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The article below describes how I replaced the right side rear diff oil seal on my own Audi S2.

No responsisbilty is accepted for anyone attempting this procedure by following the steps contained in these pages. This is intended as a guide only and all usual precautions should be heeded when attempting work on a motor vehicle. I cannot be held responsible for any damage sustained as a result of using these pages.

Tools / parts needed are as follows:

1. XZN M10 tool (see special tools)
2. 6mm allen key (driver)
3. Seal pick or similar
4. suitable drift / mandrel
5. Rear diff seal 016 409 399 B
6. 088 409 359 centre flange bolt (see notes at bottom of page)

Undo the bolts which secure the driveshaft
inner CV joint to the diff flange. These
require an M10 XZN (triple square) tool
like the one seen here. There are 6 of
these bolts.

You can see the state of the driveshaft
and flange due to the leak in this picture.

With the bolts undone, move the driveshaft
out of the way. To create extra room, you
can jack up the exhaust. You can see the
edge of the driveshaft on the left of this
picture. The centre flange bolt (6mm allen
key) can now be seen (arrowed).
Use two of the flangebolts removed above and
screw them back in to the flange threads. Use
a bar or long screwdriver to hold the flange
while undoing the centre bolt.


With the centre bolt removed, the flange can
be removed. There isn't much room but it can
be squeezed past the end of the drivehshaft.
Clean the flange of old oil / grease. I used
a wire brush.


With the flange removed, the old seal in position
can be seen here. There is a small lip which the
seal rests against. Prise the seal out using the
seal pick. Some force may be required.

Smear the outside edge of the new seal with
suitable gear oil (GL5/ SAE90). Drive the seal
in with a drift, ensuring it is straight and
against the lip.


In the finest tradition, refitting is a reverse of removal.
Use the torque values quoted below
DescriptionTightening Torque
Inner Flange bolt*10 Nm + 90 degrees
Outer flange bolts 55 Nm

*Workshop manual does not specify a replacement bolt which is unusual for a stretch bolt. 088 409 359 is the part # for reference