[AWDFTW]

Per the forum noise diagnostic quidelines:

A. When does the sound happen?

_ When engine is running
_ When transmission is in some particular gear
_ When turning
_ On throttle
X When braking
_ Over bumps
_ In cold conditions
_ At speed - wind noise

B. Where does the sound come from?

_ Can't tell
_ Drivetrain
X Suspension/wheels/brakes
X Front
_ Rear
_ Body

C. Does the sound vary with some condition?

_ Engine/transmission rpm dependent
X Wheel rpm dependent
_ Air speed/direction dependent
_ Varies according to some other condition

D. Is there a vibration associated with the noise?

_ Feel it through the floorpan or seat
_ Feel it through the steering wheel
_ Feel it through a pedal

E. Does it affect drive-ability? how? (Essay question, 2500 words or less)

No driving issues. The grinding sound comes at a slow light application of the brake, such as when one is getting stuck in traffic. Not apparent under heavy braking, just a gentle, low speed application. Sound is best described as grinding or scraping. I'm wondering if it may be front suspension related (bushing somewhere?) and I just hear it under the right conditions.

The short version is that the front brake pads and rotors were replaced about 15k and and the rears about 5k ago. Brake fluid was flushed about 4 years ago (I know, I know) and bled/topped up at the 2 most recent services. This work was done at a mechanic, as the brake hardware can easily get rusted and/or seized in the Chicago winter environment, so it is one of the few minor things I don't deal with due to the hassle of rusted bolts.

Thoughts?

 

[nickb21]

Does it occur under light higher speed braking at all, or just light low speed? How about when it's raining/wet?

I have a very similar thing going on very intermittently, but mine seems to be more wet weather related.

Any chance the ABS is kicking in?

Interested to hear what others think...

 

[AWDFTW]

I'll keep an ear out for the light higher speed, I usually have the radio up to compensate for the wind noise.

As for dry/wet, I have noticed it in both conditions at light application of lower speed braking. So far I have only noticed it at under 30 MPH.

I would expect a pulsing through the pedal or steering wheel if it was the ABS, it is still smooth when it does this. Just the grinding/scraping/creaking sound.

 

[plain OM]

Could be a brake pad coming into contact with rust on the rotor as the brake pad shifts slightly when the brakes are being applied.

Have you tried raising the wheels and manually spinning them by hand to see if the grinding/scraping sound can be repeated?

 

[Saint J VT]

I know the circumference of the front rotors on our '05 end up with major rust to the point of scaling, beginning with the inner exposed cooling fins.

Is there a ridge of rust that is hitting the caliper and/or the brake pads? Is there adequate clearance of the sheet metal back dust shield (the dust shield can become bent very easily). When trying to "wiggle" the wheel, when up on a lift, are both front wheels tight (wheel bearings), or do they move a bit? If there is a buildup or ridge of rust and if the wheel is just a bit loose at the hub, the amount of movement could be just enough to cause said rust scaling to come into contact with certain wheel and brake components, including the heavy sheet metal dust shield.

 

[1 Lucky Texan]

maybe experiment by pulling a fuse to disable the ABS - just to eliminate that system.

It does seem more like a dust shield or pad problem.

 

[tylerb83]

I feel like I'm having the same issue with my 2006 OB (107k miles). I have the same symptoms per the noise diagnostic questions. I'll add to this post instead of starting a new one...

The weird thing is that the noise is totally intermittent and there was NOTHING leading up to this issue. There could be a correlation between the noise happening once the car is warmed up. It seems to be loudest when going very slow and just approaching a complete stop. It's a WOMP WOMP WOMP noise, that has some grind to it. There is a slight steering wheel vibration (side to side) when braking at higher speeds. The calipers, rotors and pads have about 10-15k on them. Rear rotors and pads are new.

Just to add a twist: I recently moved and hauled the car on a trailer (all wheels off the ground, of course) and I wonder if ratcheting the front wheels down with those straps could be the reason for these sounds. I if maybe there was some stress on suspension or bearings??

 

[1 Lucky Texan]

I feel like I'm having the same issue with my 2006 OB (107k miles). I have the same symptoms per the noise diagnostic questions. I'll add to this post instead of starting a new one...

The weird thing is that the noise is totally intermittent and there was NOTHING leading up to this issue. There could be a correlation between the noise happening once the car is warmed up. It seems to be loudest when going very slow and just approaching a complete stop. It's a WOMP WOMP WOMP noise, that has some grind to it. There is a slight steering wheel vibration (side to side) when braking at higher speeds. The calipers, rotors and pads have about 10-15k on them. Rear rotors and pads are new.

Just to add a twist: I recently moved and hauled the car on a trailer (all wheels off the ground, of course) and I wonder if ratcheting the front wheels down with those straps could be the reason for these sounds. I if maybe there was some stress on suspension or bearings??

You're gonna need to get the front end up and inspect the pads,calipers and dust shield. Inspect the bearings and all the steering/suspension gear too.

The highspeed wobble could just be uneven pad material deposition. Might not be related to the other symptom.

If you take this in to be looked at - take the mechanic for a ride and demo everything for him. If you plan to DIY , start with a close inspection of each system involved with braking, steering and suspension. perhaps also try rotating tires front to back.

 

[Wagondude]

I feel like I'm having the same issue with my 2006 OB (107k miles). I have the same symptoms per the noise diagnostic questions. I'll add to this post instead of starting a new one...

The weird thing is that the noise is totally intermittent and there was NOTHING leading up to this issue. There could be a correlation between the noise happening once the car is warmed up. It seems to be loudest when going very slow and just approaching a complete stop. It's a WOMP WOMP WOMP noise, that has some grind to it. There is a slight steering wheel vibration (side to side) when braking at higher speeds. The calipers, rotors and pads have about 10-15k on them. Rear rotors and pads are new.

Just to add a twist: I recently moved and hauled the car on a trailer (all wheels off the ground, of course) and I wonder if ratcheting the front wheels down with those straps could be the reason for these sounds. I if maybe there was some stress on suspension or bearings??

Your high speed braking vibration has alway been worn tie rod ends anytime I have experienced it. With your miles, they would be the first suspect.

 

[catric69]

I would inspect for any type of debris in between the brake pads and rotors. I recently had a continuous grinding/scraping happening on my '10 Outback. I found a rather nice sized shard of glass stuck between the rotor and the dust shield. Problem solved! Good luck with your issue.

 

[tylerb83]

Thanks for the feedback, everyone! Haven't experienced the noise lately, but that could be due to the intermittent nature of the issue. I just moved to an apartment complex where my options for "getting up under there" have diminished.

I thought the wobble might have to do with the brake pad deposition, which I've read about here. But based on mileage, I will keep an eye on tie rod ends. The wobbles/shakes are something that seems to come and go too. I just did a tire rotation (corner to corner, non-directional tires) too.