Extremely strange noise from rear brake drum
 

Just developed a new noise and its stumping me. When letting off the brake pedal, even with the car off, the right rear brake drum emits a weird short metallic whistle. Happens every time the pedal is pressed and after getting under the car its definitely coming from inside the drum. Any thoughts? Wheel cylinder maybe? Its decently loud. I can try to see if I can post audio of the noise

Edit: Does not make this noise while driving(that i can hear) and braking is not affected. Only symptom so far is the noise everything else is normal

Have you removed the drum and looked in there to see if anything is out of place? That’s the first thing I would do.

I am curious if your right side is not self adjusting. Thus your wheel cylinder is moving more and making the noise.

Sometimes the metal dust shield lip can hit the drum of debris get between the drum and that dust lip making noises too.


I also verify your emergency brake cable is working properly as the back drum brakes can rust or bind up some that the arms dont return against the bolt on the backplate. Which can cause issues with auto adjustment of the rear shoes.

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I agree with @RandyBobandy . Pull the drum off and see what you can see. The problem might be very apparent when you get a look at the brake components.

You are probably hearing the springs retracting the shoes and a friction point is making the noise. It'll happen every time you lift the foot off the pedal. If you look at the FSM or a Haynes manual you will see how to service rear brakes. There are about a dozen points per side that get a little dab of brake grease to keep things working smooth and quiet.

If you haven't serviced the rears in a while this is likely the noise you hear. One of my old cars did it for years and I never bothered to fix it but I treat my 4runner better than that now.

Best way to really find out where the noise is coming from is to pull both drums out and take a peak. Actually with the drums on, you could have someone inside the truck put it in drive and let the rear axle move by its own (with the rear jacked up obviously, and the front chalked) and you could probably track down the noise from there (if it happens). When putting it into park, pull the e-brake up so you don't shift it while it's moving.

I did this just to see what the f*** would happen when I did my bell crank replacements a while ago but this might be a good way to track down the small noise.

While you are there with the drums, spray the whole area with brake cleaner and see if the noise goes away. It might work. Keep in mind if they haven't been off in years, you might want to back off the adjuster behind the drum shield and pound the drum with a rubber mallet.