The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Cleve on 11.07. 2018 21:07

Title: S/a a10 gearbox sprocket removal
Post by: Cleve on 11.07. 2018 21:07
Hi, hope you chaps can help, I'm trying to get the gearbox sprocket undone, I'm sure it must undo clockwise? (I'm gearing down from 21 to 19

Thanks

Cleve
Title: Re: S/a a10 gearbox sprocket removal
Post by: RoyC on 11.07. 2018 21:16
Hi, hope you chaps can help, I'm trying to get the gearbox sprocket undone, I'm sure it must undo clockwise? (I'm gearing down from 21 to 19

Thanks

Cleve

Why not change the engine sprocket instead, that way you won't upset your speedo accuracy.
Title: Re: S/a a10 gearbox sprocket removal
Post by: ellis on 11.07. 2018 21:31
And you don't need to strip the whole chain case and clutch to do it.

ELLIS
Title: Re: S/a a10 gearbox sprocket removal
Post by: Cleve on 11.07. 2018 21:38
Hi Ellis/Roy,
thanks for reply, I've got it all stripped, have a belt drive so clean job, I only put the 21 on last winter, but I can't remember which way the thread goes and can't get it loose, so before I apply more force I hope someone can confirm undo direction 😊 21 is hard work in traffic...
Title: Re: S/a a10 gearbox sprocket removal
Post by: ellis on 11.07. 2018 22:24
Hi Cleve.

From what I can remember it was a standard right hand thread.

ELLIS
Title: Re: S/a a10 gearbox sprocket removal
Post by: duTch on 11.07. 2018 22:59

 As ellis says they are Right hand thread.

 As Roy says;
 
Quote
...Why not change the engine sprocket instead, that way you won't upset your speedo accuracy.

 If it's a standard speedo it'll already be wrong, so going to a 19T will put it right, but I expect the difference will be extremely noticeable.*eek*
Title: Re: S/a a10 gearbox sprocket removal
Post by: Cleve on 12.07. 2018 08:49
Thanks again,  I will try undoing it anti clockwise tonight.

Re the speedo, I guess I will have been under reading with the 21 tooth sprocket

Regards
Title: Re: S/a a10 gearbox sprocket removal
Post by: Greybeard on 16.07. 2018 22:52
You may be able to check your speedo against a SatNav. They are very accurate, (as long as you are not riding up and down hills).
Title: Re: S/a a10 gearbox sprocket removal
Post by: trevinoz on 16.07. 2018 23:04
19 is standard so the speedo will most likely be calibrated for it.
Title: Re: S/a a10 gearbox sprocket removal
Post by: Butch (cb) on 17.07. 2018 16:58
You may be able to check your speedo against a SatNav. They are very accurate, (as long as you are not riding up and down hills).

Either Lincolnshire or the Essex badlands would be best for a calibration run then I guess.
Title: Re: S/a a10 gearbox sprocket removal
Post by: Whipstrut on 01.11. 2018 17:51
Quick query, does anyone know the actual thread size of the nut? Thinking of possibly making one from hex stock.
Title: Re: S/a a10 gearbox sprocket removal
Post by: RichardL on 01.11. 2018 18:11

 As ellis says they are Right hand thread.

 As Roy says;
 
Quote
...Why not change the engine sprocket instead, that way you won't upset your speedo accuracy.

 If it's a standard speedo it'll already be wrong, so going to a 19T will put it right, but I expect the difference will be extremely noticeable.*eek*
 

Dutch,

Did you mean, "...the difference will not be extremely noticeable," meaning the difference in the speedo's report, or did you mean the difference in riding with the 19T sprocket will be extremely noticeable."?

Richard L.
Title: Re: S/a a10 gearbox sprocket removal
Post by: duTch on 01.11. 2018 18:16

  I'll be adventurous and guessing at 20 tpi that we would call Cycle thread like most other BSA threads- you obviously don't have sleeve gear handy to measure the threads on that...

 Richard you posted while I was slowly composing...
Quote
.....Did you mean, "...the difference will not be extremely noticeable," meaning the difference in the speedo's report, or did you mean the difference in riding with the 19T sprocket will be extremely noticeable."?......

 No I think I meant what I said (hard to believe I know *smile*), that the difference will be fairly obvious.....
Title: Re: S/a a10 gearbox sprocket removal
Post by: coater87 on 01.11. 2018 20:52
I bought a 5/8 x 20 tap and made my own too.

 Lee
Title: Re: S/a a10 gearbox sprocket removal
Post by: chaterlea25 on 01.11. 2018 21:32
Hi
Quote
Quick query, does anyone know the actual thread size of the nut? Thinking of possibly making one from hex stock.

Lee, I think he is asking about the gearbox sprocket nut??

Whipstrut
If you intend to make one I would include an oil seal as on the SRM product
http://www.shop.srmclassicbikes.com/product/gearbox-sprocket-nut-oil-seal-bsa-pre-unit-swingarm-models

John