I drilled out the existing 6 rivets by drilling the spread on one side and tapping them out with a punch and hammer. This allowed me to separate the horn into its components.
The existing gaskets were paper and measured 0.018" thick. One on each side of the diaghragm. The diaphragm had a small amount of rust so I soaked it overnight in Evaporust and used 0000 steel wool to remove it. I then sprayed both sides with silicon lubricant.
I blasted the horn side completely both sides and primed it with self etching primer.
The electrical half I only blasted the outer surface, masking the inner half and the contacts.
I wiped clean of debris, and wiped on a coating of silicon lubricant. I used 400 grit sandpaper lightly in between the springloaded brass electrical contact.
The large bolt and nut does not need to be moved, but the small hex bolt next to it on the outside may need to be adjusted after dry reassembly if there is a difference in thickness from the gasket variance.
Good job, I had one of my workers change a horn on my brothers car years ago, it was on his Holden and I used one of the horns off my first XJ40 that was slowly returning to its natural Fe state.
The worker was quite pleased with the outcome until he pressed the horn, the discord, to my ear was horrendous but the worker didn’t react.
I deduced that he wasn’t musical. I suggested (strongly) that he replace the remaining horn with the other one from the Jag.
Steve-
Great write-up, photos, and video. Thanks for taking the time to post and share.
Carlo
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
6
Horn pairs normally have a weight added to one diaphragm, resulting in a different pitch. The two horns together then combine to create the distinctive honk sound, more attention-getting than either horn by itself regardless of volume.
When horns get uppity about working, it’s often the set of points inside that provide the on/off connection that vibrates the diaphragm. Rarely used, they just decide not to make a connection when needed. And when needed they may be really needed!
I have long advocated that someone needs to come up with a fix for horns that replaces the points inside with a little electronic circuit. There’s be a screw to adjust the frequency of the oscillator (pitch), which would only need to be done once. Basically, install earplugs, connect up 12V, and dial that oscillator to obtain maximum volume. From then on, your horn would work first time every time. But I dunno if anyone has actually developed that simple bit of circuitry yet.
