I've only been on a few organized trail rides and I guess it all depends on what you are listening for, but it seemed that I often heard jeep owners discussing locking differentials....that's a subject I didn't really have a grip on so I began looking for forum discussions on lockers....the l.o.s.t. site has had several "lockers for libertys" topics lately so I've learned quite a bit reading those threads....I decided that installing differential lockers would be my next jeep modification priority....I think after this, I'll probably have to stop spending money on the jeep for awhile....:rollin
I recently installed the powertrax no-slip locker in the rear differential....I did the work myself and learned a lot that reading about it just won't teach you....I wrote a report a few weeks ago where I confessed my struggles with what many consider a fairly simple project....but things are fine now with that and I'm looking forward to a trail ride where I can enjoy the benefits....last weekend I completed the locker project by installing the front true-trac limited slip unit....it's not technically a locker but I will refer to it that way for simplicity.....because of the issues I had with the rear, I was concerned about taking apart the front, a task considered much more challenging....but the front turned out well (so far) so I've written a report on that effort....this report is way too long but if you want to keep reading here goes....
---------------
I've worked on cars a little bit, especially when I was much younger, but I had never taken apart a drive axle differential before these projects....fortunately there are some detailed discussions on the l.o.s.t. site that are pretty useful if you want to try something like this....for the front end, I used the tech article written by darby walters a few years ago...[link=p087.ezboard.com/fkjjeepfrm16.showMessage?topicID=12.topic newwindow][font color=red]check here[/font][/link]....without it, I wouldn't have known where to start....but my limited experience required a little more detail....so where he might say something like "next, put on your shoes"....well, I need instruction on tying my shoe laces....
I'm not sure what the forum moderators feel about a detailed report like the one that follows....it's a lot of text and pretty dry reading except to those interested in it....additionally, the possibility of screwing up your jeep if things go wrong is not something anyone here wants to happen to a fellow lost jeeper....I wanted to install lockers in the jeep and of course I assume full responsibility for trying to do it myself....I would never grumble that this web site led me to do something that turned out poorly.....that would be my attitude towards any of you who use this information for your own locker project....it is a pretty big job and could leave you without transportation for a while if you have problems....
----------------
my front locker process begins with....
jack and support the vehicle and remove the tires....you're underneath and crawling around....be safe....good jack stands and floor jack....it can't be overstated....
[font color=red]BE SAFE[/font]....assuming you have the front skid and the transmission skid, they have to come off....you're going to pull the aluminum d30 differential housing completely out from underneath the vehicle....in order to do this, you have to disassemble many suspension and steering components....the front differential housing "pumpkin" is offset to the drivers side of the vehicle....the liberty has a independent front suspension using left and right constant velocity joint half-shaft axles....because of the offset of the housing, the passenger side axle is longer than the driver side...the aluminum housing incorporates a passenger side axle tube for the longer axle shaft....the housing and axle tube have a variety of mounting points to accomodate this assymetrical design....other than that the suspension and steering assemblies are the same on both sides....
[font color=red]many of the front end components described in the next few paragraphs are seen in the photo below....[/font]
the tire and brake rotor/wheel hub are attached to a relatively large steering knuckle....the knuckle is attached at the top to a upper control arm through a ball-joint and at the bottom to a lower control arm, also through a ball joint....the control arms are mounted to the chassis and move up and down as the terrain dictates...attached to the steering knuckle is the rack and pinion steering link (also ball joint design)....when the steering wheel turns, the rack and pinion linkage pulls the knuckles (and wheels) left or right around the ball joint pivots....
the disc brake caliper assembly is mounted with two bolts to the knuckle where the wheel hub is attached....the brake pads in the caliper sandwich the brake rotor....a hydraulic brake line runs from the caliper into the chassis....
a long curved sway bar is mounted to the front of the chassis in rubber bushings....the sway bar is attached to the lower control arm with a "dog bone" shape link....a bolt through a bushing at the sway bar end....a bolt through a bushing at the control arm....the sway bar limits the up and down motion of the lower control arm relative to the lower control arm on the opposite side of the jeep...
the suspension is dampened with a coil spring surrounding a hydraulic strut (shock)...the top of the strut assembly is mounted to the unibody chassis in the engine compartment with four bolts....at the bottom, the strut assembly is clamped with a clevis yoke...the bottom of the clevis yoke is bolted to the lower control arm....as the lower control arm rises or falls with the terrain, the spring/strut absorbs the shock....
running directly through this assembly of pieces, the constant velocity joint half-shaft axles connect the differential to the wheel hubs....each axle incorporates a inner and outer constant velocity joint which allows for a sophisticated flexibility of the axle....these axles will have to be dissengaged from the differential by pulling them out towards the wheel location....the passenger side axle has to be pulled completely out of the extended axle tube....the driver side axle is free of the differential as soon as it is pulled out a small distance...the axles are held in their assembled position by their integration into many of the components mentioned so far....the inner end of the axles are splined and slip into the differential through oil seals into matching splined gearing in the differential carrier....the outer end of the axle is threaded and held in position against the wheel hub with a large nut in the center of the brake rotor....
darby walter's instructions don't mention some of the following steps....I don't know if he was able to complete the project using only what he listed and none of my additional steps....I don't know if he left any of these out for a particular reason....I only know what I did to successfully make the instructions work for me....you're going to be switching from metric to inches to metric all through this....you need sockets, I suggest 1/2" drive with extensions and a breaker bar and a 3/8" drive set for the smaller nuts and bolts....sometimes only a wrench will work so you'll need good coverage in those also....eventually you need a torque wrench capable of 60-70 ft-lbs...a few other tools will be mentioned as we go along....you don't have to have impact tools...
as always, feel free to comment or disagree with any of this....
passenger side first....
the large jam nut that darby refers to is the nut at the outer end of the axle....it sits in the center of the brake rotor between the five wheel studs....while everything was still together, I wanted to make sure I could get this nut loose....it takes a 1 7/16" socket (I suppose it might be 36mm but once they get that big it's hard to tell metric from inches), a size larger than most shade-tree mechanics will have in their box....it will be driven with a 3/4" square drive which is also not in every tool-box....if you plan to remove this nut with a breaker bar, you will need to hold the rotation of the brake rotor....I placed a pry bar between two wheel studs....it wasn't a problem....
a clear path has to be created for the c.v. axle to slide out....I removed the sway bar linkage (two bolts)....I disconnected the steering rack linkage from the knuckle at the ball joint (one nut) by convincing it with a hammer....you don't want to beat on any of the ball joints themselves....you have to shock them apart by whacking the more durable cast knuckle with a heavy hammer in locations strategic to the direction you want the ball joint to move....unbolt the strut clevis yoke both at the bottom knuckle boss and also where it attaches to the bottom of the strut to remove it completely from the vehicle....I removed the brake caliper from the rotor (two bolts)....I left the brake hose attached and carefully tied the caliper out of the way taking care to protect the brake hose....
I removed the bottom ball joint nut, whacked the lower control arm downward with my "metric" hammer (that's a joke).....I removed the upper ball joint nut, whacked downward on the knuckle neck (the upper ball joint is a permanent part of the upper control arm)....the knuckle/brake rotor assembly is now detached at all points....slide it out over the end of the threaded axle end....and on the floor....
I make a point of always putting any bolts back in their correct positions during disassembly, thread any nuts back onto bolts....I try not to put any threaded fasteners in a coffee can....it is much easier to reassemble when you know for certain which bolt/nut goes where....
there is now nothing blocking the path of the c.v. axle....it doesn't just slide out....it needs to be popped outward....don't pull on the end of the axle....that just pulls the constant velocity joints apart....a pry bar behind the inner c.v. housing and pry against the differential axle tube....it pops out easily....slide the axle out of the tube?...NO WAY JOSE...the bottom of rusty's 2 1/2" lift strut blocks the path....
lift the engine hood, disconnect the air intake from the filter box, pull upward to pop the plastic nipples underneath the filter box out of their chassis grommets, remove the filter box to expose the (4) strut top mounting studs.....remove the nuts and drop the strut/spring assembly down and out of the wheel well....now, being careful of the oil seal in the end of the axle tube, pull the c.v. axle out and carefully place it out of the way....
the steps were repeated on the driver's side except that the shorter length of the c.v. axle did not require removing the strut assembly....
---------------
now for the differential assembly....
the differential is guarded in the front with a triangular shaped steel plate....it is bushing mounted in the front of the chassis near the lower control arm front cam bolt....the plate hanger bolt at this location was installed prior to the factory installation of the lower control arm and I couldn't remove it without removing the lower control arm....I didn't want to fool with the the lower control arm because it establishes part of the front alignment....but the plate hanger bolt can be loosened...the guard plate is also bolted to the front of the differential in three locations...when properly secured the plate covers the differential cover and also serves as part of the differential mount geometry....in order to access the differential cover bolts, the guard plate has to be detached from the differential and allowed to swing down from the above mentioned front bolt-through-bushing design....this sounds confusing but if you are under there, you will see what I mean....this guard plate also restricts access to the plastic drip funnel for the oil filter and to the differential vent tube clamped to the differential cover....both of these items have to be detached....the bottom line is that this guard plate has to be dealt with in the process of removing the differential from the chassis....
[font color=red]some views of the front guard and how it bolts on....[/font]
the differential housing and the passenger axle tube is a one piece aluminum design....on the drivers side a three bolt hanger supports the housing....on the passenger side the support is at the extreme end of the axle tube in a two bolt attachment design....this axle tube mount is then attached to the chassis with two bolts through bushings....not only do you remove the axle tube bolts but you also have to loosen the chassis mount bolts so that the differential housing can be free to move in three dimensions while wrestling it out from under the chassis....again I know this sounds confusing....
---------------
finally, the front drive shaft (propeller shaft) from the transfer case attaches to the rear of the differential in a coupling design using six 5/16" socket size bolts....I don't know if they used a chemical thread locker but the bolts were very tight to break free....they are not large diameter so I was concerned about snapping one...you will have to put the transfer case in neutral when you need to spin the propeller shaft to access these bolts, then put the transfer case in gear when you try to break them free with the socket....I then whacked the coupler with a rubber hammer to begin the separation....the propeller shaft has some freedom of motion at the transfer case which allows you to move it out of the way....I tied it off to the chassis to keep it from damage....
the differential cover comes off with ten bolts around the circumference....break them free to drain the gear lube out of the pumpkin....remove the cover, wipe out the excess oil to prevent a mess....I put my floor jack under the housing to use as a third hand....there is a chassis cross member under the housing....you have to wrestle the differential out from under the vehicle using the floor jack, your hands, your ingenuity....I didn't find this to be easy but it can be done.....
------------
installing the locker
the aluminum differential is now out where you can comfortably work on it....the open-gear carrier will be removed and replaced with the detroit true-trac unit.....the ring gear is matched to the pinion gear in the rear of the pumpkin so it will be removed from the open carrier and re-bolted to the new locker....the open carrier is held in place by two semi-circular aluminum bearing caps....the caps are machined specific to their mirror saddles in the aluminum housing....this is very important....I pin punched one side with one mark and with two marks on the other side to make sure they went back together correctly....the cap bolts are torqued to specific values to allow for dependable functioning of roller bearings and races under the caps....the bolts are steel, the caps and their mirror saddles are aluminum....over-torque of the bolts can strip the aluminum threads and/or distort the precise circle the bearings turn in.....you can determine the approximate torque value while disassembling by reversing the torque wrench direction and incrementally dialing up the click value....even still this is not accurate....it is not unusual for bolts to come apart much harder than the install setting will be....they may have used thread locker in the original assembly, etc....
the differential carrier is seated tightly in the housing saddles....a mild pry motion with the end of a hammer handle inside the aluminum cavity will free the tight fit....a shim of precise thickness is installed between the bearing race and the housing on the outside of each bearing saddle....these shims are selected from various thicknesses when originally assembled to precisely set the ring gear lash with the pinion gear....for now we need to ensure we know which shim came out of which side....my two shims were about the thickness of silver dollars and of the same diameter as the bearing races....I scraped the old gasket material off the machined surface, cleaned out the cavity with some brake-cleaner, cleaned the gasket material off the differential cover....
the only thing needed from the old carrier is the ring gear.....I placed it in a vise and unbolted it....I had thought it might need to be "worked off" in some way....the gear easily slipped off the carrier and easily slipped on the new locker.....I read in a discussion about the ring gear bolts might be left hand thread, but they were not....they were very tight and they are stamped "LE" so I could see how someone might wonder....my torque wrench clicked at over 60 ft-lbs. before they turned....they are 3/8"-fine thread which is not a very substantial size and I would not be retightening them that much....
my opinion about torque values will cause howls from some folks and I imagine I'm a fool to say this....but if you turn enough wrenches in your life, you will develop a feel for over-tightening nuts and bolts....a 1/4-20 stud with a 7/16 nut will not survive if you try to "feel" it with a 1/2" drive ratchet....a smaller wrench will allow you to feel when you're reaching the limit of the fastener....tools are made for specific purposes, impact wrenches are great for saving time and breaking large nuts free....but I'm not trying to beat the clock, so I prefer to use hand wrenches and breaker bars to feel the amount of force needed to disassemble or reassemble....I don't worry about the torque value of differential cover bolts or wheel nuts...I tighten them by hand with an appropriate wrench and quit pulling when I feel they have had enough....bearing caps, connecting rods, cylinder heads, ring gear bolts are more important because the precision machined surfaces and dimensions can be distorted when tightened improperly....even still, if you get in the ball park with the torque value, you can usually survive....I have a torque wrench and I use it, but I don't get obsessed with it....
the ring gear goes on the true-trac locker.....about 50-55 ft-lbs. with a little red loc-tite thread lock on clean dry threads....the locker came from all-j california....they listed a l.o.s.t. member discount a few months ago....I asked them to also press new tapered roller bearings on the unit so that I would not have to stop and have the old bearings pressed off the open carrier....of course the bearings come with new races....I hand packed the new bearings with grease, cleaned and regreased the oil seals where the axles come through....placed the locker and races in the saddles and slipped the lash shims back in behind the races....it went together tight which I was happy to see....I torqued the bearing cap bolts to about 50-55 ft-lbs....I don't know what the factory correct torque values are.....shame on me but again that's all I can offer....
permatex rtv gasket maker around the housing face and replace the differential cover....tighten the bolts gently in a alternating pattern and bring them down to a tight feel....we'll put the gear lube in after reinstalling the differential assembly in the chassis....
-----------
again it's time to wrestle with a fairly heavy, odd shape and get it back over the chassis cross member and get the axle tube into the passenger side mount....the front cover guard also has to swing up into place, the cover vent tube reconnected, the oil filter drip funnel back in....I rethreaded all of the mount bolts loosely first and gradually tightened them all....
slip the axle half-shafts back in till they "pop"....careful with the oil seals....reconnect all of the suspension and steering components as they came out....don't be surprised if you have to back up and resequence your steps...some things have to happen before others....this will take a little while, don't hurry, don't overlook a bolt or nut, especially when you do the final tighten sequence....remember that I took it all apart with hand tools so I have a pretty good idea how hard to tighten every thing back up...
I used valvoline 85-140 mineral gear oil....I'm still learning about the dino-synthetic debate....in my day we used (yadda yadda)....I'm a valvoline/castrol/wix filter guy but I know things have changed while I wasn't paying attention...
the difficulty of this project is knowing what the steps required are and then of course doing them....I suppose a better mechanic could have eliminated some of the disassemby I chose to do....I was concerned before I started about figuring it out....it takes basically a full day if you are doing it alone and are new to it like me....I'm pretty sure I listed here every step i took but you will still have to be innovative at times to solve problems...
I left the skids off for several days in case I had issues but I think I got lucky this time....I think it steers a little heavier now but it's nothing bad....the other night the skids went back on....that all-j plate is such a beast....
thanks for taking the time to read this....hope it is useful to someone....
Posted by Camper
Login
Register
FAQ
Search
