The set of Bosch horns on the P1800 to 1964 1800S consists of two 123mm FDG Normal Plate Horns and one 156mm FSA Strong Tone Horn, the FDG are actuated either by the Horn Button in the centre of the steering wheel or together with the FSA by the Horn Stalk on the right of the steering column.
On a 60 year old vehicle chances are very good that the condition of the horns are no better and likely worse then those in these photos, with insides caked with fine silt and rusted parts, many, many parts. Many owners have tried to restore their horns, but faced with the lack of parts in adequate condition, eventually choose to switch over to something unoriginal.
There is an alternative however, while there are no direct replacements on the market, there are horns still sold and made by Bosch to the same dimensions and similar sound frequency as these originals and are noted above as Replacement Horn(s).
Following is the method used to adapt the modern horns to the appearance of the originals.
Download the instructions as PDF file
