Was the accessory horn for a 31 the same as the one that came on the car ? Or was it a different tone ? Also the spare horn that I have has nickel plateing on the mounting bracket, and it is shaped a little different at the mounting hole. Any ideas to the difference ?

The 1935 parts book accessories section shows a matched horn unit (p/n 600780) and high and low note horns starting in 1934.

To quote the second 1931 accessory booklet "A Complete Line of Genuine Chevrolet Accessories": "The tone of this second horn harmonizes with the one already on the car, giving the clear, distinct, harmonious effect which is so popular. Both horns are of high frequency, the body is black with an attractive chromium-plated face which is in keeping with the two head lamps, radiator grill, and tie bar."

See Automobile Quarterly Vol. 42 #2, page 59.

Yes it is not the same. Bill Barker has it listed on his Chevrolet index page web site. As I recall it is a 16A. Delco Remy.

Hummm... I thought that I had both of the numbers listed.... I'll have to look for those. Naturally, you could "harmonize" two identical horns if you just change the tightness of the center screw..... couldn't you?

Just to tag onto Bill's comment regarding the center screw adjustment.....My horn sound a bit on the "flat" side. How do you adjust the tone? Is the adjustment on the center screw on the front, or as I may recall, there is a small adjustment screw on the back of the pancake?

Thanks,

The main adjustment is the small slotted head screw on the back. The inside adjustment will mainly affect the tone not the intensity. It is the small screw that controls the vibration distance and period. It changes both intensity and tone.