Rear Differential Axle Flange Seal Replacement
igor at s-cars.org
Sun Dec 8 21:56:24 EST 2002
I have just performed a Rear Differential Axle Flange Seal Replacement
wife's '98 A4TQ. Perhaps somebody will find this write-up useful.
I have based this write-up on my old write-up for the UrS6, which in
turn was based
on the yet older excellent write-up for the 200TQ by Fred Munro.
Rear Differential Axle Flange Seal Replacement
1. Roll the front of the car onto the ramps. Jack up and safely support
of the car on jackstands making certain that the car is level. This will
important in step 17. I also removed the wheels because I wanted to
supper tyres with the winter ones, but I do strongly suspect that
speaking it is not really needed.
2. Loosen the filler plug on the rear differential with a 10mm Allen
Note that the A4 does not utilise the standard 17mm Audi Allen to which
used so much. Loosen it before even attempting to loosen the drain plug.
don't want to be stuck with the empty differential facing the necessity
the car upside down for refilling if your filler plug is rusted in.
3. The best part is there is no need to remove the rear and the central
mufflers. The Bentley manual is wrong about that. I unbolted the two
exhaust mounts and carefully lowered it on the hydraulic jack as not to
the EM studs. I then swung the whole exhaust 10-15 cm to the side and
provided all the needed room for clearing the left axle.
4. Remove the bolt (the unusual for Audi 18mm hex!) that secures the top
connecting link to the upper trapezoidal suspension arm and swing out
control arm with the connecting link. You might also need to remove the
that secures the rear stabiliser to that connecting link. This is
release the inner CV joint and drop the half-shaft out of the way.
5. Remove the six 10mm triple square head bolts securing the inner CV
the axle flange. DO NOT use a Torx driver on these bolts - they take a
triple square driver. Make sure the driver is securely seated by
bolt sockets and tapping the driver home.
6. Remove the CV joint from the axle flange. This may take Croil or ZEP
Liquid Wrench if the car is old - rust between the joint and the flange
the unit together. Lower the inner end of the half shaft out of the way.
7. Remove the 6mm Allen head bolt securing the axle flange to the
carrier - it is located in the centre of the axle flange. The axle
flange can be
held while removing this bolt by inserting a drift in one of the holes
the flange stationary.
8. In case you haven't lost as much oil as you think, put a drain pan
differential. Pull out the axle flange. Inspect the seal running surface
wear and clean the flange & sealing surface.
9. Measure the old seal position with a caliper to determine how far in
from the outer rim of the seal seat. There is no inner stop to position
- the Audi driver tool has an outer flange which hits the outer rim of
seat and stops at the proper depth. My both seals was seated at
7.8 mm from the outer rim given the parallax induced by my hanging
with a Mitutoyo calliper in my teeth.
10. Pry out the old seal with a seal remover. Wipe the seal seat clean.
that it is tapered partway in but here is no inner flange to stop the
going too far. If you drive too enthusiastically, you can push the seal
into the dofferential - I can guarantee this will ruin your entire day!
11. You absolutely need at least a replica of the Audi tool. I've made
version of the Audi factory seal driver 2062 out of Aluminium with a
plate to stop the seal from falling in. You can try driving the seal in
tool with just a hammer but I can almost guarantee you that you will
seal inside of the differential.
12. Fill the space between the lips of the seal with lithium general
grease. Put the seal onto the seal driver. Drive the new seal in
squarely to the
depth measured in step 9 above.
13. Apply a thin film of grease to the sealing surface of the axle
the axle flange back into the dofferential. Insert the axle flange
bolt. This bolt is tightened to 25 Nm. Always check your Bentley for the
values since they can change at any point!
14. Bolt up the CV joint to the axle flange. It is recommended that the
between the axle flange and the CV joint be replaced whenever the joint
removed. I neglected to replace mine. The 10mm triple square bolts are
to 40 Nm.
15. Reinstall the bolt that secures the top of the connecting link to
trapezoidal suspension arm and tighten it up with a new nut. The torque
is 50 Nm
with additional 1/4 turn. Reinstall the bolt that secures the rear
that connecting link and tighten it up with a new nut. The torque is 50
Always check your Bentley for the actual values since they can change at
16. Repeat the above for the other side.
17. Drain and fill the dofferential with appropriate lube. The Audi
for GL-5 spec 90 hypoid oil. GL-5 spec 80W90 hypoid is OK, as are GL-5
synthetic gear oils. I personally like to use the Red Line synthetic
It's a good idea to put antiseize compound on the fill and drain plugs
prevent electrolytic corrosion between the steel plugs and the alloy
18. Put on the wheels, torque the wheel bolts to 110 Nm and lower the
08 December 2002
two turbo quattros
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