Bad rear axle bearing?

[Mctwist77]

I have a noise coming from the rear of the car, the noise is present when I'm going stright. However, if I turn to the left the noise seems to go away. It's not the typical wheel bearing noise. It's like a soft metallic grinding noise, it almost sounds like wind. When I put the car in neutral the noise remains the same. Any ideas?

96, cobra

 

[me32]

How many miles on the car?

 

[Mctwist77]

37k, but it has seen a lot of track days. It has the upgraded clutch packs. It is possible the noise is coming from the clutch packs? They have about 30k on them.

 

[me32]

37k, but it has seen a lot of track days. It has the upgraded clutch packs. It is possible the noise is coming from the clutch packs? They have about 30k on them.

If it uses the same clutch packs as the 03-04 cobra and 07-14 gt500 they have been know to make nosie but normally when turning not going straight. Are you sure its in the rear and not the front hubs? I had to replace my front hubs on my gt500 at 38k. Both were shot.

 

[Coz]

Check both sides of each of your brake rotors to rule out that there is no grinding from rubbing on a caliper or other hardware

 

[Mctwist77]

Will do. Also, if I apply the brakes the noise remains the same. I spoke to the previous owner, the rear axle wheel bearings have not been changed. It's weird because the noise changes if I turn to the left. Any thoughts on what it could be besides the bearings? Its definitely from the rear. It is possible that axle bearings could make that light grinding noise?

 

[Coz]

No idea. If you can put it on a lift or on jack stands and put it in gear, it may help you isolate where it's coming from.

Of course, not having a load on the axle may affect whether it even makes a sound while up in the air.

 

[Mctwist77]

What types of noises do bad carrier or pinion bearings make?

 

[Digthemup]

What types of noises do bad carrier or pinion bearings make?

Bad pinion bearing will make noise on deceleration some what like a bad U joint regardless of speed or angle.
A carrier bearing would be more like a hub bearing making a rumbling noise at speed over 25ish MPH and will change when turning. Regardless, if it is a bearing, given time it will get louder making it easier to locate.

 

[VA-Mach1]

I don't know how much this will relate but I'll try. On my 02 Explorer with IRS I had a bad wheel bearing. It would whine going straight, would whine more going left, and almost not whine at all going right. After new bearings all was well.

 

[Mctwist77]

Ok, thanks for all the info. I'll do some troubleshooting this weekend.

 

[Digthemup]

I don't know how much this will relate but I'll try. On my 02 Explorer with IRS I had a bad wheel bearing. It would whine going straight, would whine more going left, and almost not whine at all going right. After new bearings all was well.

That because you had a rear driver side bad hub bearing, and I am sure it got real loud at over 40ishmph.

 

[Digthemup]

BTW, a real bad pinion bearing would kill your seal, and you would have a leak all over your dif. at that point redo the whole thing, and maybe do your gear change if you been thinking bout it.

 

[Mctwist77]

Based on the fact that the noise is the same when the brakes are applied, can we rule out a brake issue?

 

[Mctwist77]

Also, I have an aluminum driveshaft

 

[Digthemup]

Based on the fact that the noise is the same when the brakes are applied, can we rule out a brake issue?

Brake noise you can rule out by just having someone walk the car with you, or put it on your lift to pin it. Granted, it will unload the wheels, but if caliper hanging, you will know. Just did a hub bearing assembly on my son's car, and the pads were not sliding like I like them, which was quick fix after clean and filed to size . Most my Stangs have aluminum driveshafts, except my wife's '65 with no issues.

 

[Mctwist77]

Jacked the car up and did some tests. I can't hear anything abnormal. There is a slight brake pad/rotor noise. I took the brake assembly apart and put grease everywhere. Haven't driven the car yet but I don't think that will fix my noise. Brake noise would go away once the brakes are applied, right?

Also, I did the test of pushing and pulling at the 3 and 9 o'clock and the 12 and 6 o'clock, there was a very very small amount of play if any. If I pull on the axle straight out it comes less than 1/16th of am inch.

 

[Digthemup]

took the brake assembly apart and put grease everywhere. Haven't driven the car yet but I don't think that will fix my noise. Brake noise would go away once the brakes are applied, right?

Also, I did the test of pushing and pulling at the 3 and 9 o'clock and the 12 and 6 o'clock, there was a very very small amount of play if any. If I pull on the axle straight out it comes less than 1/16th of am inch.

All the play seems well within specs, and brake noise will go away when brakes on. Careful of where you put grease on any brakes. It should be put on pins and very little on pad slides. Use only high temp brake grease.
You did say that the noise is still there when in neutral, but you didn't say if you were stopped.

 

[Mctwist77]

Yes, the noise is the same if I am in neutral. The noise gets a little quieter when I turn left, but I can still hear it. I'm kinda thinking it's the carrier bearings.

 

[Digthemup]

OK, when you are in neutral, are you rolling or are you stopped??
If you are stopped, it can't be anything related to your axles.
How old is your clutch? do you power shift alot?