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The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: JimmieS on November 06, 2019, 05:11:46 PM

Title: Thread form used on 1930 Model 2
Post by: JimmieS on November 06, 2019, 05:11:46 PM
Dry building my long dismantled Model 2. Many bolts which seem original appear to have cycle threads. Is this so?
Jim
Title: Re: Thread form used on 1930 Model 2
Post by: singleminded on November 06, 2019, 05:47:48 PM
Most frame thread up to 1932 seem to be 26tpi cycle..My '32 9A is mostly BSF on the frame, but you will find 20tpi and 26tpi cycle on some parts..The clutch nut for example was 26tpi up to 31ish and 24tpi from 31ish onwards..You need to have a thread gauge handy.
Title: Re: Thread form used on 1930 Model 2
Post by: shorrog on November 06, 2019, 05:59:27 PM
Not sure if you have seen the tables of thread sizes on the website, but they can help when identifying a thread if you can measure dia and pitch.
https://www.marston-sunbeam.org/threads/thread_british_std_cycle.php (https://www.marston-sunbeam.org/threads/thread_british_std_cycle.php)


Graham
Title: Re: Thread form used on 1930 Model 2
Post by: JimmieS on November 06, 2019, 07:04:47 PM
Many thanks for the quick replies.Much appreciated. I have a thread gauge plus set of tables but, like most things in life, I can;t find them when  needed. As none matched my BSF taps I assumed what I now know as fact.
Thanks again.
Jim
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