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Recently, I've been hearing this "bird-like" chirping sound coming from one of my rear wheels. It happens intermittently while I'm driving at regular speeds or coming to a stop. I hear a little high-pitched "chirp" with each wheel revolution ... so basically, the delay between each "chirping" becomes greater as I decrease my speed.

Can someone help me out and tell me what could be causing this and what needs to be done in order to fix it?

BTW, my cars is a 2000 focus ZTS (4 door) and on my last service at the dealership, I've had my rear drum brake baking plates lubed and the mechanic told me that my rear brakes would need to be changed soon.

I am new to car mechanics in general. So I don't really see how worn rear drum brakes would cause this sound because it happens when I'm driving ... but I might be wrong.

Oh, and one last question. What needs to be changed if the mechanic said my rear drum brakes were worned out. Is it just the pads or the shoes too? What's the difference between pads and shoes? Do I need to replace the whole drum assembly?

Thanx for helping a new focus owner!
 

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I'm not an expert of drum braks, but brakes in general have wear indicators that make high pitched noises to let you know that it's time for service. Seeing as how the mechanic told you that you'll need service on the brakes soon, it makes sense that they are noisy.
 

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Drum brakes will retract and not rub like disk brakes and should make no noise when you are not touching the pedal. Unless something is caught in the drum iteslf or a spring is loose, etc, I think the brakes are not your noise problem. Mine squeak a few times until the rust is worn off from sitting at night.

Waht needs to be changed? If the shopes are worn close to the backing metal, they need to be changed. If the drum is scored (deep gouges), it will need to be replaced or it can be cleaned or lightly turned on a lathe. Most of the time it can be turned unless it will be too big inside after turning. If the shoes are worn away totally, you will hear a metal-metal grinding sound but only whrn you apply the brakes.

Drum bakes use 2 shoes (curved pieces of metal lined with brake material) per brake. They are inside of and pushed against a round "drum" by a hydraulic wheel cylinder and springs retract them when you release the brake. They are monted and can't turn much with the drum, so they stop the drum and wheel when applied. They also have a second system...cables pull them against the drum - emergency/parking brake. Disk brakes use pads that are squeezed by a hydraulic caliper against a rotor (disk) to stop the car...similar to how most caliper bicycle brakes work. Disk brakes are generally better as they get rid of heat better and do not fade. They also dry themselves faster, as the water will spin off the disk. Drums are cheaper to build and adequate for the back of the car that does maybe 30% of the total braking.

I think the wheel bearings should be checked. Jack the car and spin the rear wheels for a start. MAke sure they are not too loose either. There should not be much play if you pull the wheel in and out. As you say, it is tied to the wheels revolving, not a bump (suspension). The backing plates being dry can cause a squeak when you apply and release the brake - just the noise of the shoes scaraping the backing plate...not the noise you hear.

I hope this helps. Let us know what the fix is.


Gary
 
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