Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

at assembly. Remove the pinion flange that the drive shaft
bolts to, first marking it in relation to pinion so as to
preserve its position since it may have more throw (run-out)
if not put back into position. Drain the rear differential oil.
Pinion Seal
[See below] First remove the center flange nut, the remove
the flange with a puller; no hammering allowed!. Seal can
be removed by any reasonable means that doesn't scratch
the opening in diff housing where seal fits. You can put a
good-sized screwdriver in between the seal and the pinion
shaft and pry it out. It will distort and tear but will come out. Or you can take a small chisel and
tap it into the little crease that exists between the edge of the metal seal and the edge of the diff
housing (be CAREFUL not to damage the differential housing!!). This will cause the tin seal
housing to bend over and loosen it's grip on the diff housing. Do this at least 50% of the way
around that outer edge and then put a large screwdriver in next to the pinion where the flange
was and use it to lever the seal right out. It should pop out with no problems if you did it right.
Carefully clean the flange where it contacts the seal. Make sure you install the seal right way
around: "outside" is stamped in the metal seal ring. Put a little lube on the seal surface so it
won't rotate dry and then tap it in place. The new seal will need to be driven in evenly to be just
below flush with front of diff housing unless it is one with a lip that stops it when the lip contacts
the diff housing. If you have a socket that is about the size of the seal use that to get it in even,
if not just keep at it gently until it is seated evenly all the way around. Re-install flange as
marked and then refit nut (volvo recommends new nut) to a torque depending on whether your
seal uses a compression sleeve or not. No compression sleeve: 148 lb-ft. NO IMPACT
WRENCH ALLOWED, TORQUE IT!!! Compression sleeve: 49 ft-lbs; ignore any instructions to
count rotations. [tip thanks to JohnB]. Failure to torque it properly will result in the pinion bearing
being overloaded which will kill the bearing and place the pinion/ring gear relation ship in a new,
different, and noisy relationship that will result in replacement of a bunch of parts ($$$$$). Oh,
don't forget to fill it up with gear lube when you're done.
Flange Torque. [Editor] Re-torque the flange coupling bolts and nuts as follows: if you have M8
bolts, torque first to 22 ftlb (30Nm) then angle tighten another sixty degrees. If you have M10
bolts, then torque to 37 ftlb (50Nm) in total.
Flange Nut Removal Tool [Dave Farrington/Tom F] Replacing the pinion seal is really pretty
easy, but the trick is to remove the u-joint flange to get at the seal.You need a good home-grown
counter-hold tool to remove the pinion flange nut! I took a piece of angle iron around 28 inches
long when I cut it down. Then I took the rear drive shaft that I had just taken out of the car and
marked two holes of the u-joint flange near the edge of one leg of the angle iron. I then bolt this
length of iron to the pinion u-joint flange, but I still have a problem. That is I can't get at the
center nut holding the pinion flange in place. Easy to fix: just mark some clearance around the
socket you plan on using - it presumably fits that nut. Then grind some of the angle iron off.