Trios

I have a 2003 with about 132k on the clock. For about the last 20k, I've been noticing a hum/whine that sounds like it's coming from the rear end; it's definitely speed related and not engine related, as the pitch increases with velocity. You'll notice it at about 15-20MPH and it gets louder as well as higher-pitched with more speed.

I've also noticed that it gets quieter or even goes away during a soft left turn, and gets louder during a right turn. It doesn't change under acceleration or coasting, always the same hum. There doesn't seem to be any added drag, I can still coast as far and as fast as I remember from before I noticed the whine.

Any suggestions on where I should begin?

EDIT: Forgot to mention I changed the fluids in the rear end and trans about 40k ago, and during my last oil change (maybe 5k?) I checked the levels thinking the whine was a low fluid level somehow. Nope, fluids full up.

rrwirsi

I have had no similiar problems with my C5 but on my 72 that I used to have I had the identical problem. Thought the worse. But it was the tires. Changed them and nothing buy slience.

73Corvette

Just curious what fluid did you use?

Trios

Royal Purple. I don't have the bottles anymore to say exactly what I got, but I made sure to get the right stuff.

89vert

I would start by checking the right rear wheel bearing.

corvette77

Which tires do you have? How much tread is left? Once they get down to needing replaced, they can get pretty loud.

Barndog Buddha

You can check tires by switching the right rear with the left rear yes I know they are directional but if it is the tires the whine will be different. If not look into wheel bearings.

Trios

Sorry to burst bubbles, but it's not the tires - it does it on my winter & my summer set.

Right rear wheel bearing, now there's a thought. This is the push top-and-bottom with the rear jacked up check, right?

89vert

Look for play in the wheel bearing top/bottom front/rear. Bearings will make a lot of noise before they get loose though.

The reason I'm thinking it is a bearing is because it changes sound when you load them differently. If it were gears or bearings in the diff the noise would not change when turning left or right.

Ask me how I know.

Trios

Alright, if the bearing isn't loose how do I determine that's it?

Time to search for bearing replacement how-tos...

kabluie

Sometimes you can just grab the top of the tire and see if it moves. If it does, then it's likely the wheel bearing. I realize that there is not much room to grab the wheel, but if I were in your shoes, I would try it anyway.

Trios

Alright, so I jacked up the rear end of the car. The right rear wheel has zero play whatsoever. The left year wheel has just the tiniest bit of wobble, both side to side and up/down. It'll wobble about the width of a credit card. Both wheels spin very freely and neither one feels like there's any bearing resistance.

My rotors are a bit corroded from the car having sat outside for the last 8 months; they seem to grab the caliper/pad just the tiniest bit as the wheels spin (a slight metal-sliding-on-metal sound that occurs once per revolution). I put the car in gear and let the wheels freewheel a bit, but I couldn't hear the whining sound without the weight on the wheels or else it's just not nearly as audible outside the car as inside (or the wheels weren't turning fast enough).

I also checked the wheels to see if either one is warmer after a freeway drive, knowing that at least on trailers a bad bearing will overheat the hub and then the wheel, but both wheels were just a tiny bit warmer than ambient, neither was anywhere near 'hot.'

I'm stumped.

c5z06.O

I bet it's the rear. Had the same problem. I ended up changing the slave clutch diff gears. Might as well get all that and more done while it's off.

Trios

Just a bit of an update. I've realized that it takes about a mile for the whine to start; it isn't immediate, so it seems like something has to warm up before the whining happens.

It hasn't gotten any worse despite being daily driven for a few weeks.

Is the small amount of play in the rear left wheel my indicator that I should replace that bearing? I was told earlier that it would be right rear if the whine went away turning left, but as I think about it, turning left puts more weight on the right wheels.

Can someone idiot check me here before I go about replacing parts? The noise is driving me nuts.

Trios

Ok. It was the driver's rear wheel bearing. I decided to just throw parts at it until it was fixed, and thankfully the first try was the trick.