Resurrecting my horn (the sans Viagra thread)

[AK260]

I’ve been meaning to fix my silent horn since I bought the car but it’s just been sitting in the corner of the garage bugging me.
 
 
So I dropped it into some lemon juice and salt mix before we went camping for a week. I love this method of de-rusting: cheap and gentle but it gets into all the places I can’t with a brush! This is the before photos (well after a couple of hours of soaking when I realised I hadn’t done a “before”)


 
 

 
 
Then when we got back, I fished this out (pic is after a rub down with micro fibre cloth to remove residues etc) - I love the fact that even the paint has been stripped off and you can read the original stamping on the back:
 


 
Now the fully rusted in screws just turned without any real resistance! One did have to get drilled out though as it was rounded off too much from previous efforts.
 
I connected it up and for the first time in my ownership it made a sound - albeit a tad muffled. Pushing it in and out by hand I could hear rust, so I took the whole thing apart to discover - wait for it - more rust!!
 

 
So back they all went into the lemon and salt mix let’s see what they look like tomorrow morning!
 

[SteveJ]

I'm actually working on some horns right now, too. I'm shooting video of it, so maybe it will help someone in the future. Anyway, I see 3 main areas for problems.

1. The rivet holding the positive terminal isn't making good electrical contact through the horn body from the tab on the outside to the coil wire.
2. The contacts between the negative side of the coil and the body of the horn are carboned up. I used a strip of 1000 grit sandpaper folded in half, worked it between the contacts, and pulled it through.
3. The bar on the diaphragm that opens the contacts isn't adjusted properly, so it doesn't open the contacts. You call tell this in a test if you feel the diaphragm pull in when you apply voltage to the horn.

[Captain Obvious]

I'm really confused... You said "I love this method of de-rusting: gets into all the places I can’t with a brush!" 

But then you found all that rust inside!!

I though it got into all the places???  Sorry, but I'm lost.   

[AK260]

I'm really confused... You said "I love this method of de-rusting: gets into all the places I can’t with a brush!" 
But then you found all that rust inside!!
I though it got into all the places???  Sorry, but I'm lost.   [emoji185]

Ha! Yes good point.

The diaphragm and gasket were totally sealing the inside. In fact it only came apart when I tried to undo the centre nut with a socket set and the outside ring / bolts removed - it was PROPERLY stuck/ sealed together. Plus the bits sandwiched together seem to have been impervious until taken apart. Probably a side effect of 40+ years of English weather!

So it seems there was an air bubble inside - otherwise the zinc plating would have gone also. You’ll notice on the before photo of the rear that there was a bit without rust on the back. This was yellow zinc which after just a couple of hours became a metallic colour you see in the photo.

[AK260]

I'm actually working on some horns right now, too. I'm shooting video of it, so maybe it will help someone in the future. Anyway, I see 3 main areas for problems.

1. The rivet holding the positive terminal isn't making good electrical contact through the horn body from the tab on the outside to the coil wire.
2. The contacts between the negative side of the coil and the body of the horn are carboned up. I used a strip of 1000 grit sandpaper folded in half, worked it between the contacts, and pulled it through.
3. The bar on the diaphragm that opens the contacts isn't adjusted properly, so it doesn't open the contacts. You call tell this in a test if you feel the diaphragm pull in when you apply voltage to the horn.

Thanks Steve, that’s super interesting and I will check all those items.

The diaphragm on mine went from not moving at all, to moving as if it was grinding with sand crunching inside. I Hence why I decided to soak / de-rust. Since the liquid didn’t get in there, I suspect that my brute force and ignorance in moving it by hand may have freed it off a bit.


Once the rust is cleaned off, I’ll be able to better see the things you mentioned above and report back.

BTW that paper gasket on mine will be toast by the time I finish with it all. What did you use? I have gasket material sheets from which I can just make a new one and seal it with Hylomar Blue or a liquid gasket of sorts. But I also suspect such things can change the tone too, right?

[Captain Obvious]

Haha! Honestly, I was just kidding about the whole process. I assumed that the inner cavity never saw any of the de-rusting chemicals. I was poking fun.  

[Tirnipgreen]

On 9/7/2023 at 1:24 AM, AK260 said:

Thanks Steve, that’s super interesting and I will check all those items.

The diaphragm on mine went from not moving at all, to moving as if it was grinding with sand crunching inside. I Hence why I decided to soak / de-rust. Since the liquid didn’t get in there, I suspect that my brute force and ignorance in moving it by hand may have freed it off a bit.


Once the rust is cleaned off, I’ll be able to better see the things you mentioned above and report back.

BTW that paper gasket on mine will be toast by the time I finish with it all. What did you use? I have gasket material sheets from which I can just make a new one and seal it with Hylomar Blue or a liquid gasket of sorts. But I also suspect such things can change the tone too, right?

Thought I would jump in. SteveJ is working on my horns after I quickly became frustrated with their lack of function. I had the parts plated and powdercoated and then reassembled them with a rebuilding kit from a guy in Canada that was available on Ebay. The kit contained Mylar self-stick gaskets and all the nuts and bolts. The gaskets were a bit difficult to deal with after peeling off the backing. I didn't really like that they were sticky-back. Anyway, I thought I had reassembled them correctly, but got nothing out of them in terms of noise or vibration...hence enlisting Steve to come to the rescue. He may regret taking the project on, but I appreciate his kindness...Thanks, Steve...!

[dutchzcarguy]

Nice way to clean parts, how much salt (grams) in the liters of lemonjuice? Also some water or??  What i remember from my horns they need a new adjustment to work right but i think you know that. There is a screw for that in the back of the horn i belief (immsmr).

[Richie G]

Reading this thread and it inspired me to work on my horns.  I have a pair nicely plated that was going in the car when I noticed the older ones were a different style.  Did a quick search but didn't really see anything leading to the difference.  I'm hoping the plated ones are appropriate for the 6/71 and was wondering what the right color was for the inner front and back non plated sections.  I'm assuming the plated pair is right since the frame has two holes for mounting.  The PO used this straight metallic plate and single mount point.

[EuroDat]

Yes the plated version is the 240Z version. The other one is a 280Z.

I think there are 3 basic models of the S30 horns and probably more finer differences in the 3.

The left horn in you photo is the later 280Z version. The single metal strip bolts to the bumper shock.

The right horn is from the 240Z.

There is also a variant on the 240Z version, I think it came in the 260Z and maybe the later 240Z. The have the same mounting bolt pattern as the 240Z, but the bracket connects to a single bolt on the back of the horn like the 280Z. See photo.

 

 

Edited September 10, 2023 by EuroDat

[Tirnipgreen]

I think the gold plated "ring" on the front is actually supposed to be kind of an olive green. That being said, mine are like yours. BTW SteveJ has mine "tooting"...! Awesome...!

[Richie G]

24 minutes ago, EuroDat said:

Yes the plated version is the 240Z version. The other one is a 280Z.

I think there are 3 basic models of the S30 horns and probably more finer differences in the 3.

The left horn in you photo is the later 280Z version. The single metal strip bolts to the bumper shock.

The right horn is from the 240Z.

Thanks so much Euro!  Appreciate the guidance.