Author Topic: bolt / nut threads  (Read 412 times)

Online RoyC

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bolt / nut threads
« on: 13.09. 2019 10:04 »
My new seat has arrived but the threads in the fixing lugs is 5/16 18 NC. is there a more common thread that I can use ?

Is it the same as 5/16 UNC ?

Thanks.
My bike is a 1958 A7SS
Stafford UK

Online RoyC

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Re: bolt / nut threads
« Reply #1 on: 13.09. 2019 11:32 »
My new seat has arrived but the threads in the fixing lugs is 5/16 18 NC. is there a more common thread that I can use ?

Is it the same as 5/16 UNC ?

Thanks.

I think they are the same as 5/16 UNC 18tpi.
I hope so, cos I've ordered some  *conf*
My bike is a 1958 A7SS
Stafford UK

Online RogerSB

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Re: bolt / nut threads
« Reply #2 on: 13.09. 2019 12:05 »
I think they are the same as 5/16 UNC 18tpi.
I hope so, cos I've ordered some  *conf*

Yes, you're ok Roy  *smile* (it's that we Brits like to put the Unified before the National Course).

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Online duTch

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Re: bolt / nut threads
« Reply #3 on: 13.09. 2019 12:17 »
 Apart from you seem to like to answer yourself, I think it's the 'same' (thread) as Whitworth but the Hex is different, that is to say a lot of bolts/nuts sold as Whitworth are actually UNC, so the hex/spanner size is different....same with 7/16" BSC/20 - 7/16"UNF  *pull hair out*
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Online RoyC

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Re: bolt / nut threads
« Reply #4 on: 13.09. 2019 12:18 »
I think they are the same as 5/16 UNC 18tpi.
I hope so, cos I've ordered some  *conf*

Yes, you're ok Roy  *smile* (it's that we Brits like to put the Unified before the National Course).

Thanks Roger.
My bike is a 1958 A7SS
Stafford UK

Online RDfella

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Re: bolt / nut threads
« Reply #5 on: 13.09. 2019 12:52 »
Although they're a slightly different thread form, Whit and UNC will interchange - expect for 1/2", where the tpi differ. One is 12tpi, the other 13tpi.
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Offline Swarfcut

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Re: bolt / nut threads
« Reply #6 on: 13.09. 2019 12:56 »
If it is a new repro seat any captive nuts stand a good chance of being Metric.

Online ellis

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Re: bolt / nut threads
« Reply #7 on: 13.09. 2019 15:57 »
Like the new avatar Roy.

ELLIS

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Re: bolt / nut threads
« Reply #8 on: 13.09. 2019 17:42 »
I bought a brand new seat, bolts were UNF ?

Online RoyC

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Re: bolt / nut threads
« Reply #9 on: 13.09. 2019 18:26 »
Like the new avatar Roy.

ELLIS

Me in my youth.  *red*

My bike is a 1958 A7SS
Stafford UK

Online RoyC

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Re: bolt / nut threads
« Reply #10 on: 13.09. 2019 19:20 »
I bought a brand new seat, bolts were UNF ?

I've tried UNF, they don't fit.
My bike is a 1958 A7SS
Stafford UK

Online RDfella

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Re: bolt / nut threads
« Reply #11 on: 13.09. 2019 19:31 »
If as Swarft says, they're metric, they'll likely be M8 (coarse). Try a bolt to see.
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Online RoyC

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Re: bolt / nut threads
« Reply #12 on: 13.09. 2019 19:36 »
If it is a new repro seat any captive nuts stand a good chance of being Metric.

Not metric, M8 won't fit, but a 5/16 NF 18 tap fits.
My bike is a 1958 A7SS
Stafford UK

Offline Swarfcut

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Re: bolt / nut threads
« Reply #13 on: 13.09. 2019 20:21 »
Whoops!!! Looks like a trip to Halfrauds* for an Oddpack of 6 (only need 4) 50mm bolts (only need 20mm) No wonder the World in the S**t.

*Halfords  A well established  national supplier of motor spares, cycle and leisure items. Usually found on retail parks along with such other esteemed brands as  Oak Furniture Land, B&Q, Argos, PC World. Nando's. KFC Maccy d's. You get the idea...you could be anywhere in the UK as corporate identities take over the landscape.

Offline berger

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Re: bolt / nut threads
« Reply #14 on: 13.09. 2019 20:59 »
hello roy I think you mean a 5/16 UNC/NC/ ANC tap fits? NF/UNF/ANF is 24 threads to inch. ps I have not been to the pub , man/ person flu has struck! *eek*