the place, hard to pinpoint the exact info I want.

EDIT: Jesus, there's an ungodly amount of conflicting information out there about the 727.

00 Ram 1500 Sport
98 Ram 1500 Sport
91 YJ 4.0
92 YJ 5.9
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post #5 of 167 Old 11-08-2013, 09:54 AM
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Good job on the write-up man. Hopefully it will answer a lot of questions before the daily "I want to put a V8 in my Jeep, what is it gonna take?" threads get started.

I'd like to put something together for Vortecs but there isnt much interest in them compared to Magnums, for YJs anyway.


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post #6 of 167 Old 11-08-2013, 11:25 AM
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This should become a sticky.

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YJ 5.2 magnum MPI, AX15, NP231 SYE, Dana 30 4.56 open/ 8.8 4.56 detriot locker. 1" shackles
2" BL, 4" stretch all on saggy waggy springs.
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post #7 of 167 Old 11-08-2013, 11:36 AM
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X2 ^^

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post #8 of 167 Old 11-19-2013, 04:53 PM
skyj
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Im having trouble finding any info on whether it matters if you use a flywheel from an OBD2 setup on a '93 OBD1 I'm assuming that it doesn't matter I found a good used flywheel out if a '97 dodge ram with new clutch and pressure plate I just dont want to purchase it until I find out for sure.I also found one from an '01 Anybody know the years that work with each other.

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YJ 5.2 magnum MPI, AX15, NP231 SYE, Dana 30 4.56 open/ 8.8 4.56 detriot locker. 1" shackles
2" BL, 4" stretch all on saggy waggy springs.
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post #9 of 167 Old 11-19-2013, 04:58 PM
kingolaf1987
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i have a amc 360 and 727 torque flight sitting in the garage. i always thought they would be way to heavy for a yj. (4.0l swap this weekend) front heavy.
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post #10 of 167 Old 11-19-2013, 05:09 PM
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Quote:
Originally Posted by kingolaf1987 View Post
i have a amc 360 and 727 torque flight sitting in the garage. i always thought they would be way to heavy for a yj. (4.0l swap this weekend) front heavy.
I would do the 360 727 swap if I had them just sitting there and forget the 4.0 swap. I know the V8 is a little heavier than the 4.0 but you can probably level it out with an extra main leaf if needed. I have waggy leaf springs in my jeep from a wagoneer with a V8 so mine should be fine. Obviously a little more work , but probably not much more if you only had the 2.5. and you will need a beefier rear axle than the dana 35 but 8.8's can be had for real cheap. Just my .02

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YJ 5.2 magnum MPI, AX15, NP231 SYE, Dana 30 4.56 open/ 8.8 4.56 detriot locker. 1" shackles
2" BL, 4" stretch all on saggy waggy springs.
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post #11 of 167 Old 11-19-2013, 05:25 PM Thread Starter
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Quote:
Originally Posted by skyj View Post
Im having trouble finding any info on whether it matters if you use a flywheel from an OBD2 setup on a '93 OBD1 I'm assuming that it doesn't matter I found a good used flywheel out if a '97 dodge ram with new clutch and pressure plate I just dont want to purchase it until I find out for sure.I also found one from an '01 Anybody know the years that work with each other.
As far as I know, as long as it's a magnum flywheel, you should be ok. I haven't found any other info stating otherwise.

00 Ram 1500 Sport
98 Ram 1500 Sport
91 YJ 4.0
92 YJ 5.9
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post #12 of 167 Old 11-19-2013, 08:37 PM
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I didn't know a flywheel would be different for either or??

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post #13 of 167 Old 11-19-2013, 09:17 PM Thread Starter
SunDevilJeeper
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The 5.9 and the 5.2 flywheels are different, so don't mess that one up. The 5.9 engine is externally balanced, and the 5.2 is internally balanced.

Other than that, I haven't found any info on the magnum flywheels being different from OBD I to OBD II.

My engine came out of a 97 ZJ, and I bought a flywheel for a 97 Ram 1500.

00 Ram 1500 Sport
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91 YJ 4.0
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post #14 of 167 Old 11-19-2013, 09:58 PM
skyj
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Quote:
Originally Posted by SH00T3R View Post
I didn't know a flywheel would be different for either or??
Yeah your going to want a 5.9 flywheel for sure.

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YJ 5.2 magnum MPI, AX15, NP231 SYE, Dana 30 4.56 open/ 8.8 4.56 detriot locker. 1" shackles
2" BL, 4" stretch all on saggy waggy springs.
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post #15 of 167 Old 11-20-2013, 03:29 PM
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Quote:
Originally Posted by skyj View Post
Yeah your going to want a 5.9 flywheel for sure.
Yeah I ment for a OBD 1 or 2 set up

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