Inside my Track Pack diff / axle seal replacement

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:

I'm wondering why friction modifier with a Torsen? Trutrack instructions say no modifier (not needed since there aren't any clutches) and no synthetic because it screws up the torque sensing/biasing voodoo that happens.

Are there any directions like that with a Torsen? The trutrack is basically a beefed up Torsen. I've never heard of the whine you speak of.

BruceH said:

I'm wondering why friction modifier with a Torsen? Trutrack instructions say no modifier (not needed since there aren't any clutches) and no synthetic because it screws up the torque sensing/biasing voodoo that happens.

Are there any directions like that with a Torsen? The trutrack is basically a beefed up Torsen. I've never heard of the whine you speak of.

Click to expand...

Pretty sure that Ford specifies synthetic oil for the Torsen, and as far as the friction modifier, I've heard it both ways with the Torsen, that you need it and that you don't.

I figured "better safe than sorry" and put it in

Here's what's listed on the Torsen site in terms of oil:

Can Torsen recommend an oil for my rear axle?
We suggest that you follow what is listed in your vehicle's owners manual. We do require that a GL4/GL5 class oil be used for the Torsen T-1. The T-1 requires an oil with extreme pressure additives for optimal function. Torsen works well in either synthetic or mineral base oils!

I went with Royal Purple which has additive included and didn't use the Ford additive. So far mines as quiet as a field mouse.

OP...did you happen to catch the part number listed on your Track Pack Diff by chance? Just curious

2013DIBGT said:

Here's what's listed on the Torsen site in terms of oil:

Can Torsen recommend an oil for my rear axle?
We suggest that you follow what is listed in your vehicle's owners manual. We do require that a GL4/GL5 class oil be used for the Torsen T-1. The T-1 requires an oil with extreme pressure additives for optimal function. Torsen works well in either synthetic or mineral base oils!

I went with Royal Purple which has additive included and didn't use the Ford additive. So far mines as quiet as a field mouse.

OP...did you happen to catch the part number listed on your Track Pack Diff by chance? Just curious

Click to expand...

I did not ... unless it's visible in one of the pics above, maybe?

2013DIBGT said:

Here's what's listed on the Torsen site in terms of oil:

Can Torsen recommend an oil for my rear axle?
We suggest that you follow what is listed in your vehicle's owners manual. We do require that a GL4/GL5 class oil be used for the Torsen T-1. The T-1 requires an oil with extreme pressure additives for optimal function. Torsen works well in either synthetic or mineral base oils!

I went with Royal Purple which has additive included and didn't use the Ford additive. So far mines as quiet as a field mouse.

OP...did you happen to catch the part number listed on your Track Pack Diff by chance? Just curious

Click to expand...

The track-pack cars come with a Torsen T-2.

No problem..Looks like the T-2 for the Track Pack uses part # (M-4204-T31)

Thanks

2013DIBGT said:

No problem..Looks like the T-2 for the Track Pack uses part # (M-4204-T31)

Thanks

Click to expand...

Not quite. All Boss/GT500/track pack cars with the Torsen use the M-4204-MB. It is a T2, but definitely different than the T31 you mention.

The only rust color I see in any of the pics is from the fluid that was in it. Aside from that, it appears normal.

Gabe said:

Pretty sure that Ford specifies synthetic oil for the Torsen, and as far as the friction modifier, I've heard it both ways with the Torsen, that you need it and that you don't.

I figured "better safe than sorry" and put it in

Click to expand...

I know I read about this in the Boss supplement that I got with my car. It recommended that you use Friction Modifier as well. Page 32 & 33 in case anyone is interested.

http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/12musbs2e.pdf

19COBRA93 said:

Not quite. All Boss/GT500/track pack cars with the Torsen use the M-4204-MB. It is a T2, but definitely different than the T31 you mention.

Click to expand...

I was referring to the GT cars with the Track Pack when I listed the T31 part #. At least that is the Part # I dug up after looking into it further.

I have the M-4204-MB installed in my car.

It sure would have been nice if Torsen added an "MB" to the end of the T-2 to avoid confusion between the different T-2 flavors.

looks fine, my gears looked like that. I believe its stained from the axle grease.

2013DIBGT said:

I was referring to the GT cars with the Track Pack when I listed the T31 part #.

Click to expand...

Even those got the MB. The T31 was never factory installed in a Mustang.

19COBRA93 said:

Even those got the MB. The T31 was never factory installed in a Mustang.

Click to expand...

I'm curious if you work for Ford Racing? If so, I'd be interested in hearing your inside scoop on why there is a T31 option if it didn't come equipped on any of the current Mustang models available and who its supposed to cater to?

What your saying is that the Torsen that came on the Boss Laguna Seca (which is the MB) and was an option on the regular Boss is the same one found in the Track Pack GT's? That's news to me.

I'm seeing X 3 different Torsen options available for purchase, all at different price points:

Ford Racing M-4204-T31 (T-2 w/2.0 Bias & Lowest Cost)
Ford Racing M-4204-T31H (T-2R w/4.0 Bias & More Expensive)
Ford Racing M-4204-MB (T-2 w/2.7 Bias & Most Expensive)

2013DIBGT said:

I'm curious if you work for Ford Racing? If so, I'd be interested in hearing your inside scoop on why there is a T31 option if it didn't come equipped on any of the current Mustang models available and who its supposed to cater to?

What your saying is that the Torsen that came on the Boss Laguna Seca (which is the MB) and was an option on the regular Boss is the same one found in the Track Pack GT's? That's news to me.

I'm seeing X 3 different Torsen options available for purchase, all at different price points:

Ford Racing M-4204-T31 (T-2 w/2.0 Bias & Lowest Cost)
Ford Racing M-4204-T31H (T-2R w/4.0 Bias & More Expensive)
Ford Racing M-4204-MB (T-2 w/2.7 Bias & Most Expensive)

Click to expand...

M-4204-T31 has been out for some time. It was the original, aftermarket Torsen available.
M-4204-T31H is the aftermarket, motorsports/racing version.
M-4204-MB is a revised version of the previous T2 (M-4204-T31). Revised torque-bias and made more durable for Ford OEM use. The original T2 is good, but not known for it's durablitly (more related to drag racing). Given the wide range of customers uses and what kind of car a Mustang is, it was necessary to upgrade the unit for extended durability.

M-4204-MB is what is used on the Boss (base option and LS), GT500 (13-14), and GT track pack (13-14), yes.

I had a seal go bad on my 2013 track pack back at 13,000 miles. Fixed under warranty not sure what fluid and if modifier was used.

TrackpkCoyote13 said:

I had a seal go bad on my 2013 track pack back at 13,000 miles. Fixed under warranty not sure what fluid and if modifier was used.

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And I could've had it done at a dealership.
I used to be a Ford service advisor, so I had my choice of the place I used to work at, or several other places.
But I chose to go to a friend's shop