Bare with me please.. I am on a 2-week long quest to determine the route to go with my current build and have read through every thread I could find regarding the FJ manual T-case swap 2 times now.

I am currently in the process of ordering the ECGS complete 3rd member/clamshell with ARB lockers front/rear for my '03 V8 4runner and while I was at it, I have considered going ahead with the FJ T-case swap... Now, I have a functional factory t-case, but I figured it would be worth my time to swap it out now for the future.

long story short... I am struggling with whether or not I would actually need to swap the front diff to an ADD differential to give it true 2wd ability. This obviously makes a difference in what I order from ECGS...

From what I read on RockSolidToys they obviously recommend the whole thing, including the front ADD diff, with their $200 ADD harness, speed sensor, etc. It states that the FJ cruiser Tcase wasn't meant to run in full time 4wd, and having it in 2wd without the add always back-drives it from the front wheels and causes premature wear and oil pressure build up, etc.

Now, regarding the wear.. with the price of these units (anywhere from $150-225 locally at junk yards) I don't really care if it were to fail 20k, 30k, hell 50k miles sooner... thats a quick swap with a cheap replacement..

So my question is.. with what seems to be a limited amount of few guys that have done the swap.. how many have retained the factory front diff, and have you seen any issues (other than added road noise inside the cabin ) that you care to share?


Best case scenario is that there is positive feedback on using the factory 4wd front diff. If that is the case, I can actually retain my electronic center diff until it craps out before doing the swap. I have RCV axles that have just shipped, and turn around on the ECGS complete members is around 1 week right now with ARB lockers so I could potentially have everything swapped over and completed by March... which would be ideal.

Any and all feedback is greatly appreciated.

thanks!

@xtremewlr is a certified FJ case swap master. I'd check his build thread on tacomaworld, there's some good pics of the process over there. Pretty sure he used the factory v8 front diff, only difference between it and using an ADD front diff is the driveshaft will get spun by the front wheels on the ground

Thank you much! I'll have to check that out tonight. I dont recall seeing that particular build. AHa on here had a really useful thread that looked like he used the factory front diff as well. I've reached out to see if he's still around.

And yea thats the difference with the ADD diff is being able to not back drive the fj transfer case.. but again, if the only concern is some extra wear on the fj case I dont really care..

I'll do some more digging tonight but im pretty set on leaving the factory front diff which will allow me to run the driveshafts and stock electronic center diff until it fails and do the swap later. This way ECGS can knock out my 3rd member and clamshell amd ill drop it in along with swapping over to my RCV axles and it'll be good to go for a while (and still retain atrac, not that it will be need much with front and rear lockers at my disposal)

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I've been doing the exact same research for about the same time. I'm unsure whether the non-ADD front diff turning the tcase front output all of the time really does any harm*; or if people just "think" that to be the case. Too few people have done this swap to draw any meaningful conclusions.

Regardless, the hole I've gone down is finding whether the CV joints, spindle, etc from a Tacoma with manual front hubs could be swapped in. Manual hubs ftw! and that would solve any concerns.

* I had a '94 XCab 4WD and defeated (locked) the ADD, thus the tcase front output in that truck was turning all of the time. When I sold it with 178k mi on it, I'd experienced exactly 0 issues. Different rig I know, but....

BTW thanks for posting this, very helpful and will follow as I think I want to go this route as well!

I've done a bit more searching and got a couple of hits back in between posting this thread. Looks like the non ADD diff is perfectly doable , at least to start with. Only concern is that at highway speeds the driveshefat backspinning the case causes excess oil pressure buildup l, but that is remedied by extending the breather tube up to the front diff.

Again, even if there is a bit of a longevity issue it doesn't really matter.. right now I have 4-5 options locally under $200 and with 90-110k miles..

Furthermore, what has been mentioned is that instead of getting a complete ADD diff assembly, is that it should be possible to just add the ADD axle shaft/disconnect motor to the non ADD diff. If that is the case than it is perfect.

My first round will just retain the factory electronic transfer case since its only got 138k miles and works for now, swap in regeared and locked front and rear diffs without having to mess with the driveshafts and extra wiring, etc. Then phase 2 would be to swap in the fj t case with twin sticks. At that point if I see issues with the non ADD diff and regular daily driving I will just add the ADD axle disconnect and call it good..

Whenever I get around to getting this swapped ill my best to document so that going forward its a bit easier to find. Plus since I daily the car ill find out pretty quick what issues arise from running a non ADD diff.

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Short answer, no, the front ADD diff is not needed for the FJ tcase swap. Anyone telling you otherwise is full of shit.

If you have a V8 4Runner right now, leave the front diff alone. It's the strongest setup you can have for IFS from Toyota. Change gearing, add a locker (air or e-locker) and leave the rest of the diff stock. Leave the whole front drivetrain stock for this swap.

ADD IS NOT NEEDED.

The FJ tcase is a direct bolt-on replacement for the AWD tcase. You just need to cut a hole in the trans tunnel and re-shape the FJ shifter.

Both driveshafts will have to be modified. Front made shorter, rear longer, if I recall correctly. Might have that swapped. Best thing to do is install the FJ tcase and then measure from flange to flange for each driveshaft and give that information to the driveshaft shop.

I have over 7200 miles on my FJ tcase swap, with the AWD front diff still in place and everything works just fine.

The FJ tcase has an internal oil pump that is driven by the chain in 2wd and 4wd. Having the front driveshaft turning in 2wd will do nothing to the tcase, will not cause frothing of the oil or build up pressure or do anything else bad that some people might think or claim. They are full of shit. I say this from personal experience with my 4runner. I daily drive it since it's currently my only vehicle.

Couldn't thank you enough man. Thanks for chiming in. You just resolved a 3 month log dilemma for me.

Ordering re-geared and air-locked front /rear differentials from ECGS now (4.56) and after that is in place I'll work on sourcing the FJ transfer case and getting parts ready for the swap while my factory T-case is still working.

2 more questions that I have for you though:
- for the driveshafts, did you have have the factory ones modified (if its even possible to lengthen) or did you have them built new?
- there is still a little bit of rewiring to do when swapping in the FJ case, correct? And if so, is this just to get the dash lights off ?

Thanks for chiming in with invaluable feedback.

Your welcome! Hopefully we see more people go this route instead of wasting time and money on trying to fix the stock tcases! This swap is fairly easy to complete and even with 2 new driveshafts, came out LESS than fixing or replacing the original tcase!

The driveshaft shop I used explained to me that they could not safely or accurately cut the original driveshafts and modify them. This was due to the manufacturing process from Toyota and how they welded them. So both of mine are new. I'm fine with that since my truck is close to 300k miles (298,800 as of today) and everything was pretty much original when I got it. I know other people that have done the swap were able to have their original shafts modified, so it might really just depend on the driveline shop you use. Either way, I would trust their recommendation. Just find one that has experience with modified 4wd vehicles if you can.

The only wiring I did was to get the 4WD and 4LO lights working. I used the center diff lock indicator light for the 4WD light. The 4LO light remains the same. Check my build thread on Tacoma World, linked in my sig, and I cover the where and what wires need to be spliced into on the 4WD computer to do this. Then just make a harness to tie into the solenoids on the FJ tcase. You don't need to worry about the neutral solenoid on the case, which I believe was the front driver side.

You *might* need to do a zero point calibration after the swap and messing with all the wiring. Mine did but it's not a big deal. Several threads on the forum here cover how to do one if you haven't done one before.

The tcase breather ties into the transmission breather and can be re-used that way. Just check the hoses to make sure they are still good and not cracked. Mine were so I replaced them with silicone hose that I already had.

Also, look at where I cut the trans tunnel and then where the shifter actually comes out. You might be able to get away with cutting less of the tunnel than what I did. Have some 1/16" sheet steel handy (you can get small sheets at Home Depot/Lowes) to build a cover plate around the shift handle once you fit it/them. I kept mine single stick but have a dual stick handy if I decide to try it out for a while.

Also, once you have the FJ case, it would behoove you to build some kind of cradle for it. I built one and it's covered in my build thread. The way I built it, it worked perfect on both tcases, without having to change anything.

And replace the transmission mount while you're at it! They use the same mount but it's nice to have a fresh new one in there, especially for these older trucks. My original one was pretty well squished and starting to break.

Oh yeah, I also swapped out the center radio/HVAC control bezel for one from a 2wd since the 4wd selector switch is no longer used. Really cleaned things up and looks much better IMO.

Damn, your info and experience are both perfect, and thanks for chiming in!

Ok, I'm in, going this route too.

Seeing that there are more people starting to show interest in possibly doing the FJ transfer case swap, I'm providing more information here to try and help out. There is some mis-information out there and there is some good information out there and all of it seems to be spread around on various forums or web sites.

These tips should apply to both V6 and V8 4Runners but I cannot verify the V6 stuff since I have never worked on one. This is not a how-to, this is just pics and tips from my swap experience and what I did. All work was done by me, at home in my garage. It's not a super difficult swap.

First off, the only viable transfer case from an FJ Cruiser for the swap is the manually shift tcase from the automatic transmission FJCs.

The AWD FJ tcase from the 6 speed manual trucks can't be used. It physically will not bolt up to anything other than that 6 speed manual transmission. If you want to swap that transmission and tcase into your 4runner, you are on your own.

This is the FJ tcase in my truck. It's from a 2011 FJC that had around 130k miles on it. Still had the OEM gear oil and looked practically brand new. I paid $269 for it from a local used part seller. LKQ is a good place to shop for stuff like this if you don't have a local self-service wrecking yard. Prices seem to range between $225 to $350 depending on mileage and condition. Make sure you get one that includes the shifter so you know the tcase hasn't been opened up or shit gotten into it.





The next big thing and a major source of confusion and misinformation from various sources, is the front axle.

For the AWD V8 4Runners, you do not need to touch anything! I will say this again... YOU DO NOT NEED TO SWAP TO AN ADD FRONT DIFFERENTIAL.

V6 trucks, you can either leave the ADD and figure out the wiring to engage/disengage the ADD or eliminate the ADD all together by swapping in a non-ADD axle and axle tube to your existing ADD differential. There are tons or write-ups out there that cover doing this. Here's a good one over on Tacoma World.

How to: Deleting ADD system | Tacoma World

There is one company that has spread this rumor/misinformation regarding the V8 4Runners, because all they want to do is take more money from you and then never deliver the parts that you paid for. Avoid RST, that's all I'm going to say.

The AWD front differential is the strongest IFS front diff setup you can have from Toyota. Period. The FJ tcase already has an internal oil pump that is driven off the chain in both 2wd and 4wd. Neither frothing nor pressure build up will happen when driving in 2wd with the front driveshaft turning. You aren't going to destroy the transfer case.

This shows you the inner workings of the FJ tcase, including the oil pump that you can see, is driven off the chain.



From my experience, having a body lift makes things a little easier when doing the swap. It's not a requirement, it just helps give you more room to work and bonus of making more room for bigger tires. I went with a 1" body lift in preparation for the swap. Lots of body lift information out there, so I'm not going to get into that here. Personally, I don't recommend anything over a 1" body lift. Mine was from Toytec.



Another strong recommendation but not a requirement is a new trans mount for the swap that I posted previously. These 4th gen 4Runners are getting old and have higher mileage so a new mount is a good idea and easy to do while you're in there since you need to remove the old one anyhow. This is the one for the V8. Since I've never worked on a V6, I don't know if they are the same or not but I assume they are since the FJC was V6 only.

The original mount on the left from my 4Runner with around 290k on it at the time.



Toyota part number for the replacement mount.



Wiring: There is no wiring that is *required* to be done for this swap to work. Only wiring that you *might* want to do is for the 4WD and 4LO dash lights to work.

For my swap, with the V8, there is no 4WD light in the dash. There is the CDL (Center Diff Lock) light however and I used that as the 4WD indicator. The 4LO light remains the same.

Different years may be slightly different, so check the wiring diagrams and locations for your specific year first. For my 2003, the 4WD computer, which is where you need to pull the wires from, is under the glove box on the passenger side. NOTE: you do NOT need to remove the glove box like I had done here. The lower panel can be unbolted and removed without removing the glove box.



That little grey box on the right is the 4WD computer. The wires needed are in the left hand plug when you have the plugs facing you to unplug. Not sure if the wire colors are consistent across years for the 4th gens or not but for my 2003, it was the green w/ red stripe wire for the CDL light and the brown w/ white stripe for the 4LO light.

Make a new harness for the swap and connect them to the shift solenoids on the FJ tcase to complete the circuits and turn on the dash lights. I strongly suggest extending the wires from the shift solenoids BEFORE installing the tcase, to make them easier to access when the tcase is under the truck.

Another thing that you will need is some way to lift/lower both transfer cases from under the truck. I already had a good floor jack, so I made a cradle for the tcases that worked on both the FJ case and the 4Runner AWD case.

First 2 pics are the FJ case on the cradle.





Here is the AWD case on the cradle.



Drive shafts: Your stock driveshafts will have to be either modified or replaced for this swap. I have new driveshafts.

• Front driveshaft gets shortened by about 1 1/4".
• Rear gets lengthened by about 1 1/4" as well.

Your measurements might be different, those were what mine ended up at. Find a good driveshaft shop for this work and they will tell you exactly what they need for measurements.

My old driveshafts with the original u-joints and over 290k miles on them.



Brand new driveshafts.



Doing the actual swap: With the driveshafts out, swapping the transfer cases is very straight forward. Unbolt and lower the old one, raise and bolt up the new one. Simple. But then you need to cut a hole in the transmission tunnel to allow the new manual shifter access to the cab.

Here is the hole that I cut for this. Note that the trans tunnel is dual layer. I used a jigsaw for the majority of the cutting. Just have a shop vac handy to vacuum up all the steel shavings. You can probably get away with a lot less than this, especially on the side where the shifter is, but it does allow you access to the top of the transfer case for removing and installing the shifter. You don't want the shifter installed when removing or installing the FJ case as it makes things much more difficult.



And the tcase in place to figure out how to re-route the shifter. It needs to clear the bottom of the transmission shifter and come up through the center console where the ashtray/cig-lighter was.





My modified shifter. I stuck with the single stick but you can also go with a twin stick if you want. Ether one will need to be cut and modified to fit. This requires welding so you need to do that yourself or find a welder to work with.



Just make sure the shifter clears everything and there is room to shift from 2HI to 4HI and 4LO. You can then fabricate up a cover for the hole you cut in the trans tunnel. I used some thin, around 22 ga, zinc coated sheet steel from Home Depot and cut it with tin snips and then shaped it as best I could to fit the trans tunnel. It's sealed to the tunnel with black RTV to prevent water from getting inside. Note how small of a hole the shifter actually needs to move through the whole range of 2WD/4HI/4LO.



I also used half of the boot for a twin stick (I have a twin stick for future use if I decide to do so) to make a shifter boot and used self tapping screws to keep it in place and seal it to the tunnel. Maybe overkill but I'm OK with that.



One thing I originally forgot to mention about this swap and where the shifter handle comes up, which is realistically the ONLY place that it will work without major modifications to other stuff. You will have to permanently remove the tube for the rear AC vents that come out of the back of the console. It's directly in the way of where the shifter handle is and the range of movement it needs. I used duct tape to seal off the attachment point under the HVAC controls and gutted everything I could of the system from the console. Vents are still there but do nothing now.

Continued in the next post because the forum won't allow more than 20 images in one post. This forum software sucks balls and is severely outdated!

And here is how it looks with the center console back in place. The shifter boot is ziptied to the console and I got it from Autozone. Just a cheap, fuax-leather shift boot. Looks decent and works well. I can still put stuff in there without worry of it disappearing under the console too. First pic is the shifter in 2WD. Sorry, it's a little out of focus.



This is 4WD hi range.



This is 4WD low range.



I also replaced the stereo dash bezel with one from a 2WD truck, without the shift selector in it. It just cleans up the dash some and gives you more room for mounting whatever.



And here is the FJ tcase under the truck with the driveshafts installed. The wires hanging down are from the shift solenoids before I hooked them up for the dash lights.



That's basically it. I have a manually shifted transfer case now and never need to worry about the crappy electronic actuators again. The swap is very straight forward and not overly difficult IMO. If you can do a timing belt swap, you can do this swap, it's way easier.

I've put over 7200 miles on this swap since completing it. I daily drive the truck, commuting to and from work 50 miles round trip each day. I drove from Tucson to Moab, Utah a week after completing the swap, wheeled in Moab and drove home without issues.

The FJ tcase uses 1.5 quarts of 75w-90 GL-5 gear oil. I personally like Redline oils but any gear oil matching that spec will work just fine.

In the end, doing this swap cost me around $900, including the FJ tcase and new driveshafts. This is MUCH cheaper and a longer lasting, better alternative to fixing or replacing the shift solenoids in the stock 4runner transfer cases. You might be able to do it even cheaper if your stock driveshafts can be re-tubed instead of replaced like mine were.

Hope this helps anyone looking at doing this swap. I have more details and descriptions of the work that I did in my build thread on Tacoma World. Details are a little spread out there, which is why I made these posts but the actual swap stuff starts around page 10 in that thread.

My daily driver 2003 4Runner Limited 4wd V8 | Tacoma World

[QUOTE=xtremewlr;[/QUOTE]

You have no idea how invaluable this information in a single thread is man.. Between the pictures and your detailed explanation it is literally what I have spent the last couple of months off and on combing through in multiple threads.

I owe you a beer.

Happy to help, man!

Believe me, I went through all the same shit you have when I first started considering the swap. Figured instead of sending people over to dig through my build thread, I'd just compile the pertinent information here and make it easier for others to find.