Lookin4knowledge

So my sister bought a 2003 by Mustang that sounds like it has had some work done to it maybe a cam I am not sure but I have been replacing whatever it needs slowly and it came around time for the wheel bearings to be replaced. I had never done it before so I watched a couple videos and three days later after the slide hammer showed up from Amazon I was finished, I did both rear wheel bearings and the axle seals as well. First mile no problem she felt good and smooth as butter, I took a corner and straightened it back out and all of a sudden a loud clicking sound going forward or backwards so I got it back figured out I stupidly forgot to put the right amount of oil back in and went on another ride....got about two miles and a horrible grinding noise for 2 seconds then it smoothed back out and now its just making this mechanical whirring sound. Took the cover off and found this....please help, what do I do next and what tools will I need?? I made hoping I can at worst just have to replace the pinion gear I dont know much about rear differentials but what overhead so far I am super intrigued. Any pointers will be appreciated listed......my sister is not happy to say the least. Lmao

houtex

Welcome to the forums!

I was going to mention friction modifier missing would do some fun noises, but seeing those gouges in the cover?

You need to find that piece what made those marks. That's definitely not right, that shouldn't ever be a thing in there. And the problem is that piece may have somehow wound up in the tubes. You're gonna have to pull the axles and inspect everything, spin the ring and pinion, maybe even disassemble it (take notes and pictures, it goes back together pretty good) and find whatever in the heck made those gouges. It may even be that you have to take the entire axle housing out to tilt it and get the piece outta the tubes... or maybe a magnet will get it if you're lucky... even a scope to send down and inspect might be in order...

Doing all this stuff be seen on many videos, but you don't need to take the pinion out, just the differential and the ring gear. Pinion can be left in the housing, it won't be your problem... unless the teeth are chewed up. And if there's damage to any of it in there, you might just wanna go find a different entire axle, maybe. That'd be more your call.

If everything passes inspection, and everything's clean, put everything back as you found it when you put it back together, and it'll be fine. Loctite (blue or orange) all the fasteners. TORQUE PROPERLY.

I know that's not the answer you want, but it's the right answer. Find. That. Piece.

As I don't know your expertise (as I sure haven't done an axle yet, I just know about what's involved) here's a good video from CJ Pony that'll help:

And I do hope that helps ya out. Good luck!