Type of diff on pavement?

So, say if somebody was looking at buying a new rwd car and one of the options from the factory was a torsen diff. Would it be worth it? Or would you save the cash and put a clutch type lsd in yourself?

I've driven plenty of torsen equipped rwd cars, and for daily driving they are great. My main concern is in the winter time, especially at speed on our icy highways, if one were to go with the clutch type, would there be any issues? I understand this to be the reasoning why factory truck lsd's typically disengage at low speed. Also, having experienced torsens in the dirt, I know they are fairly useless (not quite as bad as an open diff, but not a ton better).

For pavement its fine and since its a "new car" it will have torque vectoring strategies in the ABS which will make it work even better, more like a plate diff but without the push.

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Cosworth
For pavement its fine and since its a "new car" it will have torque vectoring strategies in the ABS which will make it work even better, more like a plate diff but without the push.

Until winter when it will be useless as a slip limiting device? Yes? No?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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john vanlandingham

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Cosworth
For pavement its fine and since its a "new car" it will have torque vectoring strategies in the ABS which will make it work even better, more like a plate diff but without the push.

Until winter when it will be useless as a slip limiting device? Yes? No?

No it will still work well in loose conditions because the ABS torques down on the slipping wheel sending the power to the other wheel. I don't know what car it is but these new systems are pretty good. (Not for racing though. You wouldn't want the rear brakes coming on mid a hot corner squatting the rear and upsetting the balance.)

With torque vectoring and a ABS, you can make a open diff act like a limited slip. The system clamps down on the wheel that is spinning, therefore transfering torque to the wheel with more grip. The brakes can shift side to side at a rapid pace to account for changing traction condidtions.

Same thing as holding the brakes on a bit with an open diff truck when you're stuck. It's ust keeping the wheel with the least traction from spinning as much. (Ultimate poor mans LSD!)

Edit: Paulinho- Either I can't read or we posted at similar times. I'm going with the fact that reading is hard...



Edited 1 time(s). Last edit at 05/17/2013 11:09AM by Robert Culbertson.

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Cosworth

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john vanlandingham

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Cosworth
For pavement its fine and since its a "new car" it will have torque vectoring strategies in the ABS which will make it work even better, more like a plate diff but without the push.

Until winter when it will be useless as a slip limiting device? Yes? No?

No it will still work well in loose conditions because the ABS torques down on the slipping wheel sending the power to the other wheel. I don't know what car it is but these new systems are pretty good. (Not for racing though. You wouldn't want the rear brakes coming on mid a hot corner squatting the rear and upsetting the balance.)

Yeah, figured it was that system (Bosch developed as far as I know), and it probably is combined with progressive reduction of throttle becasue some injur-near at a desk in Frankfurt knows better than you if you want to open the throttle or not..
Makes me think back to when Tomi Makinen was kicking the whole world's collective ass in the really rather simple Evos which at the time still had clutch-plate diffs and in an interview Andrew Cowan (Head of MRT and ex-world level driver himself) said in response to a question of "why no active diffs everywhere?" responded "Well it may not be the most modern thing, but with a clutch plate diff you always know what you have" .

In clear text: it works real well and it's predictable.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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john vanlandingham
Makes me think back to when Tomi Makinen was kicking the whole world's collective ass in the really rather simple Evos which at the time still had clutch-plate diffs and in an interview Andrew Cowan (Head of MRT and ex-world level driver himself) said in response to a question of "why no active diffs everywhere?" responded "Well it may not be the most modern thing, but with a clutch plate diff you always know what you have" .

In clear text: it works real well and it's predictable.

Didn't some GrA's homologate helical diffs for the rear on tarmac? Ford I know fir sure to reduce the god-aweful understeer of the EsCos.

As for the throttle reduction yea that's no bueno but it might be not because the engineers but some safety advocates or marketing types...

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Cosworth

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john vanlandingham
Makes me think back to when Tomi Makinen was kicking the whole world's collective ass in the really rather simple Evos which at the time still had clutch-plate diffs and in an interview Andrew Cowan (Head of MRT and ex-world level driver himself) said in response to a question of "why no active diffs everywhere?" responded "Well it may not be the most modern thing, but with a clutch plate diff you always know what you have" .

In clear text: it works real well and it's predictable.

Didn't some GrA's homologate helical diffs for the rear on tarmac? Ford I know fir sure to reduce the god-aweful understeer of the EsCos.

As for the throttle reduction yea that's no bueno but it might be not because the engineers but some safety advocates or marketing types...

We had to trade our 2wd minivan for an AWD version because Toyota's traction control and open diff would not allow the thing to move on ice or slick mud, which is 5 months of the year on our road. Traction control on, it chopped throttle to the point where it wouldn't move. Traction control off, the open diff put 100% of the torque to one wheel. Applying brakes with the left foot would confuse it and cut throttle. And this was with Nokian snows.

If the damn thing just had a real limited slip instead of a bunch of electronic nannies, 2wd would've been fine...

---

Andrew Steere
Lyndeborough, NH
KB1PJY

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fiasco
We had to trade our 2wd minivan for an AWD version because Toyota's traction control and open diff would not allow the thing to move on ice or slick mud, which is 5 months of the year on our road. Traction control on, it chopped throttle to the point where it wouldn't move. Traction control off, the open diff put 100% of the torque to one wheel. Applying brakes with the left foot would confuse it and cut throttle. And this was with Nokian snows.

If the damn thing just had a real limited slip instead of a bunch of electronic nannies, 2wd would've been fine...

Traction control is not the same thing so yeah of course it was fubar but again its a mini van, what did you expect?

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Cosworth

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john vanlandingham
Makes me think back to when Tomi Makinen was kicking the whole world's collective ass in the really rather simple Evos which at the time still had clutch-plate diffs and in an interview Andrew Cowan (Head of MRT and ex-world level driver himself) said in response to a question of "why no active diffs everywhere?" responded "Well it may not be the most modern thing, but with a clutch plate diff you always know what you have" .

In clear text: it works real well and it's predictable.

Didn't some GrA's homologate helical diffs for the rear on tarmac? Ford I know fir sure to reduce the god-aweful understeer of the EsCos.

As for the throttle reduction yea that's no bueno but it might be not because the engineers but some safety advocates or marketing types...

Never seen it, and never hear of that and I was deep into these cars since 1989..
Ford worked with FFD in Coventry back then so Viscous diffs 90% of the time till they went "active" center which was hydro pressure on clutch plates for the variable lock up... Quaiffe of course made stuff but ford didn't use it and none of the English or Swedes I knew ever used them anywhere... R&D in Daventry made a nice clutch plate front diff..
I even know the tech who was at FFD (Ferguson Fluid Developments) then in Solihul, then somebody bought them and now he runs his own place. Hi name is Bara and the place is Bara Motorsports now in Bromsgrove in Worcestershire:
http://www.baramotorsports.com/differentials.htm

(Too cool: MS 909 8.8" front diff:

And the understeer??? I know that tarmac guys would set the torque split to 50/50 and crazy stiff VC settings...and I spoke several times with the guy who won several BTRDA Gold Star events Pete Doughty who had an aerospace machine works and he said he ran LOCKED center and said "Yeah it sometimes handles like a pg, kinda like the old Quattros but we've tried everything and in the end locked 50/50 is the quickest in the end."

But normally the very thing I like about these cars is the fact they feel like a RWD+ car, which make sense since they're N/S motor and were born RWD and the + is the 1/3 power to the fronts...but 2/3 to the rear.

Understeer??? I've never seen it or felt it in my car, and Escort is just a shorter floor, prop shaft and exhaust center section but the same otherwise.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Mahh bad it wasn't the GrA escos, it was the WRC.

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Starting WRC NZ 1997

Six-speed sequential XTrac 140 box, designed in conjunction with MSPORT then licensed to Dewitts.
It was electo-hydraulically controlled front and center diffs, Torsen rear differential for tarmac, ZF rear differential for gravel

As for Bara Motorsports I know them, been there a couple of times last year to drop off some parts. Bara developed the sequential conversion for the FFD boxes for the GrA->WRC clubman conversions.

And yes understeer plagued the Cosworths terribly on low speed corners. For several reasons, until they started running the active center still in GrA. With the passive center diff it does not behave like a RWD at ALL.

torque-split <> torque-distribution