Extreme Novice Installing PowerTrax No-Slip, TrueTrac, Crown 4340 rear axle shafts
This thread aims to answer three related questions:
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:
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.
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.
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.
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,
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:
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.
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.
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.
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?
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.
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.
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.
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.
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 “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.
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:
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.
Nice write up. Thanks!:D
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.
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