Rear wheel bearing or rear diff??? - Page 2

icingdeath88 · #16 08-09-2011, 11:05 PM

Quote:

Originally Posted by showoval

I know I'm new here, but did I miss something or is this Nasioc? And I think my thread has been hijacked

This has been going on for a couple weeks. They just both got on each other's nerves and will get over it soon.

But yea, as to your initial question, a roar coming from the back is about a million times more likely to be a wheel bearing or two than the diff. Even if the diff is also bad, a wheel bearing is still likely to be bad.

What I'd do it take it to a shop, and have them drive the car on a lift and use a mechanic's stethoscope to pinpoint where the sound is coming from. Then you can make an informed decision. I would also check if the rear diff has fluid in it or not. If it is leaking fluid, then you should take care of that, but even then, there's still a very good chance it's one or both wheel bearings and not the diff causing the noise.

If you do end up changing the wheel bearings, make sure they remove all the packing grease (brakleen works well) and re-grease them with a synthetic wheel bearing grease (Mobil1 synthetic grease works well) and don't overtorque the axle nut when they put it back together. They sell the Mobil1 grease at auto parts stores, I'd take a tube of it with you to the shop when they change it, so they have no excuse, and you can make sure they actually did change the grease on it. If the grease isn't changed, or they're overtorqued, they go bad again, and very quickly (I'm talking like 5-10k miles).

bwb3 · #17 08-10-2011, 10:22 AM

Quote:

If the grease isn't changed, or they're overtorqued, they go bad again, and very quickly (I'm talking like 5-10k miles).

Yep, 10K and my left rear is roaring again. Not sure where I went wrong. Should the oil seals be changed at the same time? I also heard sonewhere to go ahead and change the axle nut.

Gene

icingdeath88 · #18 08-10-2011, 01:11 PM

Quote:

Originally Posted by bwb3

Yep, 10K and my left rear is roaring again. Not sure where I went wrong. Should the oil seals be changed at the same time? I also heard sonewhere to go ahead and change the axle nut.

Gene

The seals should be changed at the same time. There's an inner and outer seal, and they are pretty cheap from Subaru. Seals that allow grease out or water in, can cause the wheel bearings to die quickly. Axle nuts, should not be re-used because they can no longer be trusted to be torqued correctly (or something along those lines). Plus, they're only like a dollar or 2, so it's not really a biggie.

I have also seen it mentioned on the forums that a knuckle or hub that is out of round can cause wheel bearings to go bad quickly as well. So if it happens repeatedly, even having done everything right, you might have those checked out.

Also, it's worth mentioning that mechanics (even suby dealers) cannot be trusted to do this correctly, and must be told specifically what to do with these. Not necessarily out of laziness, but because most cars aren't so finicky when it comes to wheel bearings.

bwb3 · #19 08-10-2011, 01:27 PM

Thanks for the feedback. I feel that they were cleaned and packed correctly but do remember not changing the seals and axle nut because I didn't think to order them until after everything was apart.
Gene

icingdeath88 · #20 08-10-2011, 01:39 PM

Was an impact gun used to tighten the axle nut? People tend to go "nuts" on axle nuts with those. (Lug nuts too, actually.)

I apologize, that was not funny.

In my case, both wheel bearings were changed at the same time, and then one went bad much more quickly than the other (they didn't change the grease on either of them). I figure it might have been because the guy overtorqued one but not the other or something. Mastro Subaru, here in Tampa, before I knew s***. That's hardly compelling though.

showoval · #21 08-10-2011, 02:07 PM

Thanks for the tips 88, I will definitely pick up some synthetic grease and the axle nuts along with seals I was going to get. I'll make sure to give whatever shop I take to a heads up.

Geoff · #22 08-22-2011, 02:00 PM

Quote:

Originally Posted by icingdeath88

Was an impact gun used to tighten the axle nut? People tend to go "nuts" on axle nuts with those. (Lug nuts too, actually.)

Nope. Hand-tightened.

And the car was run on a lift several months ago to check for bad bearings...none were found at the time. They do tend to go bad, though.