Factory rear end. Seals & Bearings

So I got up the courage to do the rear brakes on my 75. The drivers side was in really good shape. I went ahead and changed them out with new hardware and wheel cylinders. The passenger side not so much. It was greasy and nasty. I thought the wheel cylinder leaked but the more I looked at it I think it is the rear axle seal. I cleaned the crap out of everything and swapped it all out like I did the drivers side. I'll take it out and check it again but I was wondering about how to change the seal out. Is the bearing pressed onto the axle or when the axle slides out is the bearing in the tube and the seal goes on in front of it? I looked around at the drivers side after seeing it and it appears someone has changed that side out in the past. The should have just completed the job but people are people.

The bearing is in the housing. The seal is pressed into the housing and you need to find a way to pull it out. The seal will be the most outward piece so it's right there.

Its actually an easy job if you have a "bolt in" axle like on buick, pontiac and olds cars.  Some chevys have it especially the montes.  

With the bolt in axle you can just remove the 4 bolts behind the axle hub and it slides out.  The bearing and seal will be on the axle.

But with the chevys, you have to take off the diff cover and remove the 5/16" bolt that holds the cross shaft in.  The cross shaft is a 3/4" thick hunk of steel that goes down the center of differential.  That 5/16" bolt is REAL tricky and finicky.  The whole bolt is about 1 1/4" long.  They tend to snap off regularly.  If it snaps off it usually snaps below the threads which is good.  There are only threads for about 3/8" below the hex head. Then its a smooth, thin piece with no threads.  So if the  hex comes off with the threads, only the thin piece is still inside.  First thing I do is turn the diff so this bolt is furthest to the rear of the car to give you some room.  Then you have to get in there with a strong magnet.  I like computer hard drive magnets.  I find a thrown out computer, take out the hard drive, break it open and remove the two small half moon shaped magnets.  They are super strong.  If you put them on a metal desk you can pick them up unless you slide the magnet to the edge of the desk.  I keep them on the inside lid of my tool box and it holds my spare razor blades out of the way.  I also keep one on the bottom of every oil filter in each vehicle I own.  Anyway, you can also stick one of these magnets to a small drift punch (punch with a flat front, no point).  Then stick the punch in the hole to attach the other piece of the bolt.  Hopefully you luck out and it comes out.

Now if a couple threads are still left in the hole, that will keep the remainder of the bolt from coming out.  I've had good luck with 1/8" and 1/4" LEFT HAND DRILL BITS and a 6" or 8" drill bit extension.  The drill bit extension moves your drill further towards the brakes which gives you more room to work.  I go in there with the 1/8" bit and the drill IN REVERSE and start drilling.  Careful to center it up, you dont want to mess up the threads in the diff.  After you drill in about 1/4", I'd try the magnet again.  If no good, go in with the 1/4" but only drill in about an 1/8" and try the magnet again.  You dont want to ream the hole to a 1/4" and mess up the diff threads.  Go slow and easy and try the magnet trick.

Last but not least and I'm glad I've never had to resort to this is torching it.  Its the preferred method of my mechanic friends.  Grab the torches and burn around the pin deep enough to cut the remainder of the bolt, then tap the pin out.  This destroys the diff but makes it a good time to install a posi unit.  

Once the pin is out, go out by the brakes and push the axle in towards the diff about a 1/4".  Go look in the diff and you should see the end of the axle with a "C" clip just sitting in a groove.  If you see the groove but no clip, it fell off.  Look around and grab it.  Then go and slide that axle out.  Do the same on the other side if your doing both sides which I recommend since your in there.  

Now at the end of the axle tube, use a long screw driver or something and pry out the seal.  Now to get the bearing out you have two choices.  Butcher it up and remove it which is ok, just dont hurt the axle tube.  Or go for a free tool rental at autozone or advanceautoparts and get and axle bearing removal tool.  Harbor freight and ebay have them as well.    https://shop.advanceautoparts.com/p/astro-pneumatics-rear-axle-bearing-service-set-ast78820/22981966-P?searchTerm=axle+bearing+tool

You will also have to rent a slide hammer to use the tool.  

Before you buy bearings and seals, look at your axle.  Right behind the flange where the bearing rides.  You will see the area where the bearing rides.  Does it look ok?  Is it all pitted?  Is there a groove where the seal rides?  If you have any of these issues you have two choices.  Get new axles which would be less than $150.  I installed the Ten Factory brand from Motive Gear when I built my rear.  You can see them in my build thread.  Your second choice is to find the replacement bearing and seal combo that is readily available for these issues.  It moves the bearing and seal location over just a bit so it rides on the axle in a new area where there isnt any wear.  So everything will work the way it should and you dont have to buy new axles.  They are easy to find.

I like to put a bit of grease on the lip of a new seal and I like to put some oil on the new bearings after they are installed.  BTW, if you cant find a piece of pipe or something that is the same diameter as the bearing to install it, just rent a bearing/seal installation tool.  The kit will have all the different diameter discs to install your bearing and seals perfectly.  

Install everything, TORQUE THAT 5/16" BOLT TO SPEC WITH LOCKTIGHT, fill the rear.  Then I like to jack the car up high under the axle on one side so the oil flows to the opposite side.  Let it sit 1/2 hour.  Lower the car, top off the diff then do the other side.  Might be overkill but you need to get oil to the bearing or it will have a short life.  Then I drive it around for a awhile, come home and park it on flat ground and recheck the lever after an hour or so and top it off.  Oil needs to migrate through the long axle tubes to get to the bearings.  If your low, not much gets out there.  

DO NOT REUSE THAT 5/16" BOLT !!!  GET A NEW ONE.

I'm sure there's other way of doing this but this is whats worked for me over the years.  Just my 2 cents.

Be careful like Joe says with that damn bolt. It backed out my 73 Monte and destroyed the rear. Also if you have bolt in axles like I have on my 77 Monte the bearing will have to be pressed off and back on to replace the seal. Just replace the bearing while at it and dont damage the flange. Timken part # is -set 9 for bolt in axle bearing.

I found a video where they did the bearing and seal on that popular hot rod laguna. I looks like a easy enough job, just have to get that bolt out. It looks like the drivers side has been done before so maybe just maybe they put in a new bolt and it won't be a pain to remove. I had a 67 Lemans that we did bearing and seals on. That was easy. Jack it up, removed the for retaining bolts and out that baby came. No need to get into the rear end. Not so lucky on this one. I didn't see where their were bolts that held that axle in, only the backing plate.

Olds and Pontiac rear are different than Chevys. But your car might have an Olds rear from the factory. My 77 does.