Advantage of a V8 Torsen rear differential ?

[Rocco]

Got mine installed now in the coupe,but I cant enjoy it until have again mapped


Swapping in into another rear diff casing with different final ratio of 4.11 would change it to 4.11 or it doesn't affect to this??

[Error404]

no, the ratio is in the crown wheel & pinion ratio. You did change the crown wheel over Rocco?

Does the extra grip at the rear push the front wide, like it dies on a rwd car?

Not as long as you enter a corner sensibly Drive to the front wheels keeps the snout on line until you start to break traction, then you tend to enter a 4 wheel drift which you can balance on the throttle

The torsen starts to deliver torque to the wheel that will spin easyer.It is a little better than an open diff because the transfer is not instant.A torsen on rear should get a little more torque on the rear outside wheel.
This being done(rear inside wheel not loosing traction) the rear part of the central torsen will be "harder" to spin so it will get more torque to the front part of the torsen so to the front diff.

Thats not really how a Torsen works. It diverts torque towards the slower moving side of the differential up to the limit of the torque bias ratio; the spinning wheel receives less torque.

[macspring]

Looking to modify the center torsen for more torque bias to the rear of the car next.

How do / did you do this and how did it work out ?

Thanks.

[Error404]

How do / did you do this and how did it work out ?

Thanks.

You can't alter the bias without physically changing the gear system.

[Thuppu]

You can't alter the bias without physically changing the gear system.

Alex, in fact it's possible by changing the friction inside the torsen. Changing the thrust needle bearings or teflon coated washers to basic steel washers. Very cheap mod.

[Error404]

Doesn't give you more of a torque bias to the rear though, only a (supposedly) higher ratio.
To give a rear biased torque distribution you need a different gear system altogether.

I still don't buy into this shim stack mod TBH, never seen any data to prove it - just woolly "butt dyno" reports

[andy10v]

You can change the bias ratio, allowing a greater amount of torque to go to the front or rear axle depending on the situation, but not just make it go more to the rear (as far as I know).

https://torsen.com/fsae/

Can the University Special be modified to increase performance?

Yes, to some degree. Since performance (torque bias ratio or TBR) is a direct function of the unit’s internal resistance to differentiate, changing the resistance will change the TBR. Most of this resistance comes from the gear design itself, and cannot be altered. However, there are other frictional factors that can. One of these factors is the friction coefficient of the washers, which the side gears thrust against when torque is applied. We use a variety of different washer types to adjust the TBR. Higher friction washers include plain steel, steel with nickel plating or FNC heat treating, and hardened bronze. To reduce friction, we also use needle bearings as well as washers with a Teflon-based coating. For the 012000, the torque bias ratio is about 2.6:1 in drive (throttle-on) and 4:1 in coast mode (drop-throttle/reverse) if the differential is mounted in the car with the large input spline toward the left (normally considered driver’s side). Switching the thrust washers that are situated between the side gears and differential housing end for end will reverse the torque bias ratio for drive and coast modes. This gives a drive mode increase in TBR that is normally favorable for this type of car. If the large spline is on the right when installed in the car, then the washers are already in the correct location to do this. For the M021-DHU, the needle bearings between the side gears and housing/cap can be replaced with steel washers of the same dimensions. Another variation would be to replace only the bearing on the left side of the differential (as installed in the car) with a steel washer. This may offer a better balance of performance between throttle on and off. Using less viscous oil will also raise TBR. A more viscous fluid will lower it. If you are changing the oil, be sure that you still use a GL-5 specification lubricant.

Interesting Torsen article

http://www.zhome.com/ZCMnL/tech/Torsen/Torsen.htm

4 DESIGN FLEXIBILTIES

The Torsen design provides several options for adjusting bias ratio to different operating conditions. First, it is possible to increase or diminish bias ratio. Second, it is possible to achieve significantly different bias ratios between opposite directions of relative drive axle rotation. Third, it is possible to achieve different bias ratios between vehicle operating conditions of driving and coasting. Each of these options is discussed under a separate heading below.

4.1 Overall bias control

The Torsen differential may be designed with different bias ratios ranging from approximately '2.5:1' to '6:1' or higher. This may be accomplished by varying the side gear helix angles, or by altering the friction characteristics for the primary components. An increase in helix angle increases the thrust component of the side gear meshes along the axis of the side gears so that smaller portions of the loads communicated by the side gear meshes are related to rotation of the side gears. In addition, the higher thrust component along the axis of the side gears increases frictional resistance at the end faces of the side gears which opposes side gear rotation and thereby further contributes to an increase in bias ratio.

4.2 Bias ratios between opposite directions of differentiation

The Torsen differential can also be designed so that different bias ratios are associated with different directions of differentiation between drive axles. That is, this design permits one drive axle to support a larger proportion of total drive axle torque than the other. The interaction of forces within the differential which give rise to this design characteristic are very complex. However, it may be generally explained that such different bias ratios are obtained by relatively raising the coefficient of friction which is effective between the end face of one side gear and the differential housing. This tends to increase resistance to the rotation of the drive axle associated with the one side gear with respect to the other drive axle.

This feature may be particularly advantageous in 'center box' applications where the Torsen differential is used to interconnect drive shafts to the front and rear drive axles with a single power source. In this application, it is possible to set different limits to the maximum proportions of torque which can be unequally divided between the front and rear drive axles. Since division of torque is automatically achieved by the Torsen differential in proportion to available traction, a separate 'torque splitter' is not required. In fact, such a predetermined torque split may detract from the designed torque biasing operation.

4.3 Bias ratios between drive and coast modes

It is also an important design freedom to provide for different effective bias ratios between vehicle driving and coasting modes. Since the Torsen differential is designed to have little or no effect on vehicle performance unless torque is being transferred by the differential, it should be understood that what is meant by the coasting mode is actually vehicle deceleration caused by engine braking. This mode is most evident with standard shift vehicles engaged in downshifting.

Invex gearing also makes possible this important design alternative (see Figure 7). The side gears within the differential are designed with the same hand of helix angle. When engine power is applied to the differential (i.e., drive mode), both side gears are thrust against the same end of the differential housing. Alternatively, when the engine is used to brake the drive wheels (i.e., coast mode), the side gears are thrust against the opposite end of the housing. This feature provides an opportunity to vary frictional characteristics between opposite ends of the housing to vary bias ratios between the opposite directions of power
transfer through the differential. Figure 7

The possibilities for independently varying bias ratios between the two directions of power transfer enables the differential to be designed with one bias ratio to compensate for undesirable steering effects associated with downshifting and a second bias ratio which is selected for most other purposes.

[Thuppu]

Doesn't give you more of a torque bias to the rear though, only a (supposedly) higher ratio.
To give a rear biased torque distribution you need a different gear system altogether.

I still don't buy into this shim stack mod TBH, never seen any data to prove it - just woolly "butt dyno" reports

Well, I don't know what is the right word, but if you get more torque to the rear, car over steering more easily, feels more like a RWD car... It can be done with this washer mod. Plenty of happy users here in Finland. More fun in snow you know.

[Error404]

Well I guess I'm wrong

[Audi_CQ]

The "shim mod" only give you more power to the rear if you lose traction on the front. You can get up to 85% to the rear with 75% the limit for std torsen 1 and 2 (not much of a difference......).
To get more rearward bias you need the Torsen 3 diff with 40/60 torque split.

[quattro-nick]

i bought a rs4 b7 gearbox (03a) and this has a better centerdiff ratio,correct?
still needs to go under the car
the v8 torsendiff sits already in my rear diff

[Error404]

Yes! I have this combination Nick and it is excellent. The 0A3 is a bit wider than the 01E so I think it will be a very tight fit in the B2 tunnel, if it fits at all. If it doesn't fit you can buy the ProSpeed diff carrier to fit the T3 Torsen in the 01E box

[Thuppu]

The "shim mod" only give you more power to the rear if you lose traction on the front.

This is what usually happens on track, inner front wheel is spinning the power up in smoke -> now more torque goes to the rear.

[chris]

v8 torsen

Really interesting thread , did anyone mention the correct oil to use in this diff , reckon mine could do with a change

[diesel des]

Yes! I have this combination Nick and it is excellent. The 0A3 is a bit wider than the 01E so I think it will be a very tight fit in the B2 tunnel, if it fits at all. If it doesn't fit you can buy the ProSpeed diff carrier to fit the T3 Torsen in the 01E box

It fits in my urq fine if that helps guys.

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