59 corvette horns
Has anyone rebuilt a 59 corvette horn? What is the coil resistance cold? I have drilled out the rivets and disassembled it. Thanks Pat McPherson 55168
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Re: 59 corvette horns
Pat,
I rebuilt mine (351 & 352) about 10 years ago when the complete rebuild kits were available. They included the metal diaphragms then. Today's kits don't include them. Why I don't know?I never had the confidence they'd work right so I never re-rivetd them. I used machine screws & nuts and painted everything black. They work okay but need adjustment on occasion.
I can check in the morning when I get back in the garage, but the coil resistance is probably quite low, probably 0.3 to 0.5 ohms I'd guess. This is if you have a very accurate ohmmeter. Basic meters read about 0.2 ohms at their own leads, so you have to subtract that from the coil measurement.
Rich -
Re: 59 corvette horns
Thanks for the information. I am going to try to clean up the diaphragm. I would guess getting it centered would be important so the air gap around the core would be even. I am not sure how to center it as the holes in the diaphragm appear to be larger than the rivet. I guess this is what you get when you are infected with old corvette sickness. Thanks again. Pat McPherson 55168Comment
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Re: 59 corvette horns
Hi Pat,
I did my 57 horns this past spring. 57s (339 & 340) are different, but I think internally they are quite similar. These horns are quite rare as they were only used for the last few months of 57 production.
Coil resistance is low, but be advised there is an internal resistor of about 5 ohms in parallel with the coil. There should be a block that supports one side of the points bracket. This block is a resistor. Its function is to reduce contact arcing and provide a discharge path for the coil when the contacts break.
I immersed the pieces, including the diaphragms, in Evapo-Rust for an overnight soak. Amazing how well they cleaned up.
It is important to center the diaphragm in the air gap. The outside diameter of the diaphragm is the same as the OD of the housing, so just center them and tighten the screws. This has to be the way the manufacturer did it.
I tried to duplicate the rivets by cutting the heads off of 1/4-28x1-1/2 long screws and turning the shanks in my lathe to make the end a hollow rivet. Did not work out - could not peen them over. Gave up on this approach and instead tapped the shank for #8-32 and used a Phillips screw. Turned the screw head to look like a rivet, leaving just of the head to be able to tighten them and then filling it with JB Weld. Came out fair - not perfect, but nobody will see them.
The paper gaskets are available from Zip and possibly others. I made my own. Zip also has a free video on their site that is somewhat helpful.
Adjustment is touchy, but they toot.
Lots of hours in these things. If I had it to do over again I would have sent them to one of our re-builders and had them done.
Good Luck - Let us know how you make out.
-Dan-Comment
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