Brake squeal

[24v 4.2]

I have a squeal coming front passenger side wheel. It sounds like "e e e e e" increasing with speed. And the squeal stops when the brakes are applied or when turning left. I have cleaned and lubed the slide pins and replaced and lubed the anti rattle clips.

The rotors and pads have about 6 months and 15,000 miles on them. And the pads appear to be evenly worn. Also the shield behind the rotor does not appear to be rubbing. And there is no pulsation When braking.

Any suggestions? My only guess is a bad caliper...


Also the noise stops for a little bit if I do 2 or 3 "panic" stops (abs activated).

 

[IllogicTC]

My first guess is the bearings in the hub. Were they properly installed, and of good quality?

I know it sounds weird that the sound would go away when hitting the brakes, but it's happened to me before on a different vehicle. I guess something with the overall way physics are playing out with the brake applied, I don't know. But getting it to go away when turning is also a good indicator this could be your source.

Try lifting the front end up on stands and giving the tires some manual spinning. This could let you try hearing exactly where the source of the noise is.

 

[IllogicTC]

I apologize, I thought the 2WD has the bearing in the rotor. Apparently it uses the same hub assembly as the 4WD from what I understand.

I don't know how much this video will help you, but it may assist in troubleshooting. In the video, the mechanic uses the CV boot as the indicator and will point out what should and shouldn't be moving. As the 2WD shouldn't have the CV, I don't know how helpful this video may be. I would imagine for a 2WD, doing this test and seeing how much play the tire has, and ensuring none of the suspension/steering components are moving along with it, should aid in diagnosis.

[video=youtube;5ybpuQTwoFg]http://www.youtube.com/watch?v=5ybpuQTwoFg[/video]

The same people who put that clip up also sell the assemblies on their website, 60-some for one or 114.95 for the set, they come with the whole thing already assembled and lug studs and wiring harnesses installed. They also offer Timken brand for 300-some (set). I however have not purchased anything from them before so buyer beware if they're the route you go.

At any rate, same guy also has a video on how to do the installation of new assemblies (they have a link to their wheel hub section in there if you don't feel like shopping around). Looks like a fairly painless job to do at least with pre-assembled units.

[video=youtube;yZ13Qet234c]http://www.youtube.com/watch?v=yZ13Qet234c[/video]

 

[24v 4.2]

Ok. I will check for movement. Is it possible that the hub is bad, but it does not do what is described in the video (movement)?
I am assuming that the Timken is the best replacement?

 

[Playsinsnow]

Yes Timken hubs are highly regarded around here. Many members will hear a train-like sound or heavy grinding before any significant play felt by hand. Do you have the typical grinding sound when turning either direction?

 

[Fire06]

I have always found the bearings are usually noisiest when driving genteelly turn left and then right to see if the noise gets worse. If it is worse when you turn left it is usually the right bearing and turn right the left bearing.

 

[24v 4.2]

no Grinding noise that I noticed while moving. When I had the wheel off the ground and turned it I Heard slight friction noise, but that may have just been the pads. The noise I am experiencing is a high pitched E, E, E, E, E, E that increases with speed. Could it just be glazing on the rotor? I followed the manufacturer bedding procedure

 

[24v 4.2]

The high pitched noise is there when going straight or turning right. But goes away completely when turning left. I had someone walk next to the car and confirm that the front right wheel is the culprit.

 

[Fire06]

If it was the right bearing turning left should make it the noisiest.

 

[24v 4.2]

I had the same noise in my rear drivers side wheel, it went away once I changed the rotors and pads. My guess is that it may have been a slightly sticking caliper that was freed when I compressed the piston during the brake job.

The noise in question occurs once per revolution of the wheel. I will take a video today if I can.

The noise goes away for a short time if I slam on the brakes a few times and set off the abs.

 

[Fire06]

Could be a sticking caliper. If it is not releasing properly than that is the issue.

 

[24v 4.2]

Would a sticking caliper have to be a constant noise? Or could it make a noise once per rotation (as it does in my case)?

 

[Fire06]

Could be a high spot in the rotor Not sure on the sticky caliper. Missed the part where you said only in one spot per rotation

 

[The_Roadie]

I have nothing clever to add here, but I would recommend you share the total mileage on the existing hub bearings. Over 100K and the list of suspects is a bit different from under 100K. But bearings are a bit pricey to be shotgunning with, so I'd work on the caliper slide pins first.

 

[cyberpunk]

I just went through a similar incident (yesterday and today)and it turned out to be the rear brakes. The driver side pad had cracked and part of it fell off. I would assume it was because the recent cold spell and I did not do the rear brakes when I bought the vehicle. If it does turn out to be the rear brakes you should replace them and the rotors. The squeakers or squealers(which ever you want to call them)are what are making the noise or at least in my case. A side note to this is that being an 03 model the caliper brackets can be quite corroded and cause new pads to not fit properly. The brackets are fairly inexpensive for a1cardone at AutoZone refill or Napa but they are remanufactured and do have a core charge. To be honest I just knocked off as much rust as possible and took a grinder to the ears of the pads. As per the resident GM tech that moved in. That is what he did all the time.

 

[IllogicTC]

But bearings are a bit pricey to be shotgunning with

Very true. Just what I thought may be the issue, I didn't think of the slide pins or anything. Well... if it IS the bearing, I already posted a video on replacement, at least lol.

The slide pins should be inspected to ensure they're in good condition, lubricated with the proper grease, and the rubber boot should be intact to keep the grease sheltered from the elements.

 

[Fire06]

Good luck

 

[24v 4.2]

113,250

The slide pins looked like they were in good shape, and they were still sealed and greased well. I cleaned and greased the pins and cleaned the holes they go in. Replaced the boots and rattle clips.

My best guess at this point is glazing on the rotor causing a high point. (As fire06 said above)

Would I be correct in assuming that something must be out of round since it only makes the noise once per rotation? (which would rule out the caliper sticking as that would cause a constant noise? )

 

[JerryIrons]

The other thing you can do is put some brake caliper synthetic grease (high temp synthetic grease), on the metal backs of the pads where the calipers push on it. Just a light coating. I have even greased up (just a little) where the metal ends of the pads slide. Basically anywhere you see metal rubbing metal, but light amounts, you don't want globs of grease falling onto the rotor or pad surface...no grease on pad or rotor surface!

Sometimes a small piece of rust falls and gets squeezed causing a squeal. Take it apart and inspect, use a dremel to clean out rust, etc.

If there's one thing that drives me crazy its squealy brakes!

Edit, if you get a noise once per rotation, look at that shield. It can get bent very easily enough to rub on the rotor, especially if rust builds up. Also bad bearings tend to make noise just driving without even applying brakes.