Kneegrip threads

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Pete.Silson
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Kneegrip threads

Postby Pete.Silson » Sat May 09, 2020 3:45 pm

Last year I bought a '49 single that came with a spare petrol tank that I think is from a prewar 350 but I don't really know. My question is about the knee grip fixings.
350 tank.jpg

The front holes are threaded 1/4" 26 tpi (which I would expect) but rear have studs with what appears to be 5/16" 24 tpi. The only thread I know this size 5/16" UNF but I wouldn't expect to find this on anything that old.

Does anybody know what the correct threads should be for this tank?

Pete

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paul.jameson
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Re: Kneegrip threads

Postby paul.jameson » Sat May 09, 2020 9:09 pm

Pre war tanks have a boss with a protruding 1/4 x 26tpi stud. Post war tanks have an inset 1/4 x 26tpi hole with a groove round the outside of it. So your tank looks like a pre war one where someone has had to modify the mountings for some reason.
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Pete.Silson
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Re: Kneegrip threads

Postby Pete.Silson » Sat May 09, 2020 10:51 pm

Thanks for the info Paul,

Shame they didn't bother to use a 5/16" cycle thread rather than UNF but I guess I can live with it.

Pete

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john.bebb
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Re: Kneegrip threads

Postby john.bebb » Thu May 28, 2020 7:02 am

Not to worry... Ariel used 3BA for my Sq's tank badges... now where can one get 3BA 1/4" instrument heads in stainless?
Oh well... I had some made.

Cheers, John

Pete.Silson
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Re: Kneegrip threads

Postby Pete.Silson » Thu May 28, 2020 7:42 am


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john.bebb
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Re: Kneegrip threads

Postby john.bebb » Thu May 28, 2020 11:13 am

Not to worry... Ariel used 3BA for my Sq's tank badges... now where can one get 3BA 1/4" instrument heads in stainless?
Oh well... I had some made.

Cheers, John


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