The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: terryg on 03.06. 2014 15:19

Title: Fork drain screw thread? Super Rocket
Post by: terryg on 03.06. 2014 15:19

Can anyone confirm what thread the fork drain screws are on the full width hub sliders, as on the late Super Rockets, please?

10-32 UNF?

I have some new, slightly longer, screws that are not screwing fully home.

Title: Re: Fork drain screw thread? Super Rocket
Post by: Beezageezauk on 03.06. 2014 15:52

Hi Terry,

The information that I have is as follows:-

Part number 02-1309 is a slot headed screw with a 2BA thread and is 5/16" long.

Beezageezauk.

Title: Re: Fork drain screw thread? Super Rocket
Post by: terryg on 03.06. 2014 19:16

Hello Beezageezauk - yes, that sounds entirely plausible.  My thread gauge is saying 32 tpi but that could easily be 31.4 (per 2BA) and the thread diameter (2 BA) of 0.185 inch is a better match to my measurements than 0.190 (10-32 UNF).

Good steer, many thanks!

I think it's (long passed) time I treated myself to some BA taps and dies.

While looking, I found this link - http://www.britishfasteners.com/threads/unf.html (http://www.britishfasteners.com/threads/unf.html), which looks a bit useful on thread dimensions.

ATB,
Terry

Title: Re: Fork drain screw thread? Super Rocket
Post by: trevinoz on 03.06. 2014 22:00

Definitely 2BA.

Trev.

Title: Re: Fork drain screw thread? Super Rocket
Post by: duTch on 03.06. 2014 22:30

 Hey Terry- just a thought that may be way off mark....regarding them not screwing home...

 I remember something having removable cones in the bottom of the sliders that are part of the damping system, and also are notched and the drain plugs engage with this notch to stop it turning when removing the cone retaining bolt that comes up through the bottom.....(had to say that to suggest this.)...->
 maybe the drain plugs are just a tad too long and bottoming out on the cones first...?