My current daily car is a 2001 Impala 3.4 V6.
75,000 miles.
New brakes. New Rotors. New left front caliper.

So I got this ride a couple months ago. Soon after it developed a squeal in the front after getting warmed up.
The squeal is a constant pitch, mostly. IF it changes pitch, it is at a steady speed and changes for seemingly no reason.
Otherwise, the pitch is ALWAYS the same while rolling, regardless of speed. It will go away when brakes are applied, sometimes when turning, be it lane change or into a driveway.
It's hard to trace, but I believe it to be on the left side of the front of the car.
When I got it, someone had put new rotors on it, but not pads(???) The rotors were ok, so I put the best new pads on as recommended by a friend that manages an O'Reilly's Auto Parts store.
The noise was gone for 5-7 days, and came back. I tried swapping front rotors from side-to-side. The noise came back 5-7 days later. I put on a new left front caliper and the noise went away for 1-2 months, and is back.

Ideas? (Can't do the trade in thing right now)
Thanks guys

#1 - if you jack the car and rotate the wheels, do you hear a squeal/squeak?

#2 - have you ruled out wheel bearing/etc?

#3 - are you sure you have the correct rotors and pads?

#4 - are the anti-rattle clips and shims installed?

#5 - are you running semi-metallic or ceramic pads?

I'm also wondering if you have a fluid problem. Have you done a fluid flush?

How are the hoses?

Any stopping problems?

Seems like the noise stops everytime the caliper is removed and re-installed? Possible the slide pins need to be cleaned and lubed with the disc brake lubricant? If the caliper sticks even a small amount this will set up a vibration in the pads causing the noise.

But also like Mat said, could be a brake line not releasing fluid fully keeping pressure on the caliper piston.


Joel

I tried rotating the wheel w/ it in the air and got no noise. It seems to be present when the driveline warms up. If I let it cool, it becomes more intermittent. However, the tone of the squeal does not change with speed, neither does the volume of it.
The flex hose was changed with the caliper.
The slide pins have been removed, cleaned, lubricated and reinstalled.
The anti-rattle shims are in. Correctly.
The pads were purchased for the property of being quiet, and my friend at O'Reilly said he's had great customer feedback on them.

I'm starting to lean toward the bearing hub on this thing. There's not too many other moving parts besides the hub and the C-V axle.
Just a month ago, I had to have it towed for not starting. I troubleshot as much as I could, but the weather put a stop to it all. Had it towed and repaired only to find out two days later that a local squirrel/chipmunk had eaten about 8" worth of wiring harness.
So the saga continues...

If the brakes are 100% in order, I'd start investigating other avenues.

It's been hectic around here since I was last on, but it's been suggested I put new pins in the caliper and maybe a new caliper adapter as any unevenness is able to cause misalignment and subsequent rubbing on the pad against the rotor.
Hmmmmmm.....

Went to a local boneyard and got a different caliper bracket.
Got a new bushing and shim kit along with a new set of guide pins.
Got home, cleaned up the bracket, put in new bushings and slide shims.
Took off old bracket from car, went to install "new" bracket and it was the wrong one!!!!
It"ll go back to the yard on Monday, complete with gripes and bitchin'.
So I put the rest of the new stuff into the old bracket and reinstalled it.
The adventure continues.....

I agree that pins/etc could contribute. Hope that solves the problem.

That's the reason I like the u-pull-it yards! Plus the cheaper prices.
Good luck with "new" one.

Joel

Took the "new" bracket back to the yard today after work. The guy just looked at me as if it was an impossibility to get a wrong part. But, he very nicely coughed up the cash.
The weather is going to crap right now, so I'm gonna consider my next move.

So, yesterday I put on a remanufactured bracket for that caliper.
Still got the noise, but it's considerably more intermittent and seems to be tied to that wheel's rotation.

Did you also change the slide pins?

Quote:

Yes, they've been changed.

So you've essentially replaced every brake hardware piece on that corner.

Was the vehicle ever in an accident? I'm wondering if something is out of spec/alignment if the wheel bearing checked out ok.

I don't think it's been wrecked.
I'm thinking bearing hub as well. I just hate the idea of doing the work and then it not working...
Hmmm.....

In your first post you mention the noise goes away when brakes are applied, this is usually a "good" indication of a bad bearing. As the rotor is being held by the pads, the bearing is also being supported by the rotor. At least this is my experience with front hubs. The CV shaft usually make a "thumping" sound similar to a U-Joint on a RWD vehicle. Again just based on my experience.
Any slop or motion in the front wheel when it's jacked up?


Joel

Sorry to take so long to reply Joel. I don't always get my notifications.
I think I'm at the point of agreement with you. Really the big thing keeping me from getting it swapped out is the weather. But I've been shopping for one to have on hand so I'll have it when the weather breaks. The last time I changed one of these was in our Y2k Impala, and it was so rusted I broke the spider on a slide hammer trying to get it out. A better quality slide hammer brought victory.

Hope this one goes easier for you!

So today I put in the new wheel bearing hub assembly. It was a fairly straightforward job and went well with little hassle. So once I got the old bearing assembly out, there was a shim between the hub and the knuckle. This "shim" was installed on all the cars I think as it looked innocently like a bracket or some kind of retainer for the ABS lead, however my car does not have ABS. So I figure it's necessary as a shim.
Once the old hub was finally off the car, that shim was lying on the driveway and I picked it up to clean/inspect it. It was then that I noticed that there was another reason for this shim. At the lowest point of the shim, there was a "T" shaped tab that I think is there to protect the lower ball joint from any debris or heat from the rotor. Closer inspection of this tab showed that it has been rubbing the rotor, and is quite likely the issue that has been causing the entire problem.
So, what have I re-learned here?
When you look at the components, LOOK at them. Had I actually gotten down and looked up at this and looked at the bottom as well as the top and sides, I could've saved a great deal of aggravation, time, and money!
So here's the lesson to be learned from my mistake.
LOOK at it.
This is a relief to know I Probably found the problem, but I didn't follow my own advice that I give others in this type of situation.

I'd like to thank all of you for your help. You guys are the best!

So, just what did you do to fix the problem?
Glad you got it!

Joel

Quote:

With something like this, I simply gently bent the offending tab out of the way so it no longer made contact with the rotor.

....those type things are what can make me want strong drink.....glad you found the solution.......

I've experienced that with brake rotor backing plates. Glad you found it.