NP435 in an XJ...just tossing ideas around

[JRT1393]

So a couple years back, I had a 1966 F250 flat bed with a 390 (at least that's what my grandpa was told was in it, may be a 352, which would've been the factory motor) and an NP435 granny 4 speed. Unfortunately the economy went awry, dad got laid off, and the truck had to go, but I kept the drivetrain out of it.

The engine I still have to run numbers on, I was thinking about keeping it for a project later on down the road, but now I'm pretty sure I'm going to sell it since I already have an XJ with a blown motor that I plan to have back to wheeling at least by the time next year's Crawl comes around, and a 1966 Plymouth Satellite that's sitting in the field that I'm going to build after college.

The transmission is an NP435, with a true, unsynchronized, first granny gear with a 6.68:1 ratio (if I read correctly). I'm thinking about selling it too, I just have to figure out how much I can get for it from those old Bronco guys.

However, somehow my brain formulated this insane idea of getting rid of the AW4 and 231 in my Jeep and throw the NP435 with an NP205 (maybe, still have more research to do on what case would be best). Since the XJ is now destined to live its life off the beaten path now that I have a daily driver, the extremely low gears on the street wouldn't really bother me. I've seen a couple people swap them into TJ's, CJ's, and YJ's, but no actual build threads on it. I know the NP435 is damn near bulletproof and very simple to rebuild with a press and a bearing puller. Has anyone done research on a swap like this?

I'm just tossing the idea around for now, if I decide to go with it (which my insane mind will probably somehow justify it :wow, I'll keep the transmission and start collecting parts to do the swap. If not, I'll just sell it and use the money for different Jeep parts.

Annnnnd discuss!!!

 

[Ghost]

IIRC there is a guy on here that ran the granny geard transmission but I believe he did it behind a 5.0. which is what I want to do. Let me know if you sell that transmission cheap!

 

[JRT1393]

IIRC there is a guy on here that ran the granny geard transmission but I believe he did it behind a 5.0. which is what I want to do. Let me know if you sell that transmission cheap!

Lol will do!!! I still have to do some more research to see exactly what applications it can be used for. Like I said it's out of a 2wd truck, but I believe it can be mated to a Dana 20 or NP205 without much trouble. I know in that truck you could idle it off uphill in second gear. At 55 mph it was turning like 5500RPM or so :roll: It was a freaking stump puller though, thing was insane!!!

 

[highspeed]

Lol will do!!! I still have to do some more research to see exactly what applications it can be used for. Like I said it's out of a 2wd truck, but I believe it can be mated to a Dana 20 or NP205 without much trouble. I know in that truck you could idle it off uphill in second gear. At 55 mph it was turning like 5500RPM or so :roll: It was a freaking stump puller though, thing was insane!!!

That May be more of the diff gearing than trans. Seems insane to have a truck trans geared that low. I may be wrong though

 

[JRT1393]

That May be more of the diff gearing than trans. Seems insane to have a truck trans geared that low. I may be wrong though

Yeah I have no clue what the rear diff was geared to. It was mainly used as a farm truck. Didn't see hardly any highway time

 

[shortxjdoug]

Why? You have to destroy the floor to make it fit, buy drivetrain adapters to bolt it up, the 205 has an awful low range and the whole setup is going to weigh a metric ton. I have yet to see an ax15 buckle under pressure and i have witnessed numerous 4.5k rpm clutch drops pointed vertical. Sure you dont have the granny gear but an ax15/231 bolts in and with 5.13s its VERY driveable in heavy rocks with up to 37's


Spend money on good axle tech and not 60 year old drivetrain tech

 

[Ghost]

Why? You have to destroy the floor to make it fit, buy drivetrain adapters to bolt it up, the 205 has an awful low range and the whole setup is going to weigh a metric ton. I have yet to see an ax15 buckle under pressure and i have witnessed numerous 4.5k rpm clutch drops pointed vertical. Sure you dont have the granny gear but an ax15/231 bolts in and with 5.13s its VERY driveable in heavy rocks with up to 37's


Spend money on good axle tech and not 60 year old drivetrain tech

All good points. My floor is already destroyed.

 

[highspeed]

Sell the trans and put toward axles? Not sure what those trans go for though.

 

[JRT1393]

Why? You have to destroy the floor to make it fit, buy drivetrain adapters to bolt it up, the 205 has an awful low range and the whole setup is going to weigh a metric ton. I have yet to see an ax15 buckle under pressure and i have witnessed numerous 4.5k rpm clutch drops pointed vertical. Sure you dont have the granny gear but an ax15/231 bolts in and with 5.13s its VERY driveable in heavy rocks with up to 37's


Spend money on good axle tech and not 60 year old drivetrain tech

Very good points there. Again it's just an insane idea that popped into my head since I already have the transmission. The main reason I'd want it is for that granny gear. As for the floor, it's most likely going to get cut up at some point anyway. After college when I (hopefully) have a decent paying job and some more time, I'm going to put a 4bt Cummins with an NV4500 and some kind of doubler in it, mainly for the low end torque, but also for the fact that it would be awesome haha.

All I would need to get the transmission to bolt to a 4.0 is a bellhousing from a CJ that had a 258 and a T150 or T175 transmission, then a pilot bushing that would come from Advanced Adaptors. More than likely I'll just throw another engine in the Jeep, service the AW4, and wheel it until I can build it how I would really like to, because that's the cheapest and easiest option lol

Sell the trans and put toward axles? Not sure what those trans go for though.

That's another idea I had. I honestly can't find reliable information on what it would go for either, I've seen ones that need a rebuild anywhere from $100 to $400, so I have no clue what I would price it at.

 

[Team Willys]

A 4BT in an XJ. Yeah that's a great idea.

Stick to light weight. The 4BT weighs twice as much as a 4.0, and really doesn't make any more power than 4.0 in stock trim. Now, with a big intercooler, modded pump, and a set of small compounds, its a great engine. But good luck packaging that in any jeep, much less an XJ with low hood height.

 

[JRT1393]

A 4BT in an XJ. Yeah that's a great idea.

Stick to light weight. The 4BT weighs twice as much as a 4.0, and really doesn't make any more power than 4.0 in stock trim. Now, with a big intercooler, modded pump, and a set of small compounds, its a great engine. But good luck packaging that in any jeep, much less an XJ with low hood height.

By that point hopefully I'll have built myself a full shop. When I do it, it sure as hell ain't gonna be a stock 4bt lol. I've seen a couple guys fit them into XJ's. Now a 6bt would be a piece of work, but that's been done a time or two as well. I definitely want a diesel, As for weight, yeah it's much heavier, and going downhill it won't be as stable, but I believe with coilovers (another plan of mine) and an insane cage, it'll be fine. Oh, and the roof will be going away too

 

[shortxjdoug]

By that point hopefully I'll have built myself a full shop. When I do it, it sure as hell ain't gonna be a stock 4bt lol. I've seen a couple guys fit them into XJ's. Now a 6bt would be a piece of work, but that's been done a time or two as well. I definitely want a diesel, As for weight, yeah it's much heavier, and going downhill it won't be as stable, but I believe with coilovers (another plan of mine) and an insane cage, it'll be fine. Oh, and the roof will be going away too

I have been wheeling xj's for 10 years now. Weight is your enemy off road, it always will be. You could have 1000 hp and if it was fullwidth and and 6000 lbs a smaller lighter cheaper rig will outwheel it. Why so hard for diesel? Its a crappy powerplant off road, snappy on demand power and torque is what you need. I wouldnt like driving one personally, snappy power lets you execute a lot more precise applications of oomph when you need it.

Im not trying to talk you out of any of it, the coolest thing about what we do is the handbuilt stuff that comes out of peoples garages. Im just saying that drivetrain may be better suited into a wrangler platform where the lack of body offsets the weight increase of the drivetrain if it must be diesel.

 

[Ghost]

Them two have some points...... I'd still like a 5.0 in an xj. Time and $$ will probably never allow that to happen though.

 

[JRT1393]

I have been wheeling xj's for 10 years now. Weight is your enemy off road, it always will be. You could have 1000 hp and if it was fullwidth and and 6000 lbs a smaller lighter cheaper rig will outwheel it. Why so hard for diesel? Its a crappy powerplant off road, snappy on demand power and torque is what you need. I wouldnt like driving one personally, snappy power lets you execute a lot more precise applications of oomph when you need it.

Im not trying to talk you out of any of it, the coolest thing about what we do is the handbuilt stuff that comes out of peoples garages. Im just saying that drivetrain may be better suited into a wrangler platform where the lack of body offsets the weight increase of the drivetrain if it must be diesel.

That's an excellent point. The main reason for me doing it is that it'd be different, not many people do it. I also like the simplicity of the 4bt, there's fuel and compression, if it has those, it runs. I've thought about other powerplants as well, but then I came across Project Rattletrap, and for some reason I've just wanted a diesel in mine ever since. I also have a buddy who works for a tractor trailer company where I can get an engine for cheap. Also, by the time I did all the strengthening I was going to do anyway to it, it'd be so much heavier that a 4.0 wouldn't cut it for my taste, it about don't cut it for me now, but a lot of that has to do with that fact that it's undergeared. I'd end up building a stroker, which is something else I've thought a lot about doing. Idk, I still have lots of time and research to do before I commit to anything, again, still tossing ideas around haha.

Here's one of the threads I came across that is kind if an inspiration, but mine probably won't be very streetable, and I'm not quite convinced I should cut the unibody off and build a frame yet.
http://www.pirate4x4.com/forum/jeep-non-hardcore/972182-xj-4bt-frame-build-2.html

Them two have some points...... I'd still like a 5.0 in an xj. Time and $$ will probably never allow that to happen though.

I've always thought a 408 stroker build from a Dodge 5.9 would be awesome in an XJ. There's a guy in I think it's Belmont that has a Dakota with a 408 stroker, and he's pushing close to 600hp and 600lbf-ft of torque. That'd be better suited in a prerunner though I believe.

 

[shortxjdoug]

Them two have some points...... I'd still like a 5.0 in an xj. Time and $$ will probably never allow that to happen though.

For the same time and $$ you could have an ls based powerplant. I hate to say it but theres a reason the LS is a boring everyone does it swap. More power, more tuning, more parts. You can make 400 hp from a mill straight out of the yard

 

[Ghost]

For the same time and $$ you could have an ls based powerplant. I hate to say it but theres a reason the LS is a boring everyone does it swap. More power, more tuning, more parts. You can make 400 hp from a mill straight out of the yard

IDK those LS's are pretty pricey and then you have to buy a harness and computer and then tune it all. I would think that would be about $2K easy. The 5.0 can be had fairly cheap around here. $500 or less. The mustang harness and computer can be had for about half that or less around here. Like I said dream..... :kissyou:

 

[highspeed]

Why not the 5.9 or 5.2? Doesn't both bolt up to aw4?

 

[shortxjdoug]

Why not the 5.9 or 5.2? Doesn't both bolt up to aw4?

Nope, the small block mopar bellhousing is different i believe

 

[souske]

IDK those LS's are pretty pricey and then you have to buy a harness and computer and then tune it all. I would think that would be about $2K easy. The 5.0 can be had fairly cheap around here. $500 or less. The mustang harness and computer can be had for about half that or less around here. Like I said dream..... :kissyou:

What can you get a 4bt for "around here"?

Good shocks and a cage can do alot, but they cannot defeat physics.

Weight is your enemy. To the point sliders and bumpers are being produced commercially for the wrangler crowd. Hell, even an iron block/head 350 is 50 lb lighter than the 4.0.

 

[Ghost]

What can you get a 4bt for "around here"?

Good shocks and a cage can do alot, but they cannot defeat physics.

Weight is your enemy. To the point sliders and bumpers are being produced commercially for the wrangler crowd. Hell, even an iron block/head 350 is 50 lb lighter than the 4.0.

IDK anything about the 4bt I'm talking about the Ford 5.0 in the mustang and explorer.