1966 BMW R69S Restoration: November 1998
1998 November 2 (Monday)
A rusted blob of metal with wires going to it was reputed to be a period horn. It didn’t work. Earlier this year I’d cleaned off the rust the best I could and gave it a protective coating of paint. Today I’m going to make it beep.
The horn is the right color, but painted in a flat black instead of the original gloss. At least is is an original French 6v Klaxon. This one is held together with 6 screws – I understand that some were held on with rivets. I’d broken the screws loose earlier this year, so they came out pretty easy this time.
Under the cover you can see the gasket (white ring) over the sounding plate. The original gaskets were in tatters so I made my own using several layers of waxed paper. The home made gaskets seem to be working. The bike has been riden in the rain yet the internals are dry.
The inside of the horn looked good. I pulled out the contact point arm and plate and had a look at the points: black. A file, some emery cloth, and finally a stone has them looking like metal again.
I re-installed the and the horn put back together, making sure the metal bar attached to the sounding plate is in the right position. I used an ohm meter connected to the terminal lugs to adjust the horn. The reading is open as the unit was installed with the adjusting screw barely started. The adjusting screw is turned until the ohm meter says that there is continuity. That will be my starting point.
The next check is for continuity between the terminal lugs and the case. Ooops. It should be open, but I’m reading a short. Pulled the case apart and checked everything. The adjusting screw spring was off center and touching the adjusting screw, causing the contact plate to be shorted to the case. I centered the spring re-assembled and re-adjusted the unit. No continuity this time.
Final test is to hook up a battery. Yep. It makes noise.