Rear axle wheel bearing replacement

[ragedracer]

Completed today on my M1009. I was out last weekend scouting water holes for dove season coming up. When I got home, I noticed fluid on the inside of the right rear tire. I was sure it was a leaky wheel cylinder until I pulled the drum, and sure enough you could see it was leaking down from the axle. I wish I took pictures, but I didn't think to do it until I was done. Here's a quick step by step.

TOOLS/MATERIALS NEEDED. Socket set. 8mm wrench. Bearing puller (can be rented at Checker/Autozone) I got a slide hammer puller. Small sledge (I used a 3lb engineer sledge) New wheel bearings. New oil seals. Gear oil (80W-90). RTV silicone. Razor blade or scraper.

TIME: 2-3 hours, maybe more, maybe less depending on skill level. It took me approx 2.5 hours. Have never done this before.

TIPS: Make sure you can remove the fill plug before you start. If you can't you're in a world of hurt. It's on the passenget side of the differential. Small square drive. A 3/8 ratchet with no socket or extention works best. Get a funnel with a long tube, or a syringe type suction pump for refilling differential.

1. Chock front tires. A absolute must.
2. Loosen lug nuts on rear wheels.
3. Jack up truck, support rear axle with jackstands.
4. Remove wheels and brake drums.
5. Remove all bolts from differential cover.
6. Place drain pan under differential, crack the seal (used a flat head screwdriver) and let drain.
7. Place transmission in neutral and rotate carrier until you see a very small bolt head on the right side of the gov-loc unit. This is an 8mm bolt. Remove bolt. This bolt has only a small amount of thread, with a long pin that goes through the spider gear pin. BEFORE YOU REMOVE THE SPIDER GEAR PIN: rotate carrier so that you see the square shaped piece inside the carrier. If you remove the spider gear pin first, and then rotate, you may lose the spider gears. Makes the project much more difficult.
8. Remove spider gear pin (its about 1/2" diameter pin). Push one of the axle shafts into the carrier (push on the lug nut side, it will slip into the carrier just a touch). Using a magnet, remove the "C" clip. It's very tight in there, you will see it between the gear and the square piece. Be patient, they slide right out, you just have to get it lined up with the open area opposite the way you are trying to pull. Repeat for other side.
9. Pull out the axle shafts. I recommend some sort of catch tray under the axle ends. You will get a little drainage. Mark or somehow otherwise remember which shaft came from which side.
10. Following the instructions on your puller, remove the old oil seal and bearing from both sides. For the slide hammer I rented, it has a small hook attachment that worked well to remove the seal, and then a "toggle" attachment to remove the bearing. This takes some time and a lot of force. Don't be shy. The slide hammer I rented was plain steel. I recommend wrapping a rag around the slide. It's easier on your hands. Not to mention your hands are probably covered in grease and rather slippery. (TIP: Some of the rollers on the bearings may pop off when you are hammering them out. Make sure that none are left in the axle. Just look in there and see)
11. Install the new bearings. I took the new bearing and put it in by hand as far as it would go, then lightly tapped around the edges to seat it. Then, take the old bearing and use it to drive the new one in. Hold the old bearing tight to the new and whack the old bearing with the hammer. Be a little shy here. Take your time. No need to go neanderthal on it. It does take some work, but you'll get there. Then hand press the oil seal in. Once you have it slightly in, tap all around it repeatedly till it's seated. Again, no need to pound on it. Gentle tapping works. Repeat for other side.
12. Reinstall axle shafts. Remember, you have to line them up right. No force is needed. Just get them in there and spin them a little till you feel the splines line up. Push them in as far as they will go. One side at a time. Once you have one shaft in, reinstall the c-clip. Same as it came off, just slides right in. Pull axle shaft back out til c-clip stops it. Repeat for other side.
13. Reinstall spider gear pin, making sure the small hole in the end lines up with the bolt/pin hole. Reinstall spider gear bolt/pin.
14. Clean all mating surfaces on diff and cover. Ensure there is no debris left behind in the differential.
15. Apply RTV silicone to diff cover. Make sure its one continuous line, and circle all bolt holes.
16. Immediately install diff cover, but only finger tighten bolts just until the RTV starts squishing out. Wait 30mins-1 hour (good time to return puller and clean up some tools). Torque down diff cover bolts.
17. Refill differential through fill hole just until gear oil runs out of the hole. No additives are necessary with a Gov-Loc. Replace fill hole bolt.
18. Replace wheels, let vehicle off jackstands, and clean up your mess. You WILL have a mess. Gear oil is nasty stinky stuff. I've taken 2 showers since, and washed my hands several times, and can still smell it slightly on my hands.

Hopefully that covered it. Sorry for no pics, but things should be pretty clear once you get it opened up!

 

[ragedracer]

One more thing, since you already have the drum off, now is a good time to inspect/replace brake shoes. It's very easy to do when the axles are out. A lot more room to get around all those darn springs!

 

[acmunro]

A couple of small things to add. Up here in rust country it pays to make sure the differential vent is clear. I have had the end at the differential rust shut/plug. This allows pressure to build inside the differential = leaks. Also if you cannot get your fill plug out you can also fill it through the vent hose as long as you know how much to put in. Looks like a great write up. Thanks

 

[ragedracer]

A couple of small things to add. Up here in rust country it pays to make sure the differential vent is clear. I have had the end at the differential rust shut/plug. This allows pressure to build inside the differential = leaks. Also if you cannot get your fill plug out you can also fill it through the vent hose as long as you know how much to put in. Looks like a great write up. Thanks

Nice! I guess I better check my vent line just in case. It's certainly not rust country here, but who knows!

 

[ragedracer]

Well, took her for a spin today. No leaks! Looks like I did it!

Also replaced the output shaft seal on the NP208. It's been leaking since I bought it from GL last year. Since replacing the bearings/seals was so easy, I figured I'd tackle it. It literally took me 30 minutes, including a trip to the parts shop for a new seal and ATF.

I guess I'll tell you how to do this as well.

1. Chock front tires. MUST BE DONE UNLESS YOU WANT TO DIE!!
2. Mark driveshaft with chalk or whatever at the TC (transfercase) end, you need to slip it back in in exactly the same orientation.
3. Remove u-joint straps on rear axle at driveshaft end.
4. Place a catch pan (small bucket or whatever under the output) and give the shaft a little whack with a sledge at the axle end, driving it towards the TC. Shaft will come off the axle. Pull axle out of TC. You will lose some of the ATF inside.
5. The seal is at the end of the TC. It has a "lip" that is outside the TC (look at your new seal, you'll see what I mean). Using a small flat blade screwdriver, hammer it under the lip and pry. Work your way around the seal repeating, and moving up to a bigger screwdriver if necessary. It will come it fairly easily.
6. Wipe out seal surfaces in TC output. Make sure there are no mars, scratches, etc.
7. Pre lube the seal by rubbing ATF on the rubber. Insert new seal. Gently tapping all the way around until you have driven it all the way in to the lip.
8. Using marks you made in step 2, line up the slip yoke and slide back in.
9. Install driveshaft to axle using straps removed in step 3.
10. Remove fill bolt from TC (very large, up high near where speedo cable enters). I found an adjustable wrench works well for this. It's probaly a 1.5" bolt.
11. Refill TC to just below fill hole. (Stick your pinky finger in and if it gets ATF on it when you dip into the TC, it's full. I have a little fluid pump (~6.00 at the parts store) that attaches to Qt. bottles. Works very well for ATF.
12. Replace fill bolt.
13. Clean up! Test drive, check for leaks!