Help! Why does my nut keep coming off?!

[Sam C]

Thanks both.

I'm more confident that the clutch should hold itself together now. So cheers!

On the cush drive spring, yes my initial thought was that the spring has 'lost its springness'. However, its all on now and seems to be working fine. The spring does seem to have about the level of springiness you're describing i.e. it's swiftly too tight to tighten by hand.

Cheers all

Sam

[BSA_54A10]

When new the nut will pick up about two turns when applying light compression.
When old the nut has stripped the forst 3 threads and is a bugger so you need to compress the spring to get it started without cross threading

[shuswapkev]

  I also made one like the picture...just weld a big nut on it ..a nut that matches a socket you already have..
  and bang it down with an impact wrench...I also make up the sheet metal tab washer and fit a cotter key....split pin...
  my early learning experiences with a near new commando...  had the alternator nut come right out thru the outer primary...
 what a heartbreaker...  ah well...  good reason to lift my game...

[duTch]

Quote from: Sam C on 17.05. 2016 14:55


    One very final questions:

    On the clutch, I did take the plates out in order to fit the tool. When I put the plates back in again I simply tightened up the four spring nuts to 'about right' (with a few mm of thread sticking out the end), then checked that the clutch was functioning properly and disengaging evenly - and that was it. Ever since I've been worrying that those things may come off, since it seems a bit precarious to just 'do them up a bit and hope for the best'. What do others do? Thread-lock?

    Or am I worrying about nothing?


The cups and nuts have a ''notch'' that catches (more or less) on the springs. That should be enough to keep 'em from undoing. I had the same fear, but the nuts never moved a bit on my SA's 4 springer

 I believe these notches/lobes in the cups, and corresponding tabs on the brass nuts will only work properly with Left hand wound springs.
   All the old clutch springs I have (6 spring Plunger) are left hand wound, I ordered some new ones from Draganfly specifiically L/H, but they sent me RH...

[jjbsa]

In days of old I did this nut up with a brass drift and a hammer, the drift applied to the castellations in the BSA nut.  If you do this, in my opinion it is MOST important to rest the nut, while on the drive-side mainshaft, firmly on the end of the head of a sledgehammer (use a helper to lean the bike, with the nut pressing on the head of the hammer).  While you're hitting the drift towards the hammer head the sledgehammer absorbs the impulse from the hammer and stops either bending the mainshaft or damaging the d/s main bearing.  If you have put some Loctite on it, it will never come free.  Later in life, armed with a 4 prong driver and a torque wrench I have shown it's easy to do the nut up to 70 ft lbs this way.  With Loctite 222 or 221 applied and the nut done up to 70 ft lbs, It takes about 200 ft lbs of torque to undo it once the Loctite has cured.  Mind you, I still put in the little split pin afterwards :-) HTH