Fj80 Jeep XJ inbreeding?! (1 Viewer)

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C

Chupacabre

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So I acquired a Jeep XJ from a buddy after he rolled it. It's got a better transmission, comparable engine with more aftermarket support and more cost effective ability to achieve better performance, more options for transfer cases, etc... I love my fj80 it's got the OME J springs, 35s, and does great off road. Gas mileage sucks, after market support is minimal and super expensive, and parts availability is scarce. So I've been thinking.... which usually gets me in trouble, but why not use the Jeep 4.0 HO AX15 np231 combo from the Jeep with a box for rocks np300 doubler in the 80? The Jeep strokers do as well as a mild SBC with a cheap rebuild. The 231/300 combo behind the AX15 with my FJ80 axles would give me overdriveand lower 1st gear and overall nice gearing for on and off-road. Putting the FJ on a diet (thinking boat sides, approx. 5 inch extended wheelbase due to double case, and comp cut) plus losing that heavy underpowered 3fe/a440 and radius arm setup. I'm thinking the bastard child Jeep/Landcruiser has to exist. I have found people using hybrid Toyota ax15 with Jeep transfer cases, Landcruisers with just about every engine you could imagine except this one, and Landcruisers with modified Jeep long arm kits, why not? What are your thoughts? Anyone try anything remotely resembling this? Any suggestions aside from stick with all Toyota?
 
Gots me a 4.3 in a mini, so why not a jeep part in an 80?

Show us all how it's done and be the 'first'!
 
Centered rear output and offset rear axle?


What is your final intention for this rig? Crawler?
 
Around here mainly sand and rock but I'd like to remain highway worthy if I can. Yeah I think your right on the offset axle and centered rear np231 output. Not sure what the will happen to the output after I mate a np300 behind the np231 but similar problems have been solved with CV joints. I already have the fj80 and the Jeep XJ. The Landcruiser unfortunately ran over a Jeep liberty last year and the XJ was rolled in the sand dunes during a bachelor party. Lots of good parts on both. Landcruiser has a bent front axle on the passenger side and was occasionally dieing while driving. The XJ body is trashed but complete drivetrain functional with no problems.
 
Here's the worst of the Landcruiser damage and wheeling before.

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Well I guess it's acceptable ( to me ) swap a V8 on my Cruiser .. an LSX ..? my valid excuse would the lack of power of the Toyota engine ..but more than that, goes against my honor ..
 
Motor mounts, placement of accessories (alternator hitting steering box or whatever fitment etc., maybe?) radiator hoses, exhaust routing,and as mentioned before diff location..you did mention problems such as diff location vs. tcase output have solutions..maybe put together a list of stuff to get the project rolling, double that amount, and it should give you an indicator how feasible it will all be.

The drivetrain seems like it would be a good choice. The 4.0 has been a great motor in the couple of Jeeps I've had. The price is right too! It seems like a lot of the "oddball" swaps end with the OP regretting not sticking to more traditional and proven options especially for the time spent, if not the money. Hope that helps, really like the idea in theory.
 
Thing is I already have nearly all the parts I have 2 running trucks. Plus if I don't like it and decide to go SBC the adapter from the AX15 is cheap and more common vs the adapter to the a440. The Jeep 4.0 is a very comparable engine to the 3fe. However it's known to get better performance from factory spec with same displacement. It was designed for airplanes. With a mild stroker rebuild they are getting nearly 400 up and torque is still awesome because it's a straight 6 just like the 3fe. The Toyota is heavy and the efi was bad don't get me wrong it'll run forever it's Toyota but the 3fe efi was awful on a tractor motor. Goes slow real well when the efi doesn't act up. The 2fe stroker builds are much more expensive and less productive.
 
I never had myself a J**p but I've drive few TJ / XJ / YJ / in the past with the 4.0 HO and it's great engine .. very nice power / weigh ratio power .. and it would be very interesting see how it perform on a much heavy ( everything ) platform ..
 
If you're rear driveshaft is long enough you can get away with center rear output and 80 offset rear axle. The 80 rear axles are more centered then traditional 40/60 offset. The longer your rear driveshaft the better obviously.

Ax15 might be a bit light for an 80... Consider NV4500?

No matter what if you're going to all this work I do would do a SBC so you can push your motor forwards the 7" that the front two cylinders of the 4.0 take up, more room for the doubler.
 
cruisermatt said:
If you're rear driveshaft is long enough you can get away with center rear output and 80 offset rear axle. The 80 rear axles are more centered then traditional 40/60 offset. The longer your rear driveshaft the better obviously.
Click to expand...

Agree. I have a FF 80 rear under my FJ40 and there is quite a bit of "incorrect" offset. I spoke with Tom Woods about it and he said the CV shaft should cover it. It's been fine so far.
 
Thanks for the opinions and food for thought guys. I was thinking about moving the rear axle back to make room for the doubler and get better departure angle then boat side up to just below the door hinges to improve clearance. If I decide to go small block later the adapter to the ax15 is way cheaper than the one to the a440.
 
I love what this guy did. Only real boat sides I have seen on an fj. He bobbed the tail end though instead of moving the axle back and his ride height is pretty low. I think he was setting up for big rolling California dunes or desert racing though. I'd like a little more ground clearance but it's a super cool idea. His is mid engine and some very different suspension.

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I think the doubler will add 5 inches to the drivetrain length set up with np231/box for rocks/np300.
 
Chupacabre said:
Thanks for the opinions and food for thought guys. I was thinking about moving the rear axle back to make room for the doubler and get better departure angle then boat side up to just below the door hinges to improve clearance. If I decide to go small block later the adapter to the ax15 is way cheaper than the one to the a440.
Click to expand...

Chupacabre said:
I think the doubler will add 5 inches to the drivetrain length set up with np231/box for rocks/np300.
Click to expand...

Go V8 and move your motor forwards those 5-6". So much easier then moving the axle. And there's a good chance you can get away without gas tank mods if you keep your transfer output in the "stock" location. But don't bank on that, measure it first.
 
Best parts from both the fj is a great truck except engine transmission and XJ is unit body with leaf springs but has great engine and front suspension fj front suspension is OK but doesn't flex like an 80
 
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