Q - screw-in block core plug removal

[Austin in the Shed]

Rear hub Puller thread is 1 3/8"

[jr2766]

You will rarely remove the screwed in plugs in a block without drilling them out.
I have just removed the plugs from 3 blocks.
Drill or mill out the plugs to about 7/8" to 1" diameter then drill a series of holes in the remainder. Collapse the annulus with a hammer and chisel  and retap  M32 x 1.5  which has worked well. I can confirm the thread is 1 1/4" x 16 tpi however one of the blocks has a 1" thread
Its important to get all the rust out of the area of the plug thread and for this I use Citric Acid, 1kg of crystals to 8 litres of water and after a couple of days you are left with a lovely clean grey surface. If you want quicker action just keep the solution warm.
This is much nicer to use than molasses and Muriatic acid.
I haven't had the new plugs made yet but they'll  be in SS and have two dowell holes rather than a screw driver slot and sealing will be by o ring.
If there was enough interest I may be able to supply some of these to third parties.
Jim Runciman

[Stuart Giles]

I remove the plugs by drilling a hole in the centre of the plug using drill bits increasing in size to 3/4 of an inch.
Then carefully cut out the remainder with a die grinder until the it falls out.
The thread is 1 1 /4 x 16 and a tap is available from Tracey Tools.
One of our members manufacture the new plugs in brass that are then sealed using Loc Tite 515.
The small brass plugs are also removed the same way and they are 3/8 Gas. 
New plugs available off the shelf.
This might seem to be unnecessary but I am in Australia and the temperature is currently 38 degrees Celcius.

David, That's interesting information about the thread of the large screw in core plug -@ 1 1/4" x 16 TPI it's the same as the rear axle hub thread. 

I'm hoping Stuart is wrong about the hub thread, otherwise I've just wasted my money on a 1 3/8" x 16 tpi die for the hub.

Does your car have the late "heavy" rear axle? These have bigger wheel bearings than earlier cars; ISTR that the hub thread on those is 1 3/8"

[Colin Wilks]

Does your car have the late "heavy" rear axle? These have bigger wheel bearings than earlier cars; ISTR that the hub thread on those is 1 3/8"

Just measured internal threads on my standard Austin hub puller and the 1 3/8" x 16 tpi die that I have for refreshing the hub threads. Both measure 1.298".

[Stuart Giles]

Does your car have the late "heavy" rear axle? These have bigger wheel bearings than earlier cars; ISTR that the hub thread on those is 1 3/8"

Just measured internal threads on my standard Austin hub puller and the 1 3/8" x 16 tpi die that I have for refreshing the hub threads. Both measure 1.298".

Hi Colin, Perhaps I should have been clearer; hub thread as in the rear hub nut; the one that retains the LJ 1 1/4 bearing on the rear casing on all the pre heavy rear axle cars. As you say, the hub puller thread is 1 3/8" x 16 TPI.

[Colin Wilks]

Assumptions, assumptions! Thanks for clarifying Stuart.