Roaring noise from rear end

[SmileForTheRearView]

I have searched and searched the forums and haven’t found anything.
At 40 to 60 the noise isn’t that noticeable (thanks to exhaust) but if I let off throttle it’s very much noticeable. Sounds like a growling/roaring and I’m thinking a bad bearing in the differential based on this video


I changed out my rear passenger wheel bearing/hub and had an alignment done after and the noise is still there. I even changed out the rear wheels to see if it could possibly be a bent rim.

Any and all insight appreciated!

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[Some Random Guy]

Coast side noise suggests pinion bearing issue. Bad preload or just defect causing bearing failure.
Edit: more specifically, I’ve had coast side noise at speed twice and it turned out to be insufficient pinion preload. But that was not on a Ford diff, so I’m not sure if my experience translates. The pinion is likely the problem though.
How many miles are on your ring/pinion?

 

[SmileForTheRearView]

Coast side noise suggests pinion bearing issue. Bad preload or just defect causing bearing failure.
Edit: more specifically, I’ve had coast side noise at speed twice and it turned out to be insufficient pinion preload. But that was not on a Ford diff, so I’m not sure if my experience translates. The pinion is likely the problem though.
How many miles are on your ring/pinion?

56K as far as I’m aware. Bought used with 40K miles.

 

[Cobra Jet]

Did you change out only 1 rear hub assembly or both? It could be possible if only changing 1, that the other was also bad.

However, if the finding is it's not the other hub assembly, then most likely it's rear pinion bearing failure - which is the source of the "growl" that will increase/decrease with not only MPH, but load on the rear diff.

 

[Some Random Guy]

56K as far as I’m aware. Bought used with 40K miles.

Ok, have you brought it to a dealer or are you trying to get an idea of what it is first?
Driveshaft or IRS mods may complicate a warranty claim. Obviously if someone regeared it before you that would also be a complication.
Good luck, but hopefully the actual repair is straightforward. Some dealers just swap the whole diff to avoid dealing with R&P setup.
Or I’m wrong and it’s something else, lol.

 

[SmileForTheRearView]

Did you change out only 1 rear hub assembly or both? It could be possible if only changing 1, that the other was also bad.

However, if the finding is it's not the other hub assembly, then most likely it's rear pinion bearing failure - which is the source of the "growl" that will increase/decrease with not only MPH, but load on the rear diff.

Only changed the rear passenger because that seemed to be where the noise was coming from.

I’m thinking it’s ring and pinion failure now too. Really not looking forward to that repair bill.

 

[SmileForTheRearView]

Ok, have you brought it to a dealer or are you trying to get an idea of what it is first?
Driveshaft or IRS mods may complicate a warranty claim. Obviously if someone regeared it before you that would also be a complication.
Good luck, but hopefully the actual repair is straightforward. Some dealers just swap the whole diff to avoid dealing with R&P setup.
Or I’m wrong and it’s something else, lol.

yeah the shop I called said it would be 1200 just for the labor and weren’t sure on how much the parts would be.

 

[Some Random Guy]

yeah the shop I called said it would be 1200 just for the labor and weren’t sure on how much the parts would be.

I’m guessing around $200 for a rebuild kit, maybe less if they’re confident it’s only a pinion rebuild. If the failure has caused a bad wear pattern in the R&P, that will be more. I’m not familiar with prices for this diff.
Labor sounds about right based on my experience, but I do my own now because the mechanics around me suck. They messed up multiple setups for me and denied responsibility.

 

[K4fxd]

I’m thinking it’s ring and pinion failure now too.

Doesn't take long for a bad pinion bearing to wipe out the R&P

 

[SilverUri]

yeah the shop I called said it would be 1200 just for the labor and weren’t sure on how much the parts would be.

Hi, any update what was the reason and how did you deal with it?

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