This tutorial is also available in French ➔

RH differential oil seal change on automatic Austin Mini gearbox

Vehicle ➔ Mini 1000 am1991 automatic gearbox

Difficulty ➔ Medium

Time ➔ 4 hours

Summary

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This tutorial concerns the Mini with automatic gearbox. For info, the manual gearbox has the same differential oil seals as the automatic gearbox (ADU5738) but the differential casings are different. The procedure for changing the seals remains the same.

The right-hand drive shaft oil seal is on the right when you are sitting in the driver's seat.

Over time, the differential oil seals degrade and the Mini starts to leak oil. This will greatly compromise its chances of passing the next MOT test. It's high time to change them.

The size of the automatic gearbox is very different from that of the manual gearbox. The puller (18G1240) is suitable for the manual gearbox. It needs to be slightly modified to be used on the right-hand drive shaft of the automatic gearbox (➔ see Op 14).

Required Tools

Drain the engine and gearbox (➔ see the tutorial ''Draining the engine + automatic gearbox'' Op 02 to 04).

Op 02

Remove the air filter box (➔ see the tutorial ''Changing the HS4 air filter'' Op 01 to 02).

Op 03

Disconnect the accelerator cable from the carburetor (➔ see the tutorial ''Changing the accelerator cable'' Op 02 to 04).

Op 04

Remove the carburetor (➔ see the tutorial ''Removing the HS4 carburetor'' Op 03 to 12).

Op 05

Remove the exhaust line (➔ see the tutorial ''Changing the exhaust line'' Op 04 to 09).

Op 06

Remove the right front wheel:
• Slightly loosen the 4 wheel nuts. Use an 11/16'' socket.
• Place the Mini on ramps or axle stands.
• Remove the 4 nuts. Unscrew by hand.
• Remove the wheel.

Before working under the vehicle, make sure it is properly secured with axle stands or rigid ramps. It is forbidden to work under the vehicle held only by a jack. It's too dangerous.

Separate the swivel hub

Op 07

Remove the steering ball joint fixing nut. Use a 17 mm socket.

Op 08

Pull off the steering ball joint. Use a ball joint puller.

Op 09

Remove the upper ball joint fixing nut and its washer. Use an 11/16'' socket.

Op 10

Pull off the upper ball joint. Use a ball joint puller.

Op 11

Remove the lower ball joint fixing nut and its washer. Use an 11/16'' socket.

Op 12

Pull off the lower ball joint. Use a ball joint puller.

Op 13

Detach the ball joints from the suspension arms and suspend the swivel hub. Use a piece of string or wire.

Be careful not to stretch or damage the brake hose.

Remove the oil seal

Op 14

Modify the drive shaft puller (18G1240).
Cut along the green lines and remove the shim located at the rear. Use an angle grinder.

The puller is designed to detach the drive shafts from the manual gearbox. It must be slightly notched and shortened to extract the right-hand drive shaft from the automatic gearbox.

Op 15

Detach the drive shaft from the gearbox:
• Slide the puller between the drive shaft seal and the gearbox casing (1st photo).
• Tap the puller with the hammer until the drive shaft comes loose (2nd photo).

The drive shaft is only held in place by a metal circlip. It will resist as the puller advances and it will suddenly come loose.

If you don't have a puller, you can detach the drive shaft with 2 tire levers by levering between the drive shaft and the gearbox. Position the 2 tire levers symmetrically on either side of the drive shaft. If you only use one tire lever or if you are not perfectly symmetrical, the drive shaft will be slightly skewed, it will lock and it will not come out.

Op 16

Extract the drive shaft from the gearbox. Pull sideways by hand.
Suspend the drive shaft to clear access to the oil seal. Use a piece of string.

Op 17

Remove the oil seal. Use a flathead screwdriver.

Be careful not to scratch the aluminum casing of the differential with the screwdriver.

Replace the oil seal

Op 18

Oil or grease the lip of the new oil seal (ADU5738).

Op 19

Fit the new oil seal. Use a 34 mm socket and tap with a hammer.

The 34 mm socket allows you to press evenly over the entire surface of the seal. You can hit the socket with the hammer without risk of damaging the seal.

Op 20

Engage the drive shaft in its housing. Push firmly by hand.

Recenter the circlip in its groove before engaging the drive shaft on the splined shaft.

Be careful not to damage the lip of the oil seal when you engage the drive shaft, otherwise all your efforts to stop oil leaks will be reduced to nothing.

You will hear a very slight ''click'' when the drive shaft is locked (the circlip will then have found its place).

Fit the swivel hub

Op 21

Fit the 2 ball joints on the suspension arms.

Op 22

Fit a new spring washer (GFK1127) and screw on the lower ball joint fixing nut (GFK3214). Use an 11/16'' socket.
Tighten to a torque of 52 mN. Use a torque wrench.

Op 23

Fit a new spring washer (GFK1127) and screw on the upper ball joint fixing nut (GFK3214). Use an 11/16'' socket.
Tighten to a torque of 52 mN. Use a torque wrench.

Op 24

Grease the 2 swivel joints. Use a grease gun.

Do not hesitate to rotate the swivel hub so that the grease can penetrate and be well distributed in the ball joints.

Op 25

Clean the disc. Remove any traces of grease. Use brake cleaner and a cloth.

Op 26

Fit the steering ball joint on the steering arm.
Screw on the nut (GFK3323) and tighten it to a torque of 30 mN. Use a 17 mm socket and a torque wrench.

Final actions

Op 27

Reassemble the right front wheel:
• Replace the wheel.
• Screw on the 4 nuts. Use an 11/16'' socket.
• Lower the Mini to the ground. Remove the ramps or axle stands.
• Tighten the 4 nuts to the torque corresponding to the type of rim. Use a torque wrench.

The tightening torque of the wheel nuts is:
• 63 mN for steel rims.
• 50 mN for alloy rims.

Op 28

Replace the exhaust line (➔ see the tutorial ''Changing the exhaust line'' Op 17 to 31).

Op 29

Fit the carburetor (➔ see the tutorial ''Removing the HS4 carburetor'' Op 13 to 26).

Op 30

Connect the accelerator cable to the carburetor (➔ see the tutorial ''Changing the accelerator cable'' Op 30 to 34).

Op 31

Check the carburetor oil level (➔ see the tutorial ''Removing the HS4 carburetor'' Op 28 and 29).

Op 32

Reassemble the air filter box (➔ see the tutorial ''Changing the HS4 air filter'' Op 10 to 13).

Op 33

Add oil to the engine and gearbox (➔ see the tutorial ''Draining the engine + automatic gearbox'' Op 16 to 21).

The End

The new right-hand oil seal is in place. Well done! Now you just have to change the left one.
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