RWD E-Locker Rear Diff Retrofit - Writeup w/ Pics

[AlfiT4R]

Hello all! While my fiance was travelling back from Tennessee to Texas with my 4Runner, the rear diff seals blew, and the bearings died. At 350k miles, I'm happy they lasted that long, but I took this as an opportunity to make do a nifty mod!

I installed a factory salvage E-Locker and retrofitted it onto a RWD 2000 4Runner. I made some mistakes a long the way worth noting so you won't make the same mistakes I did. I couldn't find many guides on this, so a lot of it qas guesswork to figure out. If you have any info to add, I'd be glad to have it! I did this mod half a year ago and about 5k miles, so far no issues or leaks.

Whats needed -

If RWD - Pick and choose your locking salvage differential gearing based on your needs (a quick google search shows the differenfes) common sizes are 4.10 and 4.30, supposedly 4.56 exists but I couldn't find one. I got one off of E-Bay shipped to my door for $700, local salvage yard was $1200.

If 4WD - Find a rear differential that has the same gearing as your front. If you mix and match, you will have driveline issues when 4WD is engaged, potentially severely so.

Either way - Do note the door stickers for axle codes on these 3rd gens are wrong about 60% of the time, so you'll have to do some tests to measure them. Theres a few ways to do them, I will add more info on this later on, or if someone comments one we'll give them a ton of likes :cowboy:

I used a 10 pin switch from VLD2-UKKB - DPDT (ON)-OFF-(ON) Rocker Switch | New Wire Marine
It was $50 total for a custom (ON)-OFF-(ON), DPDT type switch. The parenthesis mean that it is a temporary on, normally off switch. Its 2 ons, one for running the locker motor forwards, one for reversing it. I got it with 2 extra amber LEDs to match the factory lighting colors, one to indicate the circuit is powered (tapped accessory fuse) and one that receives the lock successful signal from the position switch on the locker. Overall, I am pleased with it, and it fits into the factory empty slots left of the steering wheel with no modification.

I also used about 20ft of 7 color 16 gauge wire. You can definately get by with smaller, just what I had in the size hanging around. You can also probably use less wire, measure twice cut once unlike me and have to splice a wire halfway back towards the switch :rain:

I also used some fuse taps that were nilight brand. As for fuse size, I used a 15amp with no issues.

Yotamasters has an E-Locker Retrofit kit that comes with the 2 long studs, 2 short studs, and a paper gasket for stenciling. I got this kit, however it is just repackaged and bundled OEM parts, if I find the part numbers, I will post then here.

Electrical tape, heat shrink, etc as needed

More continued in next post -

 

[AlfiT4R]

Step one is to disengage the rear axle shafts from the 3rd member/Differential (I will be calling it a differential for clarity sake and the housing will be the housing.)

Timmy the Toolman has some excellent content that refers to this, but heres the approx. steps I did to get prepped -

Drain rear diff fluid -> Lift rear of truck onto stands -> Remove wheels -> Remove parking brake cable connection to axle hub (pin holding cable to lever arm), disconnect unbolt/remove ABS sensors (inspect them if bearings failed), remove brake lines and cap lines with rubber caps/whatever creative method you prefer, undo the 4 bolts on back of the hub, they form a square, then slide the assembly out atleast 6 inches.

If you are doing seals remove the axles entirely, just note entire removal requires probably 4 ft clearance on each side of the vehicle to remove the shaft.

Next, you will want to disconnect the drive shaft and hang it up so it doesn't hit you in the face out of nowhere. I used rachet straps to cradle it between the exhaust and gas tank. I can confirm that you should secure it and check that it is secure, I can attest that drive shafts are heavy and your forehead will not appreciate making friends with it. eep:

To get myself more room to have a creeper to roll around on, I needed more lift, so I used 6 ton stands and some creative height gain 6x6 boards to get some more lift and raise the vehicle more. Not sure safety wise if it's rated for this but it has worked for me several times now.

More on next post

 

[AlfiT4R]

Now you simply unbolt the old differential and remove it. There are 10 studs with nuts on them, so use PBlaster if you're in the rust area the day before. Mine was very stubborn to remove and I had to "encourage" the flange with a hammer to break it free of the gasket. Be careful removing it, the differential is incredibly heavy, especially at the angles you'll be working at. My guesstimate is 60-80lbs.

At this point, I would take the time to count the teeth and check your gear ratio, and see if it's what you came up with.

At this point, clean up the interior of the housing with shop towels, and prepare the differential for modification. No going back now :art:

The three studs closest to the drivers side will be removed, I used a technique where I put two of the nuts back on, and turned them into a sort of jamnut, so that way I could unscrew the studs. You tighten the nuts against eachother, then they are tighter than the stud, allowing easy removal.

Before we start cutting, lets take a look at the "new" diff

Something to note I did not know. You can only remove the diff in the locked position from my findings. Check if the diff is currently locked via the wheel spin. Spin one axle, if the other spins the opposite way it is unlocked. If it spins the same way it is locked. You can also jamb the other axle from spinning via crowbar or partner holding it still, and see if your side will spin. If it spins, unlocked, if it won't, locked. If it is unlocked, you will need to lock it. One way to is to power the actuating motor briefly (one second or so) by the green/black wire getting a positive power, and the black getting a negative. NOTE: If done too long, this can 'overspool' the actuator, requiring rebuilding internal components Because of this, my preferred method is to manually move the 'fork'

To do this, you first unbolt the actuator housing and remove it from the diff. I would bench test it while you are here using some videos off of youtube as references. I would also clean it up a bit, source a new smaller o-ring for it, preferably made of FKM Viton (assortments on Amazon are cheap, but possibly scams). While you are here, unbolt and remove the engagement detection switch. The connector on it is easy to shatter if the diff is set down incorrectly, goodbye $24 to rockauto for a new one :Cry:

While the picture may not be great here, I outlined the fork in blue. You can slide it back and forth with a flathead screw driver to unlock/lock it. Note, my findings were that manually actuating it to unlocked would not keep it unlocked, and that it would relock itself when installed in the vehicle. It took me a few days of driving thinking I had a bad diff to realize it was just driving locked.

Finally, remove the differential using the same techniques, and onto the next steps!

More on next post

 

[GhostRing]

This almost feels like the good ol' days when people would post actual content!
Good on ya for tackling this - it will certainly be worth the effort.

Having just completed a re-gear, I also found out the e-locker actuator is
very particular in it's pinion gear position. Definitely worth taking the time
to clock it correctly with a AA battery.

 

[AlfiT4R]

Now that you've seperated the differentials, removed the 3 studs, the actuator, and the lock position sensor, let's do some prep work on the 'new' unit.

Since my truck is fairly rust free, this replacement unit would be very out of place since it's nice and rusty on the surface. While I'm not sure if this is the best method, it seems to have held up well so far. I took a drill with a brass circular brush and removed all of the loose rust on the differential, I also scraped and cleaned the mounting surface of the new unit. After applying a good amount of parts cleaner to remove any debris, I applied some POR-15 to the unit. Make sure you cover the holes left behind by the actuator and the position sensor. I kept them installed, which worsened the quality. Additionally, I believe the actuator might be an aluminum housing, so it wouldn't be rust susceptible anyway.

Now to prep the old housing for the new differential.

Overlay the gasket you (hopefully) bought and mark the new stud locations, I filled it in fully with a paint pen. There is one major difference between the locking and non locking housings besides the studs. While the axle shafts are the same, and the housing sizes are the same, there is a single notched section cut out.

I took some measurements on this notch incase the gaskets get discontinued, or life happens and your paper gasket tears. Word of caution on that, the gasket is very fragile and I tore mine, be very careful when using it to line up to studs, and be patient with removing it. It really is just as fragile as a tissue.

Here are those measurements, centered around the center stud hole (stud you already removed), on the drivers side. You will cut 33mm up from the stud hole, and 33mm down from the stud hole. Once 33mm up and down from the center of the hole are marked, you will then, at the main hole the differential slides through, mark 13mm towards the drivers wheel on the mating flange between the diff and housing. This will intersecting on both the upper and lower 33mm measurements, which you can then fill in with a paint marker to have a visual 'cut here' measurement.

Then, you will mark the other 4 holes for the studs. Incase for some reason the gasket is unavailable, cut out the axle housing notch first, slide the diff into the housing, mark the holes for the 2 new studs. You will need a narrow marking tool, something narrower than 8mm, and about 8 inches long, as they are long studs that go through the actuator housing. If you have your gasket, carefully lay it flat against the housing, and mark your new holes. Be very precise and sure it is flat, but don't tear it. I did not do this, and I tore it, and so I made my life very difficult :suspicious:

All said and done, it should look like this:

Small tangent and YMMV, but I got this Milwaukee compact angle grinder for the cutting on this job. I cannot reccommend it. The steel is just 2 plates of steel stamped together in the housing, and it constantly needed to stop and cool down before I could do more cutting. I would get maybe 5 seconds of cutting then a minute of cooldown. Not sure if it's just defective new, or if it just sucks. But yeah lol, 3/10.

To prep for cutting, I didn't want 5 million metal shavings in the axle housing, so I took some shop towels and filled the exposed parts of the axle shaft tubes, and the pumpkin of the housing itself. Hindsight, filling the area with glorified paper towels with trace oil on it next to an angle grinder may not have been the smartest idea, but hey it worked.

Cutting on the next step, more to post soon between free time at work :eyebrows:

 

[AlfiT4R]

To cut out the notch, what I did was work in segments. I cut out horizontal lines about every quarter inch then did vertical cuts to match. As previously mentioned, its 2 layers of steel, so it's nothing too pretty. You could also probably use a carbide burr with a die grinder, and get a better looking result. After cutting the shape out, ensure you have no leftover notches or nubs sticking out. I missed one and realized only when test fitting.

Next, we are going to drill and tap the holes for the studs. Use a spring loaded center hole or your preferred method to get the exact center of the stud located. Take your time and be precise, if you are off by more than .5mm, your life will get very difficult.

Side note on my mistake
The two long studs line up with the weld line of the housing, and this is what threw me off. I didn't get them centered to the hole properly due to the slope of the seam. I assume with more pressure on the punch and a bit more time to be precise you can get it exact. Because I misaligned this, I had to drill out the differential and actuator holes to a much bigger size to allow there to be enough room to fit the poor fitment. In retrospect, this was an awful idea. Because the actuator housing is aluminum, it cracked in drilling. I used FIPG to 'glue' it back together, but overall 0/10. If I were to do that again, I would look into getting a long bolt (buttonhead if possible) that had the same M8 diameter. I would oversize the hole in the housing itself, and feed the bolt shaft backwards, and use FIPG to seal it against the housing, making a new semi adjustable stud. If I couldn't find a screw that long, I would get a thread rod from the local parts store, weld/threadlock a nut onto the end of it, and cut it to length. To torque the nuts down, I would slot the end of the stud facing the front of the vehicle with a flathead spot to hold the stud steady, and torque a nut by feel with a wrench.

Next, drill out the holes to fit a M8x1.25 tap, and tap the holes. Using the same technique for removing the studs, install the new ones.

You will now have 2 long studs installed on the far drivers side vertically from one another, and 2 short studs installed on the inner holes vertically from one another. You will also have 2 new unneccessary holes that will be sealed up later.

Something I did not think about at the time of repair is that you could cut the old studs short, and screw them in from the back into those empty holes. This would minimize the sealing area required to hold a good seal, and reduce any potential sealant contamination into the gear oil.

More on the next post

 

[AlfiT4R]

Now that it's prepped to hold the unit, I would reccommend wiring up the harness to make the install faster. You will have 2 connectors, a 5 wire connector off of the actuator, and a 2 wire connector off the position switch. I attached some useful diagrams that give details of how I wired mine, and some useful sources of information I found online.

Heres how I would wire my switch and route the wiring -

Run your 7 wire harness (if you do on the spot splicing of wires you can maybe get away with 6) from the drivers side fuse box, down through the drivers floor kick panel, under the plastic floor trim, then proceed back to the back of the vehicle, going through the B pillar trim panel floor, and quarter trim. When you get by the taillight and hatch, under the floor trim for the hatch there are plastic wiring access caps you can scoot your wiring through. If you have a tow harness installed, it's probably already pierced. I would then route the wiring along the frame rail by the spare tire, towards the gas tank, then down to the diff area. I would leave yourself a foot extra on each end at least. Make sure you leave enough slack on the undercarriage side of wiring, so if you fully articulate your suspension, you don't pull the harness apart

:boom:

Also, be aware of what components may move and what may not, so it doesn't pinch itself through a coil spring or something.

While the diff is on the ground under the vehicle, attach your connectors back to it and start splicing the wires. You can technically bundle both White/Black wires to the same wire, solder and heatshrink it and call it a day. Just mark what wire color you used to what matches with the factory colors, and substitute it for the diagrams. All 7 wires total should be joined now under the vehicle. I would recommend tossing some wire loom over the section and electrical taping it.

Now, we will work on the interior of the vehicle wiring. Since I didn't need 24/7 power to it, especially since I wired in a full time light for proof of good wiring (bottom light is on with accessory, top and bottom when engaged), I tapped a fuse in the center column of interior fuses. I would double check the fuse you tapped has power only with key in via volt meter.

If you got the same 10 pin switch I got, here is how it is set up

Top of switch, push to engage
A B
C D
E F
G H
I J
Bottom of switch, push to disengage

AB - Engaged confirmation light
CD - Power switch to enge motor
EF - Power supply to motor
GH - Power switch to disengage motor
IJ - Full time power light

A - Blue/Yellow wire
B - Tapped fuse power wire
C - Tapped fuse power wire
D - Green/Black wire
E - Green/Red wire
F - Solid green wire
G - Green/Yellow wire
H - Tapped fuse power wire
I - Ground
J - Tapped fuse power wire

Since the fuse tap powers 4 wires, I took 4 wire segments and soldered them all together to the tapped fuse output, and attached female spade connectors on the ends.

I also grounded the ground(s) to the body bolt behind the drivers kick panel.

I then routed these wires through one of the factory switch spots, and set it all up. When I was done, the bottom light illuminated, and I could electrically actuate the motor.

Locked

Unlocked

Now, unplug the connectors, and replug them in when the diff is installed. Apply your preferred gasket maker to the diff, and mount it together, and torque how your gasketmaker specifies. Permatex gear oil gasketmaker is what I used, no issues so far after following instructions on the package. NOTE: Do not seal it how I did (excessive amount of FIPG, 3mm bead is all you need. See Charlie's reply below for why I went beyond overkill on how much sealant I used, mainly just ensure those unused stud holes are sealed, and that the drivers side of the housing has enough, since the face will now have less surface area.

Ensure diff is locked on reinsertion

If you want to add a nice touch, if there is any excess, smooth it out to look better than a droopy mess. It's an indicator you used too much, which could technically be harmful as if it extrudes on the outside, it does so on the inside too, next to all the bearings and gears. Live and learn op2:

Retorque as specified, and torque specs in the next post:

 

[phattyduck]

I went beyond overkill on how much sealant I used, mainly just ensure those unused stud holes are sealed, and that the drivers side of the housing has enough, since the face will now have less surface area.

I know you were thinking that overkill is the best kill... but big blobs like that are WORSE for sealing. A continuous 1/8" / 3mm bead around the sealing surface is all that is needed. This is especially true on machined surfaces that were originally meant for use with a flat (non-compressible) gasket like the rear diff. Big blobs like that can create air pockets that are WORSE for sealing rather than better - and like you mentioned, excessive squeeze-out can get in plenty of places it shouldn't go. Much more of a worry in an engine, but not great on a diff.

-Charlie

 

[AlfiT4R]

I know you were thinking that overkill is the best kill... but big blobs like that are WORSE for sealing. A continuous 1/8" / 3mm bead around the sealing surface is all that is needed. This is especially true on machined surfaces that were originally meant for use with a flat (non-compressible) gasket like the rear diff. Big blobs like that can create air pockets that are WORSE for sealing rather than better - and like you mentioned, excessive squeeze-out can get in plenty of places it shouldn't go. Much more of a worry in an engine, but not great on a diff.

-Charlie

100%, the only times I've had Toyota FIPG fail me, red or black, was when I've overapplied it. Definately a live and learn deal there. Just out of curiousity, is it always a good idea to recircle studs with FIPG, if done in the correct amount? It seems like most 3T4R applications call to circle the studs, but when I was rebuilding a 2GRFE and sealing it's timing cover, it just wanted the area between the stud and the belt sealed, nothing behind the stud. The engine is known to leak where they didn't, call for it so I applied it anyway, no issues so far. I take it the green loctite on the studs seals the threads to prevent seepage, so I could see it both ways?

Interesting to hear about the air pockets though, I hadn't heard that before. This was a project I had rushed through and paid the price along the way, good results so far in the end, but tons of mistakes along the way to learn from. Just wait til I post about my custom full length basket roof rack that ended up costing more than a new Prinsu because of how many oopsies I made! :bowl:

 

[AlfiT4R]

This almost feels like the good ol' days when people would post actual content!
Good on ya for tackling this - it will certainly be worth the effort.

Having just completed a re-gear, I also found out the e-locker actuator is
very particular in it's pinion gear position. Definitely worth taking the time
to clock it correctly with a AA battery.

Could you elaborate on this method, I had tried finicking around with the actuator with a battery to no avail, I'm curious what you had come up with?

 

[phattyduck]

Could you elaborate on this method, I had tried finicking around with the actuator with a battery to no avail, I'm curious what you had come up with?

You'd need at least a 9V battery, and even better, a 12V tool battery. Useful for rolling electric windows up and down, testing lock actuators, etc. too.

Something like this:

-Charlie

 

[phattyduck]

100%, the only times I've had Toyota FIPG fail me, red or black, was when I've overapplied it. Definately a live and learn deal there. Just out of curiousity, is it always a good idea to recircle studs with FIPG, if done in the correct amount? It seems like most 3T4R applications call to circle the studs, but when I was rebuilding a 2GRFE and sealing it's timing cover, it just wanted the area between the stud and the belt sealed, nothing behind the stud. The engine is known to leak where they didn't, call for it so I applied it anyway, no issues so far. I take it the green loctite on the studs seals the threads to prevent seepage, so I could see it both ways?

I'd be tempted to go around the stud whether or not the FSM stated to or not. The only place I'd follow the directions EXACTLY is an internal engine sealing location (say, Subaru flat engine case halves). Any studs that are open to fluid should get a sealant or thread locker with secondary sealing capability...

Then again, maybe I shouldn't talk... my rear diff has the slightest dust build up from a minor weep from the last time I did the diff (4.88s and TruTrac LSD). Now that I think about it, it could be from the studs...

-Charlie

 

[AlfiT4R]

Oil - 2.91 quarts of 80w90 (below 0F outside) / SAE 90 (wont see below 0F outside) SA-90 of FSM
Differential to Axle Housing - 18 ft/lbs WITH E-Locker - SS-36 of FSM
Driveshaft to Differential - 54 ft/lbs - SS-30 of FSM
Axle shaft to axle housing - 48 ft/lbs - SA-91 of FSM
Drain/Fill plugs - 36 ft/lbs - SA-91 of FSM
ABS Sensors - 71 INCH/lbs - SA-91 of FSM
Brake Hoses - 11 ft/lbs - SA-91 of FSM
Position Switch - 30 ft/lbs - SA-93 of FSM
Actuator Bolt(s) - 20 ft/lbs - SA-93 of FSM
Wheels - 83 ft/lbs - SS-34 of FSM

If you had to loosen sway bar -
Sway Bar Brackets - 18 ft/lbs - SA-123 of FSM
Sway Bar Links (Lower) - 51 ft/lbs - SA-123 of FSM
Sway Bar Links (Upper) - 14 ft/lbs - SA-123 of FSM

If I missed any or the FSM contradicts itself like it does with wheels, post that info and I'll edit this to have it

 

[GhostRing]

Could you elaborate on this method, I had tried finicking around with the actuator with a battery to no avail, I'm curious what you had come up with?

I followed the FSM exactly like the pic below and it worked great.
A fresh AA battery with some wire taped to both ends did the trick
and I was able to control the rotation with ease.

Take your time establishing the matchmarks and line them up with
a small straightedge to either the bolt holes exactly like the diagram,
or parallel to the little black canister's vertical edge.

*However* I was very careful installing the actuator into the already-
installed diff. (d'oh!) Just confirm the rack is fully pushed to lock, and
the actuator will slide into place with no issues.

This post was also invaluable to correctly clock everything:
e-locker actuator motor install