Need some help diff swap/axle issue

[Lilith5.0]

so I’m going from 3.73 to a 3.31 rear supposedly out of an ecoboost for my gt but it’s a iron diff and supposedly was for a manual but had an auto flange anyways.

I have the dss 2k axles they are in the same position as I had them in the 3.73 rear. Driver side went together no issues.

I went to install the passenger side and the diameter was too thick, it was too thick for the torsen diff but I was able to hammer it in anyways. So I sent it back they put on a different stub it slid in further but then just stopped and i damn near knocked the car off the stands trying to get it in. After sending it back again and them putting a new c clip still no go.

So I pulled it out and noticed where the axle seats in the carrier are different than the torsen diff. There is what looks like a bar going through this rearend where the on the torsen is a metal coupler thing pics to show the difference between them. And a pic showing that where it’s stuck at.

Do i have to flip the axles or does this rear just not work with a gt passenger axle. I never fully removed driver axle just slid out enough to pull the rear so I know i didn’t get them turned around during the swap but wasn’t sure if u have to flip them or something weird.

My cars been down for months between getting a broken rear first, getting another then trying to figure out why the passenger side won’t go back together so tia for any help.

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[Mikepol2]

On my PP1 with the Torsen, you could see straight through the differential when the axles were pulled...not sure why there's something in there on yours.

 

[Lilith5.0]

On my PP1 with the Torsen, you could see straight through the differential when the axles were pulled...not sure why there's something in there on yours.

Mines a 17 Idk if maybe a model year difference? Same pp1

 

[Cobra Jet]

Have you removed the rear cover to make sure there isn’t anything broken inside of it?

I’m all not sure what that piece of metal is seen in your one pic, that does not appear to be “normal”.

Where or who did you purchase that rear diff from?

This thread may help:
https://www.mustang6g.com/forums/threads/swapping-rear-end-gears-on-a-pp.11162/

Or this one:
https://www.mustang6g.com/forums/threads/3-73-to-3-31-or-3-15-swap.119318/#post-2498556


TIP:
- If the rear diff has Trac-loc guts, you won't be able to see through it with axles removed. There will be a "bar" in the hole which is for the spider gears.

- If the rear diff has Torsen guts, you'll be able to see through it with axles removed.

 

[Lilith5.0]

Have you removed the rear cover to make sure there isn’t anything broken inside of it?

I’m all not sure what that piece of metal is seen in your one pic, that does not appear to be “normal”.

The middle pic is the new rear end the last pic is the original rear end or are you saying the new one shouldn’t have that?

 

[Lilith5.0]

The middle pic is the new rear end the last pic is the original rear end or are you saying the new one shouldn’t have that?

I bought from lkq I’d never recommend them to anyone again though. I did find this pic on eBay of another gt rear for sale and it seems to have a bar as well can’t see through mine cause the driver side is all put together. I’m wondering if I didn’t get some kinda weird unicorn rear to begin with, it worked fine when i pulled it though.

 

[Cobra Jet]

I bought from lkq I’d never recommend them to anyone again though. I did find this pic on eBay of another gt rear for sale and it seems to have a bar as well can’t see through mine cause the driver side is all put together. I’m wondering if I didn’t get some kinda weird unicorn rear to begin with, it worked fine when i pulled it though.

According to all docs and online images of a Torsen rear diff, it will never have a "bar" and after axles are removed, you should be able to "see through" it.

The 2 pics that show that piece (bar) through the axle holes, that is most likely a Track-loc rear diff; that bar is for the spider gears.

This is from Torsen’s site (it’s NOT an S550 Torsen):

The Mustang Torsen T2’s seen here on Maximum Motorsport website do not show any metal piece (bar) in the axle hole as seen in your pics:
https://www.maximummotorsports.com/...tial-High-Bias-Ford-88-differential-P881.aspx

https://www.maximummotorsports.com/...-for-2015-Super-88-IRS-differential-P882.aspx

TIP:
- If the rear diff has Trac-loc guts, you won't be able to see through it with axles removed. There will be a "bar" in the hole which is for the spider gears.

- If the rear diff has Torsen guts, you'll be able to see through it with axles removed.

 

[Cobra Jet]

What is the part number on the rear that they sold you? Either from your receipt or found on the label which should be affixed to the rear cover.

 

[Lilith5.0]

New rear isn’t torsen don’t think they came with the 3.31 gear set, just thought maybe the non torsen was different in how the axles seat from looking at them but lkq told me they are all interchangeable, and don’t see any axles specifically for one or the other. But I’ll grab that number soon as i can.

 

[Bluelightning]

The bar that you see in the non-Torsen differential is what holds all the spider gears together. It is normal for a non-Torsen diff. Not sure why you are having a problem getting the axle to seat though.

 

[Lilith5.0]

The bar that you see in the non-Torsen differential is what holds all the spider gears together. It is normal for a non-Torsen diff. Not sure why you are having a problem getting the axle to seat though.

Yeah it’s crazy it should not take a crazy amount of force to put a cv axle in I’ve done a lot over the years, it definitely feels too long for this rear, and weird it worked in the torsen but not the other way around. And Can’t find any pics of the inside axle view of a torsen to compare mine to see if maybe it’s just different than the others.

When I was having diameter issues the first go around I tried to put the driver side in the passenger side and it was too short when all the way in so I just assumed it would be in the same order as the other.

 

[Mikepol2]

Yeah it’s crazy it should not take a crazy amount of force to put a cv axle in I’ve done a lot over the years, it definitely feels too long for this rear, and weird it worked in the torsen but not the other way around. And Can’t find any pics of the inside axle view of a torsen to compare mine to see if maybe it’s just different than the others.

Here's a pic of my diff with the Torsen...no bar across, you can see straight out the other side.

 

[Lilith5.0]

Here's a pic of my diff with the Torsen...no bar across, you can see straight out the other side.

I think i see the issue with mine that inner ring looks reversed so my axles would be backwards on the torsen in comparison to the how the stock gt/eco is so I need to swap.

Thank you guys so much going to try and pull the driver-side back apart and swap axles I’ll post results soon as I get a chance to work on it again. Hard getting the time with a young baby at home.

 

[Lilith5.0]

Well I went out today and pulled the drivers axle out waste of time it was the correct one, tried to hammer some more on the other didn’t go anywhere so I pulled it out, also pulled the clip and tried.

thought to myself why don’t I try my stock axle just to make sure it’s not an issue with the rear end. That thing went in like butter and locked in no hammering whatsoever. so while I thought it might of an issue with the rear it’s definitely is not and has to be the axle. I’m not pleased to say the least with the driveshaft shop.

 

[moffetts]

DSS has been struggling with these halfshafts lately. I don’t know what their deal is.

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