BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: falconho on 06 Nov, 2025, 23:27

Title: Petrol Tank
Post by: falconho on 06 Nov, 2025, 23:27
Hi does anyone know the thread size of the tank knee pad brackets screws and the smaller single screw in the pear shaped badge 1967 Thunderbolt UK tank , and where would I get the  taps to clean the threads Thank you
Title: Re: Petrol Tank
Post by: cdsdorset on 07 Nov, 2025, 08:32
3ba by 7/8. Only bsa would decide on that size!
Title: Re: Petrol Tank
Post by: V500 on 07 Nov, 2025, 09:51
Probably got a job lot of 3BA screws from Lucas.
Title: Re: Petrol Tank
Post by: falconho on 08 Nov, 2025, 21:33
Is that 3BA for the knee pad bracket the pear shaped badge screw is smaller do you know what size this is
Title: Re: Petrol Tank
Post by: cdsdorset on 08 Nov, 2025, 22:42
56- 68 is 3ba.
Title: Re: Petrol Tank
Post by: Ian C on 09 Nov, 2025, 11:33
Quote from: falconho on 08 Nov, 2025, 21:33 Is that 3BA for the knee pad bracket the pear shaped badge screw is smaller do you know what size this is

AFAIK, the kneegrip bracket screws which are BSA part no. 24-7178 are 1/4" x 26TPI (some sellers claim CEI and some BSF)
HTH
Title: Re: Petrol Tank
Post by: cdsdorset on 09 Nov, 2025, 13:05
Sorry. Wasnt clear 3ba is for the badges.
Title: Re: Petrol Tank
Post by: limeyrob on 09 Nov, 2025, 18:05
Confusingly in 1/4 CEI / BSC and BSF are all 26 TPI.
Title: Re: Petrol Tank
Post by: V500 on 09 Nov, 2025, 21:13
And in these days of "near enough is good enough" repro stuff, some suppliers will supply either for any given task, but back when these threads were in common use they weren't considered to be interchangeable.