S197 differential replacement

[ppuro]

I have a 2011 Mustang GT that I want to upgrade the rear diff from the stock clutch style to a gear style. From my search there are several different options, and I don't know which one I should go with. So I would like to know what everyone is using or recommendations, and why that one over another one. Thanks

 

[blacksheep-1]

Torsen, IMO they are the most reliable and can take an insane amount of abuse.

 

[ppuro]

Torsen, IMO they are the most reliable and can take an insane amount of abuse.

Thanks yeah I'm leaning toward the Torsen, but didn't know how others like Eaton would compare.

 

[Dave_W]

For street & track use, the Torque Bias Ratio (TBR) of a "regular" T2 (M-4204-T31) or Boss (M-4204-MB) Torsen or an Eaton TrueTrac are fine. The T2 has a TBR of 2:1, the Boss Torsen has a TBR of 2.7:1. The Eaton has a TBR of 3.5:1. I think the quality of the Eaton and Torsen are pretty close, though I have seen a few references to a bit of noise from the Eaton on coast.

The TBR describes the ratio of torque applied to tire with least grip vs tire with more grip. If the inside, unweighted tire can only absorb 100 lbs-ft of torque before losing traction, then a TBR of 2:1 allows applying 200 lbs-ft of torque to the outside tire before losing traction on the inside tire, for a total of 300 lbs-ft torque total. If you have a 3.5:1 TBR, then you can apply 350 lbs-ft torque to the outside tire before losing traction on the inside tire, for a total of 450 lbs-ft torque total. The downside is that higher TBR can induce understeer on corner-entry and mid-corner before return to throttle.

If you are focused on autocross, the higher 4:1 TBR of the T2R (M-4204-T31H) is useful in high-grip transient situations that cause more lateral weight transfer and loss of load on the inside tires. For high-speed flowing tracks, you're probably better off with one of the lower-TBR models. The higher the TBR, the more you need to set up the car to rotate early (loose on entry) and be able to get back to throttle early. Which is fine for autocross, but can get pretty sketchy at track speeds.

 

[stevbd]

I went with the Eaton on my 2011 GT and it's been great. I haven't noticed any unusual noise, it's totally quiet as far as I can tell. I'm sure the Torsens are excellent also. I found this article from Billy Johnson to be helpful:

Project Budget 400WHP S197 Mustang Track Car: Part 5 - Upgrading to an Eaton Truetrac LSD - MotoIQ

A performance Limited Slip Differential is a MUST for making 2005-2014 (S197) Mustangs handle predictably. We replace the weak factory LSD with Eaton’s TrueTrac helical (gear-driven) LSD which will transform…

motoiq.com

 

[EF1]

I went with the Eaton on my 2011 GT and it's been great. I haven't noticed any unusual noise, it's totally quiet as far as I can tell. I'm sure the Torsens are excellent also. I found this article from Billy Johnson to be helpful:

Project Budget 400WHP S197 Mustang Track Car: Part 5 - Upgrading to an Eaton Truetrac LSD - MotoIQ

A performance Limited Slip Differential is a MUST for making 2005-2014 (S197) Mustangs handle predictably. We replace the weak factory LSD with Eaton’s TrueTrac helical (gear-driven) LSD which will transform…

motoiq.com

I was just going to post the link to the Billy J build when I got to your post. I am planning on the TrueTrac and a gear swap after my car comes out of the body shop