Crankcase drain plug. Dominator series.

There are 2 sizes (that I know of)  The original size as fitted to most dommiies and the later ones as provided by our suppliers ,probably from Commando's.I will check my Box spanner if it helps.

Personally I would only undo the drain plug once more. When off you can drill a hole in the centre, tap a thread and then fit a sensibly sized magnetic drain plug. The hole and thread are obviously dependant on the size of the drain plug. 

Tim 

According to the Instruction book, it's 7/8" Whit, which is 37.59 mm.

Very many (most) I've seen are in a pretty bad shape. During more than fifty years, the poor bronze plugs have experienced pipe wrenches, monkey wrenches and any other unimaginable tool. Thus disfiguring the hex head so much that a proper spanner don't fit anymore.

As my motorcycle friends used to say back in the sixties, "Fitting on an English motorcycle is only depending on the size of the hammer".

The old traditional King Dick adjustable spanner can provide a snug fit.

In the Dominator Service Notes it says that the Crankcase Drain Plug needs a 7/8"  socket or box spanner. But does not specify whether WW or BSF. I am guessing WW is correct.

This overlaps with recent thread on vertical camshaft drive nuts

https://www.nortonownersclub.org/node/10452

Ian McD

Many years ago I realised that metal particles could find their way to the pump. I ordered a magnetic sump plug only to find that I did not have the facilities to fit to the brass filter.!. Biting the bullet I orderderd the complete new filter plug with magnetic drain plug fitted.I then was peeved to find that my handmade spanner did not fit the new brass filter and none of my Norton spanners fitted the drain plug. Pissed is not the word for it.  I then took an angle grinder to the new parts to make them fit  as Mr Norton intended. And I don't have to carry extra tools in the tiny tray. At this point I realised than Norton Dommy parts often meant Commando parts take it or leave it.

There is a specific box spanner, and a flat spanner, that is made specifically to remove the Dominators sump plug. I have both, and they work perfectly.

As long as you are aware there are differences hopefully you won't get palmed off with the wrong bits like I was on many occasions. Things may be better now, 

One supplier once told me that they had an single open-ended spanner which fitted the fork top nuts as well as the sump plug.  I knew they didn't because they are different sizes!  

As the plug is fairly soft bronze you don't really need a chrome-vanadium type of spanner for it.  I have considered making a simple spanner out of 3/16" / 5mm steel plate.  It doesn't need to be sophisticated or look good - just practical.  Ye Olde Disc Cutter and a few cobalt drill bits should do the job unless you have something more able to cut out the open-end jaws.

A 38mm socket works just fine on mine. Having said that, I agree with Tim, and bought the rather expensive drain plug complete with integral smaller magnetic drain plug from Norvil, which can ultimately save the threads in your crankcase. Trouble with it though is that I just cannot make it oil-tight.... 

Used a Britool 1 1/2 AF socket with 3/4 " to 1/2 " reducer for past 46yrs. Hope this helps. And RGM do a box spanner

Hi Chaps - hope you are all keeping well.  So far, so good! 

Andover Norton show a box spanner and a ring spanner - which is only £5.95 + VAT! - as below:

13.1733

SUMP PLUG SPANNER, ALL TWINS WITH LARGE FILTER PLUG

5.95 £ excl. VAT

There is no size listed, but if it's right I won't bother to try and make one!  I won't need it for a while so there's no rush.

The box spanner is 1.1/2" x 1. 5/16" and costs £15.95 + VAT.  1.1/2" is 38.1mm so should be OK but hopefully the cheap one is too.  Not something you should need very often.

Take care,

Lionel