Front and rear FJ Cruiser differential/rear end swap (1 Viewer)

[Edwinh3rd]

I purchased a complete front differential and rear end with factory E-locker (8.2 complete, rotor to rotor) from a 2014 FJ cruiser. The vehicle had 7,900 miles on. I have already installed the rear end. Just need to bleed the brakes and finish installing the Low Range harness and switch for the factory E-locker. My question is about the front axle. Other than the fact the differential is practically brand new with only 7,900 miles on it (compared to 170k on unit in GX) is there any differences between the two. Did Toyota make any improvements by 2014? Is the A- Trac the same? Will one work better than the other? I have read that the A-Trac technology improved over the years. However, I'm guessing that's all computer related. Does anyone know if any mechanical improvements were made between the 2006 GX front differential and the 2014 FJ Cruiser front differential? The donor FJ Cruiser was equipped with factory E-Locker.

Thanks you

 

[Toyoland66]

I believe the front is the same clamshell but the tube is different. The FJ has a disconnect and the GX is full time. However, the tube unbolts from the clamshell so you would just reuse the GX one.

 

[Rednexus]

ATRAC is computer-related, rather than mechanical. So the use of FJ differentials probably won't affect it.

The front differentials in these are known to be fairly stout and they don't typically have problems. I would recommend just leaving the GX470 differential in place (presuming the FJ 8.2 rear axle is also a 3.73 ratio) and selling the FJ front differential.

 

[trexoffroad]

I purchased a complete front differential and rear end with factory E-locker (8.2 complete, rotor to rotor) from a 2014 FJ cruiser. The vehicle had 7,900 miles on. I have already installed the rear end. Just need to bleed the brakes and finish installing the Low Range harness and switch for the factory E-locker. My question is about the front axle. Other than the fact the differential is practically brand new with only 7,900 miles on it (compared to 170k on unit in GX) is there any differences between the two. Did Toyota make any improvements by 2014? Is the A- Trac the same? Will one work better than the other? I have read that the A-Trac technology improved over the years. However, I'm guessing that's all computer related. Does anyone know if any mechanical improvements were made between the 2006 GX front differential and the 2014 FJ Cruiser front differential? The donor FJ Cruiser was equipped with factory E-Locker.

Thanks you

Curious how you are wiring the E locker? Friend of mine did similar swap and is having a difficult time. He stated that the vehicle speed sensors and computer are all involved in operating the e-locker and the GX doesn’t have what is needed. If you have a solution, please share? Thanks!

 

[fjc-man]

Was the donor a automatic or a manual trans? The reason I ask, is to point out that the diffs from a manual are 3.90 not 3.73

 

[rommelrommel]

Curious how you are wiring the E locker? Friend of mine did similar swap and is having a difficult time. He stated that the vehicle speed sensors and computer are all involved in operating the e-locker and the GX doesn’t have what is needed. If you have a solution, please share? Thanks!

There’s a guy that makes a harness, but it is a “dumb” harness that will just lock it up whenever you say to. His name is Wil Oberdick on FB.


I did read something about using a 3rd gen locker module to have the speed safety and such but I know to not lock the rear on the freeway.

 

[lgorman]

Curious how you are wiring the E locker? Friend of mine did similar swap and is having a difficult time. He stated that the vehicle speed sensors and computer are all involved in operating the e-locker and the GX doesn’t have what is needed. If you have a solution, please share? Thanks!

I believe that this is designed to accommodate the swap, although I have not tried to verify that:

SLEE - Toyota E-Locker Controller - Slee Off Road

Allows control of Toyota E-Locker actuators using simple on/off switch DIY board requires wiring and soldering Requires access to vehicle wiring diagrams for install

sleeoffroad.com

 

[Toyoland66]

Curious how you are wiring the E locker? Friend of mine did similar swap and is having a difficult time. He stated that the vehicle speed sensors and computer are all involved in operating the e-locker and the GX doesn’t have what is needed. If you have a solution, please share? Thanks!

All that complication isn’t required, to further what @rommelrommel said. The stock setup uses a computer to ensure the diff cant be locked except when in low range and moving less than 5 mph. If you aren’t concerned about having those “features” then the wiring isn’t that complex.

 

[captainva]

Outdoor Recreation Network - Off-Highway, Jeep, and 4x4 Fun

Toyota Tech: Installing a Toyota Electric Locker

www.4x4wire.com

 

[MADUFF3]

The front diff from the FJ has ADD (automatic differential disconnect) a friend and I were just talking about this. ADD in an FJ works like this; in 2wd the ADD is "off meaning no front driveline getting power. Once the FJ is shifted into 4HI the ADD actuator (vacuum controled) moves a collar connecting the axle to the diff and essentially making it a front locker (more or less). The only issue in the GX is we are AWD so the front driveline is always getting power.... the issue we were working though was, if the FJ differential with ADD off (2wd) would make the GX think there was slip and VSC and maybe ABS wouldn't like that... (these are just thoughts) the alternative would be making ADD be on always... rather a terrible idea to roll pavement all day with a locked front-end... that is what I know upon doing some research, would love to get some inputs from the group too. Hope this helps!

 

[Toyoland66]

@MADUFF3 the ADD is in the axle tube, not the clamshell. The FJ clamshell can be used if you swap the GX axle tube onto it.

GX

FJ

 

[MADUFF3]

@MADUFF3 the ADD is in the axle tube, not the clamshell. The FJ clamshell can be used if you swap the GX axle tube onto it.

GX
View attachment 2879820

FJ
View attachment 2879821

Sure but why bother? To change the front diff for no gain the FJ diff has the same characteristics as the gx one and the same weaknesses and strengths to the best of my knowledge. The only gains would be "newer" "lower miles"... and ADD if that could be sorted... however the front diffs in IFS toyotas and Lexus are not known to fail often, usually the CV is the weak link. If I'm miss some detail please let me know. I don't understand what is to be gained besides what I mentioned?

 

[Toyoland66]

@MADUFF3 you are correct, in this instance there isn’t anything to gain besides the lower miles on the FJ clamshell. I did however think it’s worth noting that the clamshells are interchangeable between this era GX, FJ, Tacoma, and 4runner. There are other factory gear ratios available in the other models that can be swapped in, or a donor clamshell from another model if you wanted to regear or swap in a locker without having the vehicle down during the install.

 

[ArBrnSnpr]

Having 160k less miles on your carrier bearings isn't insignificant. I'd take the time to do the swap just for that alone.

I've broken down more than a few Toyota diffs and haven't seen massive bearing slop around those amounts of miles, but there is definitely going to be less play with a 7,900 mile bearing than a 170k mile bearing (given similar use).

I'd swap it and start collecting parts to rebuild/lock your OE diff. It's a pretty straight forward job and would yield fresh fluid, a look at your diff support (a failure-prone part on older year vehicles), and the ability to rebuild a diff with new gears, bearings and a locker without having your truck down.

 

[jiggletits]

Having 160k less miles on your carrier bearings isn't insignificant. I'd take the time to do the swap just for that alone.

I've broken down more than a few Toyota diffs and haven't seen massive bearing slop around those amounts of miles, but there is definitely going to be less play with a 7,900 mile bearing than a 170k mile bearing (given similar use).

I'd swap it and start collecting parts to rebuild/lock your OE diff. It's a pretty straight forward job and would yield fresh fluid, a look at your diff support (a failure-prone part on older year vehicles), and the ability to rebuild a diff with new gears, bearings and a locker without having your truck down.

Still does not seem worth the effort. Wear and tear is one thing, failures are another. How many front diffs have failed? If the lesser mileage diff is cheap, sure... buy it. But I would keep it as a spare and save the headache of swapping.

 

[ArBrnSnpr]

Swapping a diff is easy and without going back and rereading, I'm pretty certain the OP said he already bought the front diff with a rear axle.

 

[Edwinh3rd]

Thanks for all the info. As mentioned, I had already purchased both front and rear assembly from 2014 FJ with only 7,900 miles.

Update:

I installed the rear end with factory locker using an aftermarket harness and switch from "low range offroad"

When I first installed the rear end I had an issue with a Christmas tree of lights on in my dash. After some trouble shooting, I found an open circuit on my passenger side speed sensor harness. After inspection, it looked perfect. So, just to be safe I swapped the harness out with the one on original axle housing and problem solved. No more lights.

I took it out wheeling last weekend and everything works perfect. The switch for locker works perfect and the front (still original) A-trac works perfectly paired with the locked rear end.

I've wheeled a lot in this rig and having that rear locker is a game changer. Super happy with it along with the added piece of mind having the stronger ring/pinion/axle out on the trails. Especially with the 35's.

I still need to figure out what direction to go in with the front. Obviously the lower mileage makes it a no brainer to install. However, it would be nice if adding another switch to utilize other features would be beneficial to the GX. Either way, I'm not going to install it until I regear it with 4.56's

Any thoughts?

 

[HomersCanyonero]

Any tips on how to locate/purchase a locked rear axle?

If I were you, I would keep the newer front axle as a spare. The ROI doesn't seem to be there.

 

[Edwinh3rd]

I got lucky and found them on CL in Phoenix. It was a 5 hour drive each way plus the time it took me to remove from the FJ. Needless to say, a long day!

 

[Jstawgn]

I have 4.30 tacoma 4 cylinder front diff I mine. I removed the ADD tube and actuator. Reuse the side tube from original GX front tube.there is some additional sensor in ADD front diff that is not used anyway on GX.

You can keep the ADD but there is a chance it would hit the oil pan. A new engine mount might be enough or need small spacer to raise the engine a bit. The wiring seems to be similar to rear locker actuator. Tacoma and 4Runner ADD are not that reliable and can leave you stranded in 2WD.

I would use it as a core when you regear.