The TT takes almost twice as many revolutions to react as the Quaife. The Quaife ratio is 2:1 where as the TT is more like 3:1.p m said:
They both work off the same principle using the helical gears.
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EE truetrac's and other diff's
- Thread starter no694terry
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They both work off the same principle using the helical gears.
Mike, I dislike ABS enough to pull the fuse the minute I leave the pavement. So I haven't brought myself to testing brake application with TT with ABS - but it should work the same way as TC on D2s.flyfisher11 said:...and TT with TC even easier
Luis - can you reveal the name of the person who told you that TT takes several revolutions to engage?
p m said:
Peter, In the DII and TC working I don't need to use the left foot modulation. With steady skinny pedal the TC brakes the airborn wheel allowing the TT to do it's thing although with the TT there is always a little torque bias to both wheels.
On the other hand if you are in a sittuation where you need to stand on it, the TC can hender things. This is why I wired a switch in my truck to turn it off or actually reverse "engineered" the system to work as with any early DII with CDL installed. I am referring to when you shut off the truck with the CDL engaged and restart it disengages TC/HD/ABS. I cut the wire in the SLABS to keep it from doing this but put a switch in the cut so that I can have both.
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Quaife and Tractech operate on the same principle but the Quaife has double the number of helical gears fitted. The diff is fitted with sets of "helical" gears sitting in pockets within the diff, the helical gears are unsupported so as they work together they generate friction against the sides of the pockets, the amount of friction is determined by the helix angle and preload on the gearset. In a situation where one wheel has less grip than the other there is a tendancy for this wheel to spin. Due to the friction within the internal gearset and the configuration of the gears the wheel which has retained grip can still drive "but" the torque transmitted to the "driver" will be proportional to the torque transmitted by the "slipper" this is the ATB effect and can be up to 2:1 ratio. The only down side is if the "spinner" has no grip ie torque transmitted is zero the ATB will effectively multiply this by 2 giving zero. If the car has some form of traction control there will always be torque applied to the "spinner" ie by traction control which is then enhanced by the ATB giving double the torque to the "driver" .
I know - what I meant was one should be able to achieve the same action in a D1 with a little brake application.flyfisher11 said:
Luis, I don't know what ATB effect is, but what you wrote is correct.
Now, where, in this description, is torque transfer changing (building up if you wish) depending on the number if revolutions?
TT indeed has torque bias ratio about 3.5:1. That means it is set up tighter than Quaife, and will transfer more torque to the wheel that has traction.
Now, where, in this description, is torque transfer changing (building up if you wish) depending on the number if revolutions?
TT indeed has torque bias ratio about 3.5:1. That means it is set up tighter than Quaife, and will transfer more torque to the wheel that has traction.
LuisC said:
A locker is overkill but you are willing to spend twice the price for a couple wheel revolutions to engage?
Luis, you're wrong. No Torsen based differential takes any revolutions to engage. The action is instantaneous. That's where the name came from Torque Sensing. It "senses" the torque at the wheels, and biases it to the other side. It's not intelligent in any way, it's just a clever mechanical design. I don't know if you're confusing Torsen's with viscous LSD's or Haldex systems (which aren't diffs) or what.
Peter, ATB means Automatic Torque Biasing.
I should think BTM would work on a D1, but probably not as well as a DII TC. Here's why:
Let's go with the quoted 3.5:1 bias ratio of a Tru Trac. If one wheel has 100 ft-lbs of resistive torque on it, the other wheel can supply 350 ft-lbs of torque. You'd divide this by the tire radius to find the thrust, so on a 32" wheel, so 37.5 lbs and 131.25lbs on the other side. That would be the no-brake situation of one wheel with low traction, and one with high traction.
Now, let's assume one wheel is in the air. On a D1, you apply the brakes lightly to load the diff up. For convenience, assume you are applying 100 ft-lbs of braking action on each wheel. The one in the air still provides no traction, it's in the air. The axle shaft on the other side still has 350 ft-lbs of torque, but the brake on that side is dragging too, so you only have 250 ft-lbs on the wheel, resulting in 93.75 lbs of thrust.
On a D2, the TC system would apply the brakes only to the side which is in the air, meaning the full 350 ft-lbs can be made into traction on the other side.
The quote about the number of internal gears is interesting. It could potentially mean the TT is weaker than a Quaife. The Quaife has a no-questions-asked bullet-proof guarantee. If you break it, they replace it, lifetime. As long as you put oil in... At least that's how it was when I bought mine.
It could also be a difference between a Torsen Type A and Type B that the author does not understand.
Peter, ATB means Automatic Torque Biasing.
I should think BTM would work on a D1, but probably not as well as a DII TC. Here's why:
Let's go with the quoted 3.5:1 bias ratio of a Tru Trac. If one wheel has 100 ft-lbs of resistive torque on it, the other wheel can supply 350 ft-lbs of torque. You'd divide this by the tire radius to find the thrust, so on a 32" wheel, so 37.5 lbs and 131.25lbs on the other side. That would be the no-brake situation of one wheel with low traction, and one with high traction.
Now, let's assume one wheel is in the air. On a D1, you apply the brakes lightly to load the diff up. For convenience, assume you are applying 100 ft-lbs of braking action on each wheel. The one in the air still provides no traction, it's in the air. The axle shaft on the other side still has 350 ft-lbs of torque, but the brake on that side is dragging too, so you only have 250 ft-lbs on the wheel, resulting in 93.75 lbs of thrust.
On a D2, the TC system would apply the brakes only to the side which is in the air, meaning the full 350 ft-lbs can be made into traction on the other side.
The quote about the number of internal gears is interesting. It could potentially mean the TT is weaker than a Quaife. The Quaife has a no-questions-asked bullet-proof guarantee. If you break it, they replace it, lifetime. As long as you put oil in... At least that's how it was when I bought mine.
It could also be a difference between a Torsen Type A and Type B that the author does not understand.
I'm pretty sure they work like worm gears. You can only apply power one way: worm to worm wheel. You can't turn it the other way (well, its really hard to). This principle is why there is a torque bias, not friction of the gears in the pocket.LuisC said:
http://www.youtube.com/watch?v=lZmsY2YvVsc
Mason, they're not worm gears, and they do rely on friction on the pockets.
Mason, they're not worm gears, and they do rely on friction on the pockets.
I've been trying to figure out if the TrueTrac is a Type A or B, hard to tell for sure, but it looks like a B. But a B can only achieve 3:1 bias ratio, and 4.5 is quote for the TT.
This is a Quaife, which is a Type B.
http://www.automobilesreview.com/uploads/2009/03/quaife-automatic-torque-biasing-differential-01.jpg
This is a Quaife, which is a Type B.
http://www.automobilesreview.com/uploads/2009/03/quaife-automatic-torque-biasing-differential-01.jpg
well whatevr diff i get, i gotta do something because if my 96 outback has to pull rover out of any more mud or climb one more hill that i would never even think of taking to truck up then i'm gonna have to start rethinking some things. i'm starting to like hill climbs. just wish rover could join the fun, subaru goes up them at 5k rpm with rooster tails out of all 4
Mason, they _are_ torsen differentials.
Rob - BTM on a D1 with TT works all right, except for in cross-axled situations you have to brake hard. (IME with D1, in low range the engine will always overpower the brakes).
Your theory on D1+BTM vs. D2+ETC is correct, but I don't like ETC (or ABS) placing a cyclic load on the axleshafts (or all other drivetrain components).
Rob - BTM on a D1 with TT works all right, except for in cross-axled situations you have to brake hard. (IME with D1, in low range the engine will always overpower the brakes).
Your theory on D1+BTM vs. D2+ETC is correct, but I don't like ETC (or ABS) placing a cyclic load on the axleshafts (or all other drivetrain components).
mbrummal said:
I think what you're thinking of is a Torsen Type A ? It has cross-axis gearsets.
http://www.torsen.com/products/T-1.htm
Here is the Type B, with all-parallel gearsets:
http://www.torsen.com/files/Torsen%20T-2%20Technical%20Sheet.pdf
I'm trying to figure out if Eaton and Quaife are manufacturing under license from Torsen, or if they've found a way around the patents.
Peter, my D2 is also capable of overpowering the brakes in low range. That was a surprising discovery trying to drive with huge winter boots on!
I agree with the idea of avoiding cyclic loading, but not sure it really makes a big difference real-world?
I've been going back and forth on the locker vs. TT thing for a while in my head. I like the "always there" of the TT, it's more likely to be more useful more often in my milder wheeling. But I've also been in situations where only a locker would work. Steep climb on a sandy soil hill with a washout diagonally across it. Front left in the air, FR and RL fully loaded, RR lightly loaded. Every rotation of the RR wheel, trying to get the TC to take me over, dug out more sand from the RR and tipped it over more and more.
Anybody running TT's with stock D2 axles?
I agree with the idea of avoiding cyclic loading, but not sure it really makes a big difference real-world?
I've been going back and forth on the locker vs. TT thing for a while in my head. I like the "always there" of the TT, it's more likely to be more useful more often in my milder wheeling. But I've also been in situations where only a locker would work. Steep climb on a sandy soil hill with a washout diagonally across it. Front left in the air, FR and RL fully loaded, RR lightly loaded. Every rotation of the RR wheel, trying to get the TC to take me over, dug out more sand from the RR and tipped it over more and more.
Anybody running TT's with stock D2 axles?
Also, Rob, I don't see a limit on torque biasing in torsen (B) gearsets.
Here's a cut drawing of a TrueTrac:
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_126000.jpg
From comparing the Quaife and TT photos, I'd say the ratio in diameter of axle gear to satellite gears is higher in TT, with about the same helical angle -> larger torque biasing in the TT.
Also, I never thought of that before, but it seems to me that if the satellite gears were riding on shafts fixed in the carrier (as opposed to simply dropped in pockets), the differential would still work the same.
EDIT: like I said before, a D1 with two TTs will walk over any cross-axled (diagonal wheels in the air) situation.
Here's a cut drawing of a TrueTrac:
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_126000.jpg
From comparing the Quaife and TT photos, I'd say the ratio in diameter of axle gear to satellite gears is higher in TT, with about the same helical angle -> larger torque biasing in the TT.
Also, I never thought of that before, but it seems to me that if the satellite gears were riding on shafts fixed in the carrier (as opposed to simply dropped in pockets), the differential would still work the same.
EDIT: like I said before, a D1 with two TTs will walk over any cross-axled (diagonal wheels in the air) situation.
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The maximum bias ratio is listed in this document:
http://www.torsen.com/files/Torsen%20T-2%20Technical%20Sheet.pdf
And I've seen that supported in a number of other places, that the Type B has a lower bias ration than Type A. That is why I was trying to find out if the TT is a Torsen under license, or if they have "improved" the design to get around the original Torsen patent. That might explain how the TT has a higher BR in the Type B design.
I've aslo read that the Type A has more gear backlash, which might explain why everything seems to be Type B these days. Back in college I had a "University Special" for FSAE which was a Type 1. I haven't seen the Type 1 for sale new since then.
It is odd to me that there are no shafts for the satellite gears. I don't like it, but I guess it works.
With BTM right?
http://www.torsen.com/files/Torsen%20T-2%20Technical%20Sheet.pdf
And I've seen that supported in a number of other places, that the Type B has a lower bias ration than Type A. That is why I was trying to find out if the TT is a Torsen under license, or if they have "improved" the design to get around the original Torsen patent. That might explain how the TT has a higher BR in the Type B design.
I've aslo read that the Type A has more gear backlash, which might explain why everything seems to be Type B these days. Back in college I had a "University Special" for FSAE which was a Type 1. I haven't seen the Type 1 for sale new since then.
It is odd to me that there are no shafts for the satellite gears. I don't like it, but I guess it works.
With BTM right?