The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Andy888 on 31.08. 2025 07:21

Title: Rocker box stud thread
Post by: Andy888 on 31.08. 2025 07:21

I did a trial fit of the rocker box yesterday only to find that the two rear studs are too short. I guessing it’s because either the rocker box is off another model or the alloy head has deeper holes.
Anyway I need to get some longer ones. Am I right in thinking that the thread in the rocker box is 5/16, 18 tpi??

Title: Re: Rocker box stud thread
Post by: Klaus on 31.08. 2025 10:07

Hello Andy,

the thread is 5/16 x26 its BSC

reagards Klaus

Title: Re: Rocker box stud thread
Post by: Andy888 on 31.08. 2025 10:13

Hi thanks for that but I was meaning the end that fits in the rocker box itself

Title: Re: Rocker box stud thread
Post by: chaterlea25 on 31.08. 2025 12:05

Hi Andy,
The two rear studs are short because there are two special sleeve nuts and thick collars that fit there.
Refer to the parts book or Draganfly's online parts diagrams.

John

Title: Re: Rocker box stud thread
Post by: Klaus on 31.08. 2025 13:12

Quote from: Andy888 on 31.08. 2025 10:13

Hi thanks for that but I was meaning the end that fits in the rocker box itself

Yes the long nuts John mentioned are also 5/16 BSC  *whistle*

Title: Re: Rocker box stud thread
Post by: Andy888 on 31.08. 2025 14:25

Ahhhh. Got it. All makes sense now.
Thanks all.

Title: Re: Rocker box stud thread
Post by: Swarfcut on 31.08. 2025 16:21

    5/16" X 18 is our old friend  BSW, the usual coarse thread into Alloy. UNC will also fit for most applications, especially in worn threads, being a gnat's bigger on minor diameters.

  For a handy reference use  the Nut and Bolt chart...see first listing in Forum Literature Section. This will identify the majority of fixings eg stud diameter, length and thread type from part number. Thanks to Musky....

 Swarfy.