How To Restore A Delco-Remy Horn

Vintage Horns Are Very Deceiving

By “Rotten” Rodney Bauman   –   Photography by the Author

Cruisin’ low and slow in big-city traffic I’ve certainly heard my share of automobile horns. Have you heard the shrill pitch of a typical modern horn today? Those don’t exactly issue an authoritative warning, do they? Years ago when American iron was more likely to be manufactured in America, you’d have absolutely known if you’d received a honking.

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01 our horn quest should conclude on the porch of this old house
According to ancient treasure maps and what’s left of my own memory, our horn quest should conclude on the porch of this old house.

For our long-ongoing 1955 Chevy Task Force project, it’s finally time to think about the little things. With shelves’ worth of parts inventoried on pallet racks, we have only the standard left-side horn in the mix. Coincidentally, we’ve not yet ever seen an original truck of this type with a complete pair of horns. Despite the core support’s louvers for two, so far there’s always only one.

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02 Sure enough they’re still right here in the same old orange crate For whatever reason they were pulled but not sold
Sure enough, they’re still right here in the same old orange crate. For whatever reason, they were pulled but not sold. We’ll never know that part of their story.

As decibel dispensers, a two-tone pair of originals would surely command respect. Since we know they’d bolt right on and line right up with existing louvers, it would make good sense to use them—if we could only find them.

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03 The factory provided horn mounting holes are already threaded and indeed they’re in the right places
Back at the shop, let’s first confirm fitment expectations. The factory-provided horn-mounting holes are already threaded, and indeed they’re in the right places.

At times like these it’s good to have access to an older wrecking yard. If I haven’t already mentioned this too many times before, I was brought up in that type of environment. Today there’s not much left of the inventory, but for a short time longer there’s still a few parts stashed.

04 For our horns’ initial cleanup blast we’ve stuffed some paper toweling up their snouts
For our horns’ initial cleanup blast, we’ve stuffed some paper toweling up their snouts. This’ll be their first of two laps through the old bead-blasting cabinet.

Back in California, on the front porch of one crumbling structure there’s a wall of ancient orange crates. They’re historically significant in their own right, but they were also used for pre-dismantling and stocking small parts. Last I checked there’s a matching pair of 12V horns still in one of those crates.

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05 Since it’s time to replenish anyway we’re adding new 80 grit glass beads
Since it’s time to replenish anyway, we’re adding new 80-grit glass beads. We get ours down the road from our local Harbor Freight store.

Going only by memory, the aforementioned horns are from the Delco Remy division of General Motors, and they’re early enough that they’re not made of plastic. I’d imagine they date to circa late ’60s—and that’s when horns were honkers!

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06 Here a little Harbor Freight angle die grinder with a 3 inch 36 grit Roloc type disc works well
With initial bead-blasting pretty much done, we’re grinding heads of rivets. Here a little Harbor Freight angle die grinder with a 3-inch, 36-grit, Roloc-type disc works well.

Best of all, as I recall, the pair is symmetrical, as in (right and left) mirror images of one another. Since a lifted hood will occasionally expose them, we’d like them to look as though they belong.

07 Because this pair has taken in moisture their dainty diaphragms show rust right through their protective plating
Because this pair has taken in moisture, their dainty diaphragms show rust right through their protective plating. Bead-blasting would likely ruin these parts.

In just the right positions behind the core support’s louvers, the smaller-than-stock Delco Remy horns should look right at home. Quite conveniently for us, threaded mounting holes are already present in about the right places.

08 In a manual manner we’ll clean these up as best we can
We won’t be bead-blasting the inner workings, either. In a manual manner we’ll clean these up as best we can. Obviously, there’ll be no salvaging the gaskets.

To get the mini-megaphone portions aimed properly through their louvers, the horns will need to be re-clocked. We can modify brackets for that, but providing certain rivets are uniformly spaced there may be an easier way.

09 To clean the gasket mating surfaces a short length of Emery cloth is helpful but still this is tedious work
Perhaps partly due to age, the factory’s sealant glue is tough. To clean the gasket-mating surfaces a short length of Emery cloth is helpful, but still, this is tedious work.

First things first; for any of this to actually happen there’ll be travel involved. The way our horns are hidden, shipping won’t be possible. It’s not like I can give directions to the secret stash place where no one else would ever go.

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10 With their innards now tended to it’s time for a second lap through the old bead blasting cabinet
With their innards now tended to, it’s time for a second lap through the old bead-blasting cabinet. For that we’ll fashion temporary gaskets and screw these together.

As the plan stands I’ll just go fetch that matching pair of symmetrical, two-tone, Delco Remy horns. For the return trip I’ll just stuff them in my Samsonite and roll—without much illustration for that particular step.

11 This might be a good time to enlarge mounting holes as necessary
This might be a good time to enlarge mounting holes as necessary. Since our bit wants to seize, a reversible drill is handy. From Harbor Freight, this one owes us nothing.

Have you ever wondered what (apart from a big-city motorist) makes a horn honk? Back at the shop, we’ll conduct exploratory dissection. If it turns out they’re good enough to continue working with, we’ll restore and/or modify our honkers as necessary from there.

12 These pieces can now be blown off and painted but what about the rusty diaphragms
At this point we’re satisfied with our blasting. These pieces can now be blown off and painted, but what about the rusty diaphragms?

For our own particular purposes, we don’t mind that they’re not exactly stock for our ’55 Chevy Task Force project truck, nor do we mind that a to-the-letter restorer of GM muscle cars might gladly pay up for the pair. Once they’re resplendent in shiny black urethane they should fit in with their classic truck surroundings just fine.

13 While we’re painting other pieces we’ll let Evapo Rust clean diaphragms
While we’re painting other pieces we’ll let Evapo-Rust clean diaphragms. This non-toxic rust remover is reusable, is quicker than molasses, and is sold at Harbor Freight.  
14 Back in 2018 this cute little Harbor Freight detail gun was only �11 99 on sale
Back in 2018 this cute little Harbor Freight detail gun was only $11.99 on sale. Since its purchase, it’s been shelved and waiting for just the right job.
15 Following disassembly and thorough removal of preservative lubricant it can finally be put to work
Following disassembly and thorough removal of preservative lubricant, it can finally be put to work—had I not dropped and lost one tiny packing nut, it would’ve been.
16 Due to technical difficulty (my own clumsiness) we’ll not expound the paintwork steps
Due to technical difficulty (my own clumsiness) we’ll not expound the paintwork steps. The nutshell version is, we’re pleased. Now let’s go check on our diaphragms.
17 Having soaked for 72 (or so) hours our previously rusty diaphragms have cleaned up nicely
Having soaked for 72 (or so) hours, our previously rusty diaphragms have cleaned up nicely. Around their edges a household scouring pad is used on remaining glue.
18 With parts now scrambled we discover that our diaphragms differ in thickness
With parts now scrambled we discover that our diaphragms differ in thickness. The cast seashells are marked (H ‘n’ L) so let’s use the thinner diaphragm for the high-note horn.
19 From the outside of the stamped steel housings our points are adjustable
From the outside of the stamped steel housings our points are adjustable. They look fine, but we’re using a flexible point file just the same.
20 A 1 4 inch 12 point wouldn’t fit so we ran to Harbor Freight for this E Torx set to try—prior to pliers
Later for tuning we’d like a proper socket. Our adjusting screws are stars. A 1/4-inch 12-point wouldn’t fit, so we ran to Harbor Freight for this E-Torx set to try—prior to pliers.
21 During testing without them our horns made humming sounds only
As we’ve learned, having gaskets in place is important. During testing without them our horns made humming sounds only. Now let’s reassemble and try again.
22 Here at our makeshift honk testing station we like what we hear
Here at our makeshift honk-testing station we like what we hear. They’re obviously two-tone. They’ll likely sound even better mounted solidly in place.
23 Now that we’re satisfied they’re functional and we won’t need to go back in let’s disassemble once more and seal the deal with gasket cement
Now that we’re satisfied they’re functional and we won’t need to go back in, let’s disassemble once more and seal the deal with gasket cement.
24 For final installation star washers are used for best possible grounding
For final installation, star washers are used for best-possible grounding. Bull’s-eyed right behind their louvers, mini-megaphones are downturned just right for drainage.
25 With temporary test wiring done enough it’s time for fine tuning as necessary
With temporary test-wiring done enough, it’s time for fine-tuning as necessary. This little tuner works great for stringed instruments. Let’s see how well it works for horns.
26 By ear however our horns are honking out low E and high F notes
OK, so it’s not working here. By ear, however, our horns are honking out low E and high F notes. We think they’ll sound just fine together. Next up, let’s test our theory.
27 Granted we’ve worked for this but here in the end our good ol’ American Vintage honkers emit some vicious pitches
Oh my goodness, the devastating decibels! Granted, we’ve worked for this, but here in the end our good ol’ American Vintage honkers emit some vicious pitches.
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