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Budgeting for a new differential this year, need some opinions.

55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
There's a lot of misunderstanding of how torsens function. They do not vector the torque.

A 3.0:1 TBR does not mean the outside tire is being driven 3X as fast. Think of it as the inside tires grip determines the overall grip and acceleration of the car.

If the inside tire can generate 0.3 Gs of acceleration before slipping, the outside tire will be sent 3X that amount of torque, or 0.9 GS (assuming the tire has that grip). For simiplicitys sake and the sake of understanding (at the cost of some accuracy) assume the car accelerates at 0.9 GS because the outside tire is the most heavily loaded tire and determines the majority of the cars acceleration.

Now let's say you're in the rain, and the inside tire only has 0.1 Gs of grip. The Torsen will only deliver 0.3 Gs of grip before the inside tire lights up and spins. So due to the overall decrease in grip, limited by the inside tires total tractive force, the car in this occasion will only accelerate at 0.3 Gs before lighting the inside tire up with wheel spin. The car accelerates at 1/3 the rate as the first example because the inside tires grip was reduced to 1/3.
Exactly. So, since .09G > .03g the car will veer away from the wheel pushing more torque - The outside wheel - And in effect, will steer the car around the corner. Ever seen a skid steer Bobcat? Same idea.
 
Exactly. So, since .09G > .03g the car will veer away from the wheel pushing more torque - The outside wheel - And in effect, will steer the car around the corner. Ever seen a skid steer Bobcat? Same idea.
I've driven one and it doesn't work they way nor does it vector torque.

When a tire spins, it has less grip than a tire that's at the limit of adhesion. If you've tracked torsens before and had inside wheel spin, you'll be familiar with the car losing forward drive and rate of acceleration when the inside tire spins. Thats because as the inside tire loses grip (from spinning), and less torque is transmitted to the outside tire and thus, the cars rate of acceleration is noticeably less because of it.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
I've driven one and it doesn't work they way nor does it vector torque.

When a tire spins, it has less grip than a tire that's at the limit of adhesion. If you've tracked torsens before and had inside wheel spin, you'll be familiar with the car losing forward drive and rate of acceleration when the inside tire spins. Thats because as the inside tire loses grip (from spinning), and less torque is transmitted to the outside tire and thus, the cars rate of acceleration is noticeably less because of it.
I've owned a SN95 Track car with a Torsen T2R for over 13 years. I installed the Torsen a couple years after I got the car . Check out "The Beast")

I was a NASA instructor for 5 years and I've also ran Nasa Southeast TTC with that T2R equipped car for 4 years: Here are the results

1st year: Southeast Regional Champion
2nd year: Third Place
3rd year: 2nd place
4the year: 2nd place again.

As per my original post, you get the offset torque / improved cornering UP TO A POINT. As long as you don't over do it and completely overcome the inside wheel's traction, the car definitely exits the corner harder / better / with less understeer the uneven torque does help steer .

On the other hand, if you treat the throttle like an On / Off switch / jerk the steering wheel with too much weight transfer unloading the inside wheel, or just plain overdo it then the inside wheel spins an you lose the effect.

Fact of life: When one wheel completely gets to zero traction, the Torsen actually acts like an open diff. The reason the T2R helps on track versus the standard one is that the worm gears have more pre-load / friction and it's better at resisting the open diff situation caused by unloading the inside wheel or overwhelming traction from too much throttle / not so smooth steering / Too much body roll from a less than ideal suspension / combination of all of the above.

With probably over 1000 laps done with a Torsen, I'm very familiar with it's capabilities.
 
16
11
Exp. Type
Autocross
Exp. Level
3-5 Years
South Plainfield, NJ
Fact of life: When one wheel completely gets to zero traction, the Torsen actually acts like an open diff. The reason the T2R helps on track versus the standard one is that the worm gears have more pre-load / friction and it's better at resisting the open diff situation caused by unloading the inside wheel or overwhelming traction from too much throttle / not so smooth steering / Too much body roll from a less than ideal suspension / combination of all of the above.

With probably over 1000 laps done with a Torsen, I'm very familiar with it's capabilities.
Alright stupid question time.
What happens if you're launching in a straight line with a Torsen and there is 0 traction for both sides? Does it still spin both wheels
 
I've owned a SN95 Track car with a Torsen T2R for over 13 years. I installed the Torsen a couple years after I got the car . Check out "The Beast")

I was a NASA instructor for 5 years and I've also ran Nasa Southeast TTC with that T2R equipped car for 4 years: Here are the results

1st year: Southeast Regional Champion
2nd year: Third Place
3rd year: 2nd place
4the year: 2nd place again.

As per my original post, you get the offset torque / improved cornering UP TO A POINT. As long as you don't over do it and completely overcome the inside wheel's traction, the car definitely exits the corner harder / better / with less understeer the uneven torque does help steer .

On the other hand, if you treat the throttle like an On / Off switch / jerk the steering wheel with too much weight transfer unloading the inside wheel, or just plain overdo it then the inside wheel spins an you lose the effect.

Fact of life: When one wheel completely gets to zero traction, the Torsen actually acts like an open diff. The reason the T2R helps on track versus the standard one is that the worm gears have more pre-load / friction and it's better at resisting the open diff situation caused by unloading the inside wheel or overwhelming traction from too much throttle / not so smooth steering / Too much body roll from a less than ideal suspension / combination of all of the above.

With probably over 1000 laps done with a Torsen, I'm very familiar with it's capabilities.
You might want to give the MotoIQ.com LSD article that I wrote a read.

You're still misunderstanding how Torsens work. Torsens are LIMITED by their TBR in sending power to the tire with the most grip (determined by the grip of the tire with less grip). The 3X the torque does not mean the outside tire is getting 3X the torque of the inside tire, but ONLY 3X the grip level OF the inside tire is sent to the outside tire. Most of the torque still goes through the inside tire, causing some level of inside wheel spin.

In an open diff you're rate of acceleration is pretty much determined by the grip of your inside tire. In a 3.0 TBR Torsen, you can now accelerate at 3X the grip level of the inside tire. In a locker or a salisbury differential that can lock 100%, you're not limited by the grip level of the inside tire at all.

Torsens are TORque-SENsing. NOT torque vectoring.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
You might want to give the MotoIQ.com LSD article that I wrote a read.

You're still misunderstanding how Torsens work. Torsens are LIMITED by their TBR in sending power to the tire with the most grip (determined by the grip of the tire with less grip). The 3X the torque does not mean the outside tire is getting 3X the torque of the inside tire, but ONLY 3X the grip level OF the inside tire is sent to the outside tire. Most of the torque still goes through the inside tire, causing some level of inside wheel spin.

In an open diff you're rate of acceleration is pretty much determined by the grip of your inside tire. In a 3.0 TBR Torsen, you can now accelerate at 3X the grip level of the inside tire. In a locker or a salisbury differential that can lock 100%, you're not limited by the grip level of the inside tire at all.

Torsens are TORque-SENsing.

You might want to give the MotoIQ.com LSD article that I wrote a read.

You're still misunderstanding how Torsens work. Torsens are LIMITED by their TBR in sending power to the tire with the most grip (determined by the grip of the tire with less grip). The 3X the torque does not mean the outside tire is getting 3X the torque of the inside tire, but ONLY 3X the grip level OF the inside tire is sent to the outside tire. Most of the torque still goes through the inside tire, causing some level of inside wheel spin.

In an open diff you're rate of acceleration is pretty much determined by the grip of your inside tire. In a 3.0 TBR Torsen, you can now accelerate at 3X the grip level of the inside tire. In a locker or a salisbury differential that can lock 100%, you're not limited by the grip level of the inside tire at all.

Torsens are TORque-SENsing. NOT torque vectoring.
Except that once it's 100% locked (your words) you get two possible outcomes: 1)Massive oversteer if they break loose or 2) Massive understeer of they hook- up...A

100% lock is fantastic off road or if you're a drifter. For road racing and going around corners? Not so much.
 
Except that once it's 100% locked (your words) you get two possible outcomes: 1)Massive oversteer if they break loose or 2) Massive understeer of they hook- up...A

100% lock is fantastic off road or if you're a drifter. For road racing and going around corners? Not so much.
Torsens don't lock 100% and those are not the 2 only outcomes when two tires are locked 100%.

Pretty much every NASCAR out there uses lockers that lock 100% and ive also won a few pro races in an S197 equipped with a locker. They work quite well and can be an advantage over a torsen with a low TBR like a regular T2.
 
16
11
Exp. Type
Autocross
Exp. Level
3-5 Years
South Plainfield, NJ
No such thing around here......dumb answers may be another matter.....asking about something you don't know about is something everyone around here tries to help with.............been there...done that.......join the club.............
Appreciate it. TMO seems to be the place to be compared to other Mustang forums since mostly everyone here tracks their cars in some way. Nice to hear from guys with experience with different applications.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
Torsens don't lock 100% and those are not the 2 only outcomes when two tires are locked 100%.

Pretty much every NASCAR out there uses lockers that lock 100% and ive also won a few pro races in an S197 equipped with a locker. They work quite well and can be an advantage over a torsen with a low TBR like a regular T2.
Nascar uses lockers because they are forced to do so by the rules ( They use a Detroit locker BTW). Also, they are never 'Hooked-up" in the corners, just look at the in-car camera steering wheel sawing going on. (BTW, these guys deserve a world of respect for drifting around every corner, in heavy traffic, at 170-180+ MPH, inches off the wall)

I never advocated for a low TBR Torsen... The T2R certainly isn't (4.0:1 ratio vs 2.0:1 for a regular Torsen) and neither are the ones used by Ford Performance on the Boss (2.7:1) or the GT350/ GT500.

Seems Like for Ford Performance engineers are on my side

Also, $18,000+ worth of Hoosiers won and 4 consecutive years on the Nasa Southeast TT Podium says the T2R works quite well on a road racing Mustang.

Mustang_Trophies.jpg
 
519
650
Exp. Type
Time Attack
Exp. Level
Under 3 Years
SoCal
Nascar uses lockers because they are forced to do so by the rules ( They use a Detroit locker BTW). Also, they are never 'Hooked-up" in the corners, just look at the in-car camera steering wheel sawing going on. (BTW, these guys deserve a world of respect for drifting around every corner, in heavy traffic, at 170-180+ MPH, inches off the wall)

I never advocated for a low TBR Torsen... The T2R certainly isn't (4.0:1 ratio vs 2.0:1 for a regular Torsen) and neither are the ones used by Ford Performance on the Boss (2.7:1) or the GT350/ GT500.

Seems Like for Ford Performance engineers are on my side

Also, $18,000+ worth of Hoosiers won and 4 consecutive years on the Nasa Southeast TT Podium says the T2R works quite well on a road racing Mustang.

View attachment 64891


Just want to make sure you know who you’re debating with on the Torsen.

Billy Johnson:​

48043764588-a804cd18de-o.jpg


Personal Stats:
Born: October 10, 1986
Age: 33
Birthplace: Torrance, CA
Residence: Boynton Beach, FL
Height: 6’0”
Weight: 170lbs
Years Racing: 16


Billy Johnson made his racing debut in 2000 at the age of 13 racing go-karts. The half-Japanese Californian has won multiple championships at the local, regional, to national level. In 2003, Billy moved up into auto racing after winning the Skip Barber Racing School scholarship. The next day he flew to Valencia, Spain and won another scholarship from BMW AG for the inaugural season of the Formula BMW USA championship. In the 2004 F-BMW season, Billy Finished 5th in the championship as well as received the Sportsman of the Year award.

Over the last fifteen years, Billy has raced in the FIA WEC, British GT, NASCAR Cup, NASCAR XFinity, IMSA, IMSA Michelin Pilot Sportscar Challenge (MPSC), Blancpain GT World Challenge America, Formula Star Mazda Pro, Formula BMW, Skip Barber Regional and National Series, Super Street Time Attack, Redline Time Attack and many import tuner shootouts and competitions for magazines. In those series, Billy acquired 56 wins, 115 top five finishes and an additional 139 top ten finishes.

Billy is a test driver for Multimatic Motorsports and the Ford Motor Company during the development of the Shelby GT350/R, 2016 Ford GT, Ford GT "GTE/GTLM" race car, Mustang GT4 race car, Mustang Performance Pack 2, 2019 GT350/R, and the 2020 Shelby GT500. In addition to testing and development, Billy has been hired by Ford to help develop the cirriculum and instruct in the "Road Course Clinic" over the past 10 years, teaching advanced road course techniques and racecraft to their NASCAR Sprint Cup and Xfinity drivers. He has worked for multiple racing schools over the years and does private driver coaching and development.

In the past 10 years, Billy has more victories and top-3 podium finishes than any driver in the Grand-Am Continental Tire Sports Car Challenge (CTSCC) Series with 23 wins, 49 podiums, and 61 top five finishes.

Billy has been a serious contender in the NASCAR Xfinity series road courses. He challenged for wins at Montreal in 2012 driving the #60 Roush Fenway Ford Mustang but had to pit from 2nd with 2 laps to go for fuel and finished an impressive 8th place after restarting 21st. In 2013 Billy had a dominant performance at Road America in the #16 Roush Fenway Ford Mustang before a late race accident damaged his car. A few weeks later, Billy made his NASCAR oval debut in the #16 Boston Strong Mustang in Loudon, NH. With only 5 days of oval experience under his belt ever, Johnson finished an impressive 15th place on the lead lap in a field of Nationwide and Cup regulars
 
1
1
Exp. Type
W2W Racing
Exp. Level
10-20 Years
Dallas
Nascar uses lockers because they are forced to do so by the rules ( They use a Detroit locker BTW). Also, they are never 'Hooked-up" in the corners, just look at the in-car camera steering wheel sawing going on. (BTW, these guys deserve a world of respect for drifting around every corner, in heavy traffic, at 170-180+ MPH, inches off the wall)

I never advocated for a low TBR Torsen... The T2R certainly isn't (4.0:1 ratio vs 2.0:1 for a regular Torsen) and neither are the ones used by Ford Performance on the Boss (2.7:1) or the GT350/ GT500.

Seems Like for Ford Performance engineers are on my side

Also, $18,000+ worth of Hoosiers won and 4 consecutive years on the Nasa Southeast TT Podium says the T2R works quite well on a road racing Mustang.

View attachment 64891
I don’t mean to brag. But I acquire a bit more hardware than that on a nightly basis. Through this experience, I can tell that you really don’t have a handle on how differentials work and you’re quite boastful for frequently being the first loser in your region.

Oh, and that guy you’re arguing with was responsible for how your GT350 handles 😂

894BE14F-EB46-494C-80D2-3C89F44262C7.jpeg
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
1,997
427
Southeast
I agree with a lot of the above post, except this, as I can’t imagine anyone using a Detroit Locker Diff on anything except a 1/4 mile drag strip.

But, those were the rage at Old Bridge/EnglishTown and ATCO-ATCO Sunday-Sunday, in NJ. Back in the day that is.

So help me out here & please opine on your rear-diff preference application & experience(s).

Just say’n.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
I don't doubt Billy's credentials as a driver.

The original question was about an effective differential on a road course and the Torsen T2R certainly is.

Not sure where Billy was going with the 100% locked diff but that's far from ideal for turning, it defeats the purpose of having a diff in the first place. Read-up on suspension setup and you'll find that the NASCAR chassis guys build in some inside rear wheel lift to help alleviate the bind caused by the locking rear on the tighter courses.

Torque Biasing is in fact: uneven torque. Uneven torque across the axle will affect the car's trajectory and in the Torsen's case: Favorably.

And, I'm not a pro guy but my results are certainly conclusive proving that the car works really well in the corners. My engine is a 100% stock internals 4.6 / 2V. I beat my competition in the corners, not with straight line speed.

It's not the only diff that works but short of a pro level adjustable ramp diff as seen on the GT4 it's a really good option. The Torsen is part what made the car easy to handle / predictable / and ultimately very competitive as it allowed me to push really hard confidently. All that for a reasonable cost and no maintenance beyond fluid changes.
 
I don't doubt Billy's credentials as a driver.

The original question was about an effective differential on a road course and the Torsen T2R certainly is.

Not sure where Billy was going with the 100% locked diff but that's far from ideal for turning, it defeats the purpose of having a diff in the first place. Read-up on suspension setup and you'll find that the NASCAR chassis guys build in some inside rear wheel lift to help alleviate the bind caused by the locking rear on the tighter courses.

Torque Biasing is in fact: uneven torque. Uneven torque across the axle will affect the car's trajectory and in the Torsen's case: Favorably.

And, I'm not a pro guy but my results are certainly conclusive proving that the car works really well in the corners. My engine is a 100% stock internals 4.6 / 2V. I beat my competition in the corners, not with straight line speed.

It's not the only diff that works but short of a pro level adjustable ramp diff as seen on the GT4 it's a really good option. The Torsen is part what made the car easy to handle / predictable / and ultimately very competitive as it allowed me to push really hard confidently. All that for a reasonable cost and no maintenance beyond fluid changes.
You seem to have a bit of a chip on your shoulder and have taken comments out of context.

Congrats on your successes. It's great to see people on track in Mustangs. There needs to be more of them!

Now you first claimed the BOSS 302 street car, 302 racecar, and GT350 use the T2R. They do not.

Then you claimed the Torsen vectors torque. It does not. I worked on the torque vectoring e-diff in the Focus RS, and that can drive more wheel speed and overall torque to the outside tire to give the car a yaw rotation moment. Torsens do not.

I gave a couple explanations of how torsens work and torque delivery of them vs open, salisbury and lockers. You went off on a tangent about the 100% lock comment and made more claims that weren't true. Including this comment and I will clarify that NASCAR does NOT "build in some inside rear lift to alleviate bind". Stock cars are heavy, have a ton of power and have relatively small tires. A big part about setting them up is to effectively put power down to the ground lap after lap and take care of the rear tires. What you're claiming they do is the exact opposite of what teams work towards making them fast on road courses. To qualify that statement, I've raced in the NASCAR Cup & Xfinity series and am currently doing driver coaching and setup consulting for a Cup team.

A locker is an effective tool and there are situations where they have a competitive advantage over a torsen, and vice versa. But a fast car will have to be set up quite differently when running one vs the other. Heck, Australian V8 Supercars use spools, which are 100% locked all the time and they are extremely fast, but again, the setup will vary to make them work. Throwing a spool in an s197 will cause far more problems than it will help, and people who know how to set cars up and might use a spool, wouldn't be consulting a forum for advice, so for everyone else, don't put a spool in.

To make things simple, For most S197 guys, read my lsd article:


If you just want to be told what to do without learning, then either the Eaton Truetrac or the T2R will be the best bet without doing anything crazy to the cars setup.

Now I'm not an autocrosser and don't set cars up for it, but knowing the constant problems cars with big rear sway bars and torsens have, there could be a reasonable advantage of a locker in autox.

0.02
 

Grant 302

basic and well known psychic
A locker is an effective tool and there are situations where they have a competitive advantage over a torsen, and vice versa. But a fast car will have to be set up quite differently when running one vs the other. Heck, Australian V8 Supercars use spools, which are 100% locked all the time and they are extremely fast, but again, the setup will vary to make them work. Throwing a spool in an s197 will cause far more problems than it will help, and people who know how to set cars up and might use a spool, wouldn't be consulting a forum for advice, so for everyone else, don't put a spool in.

Could you explain more or start a thread on that? I’ve thought that roll-steer properties can affect the ‘need’ for open diff properties even on the S197 setup. I was gonna ask when the Traction-Lok rebuild discussion was going on, but I didn’t think that would be of much interest or relevance.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
Nicely written article.. You reach the same conclusion I did many years ago. The comment about the overly stiff rear bar being unproductive is also accurate, I've experienced it, that's what I meant about "Less than Ideal rear suspension setup"

I meant Torsen as OEM, I was aware that the Boss Torsen's TBR is different than the T2R (2.7 vs 4.0) , also mentioned in a prior post, but I can see how you could read that I meant T2R across the board by the way it was written.

However, I do have a question: Are you stating that a different amount of torque applied to opposite wheels on the same axle have no effect on the car's trajectory? Please explain.
 
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58
I'm neither an engineer nor a racer so please be patient....

But under acceleration coming out of a corner, when an Eaton or Torsen is "engaged" and applying ~ 3x available inside wheel torque to the outside wheel, does the Eaton allow the inside and outside wheel to turn at different speeds?

I thought a big advantage of a Torsen/Eaton versus my trac-lok is that the trac-lok, when engaged, forces both rear wheels to turn the same SPEED. Whereas the Torsen/Eaton will distribute (or "bias") torque while simultaneously allowing them to turn DIFFERENT speeds. Is this not correct?

On a related point, I guess I was hoping the Eaton would allow extra torque to be applied to the outside rear wheel in this situation, without requiring the simultaneous "drag" of an inside wheel turning the same speed, and thus help reduce understeer and rotate the car into the corner. Am I hoping for too much? :)

Thanks for everyone's help, good discussion and great article and project car, Billy Johnson.
 
55
70
Exp. Type
Time Attack
Exp. Level
10-20 Years
Cumming, Georgia
From Torsen.com:

" This initial understeer is somewhat mitigated, at corner exit, by resisting inside wheelspin. In so doing, more torque is allowed to go to the outside tire once the inside tire reaches its traction limit than would otherwise be the case. That, in turn, has the effect of generating an understeer-canceling yaw moment on the chassis, serving to actually drive out of the corner with greater authority. "

That answers the question. The torque bias does yaw the chassis / helps steer the car around the corner.


On Smaller, more technical course – especially in autocross – may force you into a more aggressive differential due to tight corners and high weight transfer. There is a much greater potential to lift an inside tire off the pavement. Frankly, the T-2R owes its existence to autocross. It was due to the complaints of wheelspin and Type-2 not being aggressive enough in that environment that we created the T-2R product line.
 
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From Torsen.com:

" This initial understeer is somewhat mitigated, at corner exit, by resisting inside wheelspin. In so doing, more torque is allowed to go to the outside tire once the inside tire reaches its traction limit than would otherwise be the case. That, in turn, has the effect of generating an understeer-canceling yaw moment on the chassis, serving to actually drive out of the corner with greater authority. "
You could say the same thing about a locker, a spool, or a salisbury LSD. Cancelling (or any level of reducing) understeering yaw moments is NOT the same as over-driving the outside wheel and torque vectoring (introducing rotational yaw moments), which is what the Focus RS, Camaros, Ferraris, and other e-diff equipped cars actually do.

Maybe this exple will further help the understanding:

If you have an s197 with a big rear bar and sticky tires, there is a lot of rear weight transfer and not a lot of grip on the inside tires powering out of a corner. Let's say the it only takes 10% of the cars torque to start spinning the inside tire.

OPEN DIFF
Power takes the path of least resistance. Since in our example it only takes 10% of the cars torque to spin the inside tire, it's really easy to do exiting a corner. The vast majority of the cars torque will be lost through spinning the inside tire, with very little being sent to the outside tire to actually accelerate the car. Let's say that 95% of the cars torque is lost by spinning the inside tire and only 5% makes it to the outside tire to actually accelerate the car. This is like putting 1 tire on ice with an open diff. You're not going anywhere.

TORSEN
With a torsen, the confusion probably lies in the "3X the torque is being sent to the outside tire". But the misunderstanding here is the dimension of available grip of the inside of the tire. Since it only takes 10% of the cars torque to spin the inside tire, a 3.0 TBR means that 3X or 30% of the cars torque is sent to the outside tire. But the inside rear tire still spins and 70% of the torque still is lost through spinning the inside tire. So there really isn't much "understeer yaw cancelling" going on in this example and while the car accelerates much better than an open diff, it's still pretty bad with excessive inside wheel spin. ***View this like a torsen in a car on an autocross. If you autocross a torsen you'll quickly relate.

Now, you need/want to improve rear acceleration grip with your torsen, and you soften the rear bar. Now the inside rear tire can take 20% of the cars torque before spinning. This now means the outside rear tire is given 60% of the cars torque and accelerates very good and you're not happy with the result since 40% of the torque goes to the inside rear tire and still causes wheel spin (since 40% is still twice the torque it takes to spin the inside rear tire). In this example there still is no yaw-inducing rotation.

Put 1 tire on ice with a torsen and if there is no grip, you're still not going anywhere since 3X zero grip, still = 0. But if there's 1% of engine torque worth of grip, the Torsen will send 3% to the tire on the pavement and you'll move slowly, but 97% will be lost spinning the inside tire if you get on the throttle aggressively.

100% locked from a LOCKER/SPOOL/SALISBURY:
When a diff is locked 100%, the inside tire will never spin more than the outside tire, and the acceleration ability of the car is no longer limited by the grip of an individual tire and now is only determined by the total tractive ability of both tires together. 100% of the cars torque goes to both tires together evenly. The outside tire will always get 100% of the cars torque and so will the inside.

Back to the ice example, with no grip from the tire on the ice, the car will accelerate as much as the tire on pavement will allow. If the tire on pavement will spin if it gets 60% of the cars torque, then anything above that will spin both tires together.

OVERALL
Torsens are Limited slip differentials which LIMIT slip of the inside tire (but they still spin, often at a much higher rate than the outside tire). The don't eliminate it nor will they "lock" or send 100% of the cars torque to the outside tire like a spool/locker/salisbury (some).

Torque distribution % of a lsd is not the same as the torque % it takes to spin a tire so the above could be a little confusing, but it's the best I can do during a road rally.

Steve - did you read my article?
 

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