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D-30 Axle Shaft Oil Seal Replacement

Many of us have seen it and probably all have heard about it.....a leaky axle shaft seal in the D30 front axle.  This is one of those projects where the actual job of installing the new seal is very easy.  It is also one of those projects where getting everything else out of the way so that you can get to the seal is more work than most want to do.  So, before you decide it is too much work, read on and then make your own decision. 

A little background as to how I came to replacing a leaky seal is probably in order.  I was doing some prime time wheelin' here in Arizona (that means it was early December, the trails were dry, and the temps were in the blue-jeans and t-shirt range).  An obstacle that I had routinely done, over the past several years, was giving me grief for the second time in as many trips.  The driver's side inner axle shaft broke at the splines (although at the time, I thought I had lost a hub). 


Trust me, it doesn't take long (about 20 feet in my case) for a broke shaft to chew up an oil seal.  I winched myself up and over the obstacle (couldn't go backwards) and pulled up a short distance to get clear for the next person.  By then, I knew I had lost the driver's front side and so I hopped out, locked out both hubs on the D30, and put the vehicle into 2LO (gotta love Warn hubs and Tera 2LO) to limp off of the trail. 

So....as you can see, it wasn't that I really wanted to change the seal, and it wasn't that the seal, up until that exact moment in time, had even leaked a drop of fluid.  Its just that the oil seal (and the ARB) took some collateral damage as a result of the shaft fragmenting itself.  I had no choice but to replace it.  The passenger side seal was replaced at the same time.  Since I was in the differential, it was silly to replace one and take a chance that the other side wouldn't start leaking in a few months. 

OK....enough of the background information, time to get to the bad axle shaft seal.

To replace the axle shaft seals, you need to two perform to basic tasks in order to get to the seals.

First, you must remove the axle shafts.  Second, you must remove the differential. 

Rather than pad this write-up with information already available on the site, read through the D30 Axle Shaft Removal write-up, assuming you have not already done so.  You can skip the step, on the second page, where the axle nut is removed and the unit bearing is separated from the axle shaft.  (there is a note about it at the beginning of the page)  The axle shaft and unit bearing can be removed as an assembly. 

If you made it this far, your D30 should be looking a little bare, especially at the ends of the axle.  You are about half way there.

Next is the differential.  It must be removed in order to gain access to the axle shaft seals.  They can't be replaced if the carrier is still in the housing.  It is easier to remove the carrier from the housing if you have the vehicle on a lift, but it is not necessary.  LOTS of folks pull the carrier to install a LockRite locker and do so sitting in their driveway.  I had the opportunity to use a lift and I made use of it. 



With the axle shafts out of the housing, I removed the driver's side end of the tie-rod.  To do so, remove the cotter pin and loosen the castle nut on the tie-rod end.  Leave about 5 or 6 threads engaged on the nut.  I then took a large hammer (about a 2 pounder) and struck the steering knuckle where the tie-rod end passes through it.  After 3 or 4 good whacks, the tie-rod let loose.  The castle nut was removed and the tie rod allowed to droop out of the way.  There are other ways to remove the tie-rod, but I prefer this method over pickle forks and air tools. 

Place a fluid catch container under the differential.  Remove the bolts holding the diff cover and assuming your cover is sealed with RTV, pry it off and allow the fluid to drain. 



Hey, what happened to the lift?  Well, I didn't take a picture of the bearing caps and so I had to borrow one from my  original ARB install write-up.  (See, I told you this could be done with the vehicle on the ground).  Disregarding the fact that you are looking at an ARB (which doesn't matter in this case), remove two bolts each from the two bearing caps.  If you do have an ARB and are not familiar with how the internal copper air line is plumbed into the bulkhead fitting, read through the ARB O-Ring replacement write-up for some insight on this.  If you have an ARB, you will need to disconnect the air line so that the locker can be removed from the housing. 

NOTE:  Bearings caps are matched side to side and top to bottom.  In other words, you can mix them up putting them on the wrong side and you can also mix it up by putting them on upside down.  If you look at the caps and sealing surface of the housing, you should see some marks stamped into the steel.  It may look like "W" or "M" or an N laid on its side, or something similar.  When you find the mark on the cap, look on the flat sealing surface, right next to the bearing cap, for the same mark oriented in the same fashion.  When you put the caps back on, you must make certain that the symbols match and are positioned near each other (you don't want them on upside down) and make sure they are on the correct sides. 

So, remove the bolts and the bearing caps and set them aside.  The caps fit snuggly so jiggling the bolts in the caps a bit will help loosen them so they slide off the bearings.



At this point, you need to pry the carrier out of the housing.  Get the help of a friend for this step.  This is one method that I've used with good success.  Slip the end of a box end wrench over a ring gear bolt and rotate the ring gear until the wrench jams up against the housing.  Have your friend hold the wrench in place while you use a large pry bar under one of the ring gear teeth.  Push down on the pry bar and you will see the carrier start to rotate up and out of the housing.  Be careful....don't drop it on the floor (the carrier).  Your friend with the wrench can help you make sure it doesn't "pop out" of the housing.



If you are doing this in the driveway, another method that works is a pair of pry bars, hooked under the heads of two ring gear bolts.  Again, carefully pry the carrier out of the housing.  A friend to catch it helps here as well. 

NOTE:  The D30 uses external shims (at least my ARB does) on the driver's side.  Do not loose any of the shims as they must ALL be reinstalled when the carrier goes back into the housing.  Failure to do so will change your bearing pre-load, your backlash, and your gear pattern.  This will make your ring and pinion gears VERY unhappy....and I do mean unhappy!

Set the carrier and shims aside.  Now is a good time to clean out the housing.  I use a little bit of brake cleaner and some paper towels.  By the way, if you find broken parts, like teeth from your ring or pinion gear, it is time to have this looked at by a professional as you have other damage that needs to be fixed before you worry about your oil seals.

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