Center Head Bolt?

Andover Norton now (well for some time) are making the head bolts out of 13mm stock, easier to get seemingly but still obviously the same thread forms. Handy because 13mm sockets are on every parts shelf. I have them on one of my Commandos, only problem is on a long trip you still need to take the whitworth spanners along as well as the 13mm, not a big deal though and does make life a bit easier.

Hungry J0e said:

3/16W was referencing the whitworth socket I have to use to tighten the nut, which reads 3/16W... sorry for the confusion... this is my first foray into whitworth fasteners...

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It's not your fault, the confusion has arisen from the fact that head nut hexagons 9 & 10 would normally be 1/4W size, and not 3/16W as the 7 & 8 nuts are.

L.A.B. said:

It's not your fault, the confusion has arisen from the fact that head nut hexagons 9 & 10 would normally be 1/4W size, and not 3/16W as the 7 & 8 nuts are.

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You mean 7 & 8 are supposed to be 3/16W? We're talking about the underslung nuts, correct?

On MY bike 7 & 8 are 1/4W and 9 & 10 have 3/16W nuts...

I went through a fair amount of rigomorol to torque 7 & 8 to 30 ft-lbs... I assumed that the 20 ft-lbs were for the recessed bolts at 9 & 10 which on my bike are 3/16W...

If this is the case, very odd then that one would have stripped out at only 20 ft-lbs...

Not sure what to do about 7 & 8 now... I may leave well enough alone and leave them as is now... although I'm also afraid when everything heats up they may not withstand the additional load...

Cheers,

- HJ

Hungry J0e said:

You mean 7 & 8 are supposed to be 3/16W? We're talking about the underslung nuts, correct?

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Correct, and they should look like this: http://www.norvilmotorcycle.co.uk/063192.htm

And fit the two 3/8 studs that screw into the head (so = 30 ft. lbs)

Hungry J0e said:

On MY bike 7 & 8 are 1/4W and 9 & 10 have 3/16W nuts...

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Seems to be the opposite of what it should be?

L.A.B. said:

Seems to be the opposite of what it should be?

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I suppose... but the studs for the recessed nut (number 9 and 10 in the tightening sequence) are 5/16" studs for 20 ft-lbs or torque, correct? And the studs for the underslung nuts (7 and 8 ) are 3/8" studs for 30 ft-lbs?

I think we're doing competing edits as I thumb through my parts catalog...

So looks like my torque settings were good at least!

Cheers,

- HJ

Actually, John Hudson does mention in his NOC engine rebuild video that the early sleeve nuts (7 & 8.) were 1/4W hexagon size, and the later ones were in fact 7/16 A/F, although a 3/16W spanner/wrench also seems to fit.

Hey there, Joe.

Flip the stud over, apply Loctite stud lock and snug it down firmly, carefully feeling for a steady increase in resistance. When it feels good and tight, let it sit for several hours.

Take it out and warm it up good, then stretch it's legs and see how it holds. i'll bet it'll be fine.

L.A.B. said:

Actually, John Hudson does mention in his NOC engine rebuild video that the early sleeve nuts (7 & 8.) were 1/4W hexagon size, and the later ones were in fact 7/16 A/F, although a 3/16W spanner/wrench also seems to fit.

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The stainless sleeve nuts from RGM are 7/16" AF spanner size, and the rear nut is deeper than the original. It all helps...a bit