The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: wally on 27.07. 2025 06:08

Title: 1951 A10 Rocker Box bolt Part no. 15-1355
Post by: wally on 27.07. 2025 06:08

Can someone tell me the spanner size for the retaining bolt located inside the rocker box? The manual talks about a "special tool" needed.

Title: Re: 1951 A10 Rocker Box bolt Part no. 15-1355
Post by: Greybeard on 27.07. 2025 09:13

It's been a while... I don't recall needing a special tool to remove the rocker box 🤔

Title: Re: 1951 A10 Rocker Box bolt Part no. 15-1355
Post by: muskrat on 28.07. 2025 20:47

G'day Wally.
It should be the same as the 4 on top. 5/16 x 1,5/16 x 26tpi (CEI) so either a 1/4 Whit or 5/16 BS spanner will fit. No special spanner is needed.
Cheers

Title: Re: 1951 A10 Rocker Box bolt Part no. 15-1355
Post by: Swarfcut on 29.07. 2025 07:53

   Only special tool I can think of is the infamous pushrod comb, but this is used on re-assembly of the rocker box.

  No mention is made in the Service Sheet 204 "Decarbonising" of any special tool to access this bolt, other than perhaps using a socket rather than an open ended or ring spanner. I'd like to know where the notion of something special comes from. Sounds like a typical Haynes  type faux-pas.

 Swarfy

Title: Re: 1951 A10 Rocker Box bolt Part no. 15-1355
Post by: Ted_Flash on 29.07. 2025 09:14

The Haynes 1973 edition has no mention in the text.  There is a photograph 6.6b with text "Don't forget holding bolt inside the rear inspection cover" and shows a cranked ring spanner on the bolt.