Morris Minor Owners Club

Thoughts from another thread lead me to think about drilling and tapping my 948 axle case to take a filler plug rather than replace the entire axle... What is the thread size for the filler? Is it a tapered thread? Anyone think of any pro's and con's in doing so?

I think the casing is too thin to take any worthwhile thread. You would need to weld on a 'boss' - just use the breather hole!

Hmmm, good point - I hadn't considered the thickness....

There should be somewhere on the diff itself suitable for drilling a filler hole. You would have to be careful not to get swarf in the diff. It is a tapered pipe thread.

The obvious place is - where BMC put it!

Indeed, however, the 948 casing lacks the "boss" that is cast into the 1098 casing

The later filler plug in the axle casing is the same thread as the diff one - 1/2" BSP. The plug is tapered, but the boss does not need to be, although it could be! The tapped hole on the diff housing was a tapered thread I am pretty sure, but not the axle casing boss?

I have the early axle, so have welded on a boss à la BMC, as the casing itself is defintely too thin to tap 1/2" BSP. It was done during the restoration, so the axle was completely stripped at the time. The boss was made by cutting a mild steel pipe fitting in half - make sure if you use something similar that it is mild steel; many pipe fittings are malleable steel and it does not weld very well, and you end up with a porous weld, which is certainly not required.

With the diff removed it would be feasible to drill the hole and be able to make sure that all the swarf was removed from the inside of the casing, plus any debris from welding on the boss.

Thanks all. I agree, after having a close look, that the casing is too thin to tap. I was looking for an easy option but I guess if I want a filler I am gonna have to change the casing over or continue with the breather fill option

Fill it once with fresh oil and it should last for another 50,000 miles, or so........

I'm leaning in that direction - Maybe one day when I have nothing to do I'll swap the casings over

Some of the "modern" vehicles have a rubber plug that just snaps into the thin axle housing, sorta like the plugs in the front doors that cover the bolts that hold the window frames in at the back of the door.

It would leak knowing my luck

Or fall out. Not worth the risk there.

The ones I've seen wont fall out, they're in there pretty tight. They don't leak either, but they do have a greasy dusty spot around them, so I suspect that they seep ever so slightly.