FJ Transfer Case Swap into a V6 4th Gen
 

Reason for Swap
So swapping in an FJ case is always something I had considered but never pulled the trigger on because of how much effort it takes. But, my electronic case just crapped out on me so that has forced my hand.

This swap will be for retaining the factory J-shift pattern on the transfer case and not doing the twin stick mod.

I managed to pick up an FJ Transfer Case from a 2008 automatic FJ for $160 with only 150k miles on it. Luckily this one came with the shifter, cause a lot of the ones I found before did not have the shifter with it.

https://live.staticflickr.com/65535/...22b21c43_z.jpg

I have a V6, and most threads for this swap talk about swapping it into a V8, so I'm hoping to create this write-up to help those looking to do this swap in the future.

Why Do This Swap?
The electronic actuator on the factory 4th gen transfer cases tend to leak and not seal properly as they age, allowing dirt/mud/water/etc. to get into the actuator and mess with the electronics and the shifting process. I've always found the electronic shifting system to be rather annoying to deal with sometimes as mine always struggled to go from 2WD to 4HI.

The reason so many people do this swap is to obtain a manually shifting transfer case that has a J-shift pattern (similar to that of a 3rd gen and older Toyotas). The manual shift bypasses a lot of the complicated electronics.

What Do I Need?
I'll update this list as I get farther into the swap, but this is what I know of so far:

- FJ Transfer Case from an FJ with the automatic transmission
- Longer Rear Driveshaft
- Shorter Front Driveshaft
- Wiring harness to connect with the ADD actuator on the front diff
- Shift boot (if applicable)
- Shift knob (if applicable)

Driveshafts
The FJ case is shorter than the electronic case that comes with the 4Runners, so you'll need to do something with driveshafts to make up this difference. Here's a picture of the two cases next to each other for comparison. FJ case is on top and the 4Runner case is on the bottom:


https://live.staticflickr.com/65535/...5ede0b49_z.jpg

EDIT: The FJ case shown above is from the manual transmission. This is NOT the tcase that you need if you have the V6. I just used this picture to compare the relative sizes of the transfer cases and the mating flange locations. Thanks @xtremewlr for the catch.

After taking some rough measurements, I found that the rear driveshaft would need to be 1.25" longer and the front driveshaft would need to be 1" shorter.

My current plan for the rear driveshaft is to use a 1.25" driveshaft spacer from 4Crawler Offroad. This can be installed on either the transfer case flange or the rear diff flange.

Here's the link to the spacer: 4Crawler Offroad Products - Driveshaft Spacers for Toyota, Ford, Dodge & Chevy Vehicles

For the front driveshaft, I'm hoping to take some grease out of the slip to allow it to compress more. If that doesn't work, I'll likely cut the splines on the driveshaft alittle shorter. Haven't thought about that too much yet.

Wiring
To get the wiring to work, there's two main things you'll need to do.
1. Wire up the ADD actuator to a momentary switch to get the ADD to work. If you just slap the transfer case in and put it in 4WD, that will just make the front driveshaft spin. You have to engage the ADD actuator on the front diff to actually deliver power to the CV axles.

To do this, take the plug on the ADD actuator and wire it up to a DTPT switch (momentary switch), 12v power, and ground. This will allow you to flip a switch to engage/disengage the ADD actuator.

My current plan for this is to purchase a wiring harness with switch from a fellow 4Runner guy in NC. Rock Solid Toys does technically still sell them, but a lot of people haven't received parts from them and have been waiting for months. RST sounds like the next Pelfreybilt situation, so avoid ordering parts for now from them if you can.

2. The other half of the wiring involves connecting the transfer case position sensors to the 4wd dash lights. Personally I don't care to have these lights work that much since I'll know what gear I'm in with the manual shift knob, so I'll likely just remove those lights from the dash.

Rock Solid Toys has a pretty good and detailed write-up for all of this wiring for a 2nd gen Tacoma which should be very similar to the 4th gen:
05 + Tacoma IFS T case swap wiring instructions

Other
Outside of driveshafts and wiring, the only thing left to do is cut a hole in the floor for the shift knob to come into the cab, seal that up, throw a boot on it and you're ready to go.

This part has some more specific details involved that I will add to this thread when I get there. Happy wheeling!

Rear Driveshaft Spacer
 

Got the 4Crawler Offroad driveshaft spacer in the mail today!


https://live.staticflickr.com/65535/...6a8b40a6f7.jpg


Here's how it'll look when it's installed:

https://live.staticflickr.com/65535/...17aca150_z.jpg

One step closer to getting this thing installed.

Good luck with the swap! One of the coolest projects I've seen in awhile.

ryanking61 I have a question. Are the input shafts on both T-cases the same length/ spline count? Maybe it’s an optical illusion on the pic in the op but one looks shorter. I’m excited to see how this swap turns out. Very cool thanks

If you look at the actual FJ tcase in his first pic, which I assume is the one that he actually has, the input shaft of the tcase is the same as the stock 4R tcase.

The FJ tcase in the second pic appears to be from a manual shift, 6 speed FJ from the input shaft or is just missing the female collar on it.

Note that the FJ tcase from the manual 6 speed FJs won't work on the A750 auto trans in the 4Runners. You MUST use teh tcase from an auto.

Also note the some of the 5th gen 4Runners have manual tcases that are identical to the FJ tcase. These can also be used for this swap.

And option to retaining the front diff ADD system is to eliminate it and replace with the same, solid axle version that the V8 4Runners use. See the following link. Same parts/steps for a 4Runner as the Tacoma.

How to: Deleting ADD system | Tacoma World

@ryanking61 , great choice on doing the swap! Following along and willing to help with any questions you might have along the way. I know mine's a V8 but the swaps are virtually identical otherwise. Lots of swap info on the tacomworld 2nd gen forums as well.

Thanks for the catch on that picture, I forget to mention that the one shown was from a manual transmission FJ.

I had considered trying to remove the ADD stuff but its nice having 2WD since I still daily drive it. The FJ transfer case also doesn't have a center locking diff, so it'll actually spin both driveshafts the entire time which puts more wear on the front components and the internal oil pump for the tcase. Plus, if I keep the ADD and wire it to a switch, I'll technically be able to have 2lo :)

So, it sounds like you have been listening to the lies being fed out of RST concerning not having ADD with the FJ tcase. The only part that is actually factual in what you said is the FJ case having an internal oil pump and the part about having 2LO with running the ADD wiring and the FJ tcase. Sorry, no offense meant.

Keep in mind I have a V8, so no ADD from the factory.

The FJ tcase does have an internal oil pump, indeed. But, that pump is always working no matter what. 2WD or 4WD. It's not going to wear out prematurely from running non-ADD on the front diff.

Take a look at the link I gave to Tacomaworld for eliminating ADD. Tacoma guys have been doing this for a while, without any ill effects to the transfer case or front end parts. The non-ADD setup is also the strongest front IFS setup you can have.

Yes, the front driveshaft and everything else related on the front end is spinning when you drive but you are still in 2WD because there is no power going to the front differential unless you put the tcase into 4WD.

I have over 8500 miles on my FJ tcase swap with the non-ADD front end and have zero problems. Please don't believe the lies that have been fed out of RST. The guy is a thief and has been feeding people those lies only to try and make more money off them with unnecessary modifications.

No offense taken, I'm always open to being corrected and learning. I don't claim to have all the answers! I didn't realize that a lot of the RST information out there is false, kinda sad to hear that its a source that can't really be trusted that much. Thanks for your clarifications.

Check out this thread.

Beware!!! Rock Solid Toys | Tacoma World

What about a setup out of a 1st gen gx470. Its a non electric trans case and has the correct stuff to bolt into a 4runner.

Read your build thread over on Tacoma World and kind of got lost in which route you ended up taking. So did you keep the factory (V8, non-ADD) front axle? Also what mode options do you have? 2H, 4H and 4LO? Did you have to modify the 4wd controller wiring (was reading this on TW)?

Also sub'd for a cool swap/awesome overall build. Apologies, I'm off topic here.

I kept the stock, full time front axle on mine. So no ADD.

The transfer case gives you 2WD HI, 4WD HI and 4WD LO. That's with running the stock, single stick. Adding a twin stick or keeping the ADD gives you 2WD LO.

The 4WD controller is not used any longer for any of the 4WD stuff. It needs to remain in place for VSC and TRAC to work. Might be able to eliminate it by swapping to 2WD stuff but that's not really worth exploring. Only thing I did was pull the wires for the CDL and 4LO dash lights off the controller and wired them into the 4WD and 4LO switches on the tcase so they work when I engage the shifter.

Update
 

Just thought I'd give an update on the progress of the swap. Just ordered a shift knob from Marlin and a new transmission output shaft seal to replace that while I have things separated. Still waiting on the ADD harness but might go ahead and put the transfer case in and just run 2WD for a bit.

Currently planning to do the swap next Friday so we'll see how it goes.

You will love the FJ t case. :thumb:

Thread sub'd.

Day Before Install Update!
 

Had my shift knob from Marlin Crawler come in yesterday:


https://live.staticflickr.com/65535/...67be3303_z.jpg


And I went ahead and removed as much of the center console stuff as I can to still drive it to the shop tomorrow:


https://live.staticflickr.com/65535/...25c51e77_z.jpg


ADD Harness might not get to me until Saturday but I can drive it around in 2WD until the harness comes in. Gonna be a long day tomorrow, probably take well past dark to get everything finished up but I'm gonna try to take as many pictures as I can to post in this thread!