Oil Pump drive gear nut

[Satan's Aardvark]

I'm replacing the oil pump on my '72 750. Badly worn.

What is the correct spanner fit for the drive gear retaining nut?

None of my whitworth or AF fit, 14mm is close but I'm guessing it's not an exact fit.

 

[robs ss]

Good question!
I have just measured the nut on my 650ss (only thing at hand) and it's 13.28mm across the flats.
None of my spanners fit either (AF, Whit or Metric)
Ahhh - just use a shifter!

 

[L.A.B.]

What is the correct spanner fit for the drive gear retaining nut?

None of my whitworth or AF fit, 14mm is close but I'm guessing it's not an exact fit.

The nut is 3/8" UNF, therefore, the hexagon should be 9/16" AF (0.563")...

Andover Norton - NUT 3/8

NUT 3/8

andover-norton.co.uk

The next size smaller would be 14mm (0.551"), then 1/4"W (0.525"/13.34mm), then 13mm (0.512").

Spanner Jaw Sizes

Useful guide on spanner to nut/bolt relationships, and the selection and use of spanners and socket sets

www.crawford-space.co.uk

I have just measured the nut on my 650ss (only thing at hand) and it's 13.28mm across the flats.
None of my spanners fit either (AF, Whit or Metric)

The 650SS nut is likely to be BSC so 1/4"W (13.34mm) should be the correct spanner size.

 

[Satan's Aardvark]

Thanks for the replies.

Not sure what mine is, 1/4 WW is too small, 9/16 AF is too big. It may be something odd as the engine has been rebuilt before my time.

Perhaps a unique shifter size as Rob says.

 

[Onder]

When I first got my Rickman I tried to take out the sump drain plug. Way too small for the correct Whit socket. Puzzled! Got in close with a light and vernier and it was clear what happened: somebody had taken a file to the hex and brutally reduced it to
3/4" AF! I guess in the 70s there were a lot of bike owners who ether were skint or simply too dense to buy a few tools. It really was tough for a young guy to operate in those pre-internet days when good information was like gold. Imperial stuff was not common in the states during the Dark Ages of British Motorbikes!

 

[robs ss]

The 650SS nut is likely to be BSC so 1/4"W (13.34mm) should be the correct spanner size.

Quite right Les - careless of me.

 

[robs ss]

Thanks for the replies.

Not sure what mine is, 1/4 WW is too small, 9/16 AF is too big. It may be something odd as the engine has been rebuilt before my time.

Perhaps a unique shifter size as Rob says.

Sometimes, if you can't find the "correct" spanner there will always be a Metrinch one that will fit (and do less damage than a slightly loose conventional spanner)
The only downside with them is the "wasted throw" phenomenon due to them being an initially loose fit. Great otherwise.

 

[robs ss]

Thanks for the replies.

Not sure what mine is, 1/4 WW is too small, 9/16 AF is too big. It may be something odd as the engine has been rebuilt before my time.

Perhaps a unique shifter size as Rob says.

The Metrinch 14mm&9/16 fits my 13.28mm well so will work on yours - given that 9/16 is too big
If you have not seen them their "wave" profile engages the centre of the flats instead of the corners (which conventional spanners do)

 

[B+Bogus]

The Metrinch 14mm&9/16 fits my 13.28mm well so will work on yours - given that 9/16 is too big
If you have not seen them their "wave" profile engages the centre of the flats instead of the corners (which conventional spanners do)

I think some American cowboy outfit from Kenosha WI call it 'Flank Drive'

 

[SteveA]

Sometimes, if you can't find the "correct" spanner there will always be a Metrinch one that will fit (and do less damage than a slightly loose conventional spanner)
The only downside with them is the "wasted throw" phenomenon due to them being an initially loose fit. Great otherwise.

Always keep a small set of Metrinch combination spanners in the toolbox, rarely use them, but when you have a tricky size they are very useful.

Also called 'wall drive'

 

[MichaelB]

Metrinch???
I thought it was a typo...
Interesting, I have seen them, didn't know what they were called.

Metrinch

Metrinch.TV

metrinch.tv

 

[Satan's Aardvark]

The Metrinch 14mm&9/16 fits my 13.28mm well so will work on yours - given that 9/16 is too big
If you have not seen them their "wave" profile engages the centre of the flats instead of the corners (which conventional spanners do)

Thanks Rob

I do have those too, not metrench but some other manufacturer, and I expect they'd do the job without any issues.

Some wear is evident so I've decided to replace the gear and retaining nut anyway.

My verniers need a new battery, so unable to measure the exact width ATM but it's somewhere between 13 & 14mm.