Rear disc brake conversion makes loud humming noise

Hyp3rDeath101 · Jul 14, 2024

I did a rear disc brake conversion on my 1994 Chevy Silverado Extended Cab, as the old drum brakes were completely disabled due to wear. I used new parking brake rear calipers from a 1982 Cadillac Eldorado. After installation, I decided to start driving around for the next few weeks, and see how the brakes perform. The brakes work exceptionally well (I also have a newer style master cylinder). Unfortunately, when I first start driving, there's a horrendous humming noise that rings my ears. Any suggestions on how to eliminate that noise?

I also got these parts off the jungle site:

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Edit: I forgot to say that the humming noise only happens when pressing the brakes.

Caman96 · Jul 14, 2024

Have you removed rear wheels an re-inspected everything?

Hyp3rDeath101 · Jul 15, 2024

I have inspected everything I installed, and nothing seems to stand out. The truck has 180,000 miles on it, and everything was original when I became the owner. I'm suspecting maybe bad quality brake pads or rotors. I forgot to say that the humming noise only happens when pressing the brakes.

someotherguy · Jul 15, 2024

Which kit did you use to mount these calipers? Got a link?

Richard

Erik the Awful · Jul 15, 2024

Try cleaning the rotors thoroughly with rubbing alcohol, mineral spirits, or brake cleaner. Then scuff the rotor surfaces with emery cloth and re-clean them.

Alternatively, ditch that crappy rear disc setup and go back to stock. As a former Cadillac owner, I can tell you that 1982 Cadillac parts aren't a long-term solution. Sources are drying up.

0xDEADBEEF · Jul 15, 2024

Make sure there is slack in the parking brake cable.

Schurkey · Jul 15, 2024

Hyp3rDeath101 said:
I have inspected everything I installed, and nothing seems to stand out... ...I'm suspecting maybe bad quality ~~brake pads or rotors~~ disc brake conversion kit. I forgot to say that the humming noise only happens when pressing the brakes.

FIFY. It's a damned shame you paid good money for a bum conversion kit.

First Guess: You didn't hammer the pads tight to the caliper.

Middle two pads, "hooks" at the top in this photo.

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The outboard pads each have two "hooks" formed into the backing plate; they need to be tightened-up a bit with a few taps from a hammer to make them grab the caliper tighter. Take the calipers off, remove the outboard pads. Put the pads on the concrete with the two "hooks" facing up, and tap each the hooks (two per pad) downward just a little. When you're done, the pad will need to be squeezed back onto the caliper with a bigass plier (I use a Knipex "Cobra" pliers, but any "water pump plier"/tongue-and-groove pliers of about a foot long would work.
www.amazon.com/KNIPEX-87-02-250-Pliers/dp/B000X4PU80/ref=sr_1_8?

www.amazon.com/Channellock-440-12-Inch-Tongue-Groove/dp/B00004SBCU/ref=sr_1_5?

Without whacking the backing plates, the outboard pads are loose on the caliper and vibrate causing noise.

Hyp3rDeath101 · Jul 15, 2024

I was wondering if I forgot a step! I'll go ahead and give that suggestion a try in the next few days.

Also, the parts I purchased from multiple different sources. I got the parts off Amazon, Ebay, and the caliper bracket from Cunningham Machine.

Edit: I also tried CRC Disc Brake Quiet, but that didn't do anything.

1998_K1500_Sub · Jul 15, 2024

Hyp3rDeath101 said:
... and the caliper bracket from Cunningham Machine.

Plz post a picture of the bracket / complete installation.

Hyp3rDeath101 · Jul 15, 2024

Here's a picture that I can currently get of the bracket and caliper:

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Rear disc brake conversion makes loud humming noise

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