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Budgeting for a new differential this year, need some opinions.

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Steve - did you read my article?

Yes, several times as I have with all your articles on that car. It's a great series. And together with your posts here I think maybe I'm slowly getting it with the Eaton.

So just to double check I'm getting it, a Torsen/Eaton never "locks" the left and right sides in any manner, either on braking or acceleration, but instead just moves torque from one side to the other within the limits of the ~ 3:1 ratio and the available traction of the inside tire.

Is that about right?
 
does the Eaton allow the inside and outside wheel to turn at different speeds?

I thought a big advantage of a Torsen/Eaton versus my trac-lok is that the trac-lok, when engaged, forces both rear wheels to turn the same SPEED. Whereas the Torsen/Eaton will distribute (or "bias") torque while simultaneously allowing them to turn DIFFERENT speeds. Is this not correct?

On a related point, I guess I was hoping the Eaton would allow extra torque to be applied to the outside rear wheel in this situation, without requiring the simultaneous "drag" of an inside wheel turning the same speed, and thus help reduce understeer and rotate the car into the corner. Am I hoping for too much? :)

So just to double check I'm getting it, a Torsen/Eaton never "locks" the left and right sides in any manner, either on braking or acceleration, but instead just moves torque from one side to the other within the limits of the ~ 3:1 ratio and the available traction of the inside tire.

Is that about right?
Torsens allow different wheel speeds inside to out. Often with the inside tire spinning faster than the outside tire since most of the torque is still lost though inside wheel spin if the car has sticky tires and or a stiff rear swaybar.

Traction-loks have clutch plates that create friction against spinning at different rates. This resistance causes understeer mid corner and is what reduces inside wheel spin. More power, more grip and older clutches will all result in more inside wheel spin because the clutch plates are not strong enough to prevent inside wheel spin. You can put more aggressive plates in and add preload but this direction means you're starting to turn the diff into a spool and the car will understeer on entry and mid corner because of it.

As I mentioned in my article, the stock diff is fine when new for stock grip and power. But they wear out and no longer can handle stock power, let alone more power or grip.

Eaton's will allow the outside tire to have more acceleration force than a new or old traction lok in almost all cases. Now it is possible if you have a big swaybar and sticky tires and you're autocrossing, a brand new traction lok diff might give the outside rear tire more torque than any torsen (because the torque sent to the outside tire is determined by the grip of the inside tire, and if you unload the inside tire with a big rear bar, you're limiting the torque sent to the outside tire. This is where a clutch type diff, a locker, and a modified Tractionlok could be better than a torsen. But the wavetracs look like it solves this problem and is a better solution if you're not a race team and do a lot of testing to figure out what ramp angle and clutch setup is best in a salisbury LSD.

So it all depends.
 
1,087
876
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
A little off topic but presumably related. Why do they recommend not to put a spacesaver type tire (or any mismatched height tire) on one side of a rear axle on a Torsen equipped car?

And is there a reasonable limit (i.e. driving less than 10 miles to get off the highway).
 
2
0
Exp. Type
HPDE
Exp. Level
3-5 Years
NC
My Trac-Loc started getting weak before the end of my first autocross season in the car. I went with the Eaton TrueTrac based on the recommendation of folks here and elsewhere, combined with the cost.

For my use case (2011 Mustang GT in CAM-C, 285 RE71's), it just flat works. Mine does have a light rattle due to gear lash when costing at low speeds, which seems to be hit-or-miss with the Eaton diff. It is not objectionable to me now that I know what it is...
Do you know if there's a way to remedy the rattle? I have a Torsen T2R in my '11 GT500 that [I'm assuming] rattles when coasting and when going around sweepers. It's driving me nuts to the point that I'm considering putting the stock diff back in! If you, or anybody else, has some suggestions to a remedy, I'M ALL EARS. The rattle gets worse, to a point, as the diff heats up. If it matters, the diff is connected to a Motiv 3.90 ring and pinion. Thanks.
 
Do you know if there's a way to remedy the rattle? I have a Torsen T2R in my '11 GT500 that [I'm assuming] rattles when coasting and when going around sweepers. It's driving me nuts to the point that I'm considering putting the stock diff back in! If you, or anybody else, has some suggestions to a remedy, I'M ALL EARS. The rattle gets worse, to a point, as the diff heats up. If it matters, the diff is connected to a Motiv 3.90 ring and pinion. Thanks.
My diff is an Eaton, which is different, but... I've swapped gear oil type and weight chasing a stronger bias. With mine, the oil swap did not make a noticable impact on torque bias or noise.

In terms of fixing the rattle, I've read that going to a 1-piece driveshaft helped for some folks with the TrueTrac--not sure if that would help you or not.
 
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2
0
Exp. Type
HPDE
Exp. Level
3-5 Years
NC
My diff is an Eaton, which is different, but... I've swapped gear oil type and weight chasing a stronger bias. With mine, the oil swap did not make a noticable impact on torque bias or noise.

In terms of fixing the rattle, I've read that going to a 1-piece driveshaft helped for some folks with the TrueTrac--not sure if that would help you or not.
I already have a one-piece carbon fiber driveshaft.
 

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