Tech help! Floating rotor on Trailblazer

[MerF]

So in my hiatus from the Camaro5 family, I moved my fiance in with me (and her two kids) and we got rid of her awful G6 and picked up a 2004 Trailblazer LTZ (for less monthly than she was paying on the "new" G6).

The truck is solid and has been wonderful in it's first 4000 miles, however there is something happening I'm not sure how to handle. Not long after taking the truck home, the driver-front brakes started having excessive squealing as if the pads were gone....thought that was strange, the local Chevy dealership we picked it up from has a good reputation, but regardless I was within the 3k miles of warantee so was going to use it. However the one day before the mileage was over that I could get it in, I overslept and didn't make it.

Sooo, I took it to the base and used the wonderful auto hobby shop's lifts to take a peek at the brakes. I bought pads just in case. Let me start this with the fact that I had never dealt with floating rotors before (or never realized it if I had). I took the wheel off and scanned the rotor and saw that there was definitely a track of rubbing on the rotor...not so much it had grooved or even needed to be turned, but it was apparent something other than pad was hitting it.

I started to loosen what I thought was the bolts to get the caliper away from the rotor to check the pads when in fact I had removed the bolts that held the caliper to the suspension arm! And when I did, of course the rotor itself came loose with the caliper assembly. That blew my mind, let me tell you. I couldn't believe that was all that held everything together. While I was putting it back together so I could remove the actual bolts I needed, I noticed that the rotor was not seating well inside the caliper, and sure enough when turned the wheel, there was a part of the caliper that fit perfectly in the groove of the rotor that I had seen.

I did check the pads, and sure enough they were practically brand new so had in fact been replaced shortly before I bought the truck.

So a fellow in the bay next to me helped me try to figure out why this was happening and the best we could come up with is last time it was serviced they didn't install the wheel properly and probably over torqued one side without using star and it made the rotor sit whoppy-jawed. Can't imagine a dealership making a novice mistake like that...but it's easy enough to believe.

So we made sure the rotor was flush against the backing of the wheel (around the bearings) and together made sure the wheel was going on straight...I slowly used a star pattern several times instead of the usual twice or so to slowly seat it all together.

Success! Did a couple test passes and not a sound from the brakes from light or heavy braking. That was about 2 weeks ago.

However, early this week the sound started up again! It is the exact rubbing noise we were getting before and I'm convinced it's the rotor out of alignment again. So I'm looking to the Chevy community here to fill me in on how floating rotors are supposed to stay straight in there and what to do before I have to pay for new rotors!

Man I can write a novel, eh?

[MerF]

[Mr. Wyndham]

I don't know what to tell you, MerF. Are one of the lugnuts or some bolt, somewhere loose?? That could explain why you were able to fix it just to have a problem again later...it would also explain why the issue didn't start to happen until after you got it home.

Check all the bolts that you touched to 'fix' it, and see if any of them are loose...

Other than that...

[The_Stache]

Caliper bolts should not work themselves loose, if they do use locktite or another threadlocker. Rotors are held on by the wheel lug nuts or by a retaining nut (check to make sure one isnt missing).

The best advice i can give is to go get a haynes or chiltons manual, it will show you whats right/wrong.

Oh and if you have ANY abnormal wear on a rotor, replace it.

[MerF]

All the lug nuts where there, and they were all tight enough that the impact didn't just whip them off, it worked to get each one out. Just saying that to emphasize that they were not loose. The caliper also required a breaker bar to get the bolts loose from it, so definitely no problem there.

Not that I'm against owning a Chilton/Haynes (isn't one of them discontinued now?) but I don't think this is going to be something I find in there anyway...the whole thing was too "simple" of a system...I think there's something else I'm missing about floating rotors. Well, I'll throw it on the lift again, maybe take some pics.

[camaro1]

im a chevy tech and i can tell you that the front axleshaft seals are know for a squealing sound on those vehicles

put it all together and if you can, have all 4 tires of the ground then have someone drive it up to 25-35 mph and listen buy the front axles, usually a little spray lube right where the axle meets the seal for the front diff will quiet them up for a while

the front axle seals are actually a seal within a seal and they can make noise

just a thought,, i have seen it before and you would think it is the brakes making the noise

[MerF]

Hmm....that definitely has some merit.

The only thing is that I actually SAW the calipers rubbing the rotor with it lifted and us turning the rotor by hand...it matched perfectly with the wear marks on the rotor.