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FarmerinVA 07-02-2011 02:00 PM

Extreme Novice Installing PowerTrax No-Slip, TrueTrac, Crown 4340 rear axle shafts
This thread aims to answer three related questions:
  1. If you care only about flat land traction (not ground clearance or armor or looks), what should you do first?
  2. How cheap can you do it?
  3. As a total novice, can you do it yourself?
I’ll provide answers, photos of the installation, tool lists and torque specs and socket sizes, and the results of testing it out on my farm. I’m doing this thread because I couldn’t find one quite like it when I needed to answer these questions for myself. I also want to remedy the fact that JF doesn’t seem to have a thread that explains a DIY install of the TrueTrac in much detail.

Before we get to the answers, let’s start with a question for you. Does this photo freak you out?

If so, good. You probably suffer from axleworkophobia – the condition of fearing axles and believing that you aren’t capable of working on the guts of a differential. We’re going to cure you. I too suffered from this condition; in fact, before starting this project, I had never before messed with the mechanicals of a vehicle and I’d only even changed a tire half a dozen times in my life. Although I’m experienced at driving offroad, I was – and, I suppose, still am – about as much of a noob installer as it’s possible to be. My point is: if I figured this out on my own, you can too.

Now for the answers, or if not “the” definitive set of answers, then at least a pretty good one. What I found through a lot of reading and asking (mostly here), talking to some pros, driving other people’s TJs and JKs and my own XJs and trucks, and turning some wrenches, is that if you want traction enhancement but you also put a high value on low price and simplicity of install and operation – let’s call this “idiot-proof traction on a budget” -- a very good solution is:
  • Put a “lunchbox” automatic locker in the front (many brands work well, but I chose a PowerTrax No-Slip, for reasons I’ll explain).
  • Put a limited slip differential in the rear (the TrueTrac is the best choice).
  • Think about upgrading the rear axle shafts if you have a Dana 35 (Crown 4340 shafts and Yukon alloy shafts are both good choices; I chose the Crowns).
You’ll spend as little as $300 all the way through installation of the front “lunchbox” locker ($400 for the PowerTrax No-Slip) and under $550 all the way through installation of the rear TrueTrac, for a total of under $850. Add $350 for the upgraded shafts, which are optional but recommended, and you can still be under $1200 total with upgraded shafts. Quite a reasonable spend for a massive increase in capability and strength.

And I have to report up front: this was fun. Real fun. Easy and quick for the front axle; easy although not-so-quick for the rear axle. If you have any desire to do this yourself, for heaven’s sake, do it. You’ll have a blast and you’ll make a much better Jeep. Also, you’ll get filthy, and who doesn’t like that?

Hat tip: I’m basically copying the style of the fantastic Extreme Novice Regear thread. Brjeep, you rock.

FarmerinVA 07-02-2011 02:11 PM

This thread is mostly for a person who owns a TJ in a non-Rubicon model, probably with the standard axle package (which means an open-differential Dana 35 axle in the rear), who just wants to focus on improving dirt/mud/gravel/field traction (not real big rocks). The goal is to make a TJ more capable for the basic offroading that many flat land drivers face -- particularly in the East and South and (so I’m told) Pacific Northwest -- while also staying as cheap and simple as possible. Maybe that’s all you want to do. Maybe it’s just all you want to do for now. Whichever.

Even a total klutz can do this in a garage or driveway with normal tools. The possible exception to that “normal tools” statement involves installing the TrueTrac, where you’ll need a dial indicator and it’s preferable to use a bearing press. You can do it without a press (I’ll show how) but I recommend a press, which you can have done (pretty cheap) at any mechanic’s shop.

I’m going to be a little wordy in the first few posts, in order to give fellow novices the info that took me so long to find out on my own. I’ll shut up once we get to the installs.

FarmerinVA 07-02-2011 02:15 PM

Here’s the patient, a ’99 TJ Sahara, bone stock with Canyon rims and 30" ATs, as acquired in fall 2010. Never been offroad, never even had the doors or top off. 30x9.5 inch all terrain tires. Open differentials (more on that later) and the dreaded Dana 35 rear axle – fine for street use, but not intended as a heavy duty offroad axle.

Here it is with 31x10.5 BFG Mud Terrain tires installed, top removed, and a little dirt. Much better!

But it’s not very capable offroad in this totally stock-axle condition. The main problem is those open differentials, which are a killer in the worst mud.

This Jeep lives on a farm in Virginia, not too far from the Chesapeake Bay. It’s all offroad all the time; we’re miles from the nearest pavement. No rocks and few steep hills but, before you mock the conditions as sissy stuff, recognize that this is serious you-got-stuck country: marsh, swamp, slippery underbrush and stumps, logging trails, “roads” that are underwater at high tide (yes, I’m serious), and just-plain-old-mud. I’ve had three XJs that spent more time stuck than moving, it seemed, and even this Wrangler on mud-terrains had a tendency to bog down in 4WD.

I knew the problem was the open differentials but I didn’t know how best to fix them. So, I joined JF and posted a thread asking for the best locker or LSD combination for a working vehicle tortured by bad footing: Locker Solution for Flat-Land Mud. Jerry, mudb8, unlimited, lupinsea and IslandTJ (among others) gave me a bunch of good advice. Thanks, guys (or gals).

What I've done is what pretty much everyone told me to do.

FarmerinVA 07-02-2011 02:34 PM

Why to Replace Open Differentials, and How to Do it Cheap

Why replace the open diffs? Read Jerry Bransford’s explanation, "Why do I need a locker? I thought I had 4WD!" and watch the How a Differential Works video. Long story short, an open differential makes the wheel with the worst traction spin out, while making the other wheel sit still, and you’re stuck. As Jerry put it,


Originally Posted by Jerry Bransford (Post 5956007)
Q: Why do we need lockers, I thought I had four wheel drive??

A: We need lockers for tough terrain because the differentials installed into most of our front and rear axles have a characteristic that can turn our 4x4 Jeeps into 4x2 Jeeps in tough traction situations.

Here's a page from the 99 TJ manual about differentials. I'm really just including this page so that I have a graphic in this wordy post, but what the heck, it's kind of interesting.

So the open diffs have to go. How to do that in the cheapest, easiest way possible? Here’s what I learned.

For the front axle:
  • If money were no object, you’d almost certainly put in a selectable locker (one you can turn on to lock, and turn off to revert the diff to the open condition), such as the ARB or the OX. But the unit itself is pricey, there are things to break or malfunction, such as air lines, compressors, switches, cables (even if malfunctions are rare on the better units), and it’s difficult to install. And professional installation is expensive. Remember, we’re trying to do cheap, DIY, and very simple here, so the selectable locker is right out.
  • You could weld the spider gears together (those are the things inside the differential that …uh … differentiate), which is as cheap as it gets … if you know how to weld. But that’s really a rear-axle solution, and even then, it makes your Jeep hard to turn, and you can’t ever unlock it -- it’s permanent, obviously. For various reasons it’s a bad idea to weld a front axle, particularly if you ever need to go onto pavement at highway speeds, which I might need to do occasionally. You could also put in a “spool,” which is the same effect as a weld, and the same downsides. A little stronger but more expensive, and more work.
  • A full-differential-case automatic locker like the “Detroit Locker” is a good choice, but expensive, and is difficult to install because it’s a full carrier replacement – you’ll need to remove your carrier, install differential bearings and shims on the Detroit Locker carrier, and then reset the “backlash” between the ring gear and the pinion. Again, professional installation is expensive.
  • A limited slip differential, which is another full-case replacement, is a great choice in a front axle for the basic traction we're after in this thread. But it has the same installation difficulties and most of the same costs as a full-case auto locker, and it doesn’t work if you lift a tire off the ground (where only a locker works). Since the focus here is on dirt cheap and easy install, let’s pass on this one, at least for the front.
  • Which leaves … the “lunchbox” locker, which just replaces the spider gear “guts” of the existing front differential. In some applications, you don’t even need to take the differential case out of the axle to do this! And in the front axle, it’s selectable, sort of … because when you are in 2WD and no power therefore goes to the front axle, the front axle’s autolocker will unlock and be virtually invisible. Not actually selectable, but almost as good. Cheap, easy to install, real locking capability, and good enough, for a front axle.
If all that makes you skeptical (I am a novice installer, after all), ignore me and listen to Jerry Bransford, who said:


Originally Posted by Jerry Bransford (Post 3601072)
Why not just go for a lunchbox locker up front? They work fine and are plenty strong enough when in the front axle. I'm running a lunchbox Powertrax No-Slip in the front of my TJ (full-case Detroit Locker in the rear). I believe in full-case lockers in the back but so far, I haven't seen the need up front, at least not strength-wise. If I had my druthers, I'd have an ARB Air Locker front and rear but for now, my No-Slip is performing admirably and it has done so for many years including trips through Johnson Valley. :)

For the rear axle:
  • Most of the same considerations above apply to the rear axle but there are a few differences. The main one in my case is that locking -- however it’s done, including the cheaper options such as lunchbox locker or welding -- makes a Dana 35 axle prone to break. See this photo page (hat tip to Jerry for the pointer) for proof. A Dana 35 just isn’t a serious offroad axle. Another consideration is that a full carrier replacement (regardless of whether it's a locker or limited slip) is stronger than a lunchbox or weld. In a D30 front axle, that makes little difference – the front axle usually gets only about half of the engine’s torque (since the rear axle is always engaged), meaning that breaking the shafts or the carrier is unlikely with flatland offroading and non-crazy use of the gas pedal. But the rear axle gets 100% of the engine’s torque when the Jeep isn’t in 4WD, so it needs to be tougher.
  • A TrueTrac is a good choice for a Dana 35 because it’s not a locker, and therefore the weak Dana 35 can survive much better (the one for the Dana 35 has about a 4:1 bias ratio, which I believe means that the most that one wheel can get is 80% of the engine's max torque). And there are other benefits to the TrueTrac: it doesn’t cause steering and tire-wear issues like lockers can, and it doesn’t cause you to lose lateral stability on snow, sidehills and slick mud.
  • You may decide, like I did, to upgrade your 27-spline axle shafts in the Dana 35. That’s extra insurance against breakage; read lupinsea’s post (#6) at the Poll: Ever Break a Shaft with a TrueTrac? for a great testimonial about the durability of upgraded 27-spline shafts when combined with a TrueTrac (if they can survive what he threw at them, they should be able to sleepwalk through what I do!). One funny thing about this option is that it makes the total price of the rear-axle parts (locker + shafts) come close to the price of a Super 35 kit. The Super 35 kit gives you much beefier 30-spline axles, a locker, and bearings. Why would anyone choose to upgrade the 27-spline shafts rather than do a Super 35 kit, then? Two reasons. First, that’s the only option for upgraded shafts if you want the TrueTrac in a Dana 35 – the TrueTrac for the Dana 35 doesn’t come in a 30-spline version. Second, the Super 35 kit’s larger axles mean you must replace the axle bearings and oil seals, which requires more effort in the installation.
I really wanted the TrueTrac, so I chose the 27-spline upgrade. Lots of people prefer the Super 35 kit with a locker, particularly the option with the Detroit Locker (Softlocker). It’s up to you. But the focus of this thread is how to be as cheap as possible, and there’s no doubt that a TrueTrac with stock shafts is a lot cheaper – and even with upgraded shafts, is a little cheaper – than the Super 35 kit.

One final thought. With selectable lockers, you have an activation device (wire, hose, or cable) that penetrates the differential cover or the housing in some way. This is a potential failure point: water can get in; a trail obstacle can yank it or break it (a particular problem for flatland Jeepers who wheel through heavy vegetation, as I do; I even had a brake line yanked off once); and most will need to be disconnected or re-adjusted if you remove the diff cover. This isn't a huge issue for most people but it's nice to know that with an autolocker or a TrueTrac, you don't have to worry about it. The autolocker and TrueTrac are totally sealed off inside the diff, and they don't care if you open the cover. That's a nice little bonus.

Whew. I don’t even want to think about how many hours of JF reading went into me learning all of that.

Now to the install.

FarmerinVA 07-02-2011 02:52 PM

The Front Axle – PowerTrax No-Slip (lunchbox locker)

Or “Front Beam Iron” (FBI) axle, as Jeep calls it. Here are the specs from the manual on Mr. FBI.

Which lunchbox locker to buy? I settled on the Richmond Gear PowerTrax No-Slip for about $410 new. Here is one place where I didn’t go as cheap as possible. Other models such as the Spartan, Lock-Right and Aussie are just as effective, and $100 cheaper new (and widely available for less, used). Each has its partisans. I have no opinion between them. But the Spartan, Lock-Right and Aussie design wears them out a bit faster and causes them to be noisy (sometimes alarmingly so) when they lock or unlock. Between the added durability and not wanting to scare the pants off my Jeep’s other drivers with loud locker bangs, I decided to eat the $100 difference and get the No-Slip.

Here’s the manufacturer’s page on the No-Slip, which includes various information of dubious reliability (“stronger than titanium” – ya, riiiiiiiight) but does show you how the thing is built:

By the way, don’t worry about the apparent complexity of this unit. That is just a marketing photo to try to persuade you that the thing is an engineering marvel. The unit actually comes pre-assembled into six big parts, which are idiot proof to put together.

FarmerinVA 07-02-2011 02:57 PM

Here’s what I needed for what bolts and such. Also, here are the torque specs for the eventual reassembly, some of which aren't on the manual page shown above.

In order of disassembly. All bolts are six point (as opposed to 12-point) unless otherwise mentioned.
  • Castle nut on tie bar = inch = 55 lbs
  • Differential cover bolts = inch = 30 lbs (35lbs if using a LubeLocker gasket)
  • Wheel lug nuts = 19mm = 90-110 lbs
  • Brake caliper bolts = 13mm = 11 lbs (yes, only eleven pounds, really)
  • Wheel bearing assembly bolts = 13mm 12-point = 75 lbs
  • Bearing cap bolts = 5/8 inch = 45 lbs
  • Ring gear bolts = 11/16 inch = 70-90 lbs (I'm told that some are 3/8 inch but mine were definitely 11/16) (you must have new ring gear bolts -- reinstalling old ones is a big no-no, and besides, they are less than $1 each)
  • Differential fill plug = 3/8 inch ratchet socket end = 25 lbs (not that anyone ever actually measures the torque on this … but that’s what it says in the manual)
  • So, for the main wrench tasks, that means you need a socket wrench, torque wrench and , 5/8, and 11/16 inch sockets, a 13mm socket, a 13mm 12-point socket, and a 3-inch-long socket extension (not absolutely necessary but will make your life much easier – otherwise there isn’t much room on some of the bolt heads). You don’t need a 19mm socket if you just want to use your lug wrench instead.
  • Also highly recommended is an impact wrench (or a breaker bar and a lot of strength) for the ring gear bolts, a 13/64 diameter punch (or equivalent) to drive out the roll pin on the differential, needle-nose pliers to grab the cotter pin on the tie bar castle nut, heavy hammer, soft-faced mallet, and a crow bar. And a vise of some sort to hold the differential case when you are removing and installing ring gear bolts – my Black & Decker portable worktable worked fine for this. Finally, a small tube of Loctite 242 for the ring gear bolt re-install, one quart differential fluid, one can PB Blaster, one can brake cleaner, and about a tablespoon of heavy grease (used in the No-Slip to keep screws in place during the install).
Things I thought I might need, but didn’t:
  • tie bar puller/separator
  • differential case spreader

FarmerinVA 07-02-2011 03:05 PM

Now let’s turn some wrenches. For a true step-by-step guide to removing the guts of the Dana 30 axle, check out Stu Offroad: Removing D30 axle shafts. That’s a comprehensive guide, so I won’t try to duplicate it here. I’ll just hit the highlights, then get to the locker install.

As prep, spray all the bolts and metal-to-metal surfaces with PB blaster. Preferably, do this the night before you plan to work, and also the morning of. Helps to loosen up rusted fasteners and mated surfaces. It’s not magic but it does help a bit.

Then get to work. First, block behind the rear tires with good, purpose-built ramps (you can’t see them in these photos but they are there). Then jack the front and put SUV-sized tall stands under the frame, right behind the front control arm brackets. Why not under the front axle? Three reasons: (1) the front end goes higher this way, giving me more room to work without stooping; (2) the axle can droop lower, giving me more room to work under the wheel wells; (3) if I’m messing with the axle, I don’t want to take the chance of dislodging the jack stand in the process.

By the way, the cardboard on top of the jack stands is to prevent the jack stands from scratching the frame paint and inviting rust.

For extra insurance against having the Jeep fall on my head, I put the wheels under the skid, and added a block of 8x8 wood I had lying around, for good measure.

This is a good time to put on safety glasses. You are going to be banging a lot of metal on metal, and bad things could happen. Seriously, wear some eye protection.

Next, put an oil pan under the differential. Take out all the bolts but the top one. For the moment, you can do this without removing the tie bar (that’s the black bar running across the pic).

Encourage the oil flow by wedging a screwdriver in there, and leave it while the oil drains. However ….

… when you later go to take the cover off, remember that screwdriver!

I learned something from this mistake -- diff oil is so thick and nasty that it will float a screwdriver. Who knew?

FarmerinVA 07-02-2011 03:14 PM

While you wait for the oil to drain out, you need to remove the tie bar and axle shafts. Novices, the reason you need to remove the axle shafts is that the axle shafts are engaged into the differential’s gears. They will hold onto those gears unless you slide them out. So here’s what you do. Again, consult Stu Offroad for more detailed instructions -- that’s what I was working from. But do not remove the axle shaft from the bearing assembly as Stu did. That is not necessary. Instead, remove the axle shafts and bearing assembly together as a single unit.

Here’s the wheel bearing assembly and brakes. You need to remove the brakes, then remove the brake rotor, then remove the bearing assembly that contains the U-joints, bearing, and axle as a single unit (again, there is no need to separate the axle shaft from the bearing assembly). That sounds like a lot of work but it’s actually a cinch.

To do this, first remove the brake caliper bolts, which are on the back side where marked in yellow below. The brake then lifts right off. Zip-tie the brake to something so that it doesn’t hang from the brake line (which could damage the line). That's what I'm doing in this photo.

Remove the rotor -- it will come right off, since it was held in place only by the brake and the wheel. Then remove the three 13mm 12-point wheel bearing assembly bolts (behind the red arrows in the photo - one of them is in the back toward the bottom where I couldn't point to it).

Note: the torque spec on these wheel bearing assembly bolts is 75 lbs but (as Stu Offroad predicted) the factory had torqued them down to more than 150. I didn’t have an impact wrench at this point, and I had a heck of time getting these loose. If you have an impact wrench, use it here. Without one, I found that this was by far the hardest part of the whole job.

The bearing assembly is now free. You may need to pry it loose due to rust -- I used a screwdriver and a hammer and some gentle chiseling/prying action around the edges, and it took some doing. But once the rust breaks free, it slides right out. Make sure you are gentle when you slide it out because there is an oil seal in there, up next to the differential case, that you don’t want to damage as the axle shaft slides over it.

Wait, is it really that simple? Just undo five bolts on each side? Yes, it really is that simple. I have to admit, I was amazed. A novice really can do this!

At any time in this process, unfasten the tie bar on the driver’s side so that you can swivel it out of the way to have room to work inside the differential. This step is kind of cool – there is a “castle nut” there, which really lives up to its name (it has crenellations on it! Crenellations … I knew those architecture classes would finally pay off one day). Take a pair of needle-nose pliers, pull out the cotter pin that holds the nut down to the bolt. Knock out the bolt using a puller (which I didn’t have) or a very large punch (which I also didn’t have) or a three-inch 3/8” socket extension (which I did) – anything that doesn’t smash the threads on the bolt. Work it slowly, it’ll come. Put something under the tie bar so that the bar doesn’t smack the ground when it comes free.

FarmerinVA 07-02-2011 03:24 PM

Now we’re ready to attack the differential. The cover comes off and ….

Rats. Here’s what you’ll see if you have 3.73 gears (as I do) or lower: the ring gear blocks the cross shaft. The cross shaft is the silvery thing in the middle. It runs through two of the four spider gears, and thereby holds all the gears in place inside the diff.

If you can get to the cross shaft, as you can with 3.07 gears, you can do all the following steps right there in the differential, without removing it from the axle housing, which would be VERY easy. But I can’t get to the cross shaft. Fortunately, I already anticipated this, from other reading on JF.

[You could also grind off part of a ring gear tooth, which some people do. That, in my view, is more difficult and error prone than removing the carrier.]

To get to the cross shaft, I need to remove the ring gear, which means I first need to remove the diff from the housing. First, I remove the bearing caps on either side (5/8” socket). Then I pry the case out. There are several ways to pry out the case. As an experiment, just to do something simple, I started by hooking a crowbar on the inside of the diff case; I put a block of wood (not shown) between the bar and the housing where I was levering against the edge, so I wouldn’t damage the housing’s sealing surface; and I tapped the bar with a hammer.

I wasn’t going to do this hard because I was scared of hurting the case, but lo and behold, this worked great. Take it slow (you don’t want to launch the differential case out onto the floor). It was jammed in there good -- preloaded, as it says in the manual -- but this method eased it out quite easily, a fraction of an inch at a time. You need force, but not a lot of force. I had planned to pad the end of the crow bar but it turned out that I wasn’t using enough force to feel like I needed padding.

Which leaves you with ...

... an empty housing. Again, was it really that easy? Again, yes! I was shocked. If I can do this, anyone with a little time and the correct tools can do this. And as you’ve seen, the tools are standard and pretty few. Wow.

Try not to think about the fact that you have to get this all back together again. Take a deep breath, don’t panic. I had nobody helping me and I figured out the reinstall; in fact, I got it all back together in much less time than it took to take it apart. You’ll be fine.

This would be a good time to check the condition of your pinion. This would also be a good time to install axle seals if you need them. The axle housing, it turns out, isn’t sealed at the wheel end. There is a sort of plastic dust cover there but it won’t keep out water or slurry mud. There is an oil seal way in there next to the differential, but that leaves the rest of the interior axle housing and axle itself to bathe in filth. A solution is to get an axle seal for the wheel end, such as this one from Superior Axle and Gear, which is just a press-in fit at this stage of the work. I decided against it just based on price and the age and condition of my Jeep, but if you have a nice Jeep or the extra money, think about this.

OK, that's enough typing for today. I'm going out to drive it, since as I type this, it's long since done. More to come.

FarmerinVA 07-03-2011 10:04 AM

Now, take the diff and move to a work bench. To get to your cross shaft out if you have 3.73 gears, you first need to remove the ring gear from the differential. Here’s where I got stuck: those ring gear bolts were not budging. I got annoyed and forgot to take pictures. After trying an assortment of breaker bars and curses, I gave up and called my friend Eric, who has an electric impact wrench. Zip -- they were off in two seconds per bolt. I later discovered, with the rear axle’s ring gear bolts, that using a hammer on the end of the socket handle works just as well as the impact wrench (impact is impact).

Once the ring gear is off, clean it and the diff with brake cleaner. Spray the cleaner particularly into the ring gear's bolt holes, and dry them out with a rag, because later you will need them to be dry so that you can apply LocTite to the new ring gear bolts. Do the cleaning now, so that the holes can dry further while you work on the No-Slip.

At this point, follow the excellent directions included with the PowerTrax No-Slip. Tap out the cross shaft’s roll pin using a little punch and hammer. I didn’t have a punch, so I used the flat end of a broken 13/64 drill bit – a perfect fit, and it worked great. Then remove the cross shaft itself using an appropriate big punch. Again, I didn’t have a big punch, so I used the three inch long 3/8” ratchet extension again (you can see it to the right) -- again, worked great.

With the cross shaft out, all four spider gears will drop free. Also remove the washers between the gears and the case. You are left with this. You won’t be using the spider gears or original cross shaft again -- clean them up and keep them as a souvenir of the big deal mechanic you are becoming.

FarmerinVA 07-03-2011 10:08 AM

Now lay out the parts of the No-Slip on your bench (make sure the bench is clean). Mine originally wasn’t clean, and I ended up having to clean the darn locker … argh.

So that you can test how it all works together, mate the couplers, active spacers, drivers and cross shaft together (without springs) as a test. There is only one way to get the teeth to mesh together solidly, and you need to have the active spacer's big tab (they call it a “paddle”) of the active spacers in the correct place to do it. This shows you the "paddle" (at the bottom on the left) and the space where it will go (bottom on the right).

It will be obvious when you have it right. Once you are confident about it, do it for real in the differential, without the springs, as a test run.

Now install the springs and do it for real. Install the yellow springs into one thrust block, after coating them liberally with heavy grease, which keeps the springs in place during this process.

Repeat for the other thrust block.

Install both couplers in the differential. It is a tight fit to get them through the opening, but they just barely clear. This is idiot-proof -- they only fit one way.

Place the active spacer (left) into the driver so that the tab/”paddle” on the spacer lines up with the gap in the driver. I'm showing this again, because it's easy to get wrong, and it's the one way you can screw this up:

Then, keeping the active spacer in place so the tab-paddle is in the correct location, drop the thrust block into the differential as shown. Engage its teeth with the coupler on that side. If it engages the teeth fully, the spacer’s tab-paddle is correctly located. If it does not engage fully, the tab has slipped, and you need to pull it out and reposition the tab.

Repeat on the other side.

Push in the cross shaft through the open side of the differential, just as a test: do all the teeth fully engage? If so, you’ve succeeded. Pull out the cross shaft. Now you are ready to do the final install of the springs.

FarmerinVA 07-03-2011 01:38 PM

The almost-last step is to install the springs between the thrust blocks. Rotate the device inside the differential so that you see the slot; put the small spring inside the large spring, and install.

The large spring is quite stout, and you will need a screwdriver to compress it from the side, with some real force. As you do this, keep your other hand over the spring in case your screwdriver slips, because if it does, the spring (which is under quite a bit of tension by that point) will pop out and will go flying if you don’t have your hand there to block it. This happened to me and I easily could have lost the springs. Repeat on the other side.

Then tap the cross shaft through the differential until both ends are flush, and re-install the roll pin. The cross shaft will feel at first as if it is too big to fit, but fear not, it will fit. As you tap it in, use the roll pin as a handle to make sure the roll pin hole will line up correctly. Obviously, you need to take the roll pin out at the last bit, as you tap it in the last centimeter or so. Then re-install the roll pin in its hidey-hole, using a punch (or my 13/64” broken drill bit).

Finally, use the included “check block” to ensure that the no-slip is still installed correctly. This is a “go / no go” tool, per this page in the manual.

Here’s “go”:

Here’s “no go”:

It's a bit hard to tell from the photos but what's happening here is that the "go" side fits into the space (just barely), and the "no go" side does not (again, just barely).

Success. I’ll be darned, it worked.

FarmerinVA 07-03-2011 01:58 PM

Now re-install the ring gear, torquing the bolts to 70-90 ft/lbs after applying LocTite 242 to each bolt. Remember to tighten in a criss-cross pattern. My differential was helpfully labeled with cast-in numbers on the bolt holes that make this easy to do.

Now install the diff back into the housing. The only tricky part about this is holding the heavy diff in place with one hand while you hammer it in. I did it solo but this would be a good place for two people to work together. As a precaution, I put padding on the floor in case I dropped the diff. Fortunately I didn’t drop it.

Don’t use a steel hammer, of course. I am using a soft rubber mallet here, which worked very well. It is not capable of harming the steel ring gear and diff housing.

Install the bearing caps, torquing to 45 ft/lbs. Your differential is now back in place, ready for the re-install of your axles and everything else.

The rest of the job is just a re-install of what you took off before, but preferably you should test the locker before you put everything back together. The testing technique is explained in the manual, and you’ll need a friend to do it. Basically, slide back in both axle shafts and then turn one of the hubs back and forth while your buddy holds the other one stationary, to test the locking and unlocking. I say "preferably" you should do this, but I didn't because I didn't have a buddy to help. I just trusted that it all was working correctly. And it did, so I didn't have to assemble and then disassemble to trouble shoot, which would have been a pain.

The total re-assembly steps are:
  • Slide back in the axle shafts. The manual says you should put heavy grease on the shaft where it rides on the oil seal (the shiny part). Make sure you don’t drag the axle over the interior of the shafts, or hurt the interior oil seals as you slide it in – basically, don’t be a gorilla about this. No force is needed here.
  • Put the dust covers in place (if you have them). Or don’t, as some people don’t want them and say that they make no difference.
  • Install the wheel bearing assembly bolts, torquing to 75 ft/lbs, with a 13mm twelve-point socket.
  • Place the brake rotor on the wheel.
  • Place the brake caliper on the wheel and rotor. It tilts in.
  • Install the brake caliper bolts, torquing to 11 ft/lbs, with a 13mm six-point socket. Only 11 pounds – tighter is NOT better.
  • Install the wheels and tires, torquing the lug nuts to 85-115lbs (I use 93lbs), with a 19mm deep socket.

If everything works, button everything up. Install sealant or a gasket on the diff housing. I decided to use a LubeLocker ($20) gasket, since my diff housing’s surface was a bit pitted -- making me unsure whether a paper gasket would get a good seal -- and I didn’t want to fool with messy RTV paste sealant. Here’s a picture of the LubeLocker in the package, which also shows the installation instructions.

Install the diff cover bolts, and torque to spec. Spec on the bolts when using sealant or a paper gasket is 30 ft/lbs. The LubeLocker says to use 35 ft/lbs, so I did.

The LubeLocker is soft enough to mold to minor imperfections in the sealing surface, and supposedly reusable if you ever open the cover again. It seemed pretty idiot proof, and it went on with no leaks. Six weeks later, still no leaks. Looks like a success.

Fill the diff with 70w-90 gear oil, per the manual’s specs, and replace the fill plug.

Re-install the tie bar, torquing the castle nut to 55 ft/lbs with your 1/2 inch socket, and install the cotter pin retainer (preferably a new pin).

And that's it.

aslack99 07-03-2011 04:41 PM

Nice write up. Thanks!:D

andy02 07-03-2011 05:46 PM

I have two small suggestions on dis-assembly of the front. First, after you get the three 12 point 13MM bolts out, instead of prying on the hub to get it out, place a 2 1/2 inch bolt between the axle housing and the outer ear of the U-Joint. After that, you just turn the steering wheel a little and the hub will pop right out. It helps to have two people, but I did it myself. I believe that mrblaine originally thought that up but I could be wrong.

Second, when dis-connecting the tie rod, do not take the castled nut all the way off. Leave a couple of threads engaged and then hit the knuckle where the TRE is. It took two light whacks for me. The nut staying there prevents the tie rod from falling to the ground and with this method, there is no chance of screwing up the threads.

Great write-up!

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