Horn Tuning

[1982911SCTarga]

Since I got my cabriolet, the horn has never sounded right. It was down on both volume and tonality, but it's never been an issue preventing it from passing inspection. However, I suspected that if I ever really needed it, it wasn't going to get much attention from those around me.

I've had plenty of other sorting issues in front of this particular item, but this morning I decided to dig into it, figure out what was going on and order or begin to arrange for replacement parts.

I removed both trumpets (pretty simple job, really, after pulling the right front wheel) and tested them directly with the car's battery. The bass unit sounded pathetic, so I disassembled it and it was spotless inside. Once apart, I realized there is adjustment that can be made to the trumpets via a screw on the unit's backside. This adjustment is vaguely referenced on page 214 of the Haynes manual ("adjust horn until best note obtained"). The adjusting screw changes the relationship between the trumpet's armature and the vibrating coils.

Anyway, I re-assembled the bass unit and adjusted it until I got a nice strong note out of it. This adjustment is really sensitive so go slowly and test as you go along.

I also re-adjusted the short trumpet as well and put them both back in the car. Wow, I've got a 911 horn sound again, which might be important if I drive in another high school homecoming parade.

[Reiver]

Good tip, was unaware they could be 'tuned up'.

[Arne2]

I did the same on mine shortly after I bought the car. Only one of mine was working at all, but cleaning and tuning fixed it right up, same as the OP.

[Jdub]

Learned this with the big fat Klaxon horns on the old BMW twins. I used headphones to do this. A solid tap on the back of the horn frees stubborn springs and diaphragms so once you think you have your tone, tap it to set and perform a final test.

Great post by the way.

[1982911SCTarga]

Thanks. I was just somewhat surprised because I was fully prepared to source one or both trumpets new or used. Who knew they were serviceable?

Brian

[RDM]

Great info, thanks! I'll be doing this next week

And beautiful color on your car. What is it called?

[1982911SCTarga]

The color is moss green metallic.

Brian