FJC Harrop e-locker clamshell install (1 Viewer)

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BMThiker

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I've been slowly rebuilding my front end drive train since last August when I had an unfortunate incident on a gravel road. I won't go into that in detail here, but one of the results was a blown front differential. A few months ago I was made aware of Harrop's option for the FJC through @wardharris at Cruiser Brothers and Harrop - Eaton ELockers | Toyota Differential Lockers | 4x4

I will detail the install here which was self-performed under the guidance of my friends at ACC Garage (@ACC Toyota). Because of the nature of the failed front diff, I could still daily drive it without adverse effects to the rest of the drivability of the truck. So I purchased an entire front diff assembly (stock gears) from a junk yard in order to maintain my daily drive duties and still work on the front locker install on the weekends.

Step one was to clean it up and get the replacement parts ordered. I got my 4.56 gears and install kit from Nitro and Ward was having the e-locker carrier shipped from their warehouse on the west coast.
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Step two was to disassemble and remove the stock ring gear, pinion gears and all bearings & races from the clamshell housing. Then remove the stub shaft from the stock carrier using a slide hammer.
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Now the machined tolerances on all these new parts are so exact that you will need to use a freezer and a propane stove to make things slide together with minimal banging. First take the Harrop elocker carrier and stick it in your freezer. I think an hour is adequate dwell time.
FrontDiff-new (18).JPG


After the carrier/locker has been chilling for about 45 minutes, start making your ring gear soup on the propane stovetop. It should only take about 10-15 minutes to get this up to about 200F.
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Now you are ready to mate the ring gear to the carrier. The gear expands with heat and the carrier contracts with the cold so seating should be easier now. Line up your ring gear's tapped holes with the bolt openings in the carrier and drive it home with a weighted rubber mallet. You won't get it fully seated with the mallet, but you will get it close enough to start the bolts. Then *carefully* drive the bolts a little bit all the way around with a driver or impact. Once I got the ring gear fully seated, I backed out each bolt, applied a liberal amount of red loctite and then retorqued the bolts fully.
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Next up is preparing the housing for the new carrier. Per the instructions included with the Harrop kit, grind down the cast splines inside the housing (the 3 shiny bits at the back of the housing in this picture). This is the "driver side" of the clamshell housing. Grinding down these splines in the housing allows for the carrier to sit flat against this surface and there is a tang that will get situated between the remainder of the splines. This tang acts as an anchor for the rotating locking action to work against.
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Installing the inner pinion bearing race is no fun on these clamshell cases. I devised a tool to seat the race by using a 10" section of all thread and a oil seal setting tool (alum disc that had a hole through the middle). I cranked the nuts over fender washer/seal setting tool at each end of the pinion opening to seat the inner race.
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I used a flat piece of plate steel with a hole drilled in it for the outer surface and the fender washer/seal setting tool on the inside.
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closeup of the inside washer/seal setting stack
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Test fitting the carrier on top of the pinion gear, clearances look good.
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Now onto drilling the outer case for the e-locker wires to come through. First a mark with a center punch, then a pilot hole. Final drilled hole size is 11.5mm.
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Correction, the spec is 11.5mm drilled hole size. You might be able to get by with a 15/32" drill bit. The actual difference would be .016" bigger with 15/32" bit.
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Insert the supplied grommet and pull the wires through. It was a really tight and I had to strip back some of the shrink wrap that was on there to give me enough wiggle room inside and outside of the case.
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While I was feeding the wires I stuffed a shop towel down in there to protect the bearing surfaces as the carrier sat in there kind of cock-eyed. Small hands help here.
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Now we're ready to start checking for correct spacing on the side bearings. Button it up and check the rotational resistance of the carrier. I started with the factory spacers on each side and it was way too much preload.
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So you have to remove the whole carrier (and pull wires back out) and start shimming with the supplied spacers from the Nitro kit. This is the most frustrating part of the clamshell design, but you just got to grin and bear it.
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Next up is to check the gear teeth pattern and pinion depth. For the front diff install kit, Nitro provides a crush spacer, not my preferred choice because you have to be careful not to over torque the pinion flange nut and "overcrush the spacer", but if installed properly it's fine. The objection to using a crush spacer is that if the pinion takes a severe whack on the rocks it can impact the spacer enough to create a problem with gear meshing. However, since the front diff input flange is well protected by a heavy cross member, it is very unlikely to take a hit on the rocks. For rear diff applications, a solid sleeve spacer and shims is the way to go.

Pattern looks pretty good, so I reinsert the carrier, making sure my e-locker wires are routed back through the grommet and button up the diff case.
FrontDiff-new (35).JPG


Once everything is back together on the case, it's time to finish up the input flange side of the diff. Here's a note that is not in any install manual, but the guys at ACC and Nitro are quick to point out if you have too much preload at the pinion: DO NOT REINSTALL THE FACTORY OILER OVER THE OUTER PINION BEARING. It looks like a spacer but is designed to help sling oil from one of the passages cast into the housing onto the pinion bearing. If you install this where it normally goes, and begin to tighten the flange nut, you will notice that you cannot rotate the diff at all. Just leave it out. The pros assure me the oiling will be fine without it.
FrontDiff-new (37).JPG


Now it's time to install the input flange seal and then the flange and the nut. Once you get the nut tightened down, but not too much, stake the edge with a punch to keep it in place.
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Finally, we are on to the wiring. Here's a recommendation based on my experience...install the harness M/F factory looking clips on the diff before you install it. As of this moment in the build I just have two wires coming out the grommet in the top side of the diff. The Harrop install kit comes with everything you need to install a rocker switch on the dash. In fact, there is enough wire provided to install the switch on the back gate door if you really wanted. I neglected to look ahead in the build process and installed my diff up into the frame looking like this...
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Those two pins need to be inserted into the provided plastic harness pieces and let me tell you, this would have been 99 times easier on the bench than it was up inside the truck. Here's what you are trying to achieve. I worked for a good while trying to pull those pins through the harness clip with needle nose pliers. I was checking to see if I pulled them far enough through to make contact with the other half of the harness clip using a multimeter and a spare 12v battery. You cannot hear this locker engage by ear - the action is that quiet, so the multimeter was needed to check continuity (or something, electrical is my kryptonite, so I enlisted one of my friends at the garage to help). This harness clip system is high quality stuff with water tight seals once it's locked together - I just wished I had forethought to do this part on the bench.
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So now you have about 20 ft of wire connected to your diff. I ran this directly up from the diff and paralleled the diff breather hoses on the driver side inner fender. Added the provided plastic loom and e-taped it every 6-8".
FrontDiff (28).JPG


From here I snaked past the fuse box and over the brake booster to a grommet already in the firewall. I have other accessories going through this hole so I used an improvised "snake" made of thin spring steel with a hook in it to fish it through quickly.
FrontDiff (26).JPG


Finally I wired the rest of the switch and relay to my Blue Sea fuse panel under the steering column. I ran the wires to the switch under the steering column paralleling some factory harness that goes to the center console. I spliced the 12V ign signal that comes out of the back of the locker switch to my "cig lighter" 12V outlet on the center dash. Here's a pic of the switch wires (in yellow/orange and blue) zipped tied to the factory wiring harness as they pass under the steering column.
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Hoping to test out the new locker on some trails in Tennessee next month. Will report back with trail pictures at that time.
 
What does that coupler do in pic #4?

Good work tackling this yourself. You're going to get good at taking that apart and putting it back together.
 
Andrew, it connects the half shaft on the passenger side of the differential via the ADD actuator. This system "replaces" locking manual hubs. That splined stub shaft mates with a sliding splined collar that engages the passenger side CV assembly when the tcase is put into 4WD.
 
Andrew, it connects the half shaft on the passenger side of the differential via the ADD actuator. This system "replaces" locking manual hubs. That splined stub shaft mates with a sliding splined collar that engages the passenger side CV assembly when the tcase is put into 4WD.

Interesting. Is there a retrofit to get hubs, or is this just what you get? A buddy of mine has a '14 Ultimate Trail Edition, is this what he has in the front end? I'm going to have to take a close look at it.

Looks like good work though, and I'll bet it will test your patience.
 
Interesting. Is there a retrofit to get hubs, or is this just what you get? A buddy of mine has a '14 Ultimate Trail Edition, is this what he has in the front end? I'm going to have to take a close look at it.

Looks like good work though, and I'll bet it will test your patience.
Here's the anatomy. When you shift the tcase lever from 2WD to 4WD-Hi, a signal to the [Automatic Differential Disconnect] actuator motor shifts the fork & collar over to engage the passenger side axle with the splined stub shaft described in previous post. Now it's in 4WD with an open diff. A-trac will provide traction assist once the tcase is shifted to 4WD-Lo. If I recall the driver side axle is always spinning the spider gears in 2WD to help keep the internals spinning/lubed, instead of stationary. I think it's a better system than the auto-locking hubs that AMC/Jeep used for a while.

The only retrofit to get manual hubs that I'm aware of is to do a solid axle swap ;)

FrontDiff-labeled.jpg
 
Bump for updates to post #5 and post #6 which concludes the installation process.

I want to acknowledge @orangefj45 and @wardharris of Cruisers Brothers for helping me get the right locker kit for my FJC. My understanding is that I am one of the first to install a Harrop front locker in a US FJ Cruiser. There was a fair amount of research on their end to find a match from the AU market where Harrop e-locker originates. This Harrop locker looks like a solid piece of engineering and has fewer "pinch" points in the engineered design - no air lines to plumb or compressor needed, just a normal 12V relay and switch to activate.

I also want to acknowledge the friends I have at @ACC Toyota (Brian, Mike and James) for their assistance (heaving a front diff into the air), guidance (general diff tech) and specific knowledge (shortcuts to wiring) of Harrop lockers. These guys have installed numerous Harrop's and know them inside and out.

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Nice write up, @BMThiker. I think you're going to like the Harrop. They certainly have a good reputation among the Aussie crowd and with the Cruiser Brothers now stocking them in the USA I expect they will catch on here quickly. I installed one in the front diff of my FZJ80 last October.

But you sure about the pattern you show in post #5? Doesn't seem like much contact area. How's it sounds when you drive it?


Interesting. Is there a retrofit to get hubs, or is this just what you get? A buddy of mine has a '14 Ultimate Trail Edition, is this what he has in the front end? I'm going to have to take a close look at it.

Looks like good work though, and I'll bet it will test your patience.

Yes, that's what I've got. "ADD" - Automatic Differential Disconnect. Can be found on several Toyota 4x4 vehicles. Supposedly works well except that the small electric motor that drives it is subject to water intrusion and perhaps physical damage if you don't have a skid plate. Also I've read it's hard to R&R the motor without removing a bunch of other stuff.
 
...This Harrop locker looks like a solid piece of engineering and has fewer "pinch" points in the engineered design - no air lines to plumb or compressor needed, just a normal 12V relay and switch to activate...

And no internal O-rings to leak air like in an ARB and cause your compressor to keep cycling.
 
Yes, that's what I've got. "ADD" - Automatic Differential Disconnect. Can be found on several Toyota 4x4 vehicles. Supposedly works well except that the small electric motor that drives it is subject to water intrusion and perhaps physical damage if you don't have a skid plate. Also I've read it's hard to R&R the motor without removing a bunch of other stuff.

The ADD is actually pretty easy to get to, if you don't have a skid plate. Most failures of the ADD are due to the fact that the electrical contacts inside the housing are not soldered, they are just resting against the corresponding terminals. It's pretty easy to remove the actuator and open up the housing to solder those terminals. Water intrusion could be a failure of the seal against the axle housing, the ADD's pvc rubber seal or the breather tube being compromised. If the ADD housing took a whack and cracked it would allow water intrusion too.

As @1911 and I have expressed recently in another thread, you can remove the ADD on the trail to get 4WD operational. A few 12mm bolts hold it in place. Then you manually move the shift fork, slide the collar over inside the axle tube with your finger and remount the ADD. Here's the inside of mine after soldering the contacts on the motor. I also soldered the contacts on the switch at left.

ADD_2014-08-09 (9).JPG
 
//// If I recall the driver side axle is always spinning the spider gears in 2WD to help keep the internals spinning/lubed, instead of stationary////

I am not so sure that is true. On my 2012 after I grease the joints and check days later the drive shaft appears not to have turned. The grease has not been thrown all around the area but I can see were excess grease has been thrown around my rear drive line joints.
 
//// If I recall the driver side axle is always spinning the spider gears in 2WD to help keep the internals spinning/lubed, instead of stationary////

I am not so sure that is true. On my 2012 after I grease the joints and check days later the drive shaft appears not to have turned. The grease has not been thrown all around the area but I can see were excess grease has been thrown around my rear drive line joints.

Rick is correct; the way the ADD system is set up, the driver's side axle and the spider gears in the diff can rotate without turning the pinion gear in the diff and hence the front drive shaft.
 
Rick is correct; the way the ADD system is set up, the driver's side axle and the spider gears in the diff can rotate without turning the pinion gear in the diff and hence the front drive shaft.

Now I got it, someone just explained to me that the way it rotates is thru the front wheel causing rotation, not the driveline.
 

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