I think I have developed a bad or worn on axle bearing on the passenger side. I get a lot of high pitch noise especially around 45-55 mph. Now my question is if the bearings were in fact bad would they still make noises after taking my foot off the gas from like 55mph? Like I guess I could of been more direct and ask do bad axle bearings make noises all the time? My noises seem to go almost completely away when I lay off the pedal from a cruising speed. Also sometimes taking off from a stop I feel like there is some slack before it starts going on the same side that is bad too.

Thanks for any input in advance as always.

That sounds more like something in the center than an axle bearing. Axle bearings carry wieght all the time and usually if they make noise it will be growling or rubbing noises. A whining high pitch noise is more typical of worn pinion or carrier bearings. It can be some noise from the gear set, but usually from my expierience, I'm going to suggest that it's probably the bearings.

It's hard to diagnose for a few reasons. One is obvious, you have to be going 45mph. The other is, most of the time there won't be anything really out of the ordinary that you can really observe from the outside of the rear end. If it's something you want to address, you will need to disassemble the differential and have yourself a look. Again, if it's just whining, there may not be enough damage to put your finger on it.

During assembly, the bearing are setup with preload. This is to keep them quiet. As the bearings wear over time, the preload is reduced and you can get noise. I already know your next question. Can't you just preload the bearings a bit more and get rid of the noise? Maybe, but in the real world, if you're going to take everything apart, you would be foolish to put it all back together without replacing all the bearings. They sell kits to do the job with all the bearings, seals and a few other special parts you will need. My guess is around $150, but that's a guess.

It also takes a few special tools that you need to get your hands on. It's not rocket science, but they are different animals to work on.

So your suggesting maybe the carrier bearings could be the culprit? That have anything do with the slight slack feeling I get right before my car gets moving from a stop? Also why do the noises I am hearing go away with my foot off the throttle? Why wouldn't it be making noise all the time if everything is still in motion? Either way it looks like I am going to have to take the diff cover off and inspect...any chances just changing the fluid will cure my problem?

The noise changes when the load changes. Drive and coast are loading the bearings and gearset differently. The last one I was chasing turned out to be Pinion bearings. I found that out after I changed the carrier bearings and it still made the same noise.

The slack that you're feeling is probably not a bearing. I have seen the small gears inside the carrier break and it will cause slack, because that's what the axles spline into. If you pull the cover, look at those. Also, a sloppy U joint can create slack, but when they get really bad you get virbrations.

I doubt changing the fluid will do anything for you. It's kind of like changing the oil on an engine that is already knocking. Sometimes that can help if the posi clutches chatter going around turns, but not much good for noise. Either way, if you pull the cover you're going to replace the fluid.

My 02 Z started making noies in the right rear at about 110,000 mikes. There was nothing consistant about the noise and sometimes it would dissappear for weeks. It usually was more noticable at 70 mph or so. When I pulled the cover everything looked good until I pulled the clips and backed the axles out a little. The right axle was obviously worn and rough where the bearing rides. I got a new bearing and seal at the dealer but they wanted $350 for an axle. I ordered one from Summit racing for $87.50. It wasn't in their catalog because all they listed were complete sets but I called and told them what I needed and they had it. I was back on the road for less than $150 and have put another 30,000 since then. People said I needed to do both sides but I had the same thing happen on my 97 Suburban at 110,000 miles, I replaced only the right side and I have put another 300,000 miles on it since then. Why the right went out at 110,000 and the left has 430,000 miles on it is a mystery to me.

I have a 96 Astro Van and I started getting a axle whine at 110,000. I've been driving it like that and now it has 135,000. The sound hasn't changed much, it's just annoying to hear.

Warren

lol wow Cap'n you have 430,000 miles on your 02 Z28? I need to start taking some road trips around the world once I get this problem fixed. Thanks everyone for the info. As soon as the weather gets better here in Florida I am going to pull the cover off.

No, I have 140,000 miles on the 02 Z28. I have 430,000 on my 97 Suburban that I purchased new. I bought a new truck in 07 and that has 82,000 miles on it.The week before last I put 2500 miles on the truck and 2400 on the Harley.

I have close to the same problem on my '95. When I am at a constant throttle, I get a whine, and when I let off it whines but not as loud. I chalked it up to the "typical" gear noise from these cars, but I have been paying more attention to it, and I have noticed that when I have extra weight (passengers, cargo, etc..), the noise is louder. I have also noticed a slight gear oil smell coming from the axles, but there is no visible leak. I am going to pull the axles out to see if the seals are bad, but what should I look for if the bearings or axles are bad? Are there any measurements that I can take off of the axle to give me an I dea of whether or not it will do any good to replace bearings? Also, is it typical of the bearings to make that noise?
Thanks in advance!

Does anyone have any ideas?

the surface of the axle where it rides in the bearing should be smooth(and probably have a polished look to that area).Any pitting points to axle and bearing replacement.
To the original poster,is the noise/whine,at 50,in time(synchronized) with axle rotation,or is it more frequent then that?A noise/whine in time with axle/wheel/tire rotation indicates carrier bearing.A noise/whine more frequent then that indicates pinion bearing.

Thanks for the reply! Out of curiousity, what can I look for in the pinion and carrier bearings as well? I'm going to check the axles, and at the very least I figure that it will need new seals. But while I have it apart, I just want to check the carrier and pinion bearings as well. The last time I changed the fluid, I didn't notice any irregular wear on the ring and pinion, and I didn't see any chunks of anything in the fluid, that's why I amd asking what to look for. Thanks again for the help.

Well, I'm about to do my axle bearings, and I picked up the Timken "kit" that is supposed to put the bearing on an unworn path on the axle. I must say that these are a cool setup. The bearing and seal are all one unit, so you pull the old stuff out, but the new in, and you don't have to mess with bearings, races, and seals. I'm kind of excited to put these in and see if it gets rid of my axle whine.
Now only if it would quit raining....

Hairbear, good luck with the "kit". If it works, that will sure be cheaper than an axle along with bearings and seals.

Update on my stuff, had right rear wheel bearing go out on 4WD Suburban at about 100K miles, same on my 02 Z28. OK, so now I took my 07 4WD Silverado to Bristol for the races this past weekend (1800 mile round trip) and What the crap!. Is that a wheel bearing I hear? At 101K miles on a 2 year old truck? This is bizarre since I don't know anybody that has replaced a wheel bearing and axle. I know more than 1 guy with carrier bearing issues but just the RIGHT wheel bearing?
All three of these vehicles have limited slip which may play a part as to which one goes out, but why at 100K miles? Built in feature? Am I only making left turns or only driving on the sloped-to-the right side of the road?
I would try to have a conversation with Chevy about this (I just bought a new Malibu so thats 4 Chevys in the driveway) but I'm sure they will not be
real informative after I tell them that I have 35 inch tires on it.
I don't have a free weekend for a month or so but I guess I will be pulling it down to check soon. I think I know what to expect.

I'm not sure about it being common, but I did find out that this bearing (part number) has been in use since around 1970. I'm thinking lower quality materials more than anything though. You have to love a U.S. vehicle with Made in Mexico all over it, with parts that say made in China. It disturbs me greatly. Not only that, the bearings are VERY common for GM vehicles, but I still had to order the bearings, rear cover gasket, and the intake gaskets. It seems that retailers aren't holding as much inventory either.
But I digress....