Had a leaking left rear axle seal replaced yesterday at a buddy's shop, and took a bunch of pics.

The car does have the (what's thought to be) typical Torsen highway whine, and when we took the cover off and looked at the gears, the large ring gear seemed to look a bit "off" to me ... parts of it looked rusty?? Please see the pics below and let me know what you think.

I'm thinking I'll eventually switch to 4.10's, but most likely not after the T56 goes in, which won't be real soon, hoping by the winter / over the winter.

Now, the original Ford fluid was drained out at 10k miles and replaced with custom-blended Quantum Blue / BND Automotive fluid, with the friction modifier built right in. This fluid was supposedly good for 35-40k miles.
The new Amsoil is said to be good for 100k miles


So, here are the pics:


Cover just removed:











Center pin and metal block removed:






This is the pic that I saw spots on the ring gear on the teeth where it looked like rust:




The new parts:
(the axle seal is crossed out since it was the wrong one, it was too small, the shop had a proper new piece)




Old axle seal:






Old bearing:




New bearing installed (don't have a pic of the new seal):




Back together:

 

Subscribe. As a fellow track pack owner, I would like to know more about how these are "supposed" to wear as well.

 

I had a similar problem with my 12 GTCS without track pack. I was getting lots of noise coming from rear.
Dealer opened up the diff cover and there was a lot of what they call "Pitting" on the bearings and races. I don't know how a wet sump oiled diff can become pitted or corroded without moisture(Water) inside.