The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Rien on 16.03. 2026 15:26

Title: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 16.03. 2026 15:26

Changing the gear on a Lucas 47503 Automatic Advance (of a K2F on a A7, '54 Swinging Arm)

Hi all, small question: where can I find a loud and clear video for changing the gear?
Thanks in advance,
Greetings from Holland, Rien

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: groily on 16.03. 2026 17:45

Don"t know about a video, but this is the best description I know of if it comes through.
Thanks to Andrew at Priory Magnetos who does this stuf as well as or better than anyone on the planet:
https://docs.google.com/document/d/19LiHsh0ALtF7z0ttQZYofWhsS_3ZIsIv/edit

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 16.03. 2026 18:37

Merci bien Bill, thanks. Loud and clear info. I'am gone try. Greetings Rien

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Black Sheep on 17.03. 2026 06:50

Follow the instructions EXACTLY and it's simple. Good luck!

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 19.03. 2026 18:34

Thanks Black Sheep. See my next topic Lucas ATD with steel gear.

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 26.03. 2026 09:51

Next question: the rivets in the ATD, are they steel, stainless steel or aluminium?
Thanks,

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: chaterlea25 on 26.03. 2026 11:58

Hi Rien,
3/16 inch diameter countersunk head steel rivits

John

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 26.03. 2026 19:17

Thanks John. D=3/16" L= +/- 9/16" hard to get in Holland.

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: chaterlea25 on 26.03. 2026 23:39

Hi Rien,
Have you asked "De Groot" in Holland
There are plenty on eBay, but most seem to be in UK?
Try farm equipment shops locally, the 3/16 were used on a lot to secure cutter blade triangular sections
Alternatively ream the holes out to 5mm *eek* or machine down 5mm ?

John

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: groily on 27.03. 2026 07:04

This may be heresy, but absent the correct items I have found that good quality steel wood screws with their countersunk heads and plain sections of the correct diameter (with the screw thread cut off obviously) make excellent rivets, are made of good stuff and peen over very nicely on the 'other' end. Have used them a few times for this with no mishaps and the results look pretty.

Title: Re: Changing the gear on Lucas 47503 Automatic Advance
Post by: Rien on 27.03. 2026 07:45

Thanks Bill and John.
Roeland, the owner of 'De Groot BSA' nowadays, doesn't have them. I can try on Ebay.