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Car is making a high pitched whistle after changing the caliper?

2003 Jetta station wagon, disc brakes all around.

Recently changed all 4 pads + the rear rotors. about 2 weeks after this the car started making a horrible noise from the rear driver side wheel- like the tires were dragging metal.

We took off the wheel last night, replaced the caliper, and discovered one caliper bolt was missing. We think this caused the caliper to misplace itself and start riding the rotor. The caliper was also in pretty bad shape so we went ahead and replaced it because we had already bought the part.

Anyway, we put everything together, drove it last night a short distance, everything was fine.

Today after driving apx. 25 miles since the replacement, the car has started whistling. I’m not sure where the noise is coming from, but it only happens at higher speeds, and I don’t know if turning affects it but it happens going straight. It is a cyclical type of sound and goes away when braking.

Note: when replacing the caliper, my dad did not use the little metal brackets because we couldn’t figure out how to place them and didn’t think we needed them. Would that cause this noise? Is that dangerous to do?

UPDATE: I’ve mislead you all! Upon further inspection the whistling noise is coming from the serpentine belt area. I had assumed that it was coming from the wheel because we had JUST messed with it, but I was wrong. Now I’m wondering what’s going on with the belt!

Yeah, that could cause the noise. I’m not sure if you mean the pad guide brackets (usually flat U-shaped things that guide the pad in and out when you brake) or the anti-squeal shims (roughly pad-shaped metal pieces that stick onto the back of the pads) but either one if missing or improperly installed can cause unpleasant noises.

If it’s the guide brackets it can also cause your caliper to bind at an off angle, which will not only make an unpleasant noise but will also generate excess heat and abnormal pad wear.

If it’s the anti-squeal shims, the only thing you will hurt is your ears and your pride as everyone stares at your squealing car. :wink:

They are two metal pieces that came with the caliper, they’re mostly flat and i think they have an uptick at each end, I think your description of the “pad guide brackets” sounds more like them.

Do they look something like this picture:

If so, then yeah, those are absolutely necessary and this needs to be fixed, preferably before you drive the car again.

I think the diagnosis above is probably correct, you still got a problem with the brakes at one of the wheels. But if that doesn’t pan out another brake related cause of a whistling sound is a problem w/the power brake booster. That usually shows up more at idle rather than driving down the freeway though, but it’s something to consider at least.

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