MagDyno sprocket removal

Previously gordon_milburn wrote:

What is the thread inside the lucas magdyno drive sprocket. Does someone seel a sprocket removal tool?

I have 2 or 3 of these in storage which is pretty far from where I live. I got the strong impression the shaft was 3/8 20tpi (3/8 BSF) but I would not swear to it. If someone does not tell us by Monday, I will take a drive down there and measure it myself.

Previously Jonathan Soons wrote:

Previously gordon_milburn wrote:

What is the thread inside the lucas magdyno drive sprocket. Does someone seel a sprocket removal tool?

I have 2 or 3 of these in storage which is pretty far from where I live. I got the strong impression the shaft was 3/8 20tpi (3/8 BSF) but I would not swear to it. If someone does not tell us by Monday, I will take a drive down there and measure it myself.

yes it's 3/8" BSF (20tpi)

regards

The thread on the end of the taper is 3/8 BSF, but I think Gordon is asking about a different thread. Do you mean a female thread in the recess in the sprocket to take an extractor? If so my 1951 ES2 doesn't have a thread in this, it's just smooth and as such the sprocket is a nightmare to get off.

Andy

A thread inside the sprocket ? I can only recall a tapered bore. The WD manual details removal with a hooked tool levering back against a loosened retaining nut.

According to the spare parts list, the engine shaft is threaded 3/8" x 26tpi and the magdyno spindle is 3/8" x 20tpi.

A miniature two-legged puller with the feet ground a little can be made to fit.

Levering against the case with tyre levers or similar is not recommended but judging by the number of engines with a crack there, it's not unknown !

Manual Illustration of sprocket removal tool

Attachments
afbeelding-124-jpg

I use an old 'KING DICK' right angled adjustable spanner. The slightly open jaws fit over the sprocket with the head of the moving jaw against the inner timing case, a tap with a hammer and ping. John

I use a large tyre lever, the sort you used to get in Halfords with a right angle at one end and a very slight bend at the other. One thing you might want to do is put a piece of wood or metal plate between the mag and the chain casing to stop it flexing, the 1948 on type are fairly strong but I have also seen a couple of pre-war ones with a fracture where they have been levered too much. Regards, Richard.