Hi,

Looking to remove the large clutch centre nut on a 1941 BSA WM20. Can't get it with a spanner and not enough room for a socket. Can anyone tell me the correct tool to remove it. To view the nut in question click on the link below.

http://www.cobraclassics.com/images/bsa_wm20.jpg

Many thanks

email (option): sales@cobraclassics.com

That isn't the correct nut which is why you have a problem...I would think the only thing that might fit in there is a box spanner...Personally, I'd probably see if I could machine down a socket to fit initially....Ian

email (option): ian@wright52.plus.com

Some butchery going on there! I've no idea what that nut is in the center of the clutch. The gearbox mainshaft nut that holds the clutch on is No62 in this diagram and only requires a 5/16 Whit socket. Ron

email (option): ronpier@talk21.com

Hi Trevor -

I'm sure others, including Rob Nortier and Ron Pier and Ian Wright, will chime in on this, but I will tell you that many years ago I found that sometimes tools in their native state actually exist as precursors to their final state. Facing the exact same dilemma with my own WD M20, I simply took the appropriate sized socket and ground its outer circumference down using a hand drill with said socket suitably mounted on a short extension against a 6 or 8 inch table mounted grinding wheel. Slow and steady, finally got it thin enough to slip on the tightly ensconced nut. Have been using that same socket for over forty years now.

Regards,
Bruce Cooper

email (option): btcoop77069@aol.com

My goodness, where were you two when I started typing my response only five minutes ago?!

Like I was saying, I'm sure one of the real pros would be right along!

All the best!

Bruce Cooper

email (option): btcoop77069@aol.com

Thanks all for your quick reply. I think the ground down socket is the way to go.
I know the bike hasn't been going in about 30 years but it was owned by an engineer who probably had his own fashioned socket.
Thanks Trevor

email (option): sales@cobraclassics.com

An engineer wouldn't do that to the main shaft and clutch spring nuts!..:laughing: (though someone has modified the spring nut to adjust the lift of the pressure plate)...Good luck with removing it...

You'll need the correct puller to get the sleeve off the main shaft once you've removed the nut...Hopefully the internal extractor thread in the sleeve is intact...Ian(an engineer)

email (option): ian@wright52.plus.com

email (option): ronpier@talk21.com

BWAHAHAHAHAHAHA!!!! Thanks Bruce Cooper. Send help to get me off the floor.

That's the wrong nut some ham fisted "mechanic" installed. I see the typical
chisel and screwdriver malformations on the spring nut. SO...... Here is a classic
example of being too cheap to buy the proper tools.

Your spring nut has the REME fix to level out the clutch spring. The holes should be
2BA if done in a REME shop.

I have sets of WW tools and for that center nut I just use a 5/16 WW socket.
No big deal. I never grind down a socket as it ruins them. I think there is plenty
of room there for a regular socket.

I did make the castelated tool for the clutch spring nut, and will be doing so again
as soon as my trans continental move is over.

Check the technical section for my book chapter on a clutch rebuild. There are detailed
steps on removal and rebuild. Critics are RAVING about it.

email (option): britool51@hotmail.com

Just sayin' it's a pleasure to see a castellated nut even more bashed around than mine. It must've been off & back on a few times...

Hi Robb,

Your comment on the tapped holes in the clutch spring nut is incorrect, the army specified 3BA (not 2BA). I did this mod to my M20 35 years ago and recall having problems finding 3BA screws as it is a relatively odd size. The mod worked well too.

regards, Richard