Torsen Front Diff

[FeeltheTremor]

I had a 23 with it- I did not like it in the snow at ALL. Living in North ish Canada that was a deal breaker for me.

I live in Northern ON and drive on some really icey roads. I also have a highly modified Subaru STi so lots of experience with traction. I put studded winters on the truck this year. It's counter intuitive but you give it gas and point the tires where you want to go and it will go there. I love it, way better then my 21 without it. But the Subaru is beyond amazing in the winter as well as the track.

 

[FeeltheTremor]

I live in Northern ON and drive on some really icey roads. I also have a highly modified Subaru STi so lots of experience with traction. I put studded winters on the truck this year. It's counter intuitive but you give it gas and point the tires where you want to go and it will go there. I love it, way better then my 21 without it. But the Subaru is beyond amazing in the winter as well as the track.

But it sucks when you need to take a tight turn slowly 4H. I had to put it in 2wd for a couple U turns fom 4H. I never noticed in 4A.

 

[edubya32]

But it sucks when you need to take a tight turn slowly 4H. I had to put it in 2wd for a couple U turns fom 4H. I never noticed in 4A.

Does the Suby have 4H? I am guessing no, but I would expect tight turns in 4H to be difficult as the wheels are locked and I would expect that turns are much easier (probably the same as 2H) when you are in 4A. I don't think the Torsen has anything to do with difficult tight turns, but I'm sure some much more knowledgeable folks here could tell me I'm wrong.

 

[pittman]

But it sucks when you need to take a tight turn slowly 4H. I had to put it in 2wd for a couple U turns fom 4H. I never noticed in 4A.

Woah man. 4H isn't made for tight turns - the front and rear axles are fixed/turning at the same speed. When you go around a corner the front/rear axles have different radii so they travel different distances - hence the binding you're noticing. That's a significant amount of strain on your drivetrain. 4A allows slippage between the front and rear axles alowing you to go around corners without toasting your truck. The torsen has nothing to do with it.

 

[Bighorn Tremor]

My only question would be how it acts in the snow in 4H (because us plebes with 401a don't get 4A)

I have a 22 with the 402A package and the front Torsen differential. Most of my winter driving is in 4A and I haven't noticed any issues with the front diff - believe me, I've tried. Torsen diffs are fairly "smart" and will vary power to a slipping wheel. They are not "on-off" like a LSD.

That said, for most 4WD situations, a front locker is not a necessity. With decent tires and a locking rear differential, you'll be able to handle almost anything, especially considering the size and weight of an F-150. However, if you are in deep doo-doo, having all four wheels turn is a good thing.

For $500, the front Torsen was a good deal. I wouldn't spend several thousand to add one later unless I was building the truck out to be something special, and then it would be a real front locker.

 

[Machine]

Maybe I'm wrong here, but it was my understanding of the Torsen that it didn't act like a LSD in that LSDs preferentially apply power to the wheel with traction, due to higher torque on that wheel (in the clutchpack design, anyway) and the Torsen, when one wheel is slipping, locks the front axel to essentially act like a front locker that can automatically turn on or off depending on need. The Torsen is otherwise designed to be able to allow the front axels to rotate at different speeds such as around turns.

But, with this all in mind, a Torsen is always on, in 2WD and 4WD, completely independent of the drive mode, so couldn't a sharp turn, whether in 4A, 4H, 2H, act like wheel slippage, since it causes one wheel to turn faster than the other, and activate the Torsen? I mean, it doesn't do that, but...


I ordered a Torsen on mine because I was previously driving a 2001 Yukon, which supposedly has all wheel drive, on fairly deep snow over an icy road, and the front wheels were so slow to engage. So, when the truck would start sliding toward the edge of the road, I'd start steering toward the center of the road and would have to wait for the front wheels to kick in until I was just about off the road, then they'd engage and keep me from going off the road. (This happened once unintentionally, then several more times intentionally as I was trying to recreate it to see if it was full-time AWD or just as-needed. It didn't help that my studded snow tires were at home and I was running the bald regular tires... This was an empty country road with absolutely no traffic or I wouldn't have been playing with it like I did.) Either the wheels found traction on the shoulder or the AWD engaged- not sure which. Either way, happy to have the Torsen, though it's hard to say whether I've ever needed it since you don't really know when it's working.

 

[Aandrews109]

Maybe I'm wrong here, but it was my understanding of the Torsen that it didn't act like a LSD in that LSDs preferentially apply power to the wheel with traction, due to higher torque on that wheel (in the clutchpack design, anyway) and the Torsen, when one wheel is slipping, locks the front axel to essentially act like a front locker that can automatically turn on or off depending on need. The Torsen is otherwise designed to be able to allow the front axels to rotate at different speeds such as around turns.

But, with this all in mind, a Torsen is always on, in 2WD and 4WD, completely independent of the drive mode, so couldn't a sharp turn, whether in 4A, 4H, 2H, act like wheel slippage, since it causes one wheel to turn faster than the other, and activate the Torsen? I mean, it doesn't do that, but...


I ordered a Torsen on mine because I was previously driving a 2001 Yukon, which supposedly has all wheel drive, on fairly deep snow over an icy road, and the front wheels were so slow to engage. So, when the truck would start sliding toward the edge of the road, I'd start steering toward the center of the road and would have to wait for the front wheels to kick in until I was just about off the road, then they'd engage and keep me from going off the road. (This happened once unintentionally, then several more times intentionally as I was trying to recreate it to see if it was full-time AWD or just as-needed. It didn't help that my studded snow tires were at home and I was running the bald regular tires... This was an empty country road with absolutely no traffic or I wouldn't have been playing with it like I did.) Either the wheels found traction on the shoulder or the AWD engaged- not sure which. Either way, happy to have the Torsen, though it's hard to say whether I've ever needed it since you don't really know when it's working.

As I understand it, you are correct that the Torsen is always active.
However, if you are not in 4H or 4A, the front axles are disengaged by the IWE Actuators which essentially makes the truck 2WD.
Someone please correct me if I’m wrong.

 

[Iconic5.0]

Couple of videos that may be helpful

 

[b-real]

I still cant wrap my mind around how with gears connected at all times, and no clutch packs, the R side can spin at a different rate than the L side

 

[pittman]

As I understand it, you are correct that the Torsen is always active.
However, if you are not in 4H or 4A, the front axles are disengaged by the IWE Actuators which essentially makes the truck 2WD.
Someone please correct me if I’m wrong.

Correct. Front axle is not working unless in 4A or 4H. Torsen only works when power is sent to the front axle and one front tire is slipping - then torque is transferred to the other front wheel.

 

[Machine]

Correct. Front axle is not working unless in 4A or 4H. Torsen only works when power is sent to the front axle and one front tire is slipping - then torque is transferred to the other front wheel.

But, power isn't just transferred, correct? It is shared equally between the slipping and the gripping wheels? Versus a LSD, where the power is preferentially shifted to the gripping wheel alone?

So I guess without the 4WD actively driving the gears within the Torsen, it will do whatever it will do and can be independent right to left.

Such a simple, yet cool technology!

 

[pittman]

But, power isn't just transferred, correct? It is shared equally between the slipping and the gripping wheels? Versus a LSD, where the power is preferentially shifted to the gripping wheel alone?

So I guess without the 4WD actively driving the gears within the Torsen, it will do whatever it will do and can be independent right to left.

Such a simple, yet cool technology!

Torsen is a type of LSD. When a wheel is slipping the Torsen style LSD will transfer more torque to the wheel with more traction. How much more depends on the design of the Torsen.

When you're not in 4x4 and no power is going to the front axle there is no power going to the front wheels. What's in the differentail doesn't even matter...

But yes, very intersting design. Audi has been using them for years. I really appreciate the durability and the fact that they work seamlessly at all speeds. No engaging with a clunk or anything like the G80s GM seems to love so much.

 

[roadrunr]

I have a 22 with the 402A package and the front Torsen differential. Most of my winter driving is in 4A and I haven't noticed any issues with the front diff - believe me, I've tried. Torsen diffs are fairly "smart" and will vary power to a slipping wheel. They are not "on-off" like a LSD.

That said, for most 4WD situations, a front locker is not a necessity. With decent tires and a locking rear differential, you'll be able to handle almost anything, especially considering the size and weight of an F-150. However, if you are in deep doo-doo, having all four wheels turn is a good thing.

For $500, the front Torsen was a good deal. I wouldn't spend several thousand to add one later unless I was building the truck out to be something special, and then it would be a real front locker.

So 4A adds the center diff which allows front and rear to turn at different rates while cornering. The reason for my question is that I only have 4H so front and rear tire (one of each) have to be rotating at the same speed and when cornering that usually means one of them has to slip (which is fine in snow, one of them can slip). If the torsen shifts power from the tire that is slipping to the one that is not, how does that affect handling while in 4H? (or does it not really change anything)?

 

[FeeltheTremor]

So 4A adds the center diff which allows front and rear to turn at different rates while cornering. The reason for my question is that I only have 4H so front and rear tire (one of each) have to be rotating at the same speed and when cornering that usually means one of them has to slip (which is fine in snow, one of them can slip). If the torsen shifts power from the tire that is slipping to the one that is not, how does that affect handling while in 4H? (or does it not really change anything)?

It locks both front wheels so it's horrible to turn. I was always driving it in 4H playing in the snow. I don't know if it does that in 4A I don't remember noticing. Just when I had it in 4H and had to do a Uturn it was not good. I just kept putting it in 2wd for sharp turns. Next winter I'll have to see. Also can't do donuts even in 2WD at least I couldn't even with traction control off. Maybe it was just me but I tried in sand multiple time and it just wouldn't really do it.

 

[roadrunr]

It locks both front wheels so it's horrible to turn. I was always driving it in 4H playing in the snow. I don't know if it does that in 4A I don't remember noticing. Just when I had it in 4H and had to do a Uturn it was not good. I just kept putting it in 2wd for sharp turns. Next winter I'll have to see. Also can't do donuts even in 2WD at least I couldn't even with traction control off. Maybe it was just me but I tried in sand multiple time and it just wouldn't really do it.

That is too bad. As much as I'd like to have the torsen, it's my daily and that has to come first.

 

[FeeltheTremor]

That is too bad. As much as I'd like to have the torsen, it's my daily and that has to come first.

That could be why some people don't like it. I saw a 25 and it's standard with the 402A package, maybe only offered with 4A now?

 

[pittman]

So 4A adds the center diff which allows front and rear to turn at different rates while cornering. The reason for my question is that I only have 4H so front and rear tire (one of each) have to be rotating at the same speed and when cornering that usually means one of them has to slip (which is fine in snow, one of them can slip). If the torsen shifts power from the tire that is slipping to the one that is not, how does that affect handling while in 4H? (or does it not really change anything)?

You don't notice it much. It doesn't lock the axle - it just transfers the power to the wheel with more traction. How much torque it can transfer depends on the design (gear pitch etc) and this one is tuned for the front axle. It's a nice touch TBH.

 

[Brad99superd]

Here is a vid of it in action, pretty solid setup (maybe someone posted this not sure. I have felt mine kick in on an on ramp in the rain (and obviously in the snow here in WI) It's awesome.

 

[BillfLang]

I had a 23 with it- I did not like it in the snow at ALL. Living in North ish Canada that was a deal breaker for me.

MR McCarthy , What did you not like about it ?

 

[pittman]

It locks both front wheels so it's horrible to turn. I was always driving it in 4H playing in the snow. I don't know if it does that in 4A I don't remember noticing. Just when I had it in 4H and had to do a Uturn it was not good. I just kept putting it in 2wd for sharp turns. Next winter I'll have to see. Also can't do donuts even in 2WD at least I couldn't even with traction control off. Maybe it was just me but I tried in sand multiple time and it just wouldn't really do it.

The torsen isn't the reason why you truck feels like crap taking a corner in 4H. It's because in 4H your front and rear axles are turning at the same speeds and travelling different distances. Using 4A allows slippage in the transfer case so you can go around corners without putting extra strain on your drivetrain.

Also, the Torsen doesn't lock up the front axle. It transfers the torque to the tire with more traction. Believe it or not the front wheels can still turn at different speeds with the Torsen doing it's work.