High Tone Horn Not Working

[Hardway]

After a little trouble shooting I got the horn system working on my 1972 240z.  The low tone horn works fine but when I isolate the high tone horn it just makes a "dink" sound when the horn button is pushed.  It is obviously getting power so I pulled the horn off for a better visual inspection.  It has some over spray on it from when the car was painted but it is not damaged or rusted.  I have read several articles on rebuilding them but can see the gaskets and hardware are no longer available for them.  Is there any other tests I can perform to make it work before taking it apart?

[Namerow]

The FSM has some surprisingly detailed instructions on how to tune the horns.  Personally, I found the results no better than 'ok',  Nevertheless, you should be able to adjust so that you at least get a 'bleat' rather than a 'dink.

[Hardway]

Thank you Namerow!  You are correct, in my 1971 FSM it is page BE-23.  I will work it some tomorrow after work.  In addition to tuning, I think some clean up is in order.  Unsure if I want to take it apart since the gaskets are not available but I will see I can get some of the red paint off. It deserves it!

[Namerow]

Don't fret about the gaskets.  They're just made from coated paper.

[Patcon]

My only thought would be what voltage are you getting at the "dink" horn?

[Namerow]

If you play with the adjustment screw (X-type panhead machine screw at the 11:00 o'clock position in your picture of the rear face of your horn), you may find an easy solution to your problem.  If not, no harm done and you can move on to the next step of your troubleshooting.  The adjustment is a bit hair-triggered and requires a little patience to get it right.  If your car's PO played with this and lacked patience, he might have just given up and left it in the 'dink' adjustment zone.

[Zed Head]

18 hours ago, Hardway said:

 It is obviously getting power so I pulled the horn off for a better visual inspection. 

Don't overlook the often overlooked ground circuit.  Bad ground, bad sound.

[ramsesosirus]

3 minutes ago, Zed Head said:

Don't overlook the often overlooked ground circuit.  Bad ground, bad sound.

I can attest that grounds can be tough, sometimes it looks clean and good, but doesn't work.  Sometimes it's covered in paint or rust, but it works fine...

Had a ground issue with my headlight conversion, just needed to clean/sand the area a little bit for a good connection.  

[Hardway]

I bench tested the horn using a 2A trickle battery charger that puts out 12.27V consistently.  The FSM states testing should be done between 12V and 12.5V at 3A so I am a little short on amperage.  It also indicates more testing and volume adjustment can be done using 14V - 15V but I do not have any type of equipment that provides this output.  I was able to easily free the lock nut and adjusting screw and test from one end of the range to the other.  The best sound I could get was a some what mid to high pitch "whaaaa".  The car currently does not have carbs on it so I cannot run it but the battery tested at 12.57V and has no problem powering the low tone horn at full volume.  With the help of my wife I measured the voltage at the high tone connector and a good ground.  With the horn button pressed and the low tone horn giving off full sound, I was getting 11.10V at the high tone horn connector.  For a comparison I tested the voltage at the low tone horn connector while unplugged, with the horn button pressed and it gave 12.31V. Intrigued I went back to the high tone connector, this time with the low tone horn unplugged and it gave 12.31V with the horn button pressed.

So it appears both horns are getting equal power and my issue is with the horn itself.  I see the gaskets are made of paper but I am sure they are a certain thickness as they are part of what is essentially an electric musical instrument. Granted one that only plays one note.  At this point, sourcing another high tone horn or just running a set of aftermarket horns is going to be the easiest route.  Once I find out more on the gaskets maybe I can take a shot at rebuilding the horn and possibly restore both.  Any other ideas or suggestions are welcome.

[Namerow]

Serendipity, my friend.  I remember the' authoratative' blast of my distinctly non-USA, two-tone Z horns delivered when I was a 1970's driver . 

When I rebuilt the horns from my 70 Z, I was shocked (as in underwhelmed) by what I heard.  I love the nostalgia effect, but for the guerilla driving conditions where I now live, they need modern-tech, hi-volume reinforcement.

[Zup]

Jeff,

Regarding rebuilding your horns--

When I rebuilt mine the gaskets weren't available. I put them back together without the gaskets and they work and sound as original.

Look up seller nikkibid1972 on ebay. He makes a reproduction restoration kit that includes the die-cut gaskets and correct new nuts, bolts and washers. I have bought a couple of sets. Nice kit.

Rob does not have a listing for these currently. 

If you contact him with your request to purchase a set I think he will eventually put together  another round of them for sale.

Zup

 

[Namerow]

... or make your own gaskets. I made mine using butcher's paper.  About the right thickness and somewhat waterproof. 

Zup's successful experience using no gaskets at all suggests that they contribute nothing to the acoustic performance, so maybe they were intended to be a moisture seal (albeit, not very effective -- see picture).

 

So maybe a thin bead of silicone gasket material on each mating face would be the easiest and most effective solution.  If, for any reason, the sealant snubs the sound output, you can always strip it off and try something else.