Brakes sound like a horn

[monsterwake]

Sorry if this has been mentioned but I can't find it. My drum brakes sound like a horn. Not squeeling or screeching. A horn...
I replaced pads and cylinders because all of that was bad. Some of the springs too. The truck brakes fine. eBrake works fine too. I will attach a video with the sound.

 

[monsterwake]

Nevermind. I can only see how to attach pictures. Not videos.

 

[GoToGuy]

Turn drums? Disc pads. Drum shoes. Which did you do? There different animals.
New flat brake shoes on worn curvy brake drum, poor contact area, equals vibration, and enough vibration right frequency makes sound.

 

[Schurkey]

Sounds like a horn...at the wheels, or at the base of the steering column (faulty booster?)

 

[monsterwake]

Yes. Old Drums with new pads. The sound is from the rear wheels.
So, it sounds like I need to get the drums serviced and hope I don't need 2 new ones.

 

[RichLo]

Some older vehicles had a long coil spring wrapped around the drum to keep the harmonics to a minimum. Those were 4-wheel drum vehicles that weighed 6000lbs and really worked the brakes a lot harder than the rears in pickups. Im guessing yours are going to be beyond the minimum thickness to re-surface which is why they are humming.

 

[Erik the Awful]

Nevermind. I can only see how to attach pictures. Not videos.

You can make a YouTube account and link to the video.

 

[someotherguy]

Some older vehicles had a long coil spring wrapped around the drum to keep the harmonics to a minimum. Those were 4-wheel drum vehicles that weighed 6000lbs and really worked the brakes a lot harder than the rears in pickups. Im guessing yours are going to be beyond the minimum thickness to re-surface which is why they are humming.

My '92 ECLB did this. It wasn't all the time, and the brakes seemed to be working so I just wrote it off to high miles on a beat truck that had later become someone's custom toy. Truck stopped well, just made the noise sometimes. So when he said the brakes sound like a horn I already could hear it in my head.

Richard

 

[Schurkey]

First Guess: Shoes and drum have uneven wear, perhaps even "hot spots" cooked into the iron of the drum braking surface. Perhaps contaminated linings. The braking action isn't "smooth" leading to vibration causing noise.

Second Guess: Faulty hold-down springs leading to vibration causing noise.

 

[Road Trip]

Yes. Old Drums with new pads. The sound is from the rear wheels.
So, it sounds like I need to get the drums serviced and hope I don't need 2 new ones.

I've had similar results when I have refreshed drum brakes by combining new shoes
on as-found drums. It's the sound of the friction material doing the grab>release>grab>release
thing on the shiny drum face, and you are then hearing the drum vibrating at it's resonant
frequency -- just like a bell does when you ring (stimulate) it.

Within the past year I ended up going through the rear brakes on my chore truck, and
in order to avoid any squeal or having the drums atone for my taking a brake job short cut,
I got the original drums turned the bare minimum it took to make them round & ready
for fresh shoes to rub against them.

If you like take a look over HERE in order to see what I ended up with. And they only charged
me $20 per drum to turn them.) The results? Dead smooth, whisper quiet.

For what it's worth. And if you figure out a solution for your specific problem, please return
back and share the wealth with the members of this forum.

Best of luck!

Cheers --