Thrust Washer Replacement

I have a 1994 S-10 Blazer 4-door 4x4 with 4.3L Vortec V6, 4L60E automatic transmission, and electronic 4x4 converted to manual shift. The information in this article is based on my vehicle, but will likely be similar for all S-Series trucks and SUVs. This article is for informational purposes and I take no responsibility for its accuracy or any damage you may cause by using the information in this article. Note my Blazer is not equipped with any skid plates except the plastic one that is on the very front of every Blazer I've seen. If you have skid plates (factory or otherwise), you may need to remove one or more of them to get access to your front diff.

The front differential in a Blazer is a central axle disconnect design that is somewhat prone to problems. In my case, the vacuum system on my transfer case developed a leak causing the front diff to engage even in 2HI often at speeds in excess of 60mph where the vacuum was highest which I believe led to the broken thrust washer you see in this picture. The groove that you see in this thrust washer was cut by the pressure in the output shaft and is not there from the factory.

So, let's get to it. First, you'll need to remove the passenger side axle. If you need to replace your CV joints or just the boots or your shocks, this will be a good chance to do it. Note, the next 3 pictures are not my own. In my case, I needed to remove the steering knuckle for something else, so I removed my axle that way. This procedure doesn't require removing the steering knuckle,however, if you can't get your axle out as described below, you can remove the steering knuckle assembly. First jack the front of the vehicle up and support on jack stands. Remove the tie-rod that controls the steering. Next remove the shock by removing the nut/bolt at each end of the shock and remove the entire shock. Remove the 36mm nut on the end of the axle by first removing the cotter pin and then the nut. Slide something into the vanes of the rotor through the caliper to prevent the axle from spinning and remove the 6 bolts that connect the output shaft to the axle. You will have to removing your pinning device to spin the axle to get the right angle to remove the bolts. Once the bolts are removed, you'll probably have to hit the axle flange with a block of wood and hammer to get them to separate. Roll the axle out towards the front of the vehicle. See pictures below:

Note the arrows pointing to 2 of the 6 bolts on the flange of the axle.

Here the axle is almost removed.

And the axle is removed. The arrow is pointing to the disconnected tie-rod for the steering.

I don't have any good pictures of this next step, so sorry in advance. First remove the small bolt that holds the wire to the plastic housing and then unplug the wire from the plastic housing. You now need to remove the lower 3 bolts on the passenger side of the front diff that hold the plastic housing for the CAD cable. Have a drain pan handy as the front diff may start to leak and the 80W 90 oil that it uses is some really smelly, nasty stuff. The cable is attached by a spring ring. If you can't get the cable loose from the spring ring and can't get the plastic housing out far enough to see the spring ring, use an angled screw driver or allen wrench to remove it. Insert your tool of choice from the front of the vehicle and try to catch it on the spring. It only took me a few tries. Good luck.

There should just be 2 more bolts holding the output shaft to the front diff. Go ahead and remove these. Follow the output shaft back out towards the passenger side of the car and you will find 2 more nuts/bolts holding the output shaft to the frame. You'll need to put a wrench on the tops of the bolts in order to remove them. Now your output shaft should be loose and it should just slide out.

This is where the output shaft bolts to the front diff. The plastic housing over the CAD cable and the cable have already been removed. The 5th bolt in the 1 o'clock position is hidden by the output shaft.

This ball bearing thing came out of the plastic housing. It is part of the sensor that tells the vehicle that the front diff has successfully engaged or not. It goes inside the same area where the cable goes in line with the plug on the plastic housing. I put the socket in the image so you can get an idea of the size of the ball.

Chances are, when you removed the output shaft, some stuff just fell out and now you have no idea how it all goes back together. Have no fear, that's what the rest of this article will cover. If you find a broken washer like I did, be sure that all pieces of it are removed from the front diff area. I couldn't find the thrust washers at any of my local major parts stores, so I picked mine up at the Chevy dealer. Call around to check that they have it in stock as not all dealerships keep them on hand. At the time of writing in early 2007, they were roughly $10 and the part number is 26033623. It comes as a set of 4 including 2 identical washers of which you will only need one. The washers are pictured below. While you are at the dealership, ask them for an exploded diagram of the front diff so that you know how to put it all together. Hopefully the salesperson will print you one. The numbers in the picture correspond to the numbers of the items in the diagram that is available both from GM and on All Data.

To get to washer #8, you'll need to remove the snap ring shown already removed in this picture. Note the way that I have it in this picture it is pretty much impossible to reinstall. Instead, set the snap ring over the top and start with one side. I had to use the screw driver in the picture to pull the gear out far enough to get the snap ring on and off.

Here the snap ring is back on and the new washer #8 is in place.

Next comes washer #21 right on top. Based on my diagrams, I believe the 3 grooves shown in the picture go in the direction you see.

The long gear shown in this picture goes on next.

Washer #25 goes on last, but I found it easier to set it inside the front diff which you'll see pictured later. The slide collar has also been installed around the gears in this picture.

This is a side view without washer #25, but with the shift fork and collar in their rightful places. In this picture, the front diff is in the disengaged position.

When the CAD cable is pulled, the shift fork slides the collar over the lower gear, connecting both gears and engaging the front diff as seen in this picture.

Here is the area where the output shaft used to be.

I found it easier to reinstall the output shaft with washer #25 sitting in the diff like in this picture.

Before reassembling, put some RTV type black silicone gasket maker around lip of the output shaft where it connects to the front diff. It can take some work to get everything lined up to go back in, so be patient and make sure that nothing falls out while you're sliding it back in there. Start by putting back in the bolt in the 1 o'clock position and work your way around. Once the bolts are in place, tighten them to spec with a torque wrench. Plug the wire back into the plastic housing and bolt the wire back in place. Reinstall the bolts and nuts and washers that hold the output shaft to the frame. Grease the bearing area of the passenger axle before reinstalling. Reinstall the passenger axle including the 6 bolts on the flange, the 36mm nut with its cotter pin assembly and washers. Reinstall the shock and bolt up the tie-rod with its cotter pin. Top off any missing front diff fluid with the fluid specified in your owners' manual. Mine called for 80w90 GL-5. I had to buy 2 quarts of it to make 2.2 pints. Fill the front diff until a little bit of it starts leaking out the fill hole (that's when it is full). You'll need some kind of pump device or large syringe to push the fluid into the front diff. In my case, all of the fluid had drained out, but you may want to remove all of the fluid first using the same hand pump. Note that there is no drain plug on the front diff, just a fill plug, and no access hole either. Grease the fitting on the tie-rod to ensure that it is properly lubricated.

Congrats, you're done. Also, if it turns out that your front diff troubles weren't in the output shaft, you haven't really wasted any time. You'll have to remove the passenger output shaft anyway to remove the front diff.