Download The following describes the procedure I used to remove and replace the right and left side rear differential seals on my 1994 Audi S4. This procedure should apply to the 1992 – 1994 S4 and the 1995-1997 S6 (the left seal process may be different on the ’96-’97 cars) and should be used in conjunction with the Bentley Repair Manual. Right Side Seal 1. Jack up the right rear of the car and support solidly on jackstands. The higher you jack the car, the better the access and the less likely oil will be lost when you remove the seal. 2. Remove the plastic gravel tray (four 13 mm bolts/nuts). 3. It is not necessary to drain the differential oil. When the axle flange and seal are removed, a small amount of oil may drain out. This can be caught in a drain pan. If you do decide to drain the differential oil, remove the fill plug BEFORE removing the drain plugs. These steel plugs corrode into the alloy case, and if you drain the differential and then can’t remove the fill plug, you have a “situation” on your hands. 4. Detach the emergency brake cable from the caliper and pull the rubber cable mount from the support bracket above the right rear gravel tray bracket. Move the cable out of the way. 5. Remove the right rear gravel tray support bracket (13 mm bolt). 6. Place a jack under the inner rear trapezoidal arm mount. Remove the bushing bolt (19 mm bolt, 19 mm nut, torque 85 Nm, 63 ft.lb.) and lower the trapezoidal arm (see Photo 1). Note that the bracket secured by this bolt has a slot that engages the emergency brake cable bracket above it. Remember this for re-assembly. 7. Remove the 6 bolts securing the inner CV joint to the differential right axle flange (torque 80 Nm, 57 ft.lb.). Note that these are Triplesquare No.10 bolts NOT Torx bolts. Triplesquare drivers are available from specialty tool shops and some chain store tool outlets. If you use a Torx bit you will strip out the heads. Make sure you clean the rust and dirt out of the heads before inserting the Triplesquare bit. Drive the bit in to ensure it is well seated, there is a lot of torque on these bolts. The bolts are only accessible at the top of the joint (see Photo 2). One removal procedure is to place the transmission in first gear, loosen a bolt, put the transmission in neutral, rotate the axle to access the next bolt, put the transmission in gear, etc. An alternate procedure is to thread all the wheel bolts into the wheel hub, put the transmission in neutral, and use a bar between two wheel bolts to hold the driveshaft while loosening the flange bolts. The same method(s) apply for torquing the bolts on reassembly.