Rear Axle Oil Seal Repair

One problem which affects all 'Sevens' in time is the drip of axle oil onto the brake shoes. The best way to prevent the trouble recurring is to swap the bearings for a sealed type.  That way, the oil seals are more or less redundant.  Modern lip seals will only work on a new, shiny, oily-wet half-shaft - otherwise, stick with the felts.

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1. Jack up the car and support on axle stands, chock the wheels in contact with the ground, release the handbrake and remove road wheel.

2. Drain the axle by removing the bottom plug from the differential.

3. Remove the brake drum by removing the three small screws and pull off by hand.

4. Remove the split pin from half-shaft nut BUT MARK THE END of the shaft with hacksaw blade to show where the split pin hole is located as this will make it much easier to reassemble!

5. The hub must be prevented from rotating.  Either use a special tool made from a bar and an old brake drum, or clean the brake shoes with petrol, loosely refit drum, apply handbrake and 1st gear.  Now get an assistant to apply their foot to the brake cable.  Do not attempt to use a simple bar against the wheel studs - they will bend.

6. Undo shaft nut.  It is right a handed thread and needs a ¾ Whitworth socket.  Make sure that the socket is a good fit.  THIS NUT WILL BE VERY TIGHT!  It may be necessary to use an 18” extension bar and apply a lot of force

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CAUTION:  The exposed threads on the hub are very easily damaged if the socket is allowed to lean over.

 

 

 

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Take a spare half-shaft nut and screw it on just a turn onto the end of the half-shaft.  The idea is to make the nut seem as if its an inch (25mm) thick.

The second nut now holds the socket parallel to the half-shaft and prevents it engaging too deep. The hub threads are now protected.

 

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7. With the hub nut removed, screw a hub puller completely onto the hub, making sure that the puller is screwed all the way on.  It is often necessary to clean the hub threads with a needle file to ensure that the puller is completely screwed on. NEVER USE A “CLAW” PULLER.


8. Tighten the bolt in the hub puller.  When it is fully tight, use a hot air gun to apply heat to the hub and then hit the bolt once with a large hammer to shock it loose.

9. Remove outer hub.  Always replace the gasket.

10 Use a punch and a hammer to flatten the locking washer.  Remove the large nut holding the bearing, preferably with a box spanner.  Note that this nut is NEVER very tight – just a “pinch”.

11. Remove the bearings and inner hub: a recommended way is to loosely refit the OUTER hub with the puller still attached, fit the wheel nuts then gently tighten the puller by hand to pull the inner hub off.  It should not be tight.

12 Behind the inner hub is the felt seal.  Remove with a screwdriver.  Ensure that the new felt seals are wet with oil or a light grease on the inner bore: this is to allow the felt to wear to the shaft without being burned.

13 Refit inner hub and fit a new sealed LJ1 ¼bearing.  Wipe a little grease on the bearing before fitting, and it will never need grease again.

14 Refit the lock washer and large nut.  Tighten to just pinch the bearing then lock in place by folding the tab washer against a flat on the nut.

15 Clean inside faces of the hub.  Replace paper gasket.  No sealant is required.

16 Refit outer hub, make sure the key fits into shaft.  Fit the brake drum.

17 Tighten nut.  AGAIN, USE TWO NUTS TO PREVENT RISK OF DAMAGE TO THREAD.  Tighten the nut a little at a time until the gaps in the castellations line up with the hole that is marked.  It has to be very tight so never “back off” if you are between slots - carefully go to the tightest slot you can.  If you get stuck mid way, back it right off and come up to tight again.  Always fit a new split pin.  Wash the brakes and drums with petrol to remove all traces of oil.

18. Repeat on other side.  DO NOT MIX DRIVER SIDE HUB WITH PASSENGER SIDE HUB.  The hub will have taken the exact shape of the shaft: swapping near-side and off-side will prevent the taper seating tightly enough.

19. Then refill the differential through the plug at the back.  Allow excess oil to drain out to get the correct level.  Refit plug.

It is worth rechecking the half-shaft nuts for tightness after a couple of  hundred miles.

 

See also:

Austin Seven's Back Axle

 

This article, written by Geoff Hardman, originally appeared in CA7C Seven Focus in June 2011 pp22-24.

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