Obligatory 'Strange Noise' Topic, Caliper's Locked Up? Options

[senick]

Well, I have a 95 AT200 w/AT. Lately (for the past month) I've been hearing a noise from underneath. It's on and off, and mostly there's no noise. But when it happens, it's at low speeds, and it sounds like metal on metal contact, like the brakes are rubbing (which is what it could be). My theory is that it might be the exhaust, as I've already had some ghetto welding done on it, but I think the cat's breaking from the inside out, and the metal shavings burning on the inside are what's making the noise, which would explain the intermittent nature of the noise and why I usually only hear it at low speed. Does that sound reasonable?
As far as symptoms, she's driving like a top, aside from some rough idling at times. Shifts are great, no misfiring, oil and trans fluid are fine, engine temp good. I just had the passenger side CV axle replaced, and I know the sound isn't coming from the driver's side.
I know this is a pretty poor explanation of the problem, but if it happens again I'll try to record it and then you guys can hear it. But meantime, do you think it could be the exhaust?

Edit: The noise seems to amplify when I hit a sharp incline, or roll through a low spot in a parking lot, so that the front of the car is higher than the back.

This post has been edited by senick: Oct 6, 2011 - 10:10 AM

[rave2n]

Could be the cat...

Could also be the hub bearing. I'd check both.

[richee3]

What sort of noise is it? Metal on metal grinding, tapping, screeching, creaking?

[senick]

Well, it sounds like metal on metal, and has a harmonic frequency to it. What would the hub bearing sound like? It's not a screech or a creak, but there is some tapping to it. If I had to say, it's more like grinding.
So, I've yet to hear the noise if I'm in park and hit the accelerator, but I do hear it occasionally while idling (which makes me think it's exhaust). If I'm in park and turn the wheels there's no noise.

[senick]

I'll try to get a recording of it, but the last time I tried it wouldn't make the noise. Like I said, it's off and on, and more off than not. I actually took it in to a shop and they told me everything looks good, but I'm not sure if they checked the bearings or not...

[dudeofchaos]

Hard to tell when you don't hear it. Coming from the front or rear? I had a noise comming from the rear and it only happened when the car was shaking or whatever. It happened to be a muffler support that was shaking againsts something else.

[rave2n]

I'll try to get a recording of it, but the last time I tried it wouldn't make the noise. Like I said, it's off and on, and more off than not. I actually took it in to a shop and they told me everything looks good, but I'm not sure if they checked the bearings or not...

Yea I had a bearing that would only make noise at 40-50 mph, and worse when making turns at speed. Crunching, grinding sound.

Young enough back then I just turned the 15' up to ignore until the bearing literally broke into charred black pieces, and my wheel wouldn't turn...was interesting =P

[senick]

Well, after listening to a good number of sound bytes and asking around I'm almost positive it's a wheel bearing. I think I can get away with just the bearing and not the whole mount. Are these things easy to replace? I have all the equipment I'd need at work including a lift, which will be nice. Plus people who know what they're doing more than myself.

[rave2n]

Well, after listening to a good number of sound bytes and asking around I'm almost positive it's a wheel bearing. I think I can get away with just the bearing and not the whole mount. Are these things easy to replace? I have all the equipment I'd need at work including a lift, which will be nice. Plus people who know what they're doing more than myself.

The bearing itself is cheap, dealer or autozone.

Can't do it yourself, unless you have a press. You can take it to a local shop and they can press it in, but you will need to remove your hub and bring it to them.

Think its like 40-50 bucks to do it.

[senick]

So I'd need a press for sure? Can anyone second that? The guy I work with works on his tC and thought the bearing would be fairly simple to change. Damn 163k suspension going bad on me...

[rave2n]

No need for a second...

I'm sure.

[senick]

All right, I'll take your word for it. Thanks for your help too, I appreciate it.

[senick]

You know what though, I'm second guessing it being the wheel bearing. I don't hear anything at high speeds, usually only under 20mph. I'll have to put it on the lift and give a good check next time I work.

[rave2n]

You know what though, I'm second guessing it being the wheel bearing. I don't hear anything at high speeds, usually only under 20mph. I'll have to put it on the lift and give a good check next time I work.

Good idea. When its lifted, grab the wheel and see if you can shake it back and fourth. If it sits solid and doesn't move, bearing is good. Otherwise, any play. Bad bearing.

Edit: You may not hear it at high speed due to road noise. Try going under a tunnel, or getting close to a wall and giving a good listen.

This post has been edited by rave2n: Sep 28, 2011 - 12:04 PM

[richee3]

You don't need a press. I did it with nothing more than basic tools and quite a bit of Gojo. All I had to do was hammer the old bearing out then use what was left of it (the bearing disintegrated inside the hub, hence my fearlessness with a hammer) to tap the new bearing in. It's easier to have a shop do it but it can definitely be done yourself if you aren't afraid to get dirty.

I agree with rave, drive under some tunnels or something to see if you can still hear it. Like I said, there was nothing left of my wheel bearing. I opened the hub and all the balls fell out immediately but I didn't have any play at all.

This post has been edited by richee3: Oct 2, 2011 - 12:20 PM

[rave2n]

You don't need a press. I did nonentity nothing more than basic tools and quite a bit of Gojo. All I had to do was hammer the old bearing out then use what was left of it (the bearing disintegrated inside the hub, hence my fearlessness with a hammer) to tap the new bearing in. It's easier to have a shop do it but it can definitely be done yourself if you aren't afraid to get dirty.

Heh, good to know...I want my money back from those shops..

[senick]

Well, after a weekend of traveling on the highway I'm pretty confident it's actually not the bearing. I heard nothing like it all the way for 6+ hours at 60+mph. What I did hear though, after a while of driving, was a medium-high pitched whine when accelerating, but only into about 3rd gear, then it stopped. Not sure what that was, but it doesn't do it at non-highway speeds (alternator maybe?). Then I took it into work, put it on the lift and there was no play in the wheel, and it spins without making any excessive noise. What I'm thinking now is it's the breaks. I noticed when I had it lifted that even with the engine on and in drive, the passenger front wheel doesn't spin completely freely, like the caliper is a little seized up. What I want to do now is switch out that caliper and see what happens. It's also altering the pressure of the other caliper and cylinders in back and wearing down the breaks excessively. I'd also like to bleed the lines, but I've never done that before and don't know if it's complicated or not. Is it likely just changing the caliper would fix the problem?

[stephen_lee]

if one caliper is dragging the wheel will get considerably hotter than the others.

[richee3]

Metal on metal with a harmonic frequency sounds about right for a dragging caliper. It would be worn brake pads.