2 4 0 T U R B O . C O M
D A V E ' S   V O L V O   P A G E
Cadillac 4-Note Horns
for my Volvo 240

     UPDATED: May 14, 2019                       CONTACT       
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Send me an email if you do something like this to YOUR Volvo.

<<< My Volvo 240 originally came with these horns behind the grill.  They were just ok.  Nothing special.

There are eBay sellers who offer these horn sets. Some claim to have tested them before sending to you.  TEST THEM YOURSELF, one at a time.  One set I purchased from an eBay seller was reportedly tested, but turned out to be obviously defective (two were bad and one had no sound) and he REFUSED to accept a return until I filed a dispute. 

These horns are old and many of them will have some corrosion (rust) inside.  If there is excessive corrosion, they'll sound poorly or stop working.  Here's a video on disassembling these horns to clean and make them work again.
And here's a very detailed video on how the internal diaphragm makes sound.


I had been thinking about doing this upgrade for a while and I finally pulled the trigger.  I found a set of four (4-note) horns online and bought them. 

These are known as Cadillac 4-Note Horns. I don't know the specific years, but these horns were equipped in many Cadillacs up into the 1990s. Specifically they appear to be found in Cadillac DeVilles until about 1985 (after which the Deville was downsized). They also came in Cadillac Fleetwoods and large Buicks until about 1995. Also supposedly in Oldsmobile Toronados until about 1985.
These horns are made of steel and plastic. Much earlier Cadillacs and large GMs got 4-note horns going back into the 1950s. Those much earlier horns were all metal and may have very different markings.

The four horns below are each tuned to a separate specific note: A, C, D and F. Later cars with only 2 horns reportedly got only notes A and F. 
After the 4-note horns were discontinued, all GM cars came equipped with only two horns.

<<< Each horn has the note A, C, D or F embossed as shown here.  The round portion of these horns is stamped steel and the trumpet section is molded plastic.
 <<< The horns I found have two-wire connectors (power and ground). These are reportedly later model 4-note horns. When shopping for horns, be aware that there are some (see lower photo) which have only ONE wire to each horn.  That wire is the power wire.  These are reportedly earlier horns. On the ONE-wire horns the ground circuit is completed through the mounting bracket.  I don't think this makes any difference in how they sound.  Just be aware of it in case you have a preference.
<<< If you're doing this to a Volvo 240, you should know these cars don't have a normal horn activation circuit.  The 240 has YELLOW and BLACK wires as shown here. The yellow wire is the power wire and it has 12 volts whenever the key is in the ON #1 or ON #2 position.  The horn is then activated through the black ground wire, which is triggered by the horn button on the steering wheel.

The Volvo 240 does NOT use a relay in the horn circuit.  In order to make these 4-note horns work correctly, a relay is being added below to change how the new horns are powered and triggered. 

If you're installing these horns in a non-Volvo with a normal horn circuit, I would still advise installing a relay circuit if you don't have one.  These horns reportedly draw about 5 amps each and they'll always work better when more direct full battery voltage is available.
Here's a diagram I made. This is how I made my relay circuit. 
I used TWO relays. Each relay powers two horns. I suspect that ONE relay is enough for all four horns, but I did it this way after seeing the majority of other installations doing it this way.
Volvo 240 horn circuits are different from normal cars.  The horn switch on the steering wheel in a 240 is a ground circuit, instead of a normal car, which uses a power circuit. So if you have a 240, look for the two-wire harness going to your horns and you'll find the yellow and black wires shown below.

<<<  I carefully straightened the mounting brackets on all four horns using my bench vise and big pliers.  I also ended up cutting about an inch off the end of each bracket.  That's up to you on if this helps you mount them.

I've heard it may be possible to mount these so they're too stiff or too rigid.  I don't know if that's true, but certainly mounting them so they can't freely vibrate can negatively affect the sound. Keep this in mind if you're cutting down the brackets or changing how rigid they will be mounted.

When mounting these, keep in mind that the trumpet openings should be pointed downward so they don't collect water.  Also I have read that the best sound will be from horns that are mounted close together and, if possible, pointing all the same direction.  These horns vibrate a lot when sounding, so you should mount them so they are not touching each other or touching any other parts of the car (except of course where the brackets are mounted).

Here's a photo ABOVE of the horns installed behind the front grill in my 240. After I was done, I changed my mind because this location sucks.

 I didn't like how much air these blocked going to my condenser and radiator, so instead I and mounted them below the car, behind the left side of the bumper and spoiler. They're just a little forward of the charcoal canister. 
The brackets are actually mounted to the 240 horizontal support bracket that stabilizes the left fender. It's a TIGHT fit in this space. They just barely fit here, but they all clear and none are rubbing or touching each other or any other car parts. That's important because of how much vibration these things generate. 

You might also consider mounting them on the right (passenger) side, since there's more room because there's no charcoal canister over there. This gives you two great locations to choose from.  And I think they'll be louder in this lower position with nothing in front of the trumpet openings.  It's hard to tell from this photo, but the lowest part of the horns is above the bottom of the spoiler and they're not visible unless you get on the ground a peek under the car.
Photo below view from the ground looking up.

Here's a diagram below I created to illustrate how I mounted these horns. I bent the horn brackets to point the horns a bit forward, moving them away from that charcoal canister. And then I bolted together each pair of brackets above the 240 fender brace so that the brackets sandwiched the brace. I did this because I felt drilling holes in the brace limited my options for small adjustments in the final positioning and my goal was to get these things positioned just right so none of the horns would be rubbing or touching or vibrating against anything.

<<< If you're wondering what hole I used to bolt these brackets together in the above diagram, it's this one circled. 
Send me an email if you do something like this to YOUR Volvo.

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