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Torsen vs Standard differential

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xr7

TMO Addict?
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The Torsen T2 Diff and the Recaro seats were standard on the LS package of which about 750 units were built.

Of the 3,250 or so Boss there were only 2 options offered for the US market IIRC.

1. Recaro seats & T2 Diff. $1,995.
2. Floor Mats & Car Cover. $. 475.

I could be wrong though.
3. Block Heater $35.00
Sure glad mine has the block heater in case I ever need to bust out of here in January and its -20 in the heated garage🤪🤪
 
125
112
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HPDE
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Under 3 Years
Ann Arbor, MI
If you do get one without a Torsen, it gives you the ability to upgrade straight to the T2R version.

Hmmmm...

That brings up lots of questions to me of which I'm a total novice so I could be dead wrong on all accounts - I like the broad torque/power range in the stock Boss set up, wouldn't want to lose that. Also, the T2R must further reduce mpg for a car that is mostly street use. Then I wonder about tires, suspension etc. Not sure if we can bite on that just yet, but definitely sounds like something to think about.
 

PatientZero

@restless_performance
825
865
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W
Hmmmm...

That brings up lots of questions to me of which I'm a total novice so I could be dead wrong on all accounts - I like the broad torque/power range in the stock Boss set up, wouldn't want to lose that. Also, the T2R must further reduce mpg for a car that is mostly street use. Then I wonder about tires, suspension etc. Not sure if we can bite on that just yet, but definitely sounds like something to think about.

I can't imagine the diff having any measurable impact on gas mileage unless you swapped a 9" in there.
 
125
112
Exp. Type
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Under 3 Years
Ann Arbor, MI
I'm not a Boss expert, but if the LS diff is a traction lok (standard Ford LS diff) it can work very well and perform like a mechanically geared diff, as long as the clutch pack is in good condition. The beauty of the geared diff is the clutches don't wear, and you get consistent performance as time goes by. This may explain why you felt the LS diff was doing the job for you.

Boone, I appreciate the feedback and you picking on that. Been mulling this over and now I wonder if the difference in the '12 (with Torsen) and '13 (without Torsen but better "grip," same tires etc) could have been something as simple as differences in the the suspension damper settings or maybe even the steering setting??? Should've checked when I had the chance.
 
I don't track my Boss and the standard diff is fine with Me!!!...You track rats obviously need something more...that's why there iwas a Torsen option............you get what you pay for.....most times...........
 
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Dave_W

Cones - not just for ice cream
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That brings up lots of questions to me
I think maybe you're thinking of something else. I'm talking about a Torsen T2-R differential.

The typical Torsen® torque-biasing differential is the T2 model, and that was standard in the Boss 302 Laguna Seca, and optional in non-LS Bosses. The T2 used in the Boss has a torque bias ratio (TBR) of 2.5, so the wheel with traction can get up to 2.5 times the torque than the wheel with less traction. In contrast, a T2-R has a TBR of 4. So if the tire with less traction can only apply 100 lbs.-ft. to the ground before spinning, a car with a T2 can apply 250 lbs.-ft. to the ground with the other tire for a total of 350 lbs.-ft. before wheel spin. A car with a T2-R can apply 400 lbs.-ft. to the ground with the other tire, for a total of 500 lbs.-ft. before wheel spin. And 500 torques will accelerate the same car faster than 350.

The drawback of any torque-biasing differential is when one wheel has no traction (it can't apply any torque to the ground), then 0 lbs.ft. multiplied by any TBR is still 0. If you're stuck in snow with your Torsen-equipped car and you're just spinning a tire, the trick is to apply some light brake - the diff doesn't care if the torque on the slipping wheel comes from the ground or the brake pad - and that allows some torque to be sent to the other wheel, which hopefully has some amount of traction.

Changing an open diff (or a T2) to a T2-R doesn't change the ring & pinion ratio (unless you also change that at the same time), so it doesn't affect mileage.
 
125
112
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HPDE
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Under 3 Years
Ann Arbor, MI
I think maybe you're thinking of something else. I'm talking about a Torsen T2-R differential.

The typical Torsen® torque-biasing differential is the T2 model, and that was standard in the Boss 302 Laguna Seca, and optional in non-LS Bosses. The T2 used in the Boss has a torque bias ratio (TBR) of 2.5, so the wheel with traction can get up to 2.5 times the torque than the wheel with less traction. In contrast, a T2-R has a TBR of 4. So if the tire with less traction can only apply 100 lbs.-ft. to the ground before spinning, a car with a T2 can apply 250 lbs.-ft. to the ground with the other tire for a total of 350 lbs.-ft. before wheel spin. A car with a T2-R can apply 400 lbs.-ft. to the ground with the other tire, for a total of 500 lbs.-ft. before wheel spin. And 500 torques will accelerate the same car faster than 350.

The drawback of any torque-biasing differential is when one wheel has no traction (it can't apply any torque to the ground), then 0 lbs.ft. multiplied by any TBR is still 0. If you're stuck in snow with your Torsen-equipped car and you're just spinning a tire, the trick is to apply some light brake - the diff doesn't care if the torque on the slipping wheel comes from the ground or the brake pad - and that allows some torque to be sent to the other wheel, which hopefully has some amount of traction.

Changing an open diff (or a T2) to a T2-R doesn't change the ring & pinion ratio (unless you also change that at the same time), so it doesn't affect mileage.

Dave_W thank you for the info, that helps. I guess I was thinking back to the days when someone would put in a 4:11 positraction and lose mpg in a noticeable way, but didn’t think of ring and pinion. Also, I get the cornering benefits of the T2R but still wonder if it would change the torque “bandwidth” so to speak when going straight or when getting up in revs? I love the fact that you can be running anywhere from 30-80mph and be in most any gear, 2 thru 4, with the T2 (though that’s obviously an exaggeration). Maybe the T2 translates into less gear shifts for us novice driver’s who are trying to master heel-toe downshifting, easier on us? Again, my apologies if I’m just way out in left field in terms of my understanding of this. No need to further explain if guys are worn out on this topic, I’ll be sure to bring it up again later!
 

Boone

Professional Thread Killer
No need to further explain if guys are worn out on this topic, I’ll be sure to bring it up again later!
Not so fast my friend. Your friendly neighborhood TMO member insists that you understand the Torsen diff. That's just how we roll.

Watch this video to see how the Torsen does nothing (as in no friction loss or mileage / power penalty) while traveling in a straight line, allows different wheel speeds in a turn (acting like an open diff), but sends torque to the slower wheel when a slip condition is present (acting more like a locked rear diff, but it doesn't "lock"). The difference in the Torsen models is how much torque can be transferred (Torque Bias Ratio of 2.5 or 4.0), and there are slight handling differences associated with them. Some consider the 4.0 TBR to be too intrusive for street or road course use and perfect for autoX. Opinions on this differ, so listen to the multitude of users on TMO. I use a Detroit Truetrac diff on my S197, so I really can't chime in on which one to use. Any planetary geared diff beats the crap out of a clutch disc setup in the long run, though.

 

Fabman

Dances with Racecars
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Not so fast my friend. Your friendly neighborhood TMO member insists that you understand the Torsen diff. That's just how we roll.

Watch this video to see how the Torsen does nothing (as in no friction loss or mileage / power penalty) while traveling in a straight line, allows different wheel speeds in a turn (acting like an open diff), but sends torque to the slower wheel when a slip condition is present (acting more like a locked rear diff, but it doesn't "lock"). The difference in the Torsen models is how much torque can be transferred (Torque Bias Ratio of 2.5 or 4.0), and there are slight handling differences associated with them. Some consider the 4.0 TBR to be too intrusive for street or road course use and perfect for autoX. Opinions on this differ, so listen to the multitude of users on TMO. I use a Detroit Truetrac diff on my S197, so I really can't chime in on which one to use. Any planetary geared diff beats the crap out of a clutch disc setup in the long run, though.

Fantastic video. I especially love the German subtitles.
 
179
309
Utah
The tech has been covered so well with the articles and videos, I don’t dare add to that. However, I started tracking my 2006 Mustang GT and did so for 2 years using the stock trac-loc, then switched to a Torsen T2-R, so I can tell you the difference it made for me.

Using the trac-loc, which in simple terms is trying to drive both wheels at the same time when one slips, you can imagine the car would understeer on from apex to track out while under acceleration as both rear wheels tried to push the car straight. So, many times I would have to come out of the throttle slightly on exit to get the car to finish the turn.

After putting in the Torsen, man what a difference. The car completes the exit of the turn for you as the rear axle is now applying torque to the outside wheel when the inside wheel is light. Completely changed the car for me. It allowed me to go to throttle hard and early at apex and the car turns right around the corner with no lift to get it to turn.

That being said, I still have so much work to do as a driver (and mechanic), but I would not give up my T2-R.
 
125
112
Exp. Type
HPDE
Exp. Level
Under 3 Years
Ann Arbor, MI
Not so fast my friend. Your friendly neighborhood TMO member insists that you understand the Torsen diff. That's just how we roll.

Watch this video to see how the Torsen does nothing (as in no friction loss or mileage / power penalty) while traveling in a straight line, allows different wheel speeds in a turn (acting like an open diff), but sends torque to the slower wheel when a slip condition is present (acting more like a locked rear diff, but it doesn't "lock"). The difference in the Torsen models is how much torque can be transferred (Torque Bias Ratio of 2.5 or 4.0), and there are slight handling differences associated with them. Some consider the 4.0 TBR to be too intrusive for street or road course use and perfect for autoX. Opinions on this differ, so listen to the multitude of users on TMO. I use a Detroit Truetrac diff on my S197, so I really can't chime in on which one to use. Any planetary geared diff beats the crap out of a clutch disc setup in the long run, though.


Wow, what an engineering feat. The benefits of the Torsen are pretty obvious after watching the video, and it sounds like the positives are translated into real-world gains on the track. Thanks for that schooling, nice video Boone. T2 or T2R work well, with some personal preference involved for road course use and probably dependent to some extent on your home track layout. Fun stuff though, love the tech involved.
 

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