Torsen diff behavior on a lift?

[HoosierDaddy]

Hi, my dealer had my 2016 GT PP on a lift and noticed that if they turned one rear wheel the other remained stationary. So they believe the diff is shot and drained the fluid in preparation to replace the Torsen. They said they would bounce it off someone from Ford first, but am wondering if that might be perfectly normal.

I know an open diff will spin the other wheel the opposite direction and a clutch type diff will turn both wheels the same direction. I know a Torsen is different than a clutch type in some situations but not what it should do if you turn one wheel while up on a lift.

Can someone with first hand experience or book learn'n post what should happen if all is well? On the chance they are wrong, and Ford doesn't stop them, I would like to avoid having a perfectly good diff replaced and possible unintended consequences.

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[robwlf]

look at similar threads below your post torsen diff at gas station.... both wont spin unless theres pressure on both wheels

 

[HoosierDaddy]

look at similar threads below your post torsen diff at gas station.... both wont spin unless theres pressure on both wheels

Thanks. I had read all of those before I posted. I don't see anything in them about a situation when NEITHER wheel is on the ground with no input from the drive shaft.

 

[robwlf]

if it wasnt so cold out here id jack mine up and check for ya , if i have a chance in work today ill bring mine in and check what it does

 

[HoosierDaddy]

if it wasnt so cold out here id jack mine up and check for ya , if i have a chance in work today ill bring mine in and check what it does

Thanks, but don't go out of your way. I already owe you a lot for explaining things about the paint used for my OTT stripes.

But if anyone else happens to have their Torsen equipped car on a lift, I would really be interested in what happens if you spin one wheel. I don't know if what I saw on my car was with the trans in gear or not but suspect it was in neutral because the motion had to go somewhere and it wasn't the opposite wheel so must have been the drive shaft. I mean I can't picture any way one wheel just spins and the other and the drive shaft stay stationary. There is no slip in a Torsen just constantly meshed gears. So unless the gears are broken (all 3 sets), something else has to turn. I don't remember if I mentioned but I saw the fluid they drained and there was no visible metal and there was no noise or harshness when I spun the one wheel by hand so broken gears don't seem likely.

I guess the real question is will a Torsen just spin the drive shaft when one wheel was turned by hand rather than turn the other wheel one way or another.

 

[JohnVallo]

Thanks, but don't go out of your way. I already owe you a lot for explaining things about the paint used for my OTT stripes.

But if anyone else happens to have their Torsen equipped car on a lift, I would really be interested in what happens if you spin one wheel. I don't know if what I saw on my car was with the trans in gear or not but suspect it was in neutral because the motion had to go somewhere and it wasn't the opposite wheel so must have been the drive shaft. I mean I can't picture any way one wheel just spins and the other and the drive shaft stay stationary. There is no slip in a Torsen just constantly meshed gears. So unless the gears are broken (all 3 sets), something else has to turn. I don't remember if I mentioned but I saw the fluid they drained and there was no visible metal and there was no noise or harshness when I spun the one wheel by hand so broken gears don't seem likely.

I guess the real question is will a Torsen just spin the drive shaft when one wheel was turned by hand rather than turn the other wheel one way or another.

I've had my GT350 (Torsen) up on jack stands several times.
I've even had swapped rear-ends with different (Torsens).
This is normal behavior. I have run thru the gears with the transmission and watched as only one rear wheel will turn, while the other remains stationary.
The only thing that will happen is the ABS lights will eventually light up on the dash after one rear wheel turns without the other one turning.
This also straightens out when you let the car down, and drive it normally.

 

[HoosierDaddy]

I've had my GT350 (Torsen) up on jack stands several times.
I've even had swapped rear-ends with different (Torsens).
This is normal behavior. I have run thru the gears with the transmission and watched as only one rear wheel will turn, while the other remains stationary.
The only thing that will happen is the ABS lights will eventually light up on the dash after one rear wheel turns without the other one turning.
This also straightens out when you let the car down, and drive it normally.

Thanks. That's with the drive shaft turning the diff rather than one of the wheels but I thought what you saw would be the answer to my question. I need to make sure the dealer doesn't replace my Torsen if nothing is wrong.

Thanks.

 

[jasonstang]

It will behave like an open diff if the transmission is in gear. When you spin one wheel, the other will go backwards.
Even with a clutch type rear diff, it will behave similar because there is no load on the diff for the clutches to engage.
The only diff I can see will work differently than a pure open diff would be a viscous diff.
You WILL know when your torsen is bad. It's not like a worn clutch or anything. It will grind and make noises since it's purely gear based.

 

[HoosierDaddy]

It will behave like an open diff if the transmission is in gear. When you spin one wheel, the other will go backwards.

Since the other wheel didn't turn, I assumed it was NOT in gear and therefore the DS was being turned instead of the other wheel. I mean one or the other has to turn unless the Torsen gears are completely stripped and making a bunch of noise, which mine aren't. I just wished I'd checked to see if the DS was turning instead of assuming it later.

It sounds VERY likely there is nothing wrong with my diff.

 

[Deleted member 35644]

Look for the silver lining. A new diff on their dime. That's like a gift from Baby Jesus. If they're wrong, they're wrong. You got some new running gear.

 

[SiMuL]

Look for the silver lining. A new diff on their dime. That's like a gift from Baby Jesus. If they're wrong, they're wrong. You got some new running gear.

Sure, but do you want nutjobs that don't even know how their own products are supposed to work, changing out the diff? I'm not sure I'd trust them touching anything on the car at that point.

 

[Jetnoise]

Sure, but do you want nutjobs that don't even know how their own products are supposed to work, changing out the diff? I'm not sure I'd trust them touching anything on the car at that point.

Why not just do a burnout and see if 2 parallel lines are left behind.....

If it ain't broke....

 

[HoosierDaddy]

Look for the silver lining. A new diff on their dime. That's like a gift from Baby Jesus. If they're wrong, they're wrong. You got some new running gear.

But the other side of that coin is the risk. If your doctor told you insurance would pay for a heart transplant from a corpse 2 years younger than you, would you do it?

Statistically, the factory does a better job installing just about anything on the car. Even if a particular dealer tech can match that most of the time, how do you know your's is "the one"? I had a manual transmission problem with my new '89 LX 5.0. Dealer rebuild it twice, and each time it was worse than before and with new issues. Ford finally gave up and sent them a new trans. That was simple enough for those particular techs to do right.

Yeah, installing a new Torsen may be easier than rebuilding a trans but who knows where a particular mystery tech's limits fall. And would Ford replace it or maybe want them to rebuild it. And either way, does the process mean the ring and pinion alignment have to be reset; never a sure thing after broken in. I might be okay with getting as new clutch pack with a clutch style diff because those are wear items, but I think a Torsen is pretty much good for life in street car.

Now if my clunk is coming from bad pinion backlash, I have to let them do what they have to do to fix that but I don't think that would necessarily mean a new Torsen.

 

[HoosierDaddy]

Why not just do a burnout and see if 2 parallel lines are left behind.....

If it ain't broke....

I'm pretty sure it would. I push it hard enough to spin a tire with an open diff and that wasn't happening. But at this point, I doubt they would be willing to put fluid back in just to do a burnout test.

But on the plus side, I noticed its time for new tires so the line lock will be losing its virginity in the Discount Tire parking lot when I get the car back.

 

[BmacIL]

But the other side of that coin is the risk. If your doctor told you insurance would pay for a heart transplant from a corpse 2 years younger than you, would you do it?

Statistically, the factory does a better job installing just about anything on the car. Even if a particular dealer tech can match that most of the time, how do you know your's is "the one"? I had a manual transmission problem with my new '89 LX 5.0. Dealer rebuild it twice, and each time it was worse than before and with new issues. Ford finally gave up and sent them a new trans. That was simple enough for those particular techs to do right.

Yeah, installing a new Torsen may be easier than rebuilding a trans but who knows where a particular mystery tech's limits fall. And would Ford replace it or maybe want them to rebuild it. And either way, does the process mean the ring and pinion alignment have to be reset; never a sure thing after broken in. I might be okay with getting as new clutch pack with a clutch style diff because those are wear items, but I think a Torsen is pretty much good for life in street car.

Now if my clunk is coming from bad pinion backlash, I have to let them do what they have to do to fix that but I don't think that would necessarily mean a new Torsen.

Everyone has the clunk, and your torsen appears to be operating normally.

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