Who gives a toot???
It has often been said that if you want fame, fortune and recognition, you need to toot your own horn. On some of our old LaSalles or Cadillacs, you may have a beautiful high-point car until you toot your horn and you hear a sound like a small dog that got a tail caught in the car door, or that you have a bad case of stomach gas or both. In which case, the admiring looks along with the “ooh’s” and “aah’s” will quickly change to snickers or outright laughter.
Surprising enough is the fact that the horns on most of these old cars are usually capable of being restored and tuned without a lot of trouble, and you can really have a lot of fun doing it, especially the tuning.
The first step after taking the horns off of the car will be to take them apart one at a time, (for the obvious reason of having a model to work from) and clean them thoroughly. You may find right away that there was an old insect nest crammed into the trumpet part.
Clean and sandblast the trumpet, cover and mounting bracket and paint them with gloss black engine enamel—being careful not to paint any of the electrical assemblies. The diaphragm or reed needs to be cleaned and polished with fine steel wool. It takes just a little rust on this diaphragm to ruin the tone of the horn. A little oil or wax will retard future rust.
Check out all the electrical connections and solder on new wires if they are frayed or the insulation is bad. Each horn requires about 20 amps to blow and sound right, which means that poor wires or poor grounding will cut down the amps resulting in very sick “toots.” During the cleaning process, be sure to clean the points and magnet bar surfaces.
When all of the parts are cleaned and those parts that were painted are dry, you are ready to start reassembly. Make sure the mounting bracket is free of paint where it mounts to the horn assembly and where it fastens to the car.
With the cover off the electrical part, mount the horn solidly in your bench vise. You will need a fully-charged battery and two leads of No. 10 (but no smaller than No. 12) wire and you are ready for the fun part, which is testing and tuning the horns to your liking.
Before you can tune the horns, you will need to understand the basic principles of how they operate. There are usually two horns, and the trumpets are different lengths that are either straight or coiled. One (the shorter one) is a higher tone and the other is a lower tone. Other than trumpet length and tone, they are identical.
The magnet bar is connected to the diaphragm (or reed) and when the magnet is energized, the bar is pulled down against the magnet and flexes the diaphragm. At the same time, it opens a set of points that interrupts the current to de-energize the magnet, and flat steel springs return the magnet bar to the upward position while simultaneously closing the points, allowing current back into the magnet.
This process completes itself 40 to 60 times per second, making the horn sound by the vibration of the diaphragm, which is transmitted through the trumpet.
On most horns, there are two basic adjustments. The first and most obvious is the nut that adjusts the distance between the points and regulates the speed of the vibration cycle. There is a locking jam nut on top to keep the setting. The second adjustment normally consists of three or four bolts that hold the magnet bar frame in place.
There are two nuts on each bolt, one on each side of the magnet bar frame. These adjust the distance of the magnet bar from the magnet itself and thus, the distance the bar travels, which determines the amount of flex in the diaphragm resulting in some control of the loudness of the horn.
The first adjustment will be to the points. There is a locking nut over the adjustment nut on the upright screw. When you first test the horn by applying current to the electrical connection from the battery, you will probably need to make several adjustments in order to get the maximum vibration and sound. Make sure the nuts are jammed tightly against each other to prevent movement from vibration, of which there is a lot. Then you can adjust the three or four locking nuts on the magnet bar.
As you continue to adjust these nuts, make sure they are all even by using feeler gauges. You will probably need to make several tests to get the maximum desired volume. No doubt you will now have to readjust the points for maximum smoothness of vibration. This process may need to be repeated a few times in order to get the desired tone and volume.
Repeat this entire process on the other horn, by which time the neighbors and family will be wondering what’s happening in the garage with all of the horn-blowing they are hearing. Some may even come out to check if you are okay, or call the police complaining of a disturbance.
If you cannot get a desirable tone from each horn individually, you may have an unrestorable horn and you will need to look for replacement(s) and you can start all over again. When you make your installation on the car, make sure you have good grounding throughout.
The horn button itself and the horn relay is a whole story in itself that will be covered in a future article.
Everybody has a personal opinion as to how a horn should sound. My Mom always said she wanted a horn that says, “Please,” while my Dad always figured a horn should say, “Get the hell out of the way!” My own idea is that the horns should very loudly convey the message, “Get the hell out of the way—please!” What’s your choice?
See ya in a later issue,