Eaton Detroit TrueTrac Differentials

[apex96]

Eaton came out with new limited slip differentials this year. They're pretty new, I'm not sure if anyone with an expedition has installed them yet. It looks like a few folks over on the F150 forums have gotten them installed and have given them good reviews. If anyone has installed them (front and rear) and would like to give a review on the what was required to install and how they're holding up that would be great.

Listed the information from Eaton below, I believe these are the correct units for the 3.31 open diffs in the4th gen expedition. Right now, I can purchase from Stage3Motorsports for around $1,400 for the pair.

2009 -2024 Ford IFS Snap Ring 8.8” 1.32" 31 spline All ratios part #917A738
2015 -2024 Ford Super C-Clip 8.8” 1.36" 34 spline 3.31 & up part #917A739

 

[LokiWolf]

Eaton came out with new limited slip differentials this year. They're pretty new, I'm not sure if anyone with an expedition has installed them yet. It looks like a few folks over on the F150 forums have gotten them installed and have given them good reviews. If anyone has installed them (front and rear) and would like to give a review on the what was required to install and how they're holding up that would be great.

Listed the information from Eaton below, I believe these are the correct units for the 3.31 open diffs in the4th gen expedition. Right now, I can purchase from Stage3Motorsports for around $1,400 for the pair.

2009 -2024 Ford IFS Snap Ring 8.8” 1.32" 31 spline All ratios part #917A738
2015 -2024 Ford Super C-Clip 8.8” 1.36" 34 spline 3.31 & up part #917A739

Definitely going to look into this for the front of my 150!

 

[apex96]

Definitely going to look into this for the front of my 150!

I'm looking hard at them, if I do pull the trigger, it will be done before my October trip to Carova Beach, want it in place for my 10 mile trek on the beach to the vacation rental. Used a rental Suburban Premier this year (Expedition was in the shop getting cooling fans diagnosed for no power/high temps) and that thing was an absolute mule on the sand with its 4hi and 4low options... Since the 3.31s are open differentials I want at least the rear to be able to "lock" or place the power to the wheel that has traction.

I will be calling around this spring to shops in my area to see what install prices may be.

If you pull the trigger before i do, be sure to do a write-up on it!

 

[gtncpa]

Of all the mods I did to my Mustang, the Eaton TrueTrac was the best! I had the electronic traction control turned off permanently. I would love to add this mod to my Expedition! Following ...

 

[LokiWolf]

Of all the mods I did to my Mustang, the Eaton TrueTrac was the best! I had the electronic traction control turned off permanently. I would love to add this mod to my Expedition! Following ...

If you have the ELSD in the rear, it is a excellent system. It is COMPLETELY different than Traction control alone. If you do not have the ELSD this could be a great option.

 

[Left Coast Geek]

I was going to put TrueTrac on my 2002 F250 diesel 4x4, front and rear, but I never did get around to it.

 

[apex96]

Wanted to update my research on swapping in a LSD into the Super 8.8 rear ends in the expedition. Talked it over with a performance shop that specializes in fords. The concern with the part number I listed above is that it has C-clips where the shop believes the expedition may use some sort of snap ring setup since it's IRS and not solid axle. Eaton does have the following for newer high performance mustangs with IRS:

2015 - 2023 Ford Super S550 Mustang-Excl. 5.2L/GT350/GT500 8.8" 34 spline 3.31 & up Part # 917A731

Since the mustangs use an IRS setup an truetrac for a mustang may be the better option. I'd be happy to have the shop open the diff and see, but there's one major hurdle... The rear diff cover on the expys is also a mounting point for the rear suspension. This means to service the diff it has to be completely removed from the truck... F@&k... This is a seriously labor intensive job and without knowing for certain if an Eaton Truetrac can be installed it's a huge gamble on ordering parts...

I've messaged Eaton to see if they have any information on if the mustang unit would work in the expedition, I'll update with what I find out.

 

[gtncpa]

The 2008 Mustang has a solid rear axle. Would the IRS on the newer Mustangs make it complicated?

 

[apex96]

The short answer is yes, the IRS makes it way more complicated than a solid axle. Heres a link to the MustangG6 forum where the solid axle and IRS Super 8.8 diffs are compared.

https://www.mustang6g.com/forums/threads/inside-the-super-8-8-rear-end.150514/

The information provided gives me hope that the mustange truetrac for the newer S550 generation may be a direct swap into an expedition as the spline counts are the same at 34. Still awaiting any response from Eaton as to whether the S550 will work in an expedition. I have confirmed that we use a snap ring style retainer on the expedition which has a smaller groove compared to the C clip retainer in a solid axle F150. The S550 mustang uses the snap ring style retainer.