Additional notes on changing rear axle pinion bearing seal

[rutger kohler]

I have recently changed my rear axle pinion bearing seal. There are already a lot of useful comments on this website but below are several points which may also  be useful.

1 Despite some earlier posts commenting that the pinion shaft nut, holding the mating flange for the driveshaft being relatively easy to remove, I found mine extremly tight.  I tried a socket that Andy Burns had ground with 4 prongs for a start but this was no good at all.

I then machined up a tool that fitted the four slots exactly, and still could not move the nut.  Eventually I made the gear up shown in the attached photo.  I still couldn't move the nut with all my weight on the 16" tommy bar, and luckily my 6' 3" son-in-law took pity on me and just manged to slacken the nut off.

I can take photos of the arrangement pulled to pieces if anyone wants and also I would be happy to lend to anyone in OZ or NZ if they want to use it.  I spend quite a bit of time in Sydney on Northern beaches, sadly without my car.

Several experts tell me that they have the car up on a hoist and have to fit a piece of pipe on the tommy bar to loosen it. One other point both of them made is that they mark the shaft and the nut before they slacken it and pull the nut back up so that the marks line up again rather than trying the bar and scales arrangment mentioned on this website.  This makes sense to me as earlier posts mention a plastic crush ring between the two opposing bearings that deforms on the first tighten and doesn't recover.  I did use a hanging scale before and after I took the nut off.  Putting one hook in a flange bolthole and pulling down from the 3 o'clock position it took approx 2.75 kG  to move the road wheels with the hand brake off both before and after the repair.

Another point worth mentioning is that the lock washer is a metal skirt that is riveted to the nut itself rather than the old tab washer idea  (1969 280SL).  Care needs to be taken to carefully lift the part of the skirt that has been hammered down to lock so that it comes back smoothly otherwise it is easy for it to pick up.  There is not much clearance.

[Larry & Norma]

Wow that's a lot of effort.
I thought I would change my seal as I had my axle out. There  was a slight leak
from the seal.
After trying all sorts methods other than destructive I gave up

Put the axle back in the car, it has not leaked since

[Benz Dr.]

I use an impact gun. The thread is fine on the pinion shaft so it will really torque down. A constant pull will often fail where a quick shock will make it turn easily; at least most of the time it will. 

[jameshoward]

I use an impact gun. The thread is fine on the pinion shaft so it will really torque down. A constant pull will often fail where a quick shock will make it turn easily; at least most of the time it will. 

+1. As Dan says, impact is the way to go.

[rutger kohler]

Sounds like it works, never thought of an impact gun.  I had to laugh at Larry and Norma's post, is that the inverse to Murphy's law?

[Benz Dr.]

Yeah, maybe.  The more you have in the axle the more it doesn't leak is directly poportional to the less you have in it the faster it will burn up.  ( maybe that doesn't make sense )

[Larry & Norma]

Axle was topped up with oil when reinstalled, I can only think that my efforts
to remove the nut somehow re seated the seal maybe

[star63]

Axle was topped up with oil when reinstalled, I can only think that my efforts
to remove the nut somehow re seated the seal maybe

Or the breather tube had been plugged and it started to "breathe" again...?

[rutger kohler]

Something else i forgot to mention, I had a great deal of trouble starting the new oil seal off in the housing.  I then machined up a ring the right size and spot welded a plate on the back of it  so that I could get the oil seal to start all the way round, at the same time.  Again if anyone wants to borrow it they are welcome.