Brakes squeal after brake job?

Question

I had a nasty squeal coming from my brakes whenever I slowly braked. So I took my car to the shop about 3 weeks ago and the mechanic said the rotors needed to be cut because I had cheap pads on (bought my car used). So he cut the rotor and put new pads on.

Couple days later I started hearing a squealing again. Not as bad as before but its was back again. Any idea why? Well, its been 3-4 weeks since I had the job done and I hear squealing. Seems worse when I just start driving and improves with a little time. Maybe its cause they are new and need to adjust? (I dont really drive my car too much, could be why its been 3 weeks) thx for any help.

Answer 1

Disc brakes have a strong tendency to squeal and make similar noises. The pads are clamped to the rotor by the calipers, like bicycle brakes that pinch rubber or plastic pads against the bicycle rim. When this happens, the pads and associated hardware can vibrate as the pads rub against the rotor, like a bow on a violin string. Poor quality pads and hardware can make the problem more prominent, but all disc brakes have this tendency. This kind of disc brake noise is typically most noticeable under light brake application after the car has been sitting and a little rust may have accumulated on the rotors.

Part of the solution is to use good quality parts and machine rotors to provide a not too-coarse finish, but also to clean and lubricate mounting points as specified by the manufacturer, install new brake hardware and treat the metal backing plate of the pads with anti-squeal compound sold in auto parts stores. Anti-noise compound (often included in a small plastic tube with brake pads) dries to a rubbery or sticky goo that dampens pad vibration.

Brake hardware -- springs, pins, clips and such -- different arrangements are used by different manufacturers -- is usually not expensive (10's of dollars) compared to a brake job. Brake hardware weakens and wears out in normal use.

Most automotive disc brakes also have a warning device that scrapes the rotor when the pads get thin. Their purpose is to make make noise to attract attention before the metal backing plated of the brake pads gouges the rotor and causes more damage than need be.

Any brake noise that is continuous, regular and repeatable and can be described as grinding needs to be investigated as the lining may have worn out completely.

Answer 2

well it could be that the mechanic put cheap pads back on, or it could be that you haven;t driven enough for the pads to wear in. when you say they cut the rotors do you mean they took out the grooves, i ask becuase your rortors may be glazed. it is also possible that some brake fluid wasspilled on the pads or rotors, which would also result in a squel. does the noise coem from both sides or jsut one. my advice, take the car out for a nice long drive, nothing that is hard on it, but get teh brakes warmed up and apply them several times through out the drive, if the squeal persist, go back to you machanic.

Answer 3

I would continue a few more weeks and if it still hasn't stopped than take it back to the shop and find out why.

It was the very reason that you had your breaks repaired in the first place. The squealing. He used the cheap brake pads as an excuse before. So ask him why now.

Answer 4

Follow RPK's advice to a T. Cheap off-shore rotors are a waste of time. If necessary, replace with Wagner, AC Delco or EBC. And do not forget the CRC Brake Quiet silicone application on the metal backside of all the brake pads. The CRC product can be found at any NAPA auto parts store. Good luck!

Answer 5

the edges on the pads need ground off to be round and the rotors need sanded down some.

Answer 6

My car has been doing this too. my friend is a mechanic and he gave me some stuff to spray on the rotors, after i sprayed it on its been working fine ever since.

Answer 7

I've been told that brake dust or brakes that have not been properly bled (leaving air pockets) can cause squealing.