When the earlier horn is fitted in the position below the riders saddle spring on an M20 are there two or three flat plates making up the mounting?.....I'm assuming those are made from spring steel...Does anyone have information on that?....Ian

email (option): ian@wright52.plus.com

Ian the very early (1939) pattern was the HF1140, followed by the HF1141. There are details in the electrical section in technical that Henk posted. It shows just one steel mounting strap. I don't see the need for spring steel myself?? Ron

email (option): ronpier@talk21.com

Thanks Ron...I would imagine the benefits of spring steel might be to absorb some vibration...Two or three thin plates made of spring steel would consitute a leaf spring....
My horn has two thin plates which had to come from somewhere!...Perhaps a later version or an alternative application for the same horn?....

I'll have to check a parts list and see if the mounting plate is listed...Ian

email (option): ian@wright52.plus.com

OK...I've done some digging through documents....An early post war illustrated Lucas catalogue shows these plates as part number 701851 and shows two...One end of the plates differs from the M20 type as it has two small attachment holes not one...The key thing here though is that they are listed as 'Laminations'....

From a 1940 dated document 'List of Proprietary Equipment and Makers spare parts for BSA 500cc motorcycles Contract C6126'...

[Horn Electric, LUCAS Type HF1141/AC. Motorcycle 6 volt]...

LU700824/8...Laminations (pair).....Qty. 1

This confirms two laminations made up the mounting bracket, at least for that contract....Ian

email (option): ian@wright52.plus.com

Ian,

If this helps, my HF1140 horn has 2 plates. I bought this from Taff, so I would think that it's correct.

Dave

My hf 1140 also have 2 plates ..
I think i have some lasercuttex stainless steel in stock as i made some a couple of years ago.

Dave...Can you accurately measure the combined thickness of the two plates?.....Ian:relaxed:

email (option): ian@wright52.plus.com

Good Grief...I saw the title to this thread and thought that Ian was asking for advice about "waking with the flag raised"...at his age ! :astonished:

Sorry Ian,
At the moment the bikes away at someone else garage.

Dave

Just noticed this original (post war) horn on eBay. 4 plates...?

email (option): wd.register@gmail.com

I'm going with two as the 1940 parts list clearly states that quantity (pair...Qty.1)...

The questions now are how thick were the plates and were they spring steel...By gently applying some pressure to the ones I have I can test their ability to return to the original shape...If they are spring steel that will be obvious..However, these didn't come with the horn and look rather too good to be originals so I'm not keen to use these as definitive proof of anything.....So, the two questions remain...Ian

email (option): ian@wright52.plus.com