creaking shhh from brakes

[gathermewool]

97 Subaru Legacy GT with 205kmi (Auto)

The calipers are all pretty new - replaced with AA reman'd. The passenger front was replaced again a few months ago due to leaking around th piston.

The rotors and pads are all only a few months old.

Normally, with the windows down, and while coasting (minimal extraneous noise), I can hear the squish of the tires and almost no other noises coming from the car. Normally, when I apply the brakes, I'll hear the familiar shhhhh sounds of pad on rotor. Lately I've noticed the noise has changed - it sounds like the shhhh with a soft constant frequency creak. The shh-and-creak-noise does not change amplitude (it doesn’t get louder or softer) when I apply more or less pressure on the pedal. When I release the brake pedal, the shh-and-creak slowly fades, as would be expected as the piston slowly retracts to the point where the pad is barely making contact. This is repeatable, and does not change from braking instance to braking instance.

The only other issue that may or may not be related is a slight clunk when I first let off the brake suddenly, and another clunk if I I’m moving forward slowly ( < 3mph) and hit the brakes pretty hard. The clunks don’t occur all of the time, but are frequent enough to be noticeable. I changed the oil last Thursday, and nothing was obviously loose – I checked the drive shaft, tie rods struts and calipers. Nothing seemed loose or broken.

As an aside, I’ve posted up here about a vibration issue I’ve been having when accelerating at around 1800-2500 RPM in second or third gear, usually uphill and regardless of load. Vibration is also present while stopped in gear. The vibration while accelerating is always repeatable, while the vibration while stopped will change in severity, and will sometimes be mostly normal (for a car with 205k.) I’m only mentioning this because it may be related, not because I want an answer to the vibration issue. I wouldn’t mind one, but I’ve already posted that issue in another thread.

 

[mechtech2]

So the 'crunch' or 'creak' noise is only with brake application while moving?
Some pad and rotor materials don't agree well with each other.
You could try a number of hard slowdowns from highway speeds to 20 MPH. See what changes - hopefully it fixes it.
Of course, do this when no traffic is around to be safe for you and others.

 

[gathermewool]

The clunk happens when, say, I'm moving slowly in a parking lot, then hit the brakes. Another clunkish noise, albeit a little different than what I just described, happens when I'm doing maybe 10-20 mph with brakes applied to slow down, then release them suddenly.

The constant frequency creak (think of it as a softer version of you immitating a creaking door,) kind of like the brakes are groaning in annoyance that I'm asking them to do something for me haha. Again, the noise is there from light braking to moderate braking, and will fade in a second or two after releasing the brake pedal.

I got the rotors and pads as a set from a guy on the Subie forums. They're cross-drilled rotors with what look to be semi-metalic pads. I don't have the name in front of me, but they perform a lot better than the AA rotors and thermoquiets I had on before. I bedded the new brake-rotor combo in by braking moderately from 30-5 mph a few times to warm the brakes up, then heavily from 50-5 mph around eight times, IIRC.

 

[gathermewool]

I've been trying to think of exactly what the sound resembles, and I think the closest I could come is cicada. It sounds very similar to the sound a cicada would make, if maybe they ever made brakes out of cicadas. Sorry I can't be of more help. I noticed the clunk while turning over bump as well. I think I was spoiled when I bought the car with out any issues besides needing new struts @175kmi. Now, with 205kmi, it seems everything is making noise, vibrating or showing its age : (

 

[The Critic]

Check the hardware. See if the pads are loose.

I would also remove the pads and check to make sure they are not cracked severely.

 

[gathermewool]

Originally Posted By: The Critic
Check the hardware. See if the pads are loose.

I would also remove the pads and check to make sure they are not cracked severely.


I've never had a caliper bracket come loose, but you could be right, that could be my clunking. I didn't even think about the brake pads being cracked or damaged.

In that case I'll be in the shop tomorrow morning to check things out. The girlfriend is in town, but that's ok; she can hold the flashlight!

 

[mechtech2]

Slight play in calipers of sliding pins can cause a clunk - this is most frequent.
But another loose suspension component can also clunk when the brakes jerk it around.
The 'cicada' noise is another problem with the brakes.
Try the hard stop thing.

 

[gathermewool]

I might take it out later tonight for another bed-in-type braking sequence. The hobby shop was full up, so I'll have to check it out another time, unfortunately.

 

[gathermewool]

Rebedding the brakes didn't change the sound. The pads looked fine. What I forgot to mention is that the new rotors that have been on since late last year are cross-drilled. Would this matter? I didn't notice the noise until the recent warm weather permitted opening the windows, so maybe the noise has been there since I replaced the rotors and pads.

 

[mechtech2]

Oh no!
You didn't get drilled rotors, did you?
What a colossal rip!

They are for sure noise makers.
And pad wearers.
And dirt/water retention devices.
And crack inducers.
And a dirty trick to a future machinist who may have the unfortunate job of cutting them.
And more expensive.
And etc..

 

[gathermewool]

I got all four cadmium-coated rotors (and pads) for around $100 - half what guy who sold them to me bought them for. He has the model with smaller rims, and didn't realize his mistake until after he bought them.

I don't mind noise or pad wear at all. When the pads that came with them wear out I'll put my old thermo quiets back on, which have a lifetime warranty through AA. I can't see them being any harder to cut. Worst case is I'll have to groom the holes myself after the cut.

The reason I switched was because the cheap AA rotors I bought warped. I replaced both fronts, and they warped again after 6 months. These have been one since late last year, and I've got to say, the braking is MUCH improved! Initial bite, even when cold, is much better than what I had, and brake fade is almost non-existant. The only issue I've had is the unusual noise, and slight squeal while lightly braking. As long as the extra noise is normal, I couldn't care less!

 

[mechtech2]

If initial bite and brake fade are better, it is 100% because of the pad material.

 

[gathermewool]

I wasn't expecting anything amazing, but I'm satisfied with the performance, regardless of whether it's fully attributable to the pads or a combination of pads and rotors. Either way, I've only had them on for six month, and pad wear has been negligible. Granted, I spend the majority of my time coasting from stop sign to stop sing or when I see a red light ahead, so that may help. On a side note: I never really understood people who speed all the way down hill then hard brake just before a line of people at a red light? I can understand doing this with stop signs, but come on - are people really THAT impatient?

 

[willix]

It's possible a wheel bearing has a touch of play in it and the rotor doesn't have a true 90' angle with the caliper assy. When the brake applies this allows the pads to monentarily lift and edge off the piston & dead side of the caliper that would otherwise lay flat. The noise may actually be the spring clip that holds the inside pad from rattling. it pushes into the piston ID.

 

[gathermewool]

The noise does not change amplitute from barely applying the brakes to moderate braking. The noise is also very consistent and predictable - it is always there when I apply my braks every time I apply my brakes.

I'm not sure what you mean about the spring clip. The metal peice that clips intot the caliper bracket doesn't come close to contacting anything. Well, not unless I ran my pad down to the squealer ; )

 

[gathermewool]

Great, today I noticed a new noise while braking: if I brake lightly, I'll hear a creaking sound like if you push up and down on a creaky spring mattress from 10 mph until I've fully stopped. It goes away when I brake harder, and isn't there while braking at higher speeds.

 

[Spykem4e]

Originally Posted By: gathermewool
Great, today I noticed a new noise while braking: if I brake lightly, I'll hear a creaking sound like if you push up and down on a creaky spring mattress from 10 mph until I've fully stopped. It goes away when I brake harder, and isn't there while braking at higher speeds.


I had that problem with my previous rotors and brakes pads.

I decided to change both rotors and pads for ceramic ones and also the same brand. Since then, no more sound! Quiet!

I've been dealing with the dealer over and over and over about that creaky spring mattress sound from my brakes! After a year dealing with them and the sound, I decided to do the job myself and voilà!

 

[freeze12]

Originally Posted By: gathermewool
Great, today I noticed a new noise while braking: if I brake lightly, I'll hear a creaking sound like if you push up and down on a creaky spring mattress from 10 mph until I've fully stopped. It goes away when I brake harder, and isn't there while braking at higher speeds.

Most likely a bad Caliper as when the piston rides on the dry square cut seal it will make that noise.I just rebuilt My Caliper on My Alero & am installing it tomorrow due to the brake creaking noise I have.

 

[gathermewool]

If you could, please post back up what your results were. I replaced all three calipers two years ago (one again after it started leaking by the piston seal). The noise seems to be coming from the one I had to pay a shop to replace, since it locked up and I was in a bind. It costs nearly as much for that as it did for me to replace the other three combined!

Anyway, I'm giving this car to my sister, who just wrecked her car (she's fine) and want to make sure it'll get her along reliably. I've got until next Tuesday to little-sister-proof it. : )

 

[freeze12]

well I rebuilt the caliper and I also made a semi runny mix of Silicone spray & Napa Syl-Glyde and put it in a hypodermic syringe and then carefully separated the dust seal from the caliper Piston & injected the mix all around the piston assembled the Caliper etc, and no more noise & great braking!