H3 Eaton locker installation

MaxPF installed an Eaton locker into my truck yesterday and we took the opportunity to capture some of the basic elements of the install

Eaton selectable locker (source: his former 10 bolt front locker)
2 - Timken bearings LM603012 wheeling bearings
2 - Timken races 603049
2 - AC Delco 291-315 rear axle seals
3 quarts - Red Line 75W-90 full synthetic gear oil

Naturally the first step was to remove the diff cover (and Purple Cranium, in my case) and drain the oil into a pan. The oil and casing were inspected for metal pieces (none) and shavings (nominal) so after 98,000 miles the rear diff was still holding up well.

Here's the stock, unlocked setup


The backlash was measured and it was determined I was at .016", a bit high but not worrisome due to the miles. That could just be wear and tear on the bearings and races


After the backlash was measured the carrier was removed from the housing. To remove the carrier we had to pull the axles. The axles are held on by C-clips and they did not want to easily come out. The C-clips were made accessible by using a pry bar inside the diff housing to pull the axle and clip inward, allowing the clip to be removed and the axles to be pulled out. Here is the original carrier on the bench with the Eaton carrier right next to it, waiting for its home


These bolts are machined the opposite of standard bolts, meaning "righty-loosey", "lefty-tightie". They are being removed here with an impact wrench


The ring gear is then removed from the carrier with the assistance of the plastic hammer.


The ring gear is inspected for damage or excessive wear; neither is present


The empty diff housing


The ring gear is put onto the Eaton carrier with assembly lube on each bolt. The bolts are torqued to 90 ft/lbs. We put a long pipe through the carrier to hold it in place while the bolts were torqued.


The carrier was reinserted into the diff housing with the original shims and spacers and measured for backlash. The backlash actually came out at 0.0", below the spec for new gears (according to an older GM 8.6" manual) of .004 to .009. We purchased a new shim pack from the dealer, with two new spacers ($100 and $13 respectively!) and reinstalled the carrier. The new backlash came out at .012 and we were happy with that final figure.


Once we had a good setup it was time to drill a 1/2" hole into the diff cover for the Eaton locker. The hole will be sealed with the OEM gasket.


The new gears were lubed and the carrier was reassembled


The internals and the locking mechanism were installed into the carrier. Note the piece with the six oval grooves. That is the part that the locking pins insert into. A new locker has very square edged pins and receiving holes. An abused or worn locker has rounded pins and holes (there is a rounded pin in this picture at the top of the wrenches)


The bolts were torqued to 60 ft/lbs


New axle seals were installed for good measure


The axles were reinstalled, c-clips inserted and the diff cover was put back on after it was cleaned and the outside was repainted. The gasket is reusable and it was reused after cleaning. Oil was put in until it began overflowing, approx. 2.5 qts. You can see the wiring at the top of the diff.

I put a switch into one of the blanks in the lower part of the dash, ahead of the shifter, and wired it through a relay under the hood. The ground for the locker is the same ground used by another item (fuel management?) about 2' behind the rear axle. The line for the power ran from the firewall, under the truck along the driver's side, over the fuel tank and is secured wherever possible. It is also in a wire loom for protection.


I'm in the process of redoing the accessory wiring under the hood and the first step was setting up this Blue Sea Systems fuseblock (thanks for the recommendation, Hunner). It has a common ground and power point with space for six accessories, each with their own fuse.


We did a thorough testing of the locker - turned it on, tried to turn on asphalt and the rear tires chirped. Success!

Thanks for sharing the install Alrock!!

Nice. I need to go to Scottsdale and visit MaxPF's shop!

I figured out this week I need lockers.

Ahhh! Good memories looking at an empty diff...When I did my locker install I do not remember the backlash being that high but I have less miles and less off road miles on mine. You will love the locker, you can feel it push you through obstacles. Cant wait to see your opinion on the locker out on the dirt.

DJinCO said:

Nice. I need to go to Scottsdale and visit MaxPF's shop!

I figured out this week I need lockers.

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MaxPF's knowledge is so valuable here. He always seem to have a soultion

06 H3 said:

Ahhh! Good memories looking at an empty diff...When I did my locker install I do not remember the backlash being that high but I have less miles and less off road miles on mine. You will love the locker, you can feel it push you through obstacles. Cant wait to see your opinion on the locker out on the dirt.

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Yeah, the backlash was at the limit for a used set of gears. Also, there was almost lo preload left on the stock bearings. Alex definitely put some hard use on his diff When I first set up with new shims I ended up at .005" backlash, but insufficient preload (pretty much none). i wanted looser backlash because the established wear pattern on Alex's gears was out at the looser end of the range. A switch of shims set the backlash to the final .012" and gave a solid .008" preload on the new bearings, which was perfect. All in all I had the carrier in and out probably a half dozen times before I was completely satisfied, and my arms are feeling it this morning.

I took some pics as well and will add some more thoughts to this thread later. Gotta go work on my own junk right now :wink:

Nice job! Can't wait to see it in action.

Nice job! But seeing you wheel, did you actually need it? And did you get the caliper fixed too?

I figured I would post up pics and descriptions of an E-Locker rebuild. Technically, I did not "rebuild" Alex's locker since all the internals were in excellent shape (it was in my front axle and never got much use). Rather, I cleaned and inspected everything to make sure Alex wouldn't have any issues with his new toy.

This is the carrier along with all the locking mechanism parts (lower left and in the baggie) and new bearings (boxes on the right):



The two most critical items when inspecting an E-Locker is the condition of the recesses in the side gear and the lock pins themselves. These can actually be inspected without disassembling the carrier, or even removing it from the axle. Removing the center pin, both axles, and the side gear are necessary however, so more than just a axle cover removal is necessary.

Alex posted this pic of the side gear (the liquid is dirty solvent - the gear got further cleaned with fresh solvent before installation):



The six recesses are where the six lock pins engage the gear and force it to rotate with the carrier, effectively turning the open diff into a spool. They are elongated because the pins take some relative motion to the gear to fully engage - simple holes would not allow the pins to drop down fully, and the locker wouldn't last long if it even worked at all. What you are looking for is substantial ramping of each end of each recess. A very small amount of rounding is normal, and a bit of wear is acceptable, but if it looks bad, then a rebuild kit is needed (available from Eaton). Likewise, the edges of the pins should be well defined with minimal rounding (new pins and little used pins like the one shown below will have a small amount of rounding from the deburr process during manufacture - same with the edges of the side gear recesses - this is normal):



If the pin looks like the one below, then a rebuild kit is in order:







The damaged pins shown above is out of a locker I rebuilt for another H3 owner. This is not normal wear; it is caused by misuse/abuse. It was not really the owners fault as the H3 owners manual does not appear to say anything about proper locker use and avoiding damage. I will go into this in a bit.

Anyway, after all the parts are thoroughly cleaned installation can commence. First up are the six return springs:



They drop into the six blind recesses in the carrier:



Nest piece of the puzzle are the pins and retaining ring. The slots in the pins engage in slots in the ring like shown in this blurry pic:



Lightly coat the pins with some type of assembly lube (I used Comp Cams camshaft assembly lube because I had it and its nearly odorless - gear oil will work but it smells - motor oil works and doesnt stink), assemble them onto the retainer, and insert into the six through holes in the carrier:



You will notice that three tabs on the retainer sit atop three of the springs. The springs disengage the pins when the magnet turns off and the mechanism is released. Next up is the ball ramp actuator plate. It has three ears as well that sit atop the remaining three return springs. Lightly lube the inner diameter and the outside of the ears, install atop the pin retainer and springs, and put more lube in the ball ramp pockets:



Then you place a ball in each pocket:





And then the top ball ramp plate goes on. It has pockets just like the actuator plate that fit over the balls. Once again, lube the inner diameter lightly:



Next is the drag plate. It has three tangs that match the three recesses on the periphery of the upper ball ramp plate. Install it with the radial grooves facing up:



Then the magnet gets placed atop the drag plate as shown:



Holding it all together is the upper retainer:



There is also a Torrington thrust bearing that goes between the retainer and the upper ball ramp plate. I used the thick, sticky assembly lube to stick it to the retainer and installed it as an assembly:



But if you are using a less sticky lubricant you can just center the bearing atop the upper ball plate and install the retainer over it. As long as the bearing gets put in there it's all good. Make sure the ID and OD of the retainer are well lubed and install it inside the magnet atop the bearing and upper ball plate. The flange on the retainer will be up, and it mates to a recess in the magnet and holds the magnet on:



You will notice that the snap ring groove in the carrier is not visible. That is because the springs are holding the assembly up slightly. It doesn't take much to compress the springs enough to get the snap ring installed. Todd used his fingers to press the retainer down, and I popped the snap ring in place:

Finally, the bearings can go on. Alex already listed the part numbers for the bearings above. They are Timken part numbers, but you can cross reference them to other brands:



A lot of people on various automotive forums seem to think Timken bearings are the best and all others are junk, but that is hardly the case. The OE's use bearings from many major manufacturers: SKF, NTN, BCA (Federal Mogul), ***/INA (Schaeffler), etc. The main thing isn't the brand, but WHERE they are made. I have found Chinese bearings to be generally inferior to bearings made in the USA, Europe (including Eastern Europe), Japan, and elsewhere. There may be good Chinese made bearings, but all the ones I have seen had noticeable rumble in them when new. So, regardless of brand, check where they are made. If they say China, inspect them carefully before deciding to use them. When in doubt, get another brand. Alex's Timkens were made in USA, so they're good stuff:



In order to avoid damaging the bearings Todd whipped out an aluminum tool to press on the inner race of the bearing without contacting the cage retaining the rollers or the end of the carrier, and the bearings were pressed on until they seated onto the face of the carrier journal :



And thats it for the carrier assembly. I did however manage to snap a pic of Alex actually doing something mechanical :wink:



After that pic he commenced to hold a chair down while I did all the REAL work

Ok, not really, he actually worked on getting his brakes sorted out, cleaning the diff cover, and fetching me tools when I didn't feel like climbing out from under his truck for the umpteenth time. Alex definitely doesn't mind getting his hands dirty, but I think he sandbags a bit... he probably could've installed the locker himself. He just enjoys watching me work while he relaxes :hjob:

Oh, I was going to talk about proper E-Locker operation. First, I will explain how the locker works so hopefully you better understand why there is a certain procedure to using it without causing damage.

When you flip the switch and apply power to the electromagnet, it grabs the drag plate. Since the magnet is held stationary by a retainer bracket in the housing, the drag plate is held stationary as well. As the carrier turns, the upper ball ramp plate is being held stationary by the drag plate while the lower ball ramp actuator plate is forced to rotate with the carrier due to it's "ears" being locked in recesses in the carrier (atop the springs). This relative motion causes the balls to roll up the ramps, forcing the actuator plate to apply force to the lock pins and push them into the side gear. Once the recesses line up with the pins, they will drop in place and lock the gear to the carrier. At that point, the carrier is locked and is effectively a spool - both axles are solidly connected to the carrier with no differentiation allowed to occur.

Here's a video showing the process:

http://www.youtube.com/watch?feature=endscreen&NR=1&v=-VPPGsYq6TE

The important thing to note is that the axle is NOT immediately locked as soon as you poke the button. It takes approximately 1/3 of a full carrier rotation before lockup occurs. You want to avoid having either rear tire spin more than a few RPM during this time, otherwise the large speed difference between the pins and the side gear will cause damage to both. Once the locker is engaged, then it is okay to hammer on it and spin the tires.

However, there is still one very important caveat: the locker only stays engaged as long as you don't reverse direction. In the video I posted, they show the ball ramp mechanism operating in detail at 54 seconds. You will notice that when the direction is reversed the mechanism disengages and then re-engages. If you reverse direction (going from forward to reverse or vice-versa, or even rolling backwards while in forward gear or vice-versa) the locker unlocks and then relocks, which takes a total of about 2/3rds of a full carrier rotation. If you are going forward (or reverse), get stuck, throw it in reverse (or drive) and stand on it, you will cause damage just as if you have a wheel spinning and engage the locker (or engage the locker and stand on it).

Avoiding damage is easy. Any time you engage the locker, allow one or both tires to roll for about 1/2-1 revolution before you get on it. If you have to reverse direction on an obstacle with the locker on, treat it just as if you are engaging the locker when you start to apply throttle. The damage caused by violating this rule is generally not immediate but rather cumulative - the locker won't blow up or fail. It will simply accumulate damage, slowly rounding off the pins and side gear until it no longer locks but "ratchets". At that point, you get to buy a rebuild kit for $200 and pay someone to install it it you can't do it yourself So, if you can't avoid some wheelspin during engagement (i.e your stuck BAD and have nobody to give you a tug) then by all means. Just try not to do it if it isn't absolutely necessary.

Finally, do NOT ever, under any circumstances, drive at speed (i.e. greater than, say, 20MPH) with the locker continuously engaged. It's ok for very short periods, say for wheelspin to get through a mud hole, but not actual driving for any distance. If you again refer to the operation, you have a drag plate stuck to the magnet. Once the ball ramp mechanism engages the pins, the entire assembly including the drag plate rotate, hence the name "drag" plate. the grooves in the plate and magnet are there so oil will minimize wear as the plate spins against the magnet. Al low speed it could do this for days with no real wear or problems, but at higher speeds the friction will start building heat. Eventually, it will get hot enough to destroy the plate and magnet and cook the gear oil. So, it's best to avoid this

I should mention that I do not want to make it sound like the E-Locker is fragile. On the contrary, they are quite tough. The warning about avoiding wheelspin during engagement and rolling a bit before getting on it applies equally to the ARB air locker. While the ARB has no ball ramp mechanism, it has teeth which must be in the correct position to mesh. When you hit the air, the teeth may not be in the proper position, so a bit of carrier rotation may be needed to line them up. Get on it before they engage and you round off the teeth and risk breakage. The ARB does not disengage and reengage during direction reversal (it stays locked until the air pressure is released, period), nor does it have a drag plate that will get hot if left engaged at speed (it will probably kill the air seal much faster if driven at speed while engaged though...), so those are advantages over the E-Locker. OTOH, the E-Locker has the advantage of being maintenance free (no air seals to wear out and leak) and not needing an onboard air source. I like the ARB a lot, but for a daily driver/weekend wheeler I think the E-Locker is a much more practical design. Both are excellent products, and I don't see anyone going wrong with either unit. Just thought I would throw my loose change in there since someone is bound to ask

MaxPF said:

He just enjoys watching me work while he relaxes :hjob:

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....you say that as if it's abnormal?

Wow, I can't believe you finally did it! You will see significant decrease in wear on all your other parts now you have the locker provided you use it.

There won't be any stopping Alex now.

This makes me want to install an e-locker now!! Thanks for the write up guys, this is def going on my mod list!

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Great write-up! I won't pretend to really understand what some of that jargon was, but I can dig it! :wink:

BTW, MaxPF understated my involvement in this project. I also purchased Chick-fil-A for our lunch.

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alrock said:

I also purchased Chick-fil-A for our lunch.

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This, I can understand.

Max, I really appreciate that you took the time to explain how to use the locker. Im sure a lot of unnecessary wear is put on them by most people (like me) who just engage it and go...

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alrock said:

BTW, MaxPF understated my involvement in this project. I also purchased Chick-fil-A for our lunch.

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And ridiculously overpriced (but VERY tasty) pizza and wings for dinner :thumbs:

06 H3 said:

Max, I really appreciate that you took the time to explain how to use the locker. Im sure a lot of unnecessary wear is put on them by most people (like me) who just engage it and go...

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:agree:

I was in the same boat as Chris and never really knew how to properly operate a locker. Fortunately, I had the rear diff rebuilt not too long ago under warranty.

It now makes sense why it took so long for the locker to engage. I am used to waiting until I really need it (climbing a steep hill typically) and then engaging. I typically notice a few "hops" before the truck pulls me up after pushing the locker button.

You're better off engaging the rear locker before you start on an obstacle rather than waiting until you're stuck. Front lockers are a different story; I never used mine until it was clear I needed it, since locking the front axle seriously impairs steering.

Wheeling with the H1, H2, and H3, we never needed lockers. I only use mine when I needed to give Alex a toe.

Thanks Todd, you always know how to give a guy a boost :shame:

crawler said:

Wheeling with the H1, H2, and H3, we never needed lockers. I only use mine when I needed to give Alex a toe.

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I guess you haven't tried to BTM with a manual transmission. :giggle: