VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 '37 T/C horns

Hello Everyone,

Does anyone have pics of '37 T/C horns and it's mounting bracket ??

I have acquired what I believe are '37 T/C horns, but without the cross bracket that attaches the horns to the radiator support V-rod. ( The trumpets measure 15 1/4 and 12 3/4 in length which matches measurements in another post) In my quest for the bracket I was able to acquire another set of horns with a bracket.

The trumpets of the second set unscrew from the diaphragm so as to pass thru a second support which is part of the bracket.
The trumpet lengths are over 19" and 12" and they have a set of studs that pass thru a part of the bracket to secure them to the V-rod bracket. Unfortunately these horns don't work and the bracket can not be used for the working set of horns because the trumpets do not come apart or have the mounting studs.

So now I'm looking for a bracket again or a pair working diaphragms for the second set of horns.

Check the 8th post in this thread: https://vccachat.org/ubbthreads.php/topics/264874/Re_1937_Chevy_1_2_ton_Truck_Ba#Post264874

I posted a photo of the dual horns and bracket that I believe may have been original to my 37 Chev pickup.

Mark

I believe they are the same as on my '38. Below are a couple of pics showing them mounted. The second picture was taken during my inspection of the car before buying it and rescuing it from the barn.

Hello Tiny,

The pics of your horns shows the V-rod bracket I have and the relay is mounted on the bracket. The only difference is the apparent length of the shorter trumpet. Yours is much longer than mine.

Is there anything I can do short of drilling out the rivets to get them to work ??

Might someone have a working pair of diaphragms ??

As soon as I get my computer "cleaned" I'll post picks of both sets.

Nice before and after pics and nice work on everything else.

The diaphragm is actually inside the housing where the horn bell screws into. It's metal and would be pretty difficult to ruin. Have you removed the back (round part) and inspected the non working horns? If you remove the screws around the periphery you can access the diaphragm. If you do take it apart be sure to pay attention (take pics of every step) to how the diaphragm mounts. If it's not put back in the correct orientation to the mechanism the horn won't work. I found that out the hard way but finally discovered my mistake.

I have the mounting bracket for a '37 + the horn trumpets are there but no guts.

Hello Mark,

Your horns look like my 2nd set and Tiny's set.

Hello Chevgene,

Do you have pics of yours ?? The 1st set of horns, without the bracket, are painted green and the trumpets do nut unscrew from the diaphragms. ( I'll double check that tomorrow)

Hello Tiny,

I'll have to look at the horns more closely again tomorrow, but I think (because it's late here) that the diaphragms are riveted together not bolted.

[img]http://s751.photobucket.com/user/ollieo/media/tampc.jpeg.html[/img]

so..? my 38 coupe has a 37 bracket ?? and aftermarket rightangle pots .. ?? 70 years .. stuff's bound to get swapped out ...

They are small carriage bolts (my apology for calling them screws) that may look like rivets on one side (if they are the same as mine).

Tiny,

I didn't realize that the single screw at the back of the cup actually held it on. I removed the screw and cup to reveal the inside.
I'll take it apart tomorrow and clean it and see if I can get it to work.

There is an adjustment screw that sets the distance or gap between the magnet and the arm. But I wouldn't do anything to the horn until you have a good diaphragm. If the diaphragm is bad the gap could be bad but not need adjustment. I had a hard time with mine until I found a guy in Iowa that had good horns with the same type diaphragms. I do have a few horn parts left over but no diaphragms.

Brian

If the horns are painted green and trumpets do no unscrew they are some kind of aftermarket horn.
My brackets looks just like what Tiny has pictured. The rod clamps are still on the bracket.

Horn support bar.



Brian

Hello Brian,

I need one of these. Thank you for the pic and measurements.

Brian...can you trace the bracket on a piece of paper and measure what the angle is on the ends of the bracket you posted? thx. Billu38

Sorry Brian...I think you told me the picture of the bracket came from an Ebay seller so you probably can't do what I asked......Billu38

I didn't actually follow those dimensions, other than the length of the tabs at the end. I bought a 3/4" flat bar and made one end tab, 1 1/8" long, with a hole, mounted that on the firewall and put the horns in their location. I bent the bar until it ran right next to the bottom of the horn support plate (the flat plat the horns mount to). I marked that location, subtracted the thickness of the flat bar and bent the bar and cut it a little long, about 2". Mounted the bar again, located the hole and cut off the excess.

Brian

Hi Brian,

Checked out the horns tonight with my brother and got one to work. It has a bad power wire. The other one kind of works. I can get it to make noise but it is struggling to do what little it is.

I wish I could post photos but still have a computer problem.

I did a couple of point to point checks and found this.....

There is a power wire soldered to an insulated board. Soldered at the same point is a single strand of wire that is wrapped around this insulated board, spaced about 1/32 apart and ends at a ground point.

I took an ohms reading on the working horn, solder point to the ground point...0.002

I took an ohms reading on the none working horn at the same points.....3.4

Any thoughts ??

Not exactly where you are measuring, do have a picture? The coil should have no resistance so I would look for a damage to the coil or rust/corrosion to the connections that would create the resistance.

Brian

I'm sorry, I can't post pics yet. Have an appointment to get my computer fixed Friday afternoon.

I put a jumper wire from the solder point to the ground point of the board, by-passing the wound wire, and got the center piece to actually move, but it would not "flutter" and make noise but at least now it's moving. There may be a short in the coil area, so I'll take it apart tomorrow and see if there maybe a problem there.

In further conversations with the guy's in work, the insulated board with the wound wire is a form of resistor that causes the coil to dump it's power and allow the coil to recharge. The fluctuation is what causes the horn to make noise.

There is suppose to be a ratio between the power of the coil and the resistance of the board/wire that causes the coil to dump power and allow the diaphragm to flex. The speed at which this happens causes the diaphragm to make noise.

The resistance is high enough that the ratio is way off.

I'm taking them to work tomorrow to measure them again and see if there is modern resistor with the right impedance (if thats the correct word) to replace the old board/wire combo.

Thats it for now.

I don't think they work like that. I believe they are Faraday type horns. The coil creates a magnetic field that pulls the piston up, when the piston moves it breaks the circuit, the magnetic field drops, and the piston drops back down. The spring on the piston, coil winding, and the gap determine the frequency of the piston, thus the rate the diaphragm vibrates (it's attached to the piston) and the sound the horn makes.

I'm not sure what you are looking at but I doubt you can replace it with a resistor.

Brian

bigbth,

I have to agree after looking closer at the internals.

I will say that I may have accidentally fixed the horn by grounding the board causing the piston to snap into place. It must have been cocked/stuck. After it moved I checked the ohms reading between the power point of the board and the boards ground point where the wire terminates.......the multimeter showed 0.003, damn close to the other horn, which showed a reading of 0.002.

I will post pics soon. Thank you all for participating, and following along,