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if you're new here, you might not know that a large amount of jeep liberty discussion history got whacked just before the forum big-shots moved us to this current web address...of course it hasn't taken long for this new site to be populated and everyone is anxious to replace the useful stuff that's gone...I was asked to replace a story I wrote last winter about installing the no-slip locker in my jeep...I think the idea was that since I fouled up the process, it might be interesting to some of you and save someone some grief...many folks have completed this job with no problems and problably could better explain how to do it...my story is long and I think it might sound like I'm full of myself...that's not really what I'm about...I just really enjoy this l.o.s.t. stuff...
about a year ago, owning a jeep was the farthest thing from my mind....now I spend way too much time hanging out on this web site and a few others devoted to jeeps...I've learned quite a lot in just a few months about trail rides, jeep clubs, jeep models, aftermarket modifications, etc. and still I don't know much compared to most....I loaded up my credit card on stuff that was recommended here and my wife and I went to moab to scuff our boots in the dust....
I can't claim any great mechanic skills, but I did install the rusty's coil spring and strut lift, the boulderbars rock rails and transmission skid from all-j products, a front hitch receiver requiring removal of the bumper facia, and a few other smaller jobs....I did all of these things by myself in my garage out of my own toolbox....I found it extremely useful to have read the discussion threads on this web site prior to each saturday project....in most cases there were links to printed instructions....generally all projects went smoothly....but as a rule, there is always some element requiring improvisation and a hammer....(since I first wrote this stuff, I've pulled the front differential and installed a detroit truetrac unit...I took some pictures and wrote a story about that...it's listed here in the tech section...)
I hope some of you might find this interesting and feel I made a small contribution to the fire...I'm definitely shade-tree so please feel free to comment and correct anything that follows so that it is helpful to others on this web site....
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there have been recent discussions about the installation of the powertrax no-slip locker mechanism in the jeep liberty rear differential....a few months ago I also put this set-up in my jeep and offer a few comments here....
if this powertrax subject has been of interest to you, you probably noted in other discussions the claim that the install is not difficult and can be performed by a modestly capable person with a jack and a socket set....it's true that the locker components come with a detailed instruction booklet and I was able to install it correctly....I had intended to take a lot of pictures and report in detail the install steps....not long into the job I ran into a few problems that were not covered in the instructions and had not been mentioned in anything I'd read here....patience is not one of my virtues and I got aggravated and made the job more difficult than it has to be....my hands were greasy and the photo inspiration left me....now I wish I had taken more pictures....
I have an '04 liberty sport with rear disc brakes....most of us have either the open differential rear end or the factory trac-loc limited slip design in the chrysler corporation 8 1/4 inch, 29 spline axle, rear differential...(I know there is also another rear axle that someone described in an old discussion but I don't think it's common)...I have the limited slip design....there is a powertrax no-slip locker part number that specifically replaces this set-up....part no. 92-0382-2925...I purchased mine from the tellico4x4.com web site....they were offering a 10% discount at the time...so the unit for my rear differential was about $325 plus shipping...(in case you have the open differential design, the part no. is 92-0382-2905)...
there is also a part no. for a chrysler rear end 8 1/4 - 27 spline....not sure what vehicles those are found in...anyway, be sure to remember that the KJ is a 29 spline axle...
in addition to the correct powertrax unit for your rear differential (open or trac-loc limited slip), you'll need a socket set with 1/2" socket for the differential cover bolts, a drain pan to catch the old gear lube when you break the cover seal, a stiff putty knife or gasket scraper to remove the old gasket sealant, some solvent like brake cleaner to clean up a little, some rtv gasket maker to reseal the cover, about 2 quarts of your favorite gear lube (I used valvoline 85w-140 mineral)...you also will need a small amount of wheel bearing grease and a sharpie marker is useful....I also purchased a "poison spyder" brand differential guard which uses allen wrench type socket bolts instead of the factory cover bolts...you don't have to have a torque wrench...
by the way, if you aren't familiar with brake-cleaner in aerosol cans, it's like a miracle product...many uses in the garage....de-greases better than gasoline and evaporates quick like alcohol....(I use to sell auto parts when I was younger and people would buy it by the case to use as roach killer...better than RAID)...also, I was told by a jeep mechanic that the gasket maker of choice is called "the right stuff" by permatex...comes in cheez-wiz can...but you can use the toothpaste tube flavors if that's what you like...
if you're lucky, this job would be much more fun if you can put your jeep on a lift...then you can stand up and reach into the heart of the rear end in comfort instead of laying on your back...otherwise, you jack and safely support the rear of the jeep and remove the two rear tires/wheels...if you're a casual mechanic like me, I think the most important thing to consider is safety....I sometimes shudder when I think about the times I've crawled around under my jeep with the wheels off...be really careful about your jack and car stands...
you can now remove the (10) differential cover bolts...it might be of interest to know that the cover will not fall off nor will the gear lube leak out yet...the gasket material holds the cover on tight....(so if you just want to pull the bolts to install a cover guard, it's no sweat)....pry the cover loose near the bottom and drain the old gear lube into a pan...be prepared for the smell of old gear lube...it has a distinct smell that I don't care for...if you get it in your clothes, the smell won't go away...
scrape the old gasket material off the machined face of the differential housing, clean up the cover and scrape the gasket material off of it also....I used an old rag to pull the old gear lube out of the bottom of the housing and then killed a can of brake-cleaner to finish the job...there's a small magnet epoxyed to the bottom of the housing to capture metal particles so remember to wipe that off...
now you will follow the instructions book to remove some of the components in the factory differential...these will be replaced with the new locker mechanism....it probably isn't necessary to list all the installation steps since they are included in a detailed booklet that comes with the locker...I'll throw a few things in here that stick in my mind...
there were a few details that would have been useful but were not provided....the instructions will describe the necessity for moving the axle stubs in and out of the differential by moving the brake rotor in and out....they don't specifically state that you first must remove the disc brake caliper assemblies....this is not difficult, two bolts (1/2" socket) on each caliper come off and then slip the caliper off the brake rotor, hang the calipers with some wire or rope safely out of the way so as not to foul up the brake hoses....now the axles can be moved in or out as needed....I don't know about you guys with drum brake rear axles...maybe someone can add a comment...
the large cavity in which all of the diffential components are found is called the housing or "pumpkin" by some....the rear drive shaft is connected to a pinion gear in the lower housing which engages a 8 1/4 inch diameter ring gear (so it's a chrysler corporation 8 1/4 rear diff.) that rotates in the same plane and direction as the wheels....the precise fit of these two gears is critical to their operation and the tolerances are measured in just a few thousands of an inch....the ring gear is bolted to a "carrier" or "case" which is "hollow" and inside of which are four intermeshed gears....these gears rotate as a unit with the ring gear/carrier and also turn independently of the carrier when the the two rear wheels need to roll at different rates while cornering....hence "differential"...
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in the two diagrams above, they refer to what I call spider gears as "pinion gears"....not the same thing as the pinion gear that turns off the rear drive shaft....
for most of us, the pinion gear/drive shaft turns 3.73 times for every (1) revolution of the larger ring gear...so most of us have 3.73:1 gear ratio...the "drive" is now changed to a rotation along the plane of the axles/wheels...this rotation torque is carried to the axles through the assembly of the four differential gears...I'll throw a couple of diagrams in here to pad this story but I'll leave it to you to study it...
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the letter "D" represents the drive force applied to the spider gears through the pinion shaft which turns with the carrier...."R" represents the reaction forces that the side gears exert to counter this drive force....this force on the side gears supplies the torque to the axles....
the two gears that rotate in the same plane as the ring gear and are splined (29 spline) to match the ends of the axles....the axles turn inside of the tubes that run from the differential housing out to the left and right wheel hubs...the axles are secured to the splined "side" gears by c-rings....
in the diagram below, the pinion shaft has been removed and the axle stub has been pushed inward to allow removal of the c-ring....
this c-ring design is of some interest to jeep mechanics in that it is different from some of the other popular jeep axles and presents certain vulnerabilities should a axle break on the trail....however, the chrysler 8 1/4 rear end with 29 spline axles is considered to be a pretty stout unit, also used in some of the cherokees and some dodge pickups, and compares favorably to the popular dana 44 rear set-up....(anyone who knows more about this can please confirm or correct me)...
the other two differential gears that mesh with the side gears are refered to as spider gears and they turn on a pinion mate shaft that runs through the center of the carrier assembly....this pinion shaft also prevents the two axles from moving inward and allowing the c-rings to fall out....in my case with the trac-loc limited slip differential, there are also a stack of clutch plates on both the left and right behind the side gears which are spring loaded and exert a force inward on these four differential gears.....
the four differential gears and the clutch plates are removed before installing the powertrax no-slip locker....the instructions leading up to this point are clear and the procedure is pretty simple...the pinion shaft comes out allowing the two axles to be pushed slightly inward...this allows the c-rings to be removed...once the c-rings are out, the axles can be pulled outward...(and removed completely should that ever be necessary)...
after removing the pinion shaft and sliding the axles out a little, the instructions simply state "remove spider gears".....the implication is that they are easily removed, that they might fall out in your hands?....perhaps this is basically true for the open differential design but in my case they were not loose and I did not know the "trick" to remove them...supposedly, if you put your tires back on the rotors temporarily, you can turn one side while someone holds the opposite side stationary...the rotating side gear will turn the spider gears out of their seat and fall out...(I didn't know how to do this at the time so if someone wants to pile on here and explain it better...)
anyway, I'm guessing that since my trac-loc clutch packs were essentially new and not at all worn out, their spring load effect on the side gears and spider gears made the gears remain tightly seated....(again, I'd like to hear more about this theory from you guys)....I tapped on them with a punch and hammer but I was concerened with damaging something that would cause problems later....after studying the problem, I tapped on them just a little harder....I re-read the instructions and drank another beer and whacked them a little harder and got them just a little cocked so that the pinion shaft was not going to go back in if I needed to back up and reassemble everything....bear in mind, I'm lying on my back, reaching essentially upside down, smelling old gear lube, busting my knuckles, and I got a little aggravated....
this is the part where I F-up...
I thought about who I might phone for advice, found a number for someone on this web site that I had not yet met and placed a call....I got voice mail....I lost a good portion of the afternoon waiting for a return call that was not guaranteed....so I finally decided to remove the entire carrier assembly and put it on my work bench so I could stand up and study the problem....
if you DO NOT remove the carrier assembly you will not need to understand this next stuff...
two larger bearing cap bolts on the left and two on the right of the carrier assembly and which are visible in a photo above, fasten two bearing caps to matching saddles in the housing....these caps secure the races for two tapered roller bearings....the roller bearings are pressed onto the ends of the carrier assembly and support the rotation of the ring gear/carrier....in the assembly process, the bearing races (or cups) are moved inward to their correct locations by discs that are threaded around their outside diameter and they match the diameter of the races...these discs turn in threads cut into the bearing caps and the saddles in the housing....(imagine how a light bulb screws into a socket)...these discs (spanners) are turned with a special long tool which slips through the length of the axle tubes...(this tool is like a very big allen wrench that you can put a socket and torque wrench on the end of)...the effect of which is to move the races into the bearing rollers and move the ring gear into or away from its interface with the pinion gear....anyway, when you remove the bearing cap bolts, then the carrier asssembly, the bearing races, and the spanners literally fall out of the housing....
removing the carrier assembly is something you specifically DO NOT WANT TO DO when installing the powertrax locker....so now I had disengaged the ring gear from the pinion gear which as I mentioned requires a precise fit to operate dependably at high rpm's....the reinstallation to these tolerances requires special tools and special skills....in fairness, I knew I was taking a chance here...(though I'm obviously not that smart)...I worked in a automotive machine shop for many years when I was much younger and I understand precision machine measurements...I hoped that I could pull off a shade-tree mechanic, award winning move and put it back together, but for now I just wanted to figure out how to "remove the spider gears"....
within a few minutes of dropping that carrier assembly out of the housing, my phone rang with a return call from a super nice guy from the l.o.s.t. web site who told me how to solve my problem....with a hammer and punch, turn the side gears as if they were on the axle and "rotate out" the spider gears...(I could have done this by remounting a tire and turning an axle and I'm a little ashamed I didn't figure that out)....anyway, I've got it on my work-bench now and I had to really whale on it with a hammer and punch and as the side gears turned, the spider gears worked their way out....and when they fell out, so did the side gears and the trac-loc clutch plates....(I've since read that there are special tools used to load the clutch plates and I doubt I would have ever put it back together at that point)...
I would now have to reinstall the ring gear/carrier with the bearing races and the adjusment spanners before I could finally begin to install the powertrax no-slip locker....there was no way I was going to be able to get the spanners set to specifications without the special axle length wrench....I would also need to set up a dial indicator and move the carrier left or right to set up the correct gear lash which I really don't know how to do....I was planning to drive across country in a few weeks and aslo, the jeep is new....so I was now resigned to taking it somewhere to have the gears set up correctly....
but first I had to put it all back together at least temporarily so I could at least roll the jeep out of the garage....in fact it turned out better than that, but I was very concerned at the time....I set the bearing races/spanners as snuggly as possible by hand, took special care not to ding the bearings or cross-thread the spanners, torqued the bearing cap bolts, and picked up the process where anyone else would have been hours before....I might be making this seem "minor" or "easy" and it was not that way...it was a bear and I was pretty PO'd....I struggled in my attempts to hold the carrier with one hand while laying on my back and using my free hand to snug up the bearing cap assemblies....it is very easy to cross the threads on the spanners and on the bearing cap bolts....
installing the no-slip finally....
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even though I knew the pieces were going to have to come back out when I took the jeep to a garage for the gear set-up, I now had to install the powertrax locker....the locker goes into the cavity where the differential gears used to be....there are several pieces and you position into the carrier cavity one piece at a time with your fingers....it has to be assembled exactly correct (like a puzzle) and is not exactly easy to do but the instructions are pretty straight forward and I did in fact install it correctly....I suggest you put it together on a bench and mark with a sharpie the exact line-up of teeth so that when you finally install it, you'll know it's set up as directed....I think it helps if you understand how it works so that would be the time to study the design...also, when you're ready to put it together for the final time, paint it with wheel bearing grease to "hold it together"...
the locker design uses those axle c-rings...they are about the size of a half-dollar outside diameter....they wrap around the axle stub like your thumb and finger wraps around your wrist...after slipping them back in, when you pull the axles out to "seat" the c-rings, they have to sit in the bottom of a cup...much like a half-dollar would sit in the bottom of a coffee cup...you will need to test these on the work bench....it's common for them to be too large....I held mine in a bench vise and used a flat file to take down the outside diameter of the c-rings till they fit comfortably....you don't have to have a grinder or dremel tool....removing the c-ring from the locker when it's in the carrier is tricky so this is important so that the locker can be easily removed at a later time....
also, I finally caved and asked my wife to come out and push and pull the axles/hubs while I lay under the rear end and put the pieces in the carrier...(but I could have done it alone)...someone made a comment here recently that I agree with...doing this install a second time will probably be much quicker than the first time...
the instructions describe a wheel turn test to confirm the installation but to be honest I couldn't say that I got that test to work....I turned the wheels by hand, the components inside the carrier didn't fall out, the rear drive shaft rotated, there wasn't a lot of slop (surprisingly since I had pretty well fouled up as I described)....so I sealed up the cover and filled it with gear lube....I carefully drove it around the subdivision block and it made no clunk noises....no noises at all....I had another beer....
you don't need to boatload the rtv sealant on the differential cover...run a modest bead completely around the cover and it will spread when the cover is tightened...after applying the sealant to the cover, find something else to do for a few minutes and the sealant will set up a little before you place it in position...use a gradual, alternating tightening sequence....use a 3/8 drive ratchet so you can feel in your hand how the bolts are snugging up....you don't need a torque wrench....consider that a leak would most likely occur on the bottom and try not to slide the cover around while putting the bolts in...a short length of fuel hose or surgical tubing on the tip of the gear lube bottle will make it a little easier to fill the differential....I like valvoline products but that's just an old man's habit...
I'm probably going to change my gear lube soon since its been a while now and I drove out west a couple months ago....when in operation, the differential builds up heat....if you suddenly submerge it into a cold stream on a trail ride, the rapid cooling creates a vacuum in the housing which can pull moisture through the seals into the differential....water and oil don't mix well....just something to keep in mind when you're thinking about service intervals....I read this in a jeep magazine but it sounds smart....
so anyway, I'm rolling now and I even drove to work with no apparent problems...monday morning I made a few phone calls, found a jeep shop with a recommended gear mechanic and made an appointment to have my work "inspected"....I've been long winded here in this report and I know I say too much for my own good....if you haven't tried this work before, then it probably got pretty boring several paragraphs ago...but if you've had your hands in places I've described then you can envision everything I did....and that is a point I wanted to make....
I don't want to sell myself short...my dad taught me a few things about working on cars when I was a teenager and I own a pretty good box of tools...but that's about it...over the years of your life you discover new interests and when this "jeep thing" grabbed me several months ago, I decided I wanted to try and learn as much as reasonably possible about the popular modifications that jeep people stand around and talk about....so I took a chance with the suspension lift and installed it myself and I guess I got lucky because I've had no problems with it and I learned a little about how the suspension is assembled, etc...so now I can easily remove the sway bar links for a afternoon of trail riding and I can lay underneath the jeep and reinstall them in just a few minutes while saying goodbye to the gang I spent the day with....I know which wrenches I want to carry in my jeep tool bag, and I can volunteer to help with "some" trail repairs if the occasion arises...
I took my KJ jeep in to have the locker removed, the ring gear/carrier set to specifications and the locker reinstalled....it cost me $200 labor/shop fee/gear lube....I was able to accurately describe to the mechanic the components of the rear differential and the things I knew I needed to have done to make it right....he was a recommended guy and I guess he was rolling his eyes when I told him what I had done...but I knew what I was talking about and we established a connection...I was able to watch from a distance the work he did....by the time he was about finished I think he saw that I had in fact not screwed it all up and did not make his job more difficult...he said I did it right...at any rate, while the jeep was still on the lift and the cover open, he invited me underneath and we spent about a half hour shooting the breeze about jeep rear ends, the powertrax lockers, the liberty as a trail rig, his opinion on synthetic lubricants, etc....he asked me to send him a picture of the jeep "dirty"....when I went back up front to pay the shop owner, he said "wow, he never invites the customer back there"....
I don't mean any of this in any vanity....I was pretty foolish and I'm lucky to not have caused any damage....I wish I had that $200....but I learned a lot for my aggravation and I found a good independent jeep shop that does good work and sells the popular jeep stuff....I've since e-mailed the shop owner some pictures of our moab vacation and a link to this forum...I've spoken to him a few times and purchased a few things from him...he remembers me and he now knows about our l.o.s.t. culture...he's cool, he's a jeep guy and I'm glad I got to know him...
I guess I've put about 9,000 miles on the jeep since the install....I went to the moab thing and was told that we rode on real off-road trails...so I guess I'm officially trail-rated....I crawled over every rock I could get to and tried to make every trail a "double diamond"....as for daily driving, I don't hear the locker and it causes no problems for me...in my work commute, I have to make a couple sharp accelerating turns into heavy traffic...I can feel the inside tire jump then...I do notice a driveline slop when I'm stuck in stop-and-go interstate traffic...a little gas, a little brake, a little gas...you can feel the "clunk"...the literature says this is normal but I have to say it's annoying...all in all though, I'm not disappointed...
I think my biggest concern is what will I do if it fails on the trail...when you hold the pieces in your hands, they don't appear to be that substantial....if it fails, I have no rear drive...if I carried a spare locker ($$$), I could maybe replace it (with some aggravation) since I did it once before...I read in a magazine that the limited slip carrier is slightly less durable than an open one since it has been machined to accept the clutch packs...I doubt with the limited tire size we run that I need to worry about that...if I had to do it again I would have the open carrier design and then I could just replace the spider gears (though I've not done that before)...I need to talk to someone about a detroit locker...I hear they're the bomb...
thanks for taking the time to read this guys...
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