1. Jack up the rear
of the car. Make sure that the jack stands are in a position that
allows the rear end to droop (i.e. don’t put the jack stands under the
axles), but also provides a safe, stable location for the car to rest in
the air. I chose to put the stands under the front mount for the
lower control arms, with a second set of stands under the fully drooped
axle. |
2. Disconnect your
battery. There’s absolutely no benefit to doing this since you won’t be near any electronics, but all the good tech articles tell
you to do this. |
3. Once under the
car, locate the rear of the driveshaft where it’s held to the rear yoke
assembly (Figure 1) |
4. Put the car into
neutral with the emergency brake off, then get back under the car and
rotate the driveshaft by hand until two of the bolts holding the u-joint
into the yoke are facing down just like in Figure 1. Get back up,
and put the car back into gear to prevent the driveshaft from turning,
then get back under the car and use your ratchet with the 11mm socket to
remove the two nuts. Get back up and put the car into neutral, then
get back under the car, rotate the driveshaft until the other 2 bolts are
down, then get back up to put the car back into gear, then get back down
and remove those two bolts. Then get back up, then back down, then
back up, then back down. Repeat 10 more times for a slimmer, more
toned midsection and after 30 days, I guarantee that you’ll drop at least one dress size. |
|
5. Now use your large screwdriver,
small pry bar, or some other suitable tool to pop the
driveshaft apart from the yoke. I do this by sticking a large
screwdriver behind the u-joint and prying to separate the u-joint from the
yoke. Just use caution to make sure that the bearing caps on the
u-joint don’t come apart or you’ll wind up replacing that too. Once
it’s done, drop the rear of the driveshaft down and swing it out of the
way, but don’t remove it from the transmission or you’ll lose all of your
transmission fluid. The back of your car should now look strikingly
similar to Figure 2. |
|
6. Now you need to mark the large nut and
the pinion shaft so that you can re-install the nut to the exact same
place later. If you don’t do this, the preload on your pinion won’t
be the same, which is something you want to avoid. A word of caution
here: A sharpie or a paint mark might not survive after you remove
the nut. If that happens, you’re not going to know when it’s
reinstalled properly, so I would suggest something more permanent. I
used a dremmel with a cutoff wheel to mark the threads and the nut.
If you take it easy with the cutoff wheel, you’ll more or less just put a
flat shiny spot into the threads and won’t do anything that could
potentially damage the threads or the nut. You’re not trying to cut
the thing off here, but just put a visible mark in it. Figure 3
shows my resultant mark, though it doesn’t show it terribly well.
You should see the shiny spot on the threads and on the nut at around the
6:00 location in my pic (Figure 3). |
|
7. Now you need to
remove the nut holding the pinion on. Get back up and crank on your
emergency brake or chock your rear wheels to prevent them from
turning. Get back under the car (congratulations, you’re already
halfway to a slimmer you!) and use your 1/2″ breaker bar with the 1 1/4″
socket to loosen the retaining nut. Once you remove that nut, the
yoke should slide right off the pinion. If it doesn’t, you may need
to persuade it with a rubber hammer. If that doesn’t work, persuade
it with something harder (like a regular hammer)
at your own risk. Mine slid right off without the use of any persuasion. Once it’s off,
your project should look like Figure 4. |
|
8. Your next step is to remove the pinion
seal. To start off, take a look at your new one so that you’ll be
familiar with the shape of the item, specifically the outer flange.
Once you’ve burned that image into your retina, look at the pinion seal on
your car and recognize the outer flange of that seal. What you need
to do, after thoroughly cleaning the area so that crap doesn’t get into
your differential, is to start tapping your chisel underneath that outer
flange. I used a chisel of around 7/8″ width, but anything will
work. You need to slowly work your way around as much of it as you
can get. With careful chisel angles, you can work your way around
approximately 70% of it, with the upper most area being pretty much
inaccessable. Be careful not to mark up the differential housing,
especially inside the area where the seal sits. Slowly keep working
around it until you tap that lip up as much as you can. At that
point you want to try angling the chisel slightly back toward you and
striking it in a way to help slide the seal out of the differential.
After you work that lip up, try a more blunt tool (such as a cold-rolled
chisel or a dull screwdriver) so that you don’t just poke the chisel
through the metal. The goal here isn’t to destroy the seal, but to
slowly work it out of it’s resting place. Once you get past a
certain point, you’ll really start to see it coming out, and eventually
you’ll get to the point that it looks like Figure 5, at which point it’s
virtually ready to fall out. You’ll also get plenty of fluid pouring
out, so be ready with a catch can and some speedy dry. |
|
9. Once you’ve got the old
seal out, thoroughly clean the area. Apply a very thin application of
RTV to the outer ring of the new seal flange. Installing the new
seal needs to be done with care so that you don’t distort it. The
best solution is to find a large enough socket or other circular item to
encompass the whole outer ring so that you can tap it evenly into place.
If you don’t have such a device, you need to carefully use your hammer to
tap all around the seal while using your hands opposite the
part you’re hitting. If you just smack one spot with the hammer, the
opposite side will pop out. For example, apply pressure to the 3:00
position and tap the 9:00 position with a hammer. This will take a
while, but eventually you’ll get it to start to sink into place, then you
just keep tapping all around until that outer lip is securely against the
differential housing and a little bit of RTV squeezes out all around. |
10. Once the seal is properly installed,
everything else goes on more or less the way it came off. Put the
yoke on and tighten the nut back to its original position and no
further. Once that’s on, put the driveshaft back and install the
caps that hold the u-joint into the yoke. Get up and down 20 times
to put the car in and out of gear while you tighten the 4 bolts. |
11. Use the 1/2″ ratchet to remove the
upper plug in the differential, then fill it with your differential fluid
of choice. If you have a limited slip rear end, make sure to also
add the appropriate limited slip fluid. I’ve found that the GM
Positrac fluid is about the best. |
12. You’re
done. Safely get the car off the jack stands, reconnect the battery
(you didn’t really disconnect it, did you?) and go use the car. |
