98 Camaro v6 base. Was working on the rear brakes the other day. Finished tightening down the caliper and gave the hub a spin. That's when I heard it... Inside the axle, almost exactly between the hub and the pumpkin on the passenger side, is what sounds like fine sandpaper rubbing when you turn the wheel... There is no effect as to performance, and it is far from un-drivable. But I have noticed a quiet sandpaper sound when driving slower with the windows down (that it might be the brakes, which is one of the reasons I was working on the brakes to begin with...).

Is there anything I can do to slow down whatever wear is going on? What I mean is, looking at other forums, others INSIST that GM says you never need to change differential fluid in those axles. But the car is getting old. Isn't it possible that I need to do maintenance on the rear end so new fluid can circulate to the area I hear rubbing...? The rear end has never actively leaked during the 4 years I have had it, but there are signs it may have leaked a little in the past.

I think I should take it apart and clean, regrease, then refill the axle. But from what I understand it is a stinking, messy job - so I don't want to do it if it is a lost cause... Does the fluid even reach the area where I described the noise? Thank You in advance for your advice.

 

I do not know what forums are saying you're not supposed to change the diff fluid, but it is a regular maintenance item. Replacing the gear oil is not that bad of a job. 10 bolts, a few minutes of letting the oil fluid drain (run the car beforehand, makes it quicker), wipe the inside down, clean the magnet, clean mating surfaces of both the housing the and the cover, put a new gasket on, tighten cover, and refill with fluid. Fill hole is on the passenger side of the axle. Use a 3/8 ratchet to remove it. Fill till it starts to drip and tighten down fill nut.

Gear oil circulates through out the axle and lubes the wheel bearings. I would try and pin point exactly where the noise is coming from

 

Step one, remove cover and look for metal on the magnet. I you find metal shanving you could cut yourself on or if the oil looks like metal flake paint the rear is spent. If it has a small amount of metal it could just be normal wear. It could last another 100K miles.

Nice thing about rears is they tend to complain alot before they go. If it a bearing it will just continue to get loader. If it is a gear it could run like that for a long time.

New gasket and oil change either way. If you are on a budget just find a used whole rear axle and swap it in.

 

Sounds like you need new axel bearings. You can do it yourself pretty cheap. Get the SKF bearing kit as it also comes with seals. Don't drive the car too much with bad bearings.

 

Thanks for the info. At this point, as Gorn stated, it is more at the complaining stage than the going-out stage. I am going to do the maintenance on it. By the way, it was in ls1tech.com where there was a kind of heated discussion on the differential. I got tired of it so kept looking - and found my way here.

Its about to be winter here, so will be parking it in a month or two (worse car ever in the snow imo, lol). So will see if the fluid change makes a difference. If not, will come up with a plan over winter. Am about to go gather supplies and do the job. Will hopefully post this afternoon/evening how it went. I have a suspicion there was a leak in the past...maybe a previous owner...

Thanks again for the suggestions!

 

If you're going to be changing the diff oil remember to get the additive from the dealer.

 

You'll know if it's bad as soon as you take off the filling bolt with your ratchet because it will stink to high heaven. I park mine in the winter too because the salt here would ruin the car in 2 years. Make sure when you remove the pumpkin that when the fluid is drained, you check the magnet on the inside of the cover. If there's a lot of metal filings or chunks it's not a good sign. Spray it and clean it our well with brake cleaner. Be generous and use 2 cans if you have to. Let it dry fully. While you wait for it to dry, scrape off the old gasket and get the area ready for the new gasket. Once the pumpkin is back on with the new gasket you can refill the fluid. I personally suggest you mix the gear oil and additive together before filling it in your pumpkin. This will assure a proper mix.


A few notes:
1. Some people have put sawdust in the pumpkin when the gears were grinding or failing to stop the noise. If you see this, then it's a really bad sign.
2. After driving around a few days check for leaks. If you have a leak then you need to change the pinion seal.
3. With the rear wheels on axel stands or a hoist check for play back and forth up and down. If there's play you need axel bearings.
4. Check your U-joints! Rule of thumb is when you change your gear oil, check your U-joints!

 

Winter tires make all the difference! I drove my car through one and half PA winters. The first one I had no snow tires. The second winter I bought a set for the rear and it was night and day on traction.



He only needs the additive if he has a limited slip. Many gear oils already come with the additive pre-mixed in the bottle. I used Lucas with the additive already mixed when I first changed mine and that was over a year ago and my rear works as it should. It is a user choice though.

 

Done. By FAR the worst part was scraping off the old gasket... Definite signs that it had leaked in the past. I took the plug out and checked the level first and couldn't reach any with my pinky so was definitely low - at least some still came out when I opened the pumpkin. All looked fine inside. A bit of silver sludge around the magnet but nothing excessive and no big pieces. I put the jack stands under the body so the axle would hang as much as possible giving room to add the gear oil right out of the bottle. I did not put in the additive because I am positive I do not have limited slip; however, the Valvoline gear oil I used said "Limited Slip" on the bottle in one place with no additional language (so the wording didn't actually say anything like you didn't still need the additive), so I don't know. Doesn't really matter. Drove it around a bit and didn't hear the sandpaper sound yet. Will give it a few days to circulate and will jack it back up and look for the sound again.

Yeah, I just put a full set of BF Goodrich Traction T/A's on (I have the 55's option tires so the options are REALLY limited). HOPING winter driving will be a little better. I'm in northern MN and it freezes hard here and they have really cut back on sand/salt on the roads in these small towns, so the roads are just sheets of ice for months and that car is all over the place. SGS or not, it's not a car made for ice

Thanks all for the input, I will update if there are any changes, but I think all is good for now.

 

When you get the chance, jack up the rear again and spin the tires while in neutral, if they spin the same way, you got limited slip. If they spin opposite, you're open, which is most likely what you have. Also, that bottle has the additive in it.

Nothing is good on ice. But all season tires are nothing compared to winter specific tires. Winter tires use a softer tread and bite better through snow and ice, especially with studs.