What rear diff technology does my 16 GT have?

fogus · Dec 26, 2016

I was looking into some 4WD/AWD videos recently, for example, this video: . I was wondering: what style rear diff does my 2016 GT (non-PP) have?

I know that "Torsen" is a registered trademark, and I don't want a "no true Torsen" argument--just focus on the torsen/non-torsen technology please (it must be out of patent since it was patented in 1958). I see on https://en.wikipedia.org/wiki/Torsen that "2015-2016 Ford Mustang GT, included in Performance Package" is listed. Does this mean that it is the PP only?

If the GT doesn't have a torsen (small "t"), what does it have? Is it clutch based? Something else? Anyone have a video explaining it?

xXANCHORMONXx · Dec 26, 2016

fogus said:
I was looking into some 4WD/AWD videos recently, for example, this video: . I was wondering: what style rear diff does my 2016 GT (non-PP) have?

I know that "Torsen" is a registered trademark, and I don't want a "no true Torsen" argument--just focus on the torsen/non-torsen technology please (it must be out of patent since it was patented in 1958). I see on https://en.wikipedia.org/wiki/Torsen that "2015-2016 Ford Mustang GT, included in Performance Package" is listed. Does this mean that it is the PP only?

If the GT doesn't have a torsen (small "t"), what does it have? Is it clutch based? Something else? Anyone have a video explaining it?

It has a shit spring loaded lsd. Called Trac Lok I believe.

It's not a clutch pack style so unlike other cars you can't pack in more discs etc.

Depending on what you are doing with the car the Torsen is a nice upgrade and then there's quaife and wavetrac

jasonstang · Dec 26, 2016

It's a spring loaded clutch type diff.
When the wheels are spinning at different speeds, the gears compress the spring too apply force to send torque to the other side.
What happens is when torque is applied to the spider gears, they push the side gears outward which applies force to the clutch packs which applies friction between the axles and the diff housing.

Torsen uses worm gears which can only spin the side gears not the other way round. That way it allows torque transfer when differencial speeds are seen.
It's a much faster acting mechanism and does not need service. However, they are more delicate and prone to damage when sudden shock is applied.

fogus · Dec 26, 2016

Then the clutch plates will eventually wear out, right?

09jsw · Dec 26, 2016

fogus said:
Then the clutch plates will eventually wear out, right?

Yes the clutches do wear out over time.

Dominant1 · Dec 27, 2016

Wonder if Eaton will make a true track for the super 8! if they ever do thats the way to go. Stronger then a torsen and zero maintenance!

dgc333 · Dec 27, 2016

jasonstang said:
It's a spring loaded clutch type diff.
When the wheels are spinning at different speeds, the gears compress the spring too apply force to send torque to the other side.
What happens is when torque is applied to the spider gears, they push the side gears outward which applies force to the clutch packs which applies friction between the axles and the diff housing.

That's not really how a limited slip differential works. The springs in the diff apply constant pressure all the time to keep the differential locked. When a torque difference between the two sides occurs such as when going around a corner the clutches slip allowing a speed difference to occur. This is where the name "limited slip" comes from.

It is the slipping action that requires limited slips to have an additive that eliminates chattering when turning.

With a limited slip if one wheel is on a zero traction surface you will still will have torque equal to the clamping force of the clutch at the other wheel. This is where a limited slip has a distinct advantage over a torsen differential. A torsen due to its gear design transfers torque to the wheel with the most traction in a ratio, for example 3:1. But when one wheel has zero traction there is no torque to transfer. Get one wheel off the ground and you no forward driving torque going to the other wheel.

Only the GT with performance package has a torsen differential, all other Mustangs have a limited slip.

PatrickGT · Dec 27, 2016

Incorrect. "Limited Slip" differential is the overarching terminology which includes TORSEN, torque-biasing, clutch-pack, and all types of limited slip differentials so even TORSEN equipped Mustangs have a limited slip differential.

jasonstang · Dec 27, 2016

dgc333 said:
That's not really how a limited slip differential works. The springs in the diff apply constant pressure all the time to keep the differential locked. When a torque difference between the two sides occurs such as when going around a corner the clutches slip allowing a speed difference to occur. This is where the name "limited slip" comes from.

It is the slipping action that requires limited slips to have an additive that eliminates chattering when turning.

With a limited slip if one wheel is on a zero traction surface you will still will have torque equal to the clamping force of the clutch at the other wheel. This is where a limited slip has a distinct advantage over a torsen differential. A torsen due to its gear design transfers torque to the wheel with the most traction in a ratio, for example 3:1. But when one wheel has zero traction there is no torque to transfer. Get one wheel off the ground and you no forward driving torque going to the other wheel.

Only the GT with performance package has a torsen differential, all other Mustangs have a limited slip.

I though the spring is just a preload on the clutch.
When there is a torque difference between the axles, the design of the spider gears allow the side gears to push outwards creating pressure to engage the clutches.
Clutch type only becomes locked when under power. The springs has some tension on the side gear to keep it from chattering as well as allowing some LSD action when one wheel is free spinning (when one wheel is free spinning, there is no tension between the spider and side gears to push the side gear against the clutch pack).

dgc333 · Dec 27, 2016

There are torque sensing diffs that as the drive shaft applies more torque to the diff it clamps the clutches tighter the picture you posted is of that type of diff. The picture you posted is of a version that has no preload springs so at low torque inputs this diff acts as an open diff.

dgc333 · Dec 27, 2016

PatrickGT said:
Incorrect. "Limited Slip" differential is the overarching terminology which includes TORSEN, torque-biasing, clutch-pack, and all types of limited slip differentials so even TORSEN equipped Mustangs have a limited slip differential.

I would agree the term "limited slip" has been applied to all diffs that are not open or locked but it is a miss use of the term.

The term "limited slip" was first coined to describe diffs that used clutches or cones that locked the axles together until a predetermined torque difference occured between the axels then they slipped allowing a speed difference between the axles.

Torsen, Quaife and other gear type torque sensing diffs do not "slip" so they are not "limited slip" differentials.

fogus · Dec 27, 2016

I always thought "limited slip" meant the amount of wheel slipping on the ground was limited.

GJarrett · Dec 27, 2016

xXANCHORMONXx said:
It has a shit spring loaded lsd. Called Trac Lok I believe.

It's not a clutch pack style so unlike other cars you can't pack in more discs etc.

Actually, if it is like other Ford Trac Loks, you can (with effort) cram an extra clutch disk in there to tighten it up and give more grip. I've done it with 8.8 Trac Lok rears on 4x4 Explorers to give better offroad traction on the trail.

Cobra Jet · Dec 28, 2016

In the older 8.8's, you could add additional clutch discs - it was a trick most die hard racers would do to improve the functionality of the traction lock.

CraigS · Feb 22, 2017

Dominant1 said:
Wonder if Eaton will make a true track for the super 8! if they ever do thats the way to go. Stronger then a torsen and zero maintenance!

Until it wears out and then you get to buy a new unit. There are no replaceable parts in a TrueTrac. The one I ran in my 8.8 solid axle in my cobra replica lasted 4 seasons of autocross. Then the side gears wore out and I ended up w/ a bunch of axle knockback and wobble.

What rear diff technology does my 16 GT have?

fogus

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