[urq] [torsen] 01E Torsen Madness

jeffreygoggin at cox.net jeffreygoggin at cox.net
Tue Apr 12 22:12:32 PDT 2011


I have one of these in my A4's rear diff housing.  Except for some minor clearancing with a die-grinder, it drops right into the case and if you're lucky, you may not even need to adjust the gear lash.  That said, there's no way that it'll work as a center diff in a Type 01E tranny or even fit inside the housing.

As for its behavior, the reason a clutch-type LSD is so useful as a rear diff in a car with a Torsen center diff is that it never unlocks completely.  Although the majority of the locking force is supplied by the pinion gears climbing the ramps machined into the thrust plates, a portion of it is also supplied by the Belleville washers/springs that pre-load the clutch plates so the diff is never open.   It will never behave like an open diff, which is why it insures the Torsen center diff always sees some load even when a rear wheel is hanging in the air.  And no, it doesn't open under braking, either.
 
I will also point out the the OEM 944 diff isn't setup optimally for use in an AWD Audi, either.   But the diffs are made by ZF and the bits and pieces inside it can be swapped with other ZF LSDs to tune its performance, plus aftermarket companies such as Guard can also provide you with various parts to tweak its performance as well.

And in case you're wondering, No, I have no idea whether one will drop into an UrQ rear diff case or if doesn't, how much work will be needed to make it fit,so you're on your own here.

JG.

---- AF <afinn1 at gmail.com> wrote: 
> What about a clutch type LSD from the 944. There are rumors that they can be
> retrofitted into the 01E center. Has anyone had any experience with this?
> Would clutch-type LSDs behave any differently under braking, or would they
> also be "open" in this situation?Thanks.
> 
> Andrew Finney
> 1985 UrQ V8.
> 
> On Tue, Apr 12, 2011 at 7:12 AM, <qshipq at aol.com> wrote:
> 
> > The short answer is 'no'.  That said, anything is possible with enough
> > money.  But the 01A/O1E transmissions are completely redesigned (basically
> > O1A/E Series are based on a racing gearbox design) and not much from an 016
> > will fit into the 01E/A.  So little will exchange in fact, about the only
> > thing we know about both being 'similar', is the block bolt pattern is the
> > same.
> >
> > From a modification perspective, I suspect that the torsen could be removed
> > from the 01E, then a custom fabricated dog clutch center diff could be put
> > in it's place, but I bet that would be very pricey.
> >
> > HTH and my .02
> >
> > Scott J
> >
> >
> > -----Original Message-----
> > From: AF <afinn1 at gmail.com>
> > To: qshipq at aol.com
> > Cc: urq at audifans.com; torsen at audifans.com
> > Sent: Mon, Apr 11, 2011 6:41 pm
> > Subject: Re: [urq] 01E Torsen Madness
> >
> >  Thanks for the informative post Scott. To round this out though, for
> > those of us who have not delved deep into the mechanical overhaul of a
> > transmission, can the center section (diff) be removed from another vehicle
> > with locking capabilities and "retrofitted" on an 01E, or is it 6 spd =
> > torsen? Is it possible to fit an 016 locker on a 01E, 'cause that sounds
> > ballsy to me. Thanks so much.
> >
> > Andrew Finney
> > 1985 UrQ 4.2L
> >
> > On Mon, Apr 11, 2011 at 7:58 AM, <qshipq at aol.com> wrote:
> >
> >>
> >>
> >> Hey Andrew
> >> It took a while for me to study and understand the Wavetrac operation.
> >> I'm not sure that is the answer, probably better than a torsen, but it still
> >> isn't going to act like a locker under braking.  The Wavetrac works the same
> >> way Left Foot Braking works on a Torsen.  If there is no load on a torsen
> >> (wheel lift) there is no drive to the wheels (0 x TBR = 0).  What many have
> >> found out is the Torsen can be fooled by using the brakes to add load to the
> >> slipping axle.  The Wavetrac appears to work the same way, but it just
> >> internally adds load to the axles by forcing the axles to 'climb' the wave
> >> profile built into the axle, forcing 'load' on both axles regardless of
> >> traction.  For more on how this works
> >> http://www.wavetrac.net/technical.htm
> >> That 'preload' is also adjustable, but I really don't see that being so
> >> high as to assist in Ideal Brake Force Distribution.  Put another way, if
> >> you preload the Wavetrac enough to bring on Ideal Brake Force Distribution,
> >> it will likely not really be any more driveable than a locked center.
> >> Further, if you envision a braking scenario where a rear is 'impending'
> >> lockup, you will be bouncing up and down that wave profile at the same time
> >> you are trying to 'unlock' rear brakes.  IMO, this will be worse under
> >> braking than a torsen, as in a straight line (acceleration or
> >> deceleration/braking) the torsen is consistent in allocation of torque,
> >> which means it will not 'interfere' with braking.
> >>
> >> I see a lot of hype on MG about modifying a Torsen to be "High Bias" ala
> >> Stasis modifications.  The fundamental problem with this mod IMO, is almost
> >> every quattro car is a static understeering chassis.  Which means, if the
> >> rear wheels lose traction from this modification, the car will understeer
> >> when the (TBR x 0 = 0) occurs, OR the loss in traction shifts torque
> >> forward.  In a street car, the effect of this will be a spider bite later in
> >> the turn (after apex vs at the apex), but IMO, it's not able to eliminate
> >> it.  Add in more rear bar, also adds more propensity to lift a wheel, which
> >> then brings you back to the 0TBR formula.
> >>
> >> I'm quite surprised that Stasis hasn't moved to the clutchpak rear diff as
> >> Jeff G proposes.  The key to any of these TBR mods, is to keep the traction
> >> at the rear.  An open rear diff or a torsen rear diff won't do that in a
> >> wheel lift scenario, because you are back to the 0TBR problem.  Plus a
> >> torsen rear that goes up in the air, then hits the ground has a tendency to
> >> explode, btrepaired that.  Back to your quandry.....
> >>
> >> For a non-abs car, adding a torsen is fine for 9/10ths of driving.
> >> However, a 'big' issue of brake balance comes into play, which the torsen
> >> also affects.  I expect to see a lot of problems with retrofitted torsens in
> >> a performance environment, and the gains going back to the guy with the
> >> locking button for his center diff.  What we fail to point out in many of
> >> these discussions is, the locker center in 'open' mode, is still awd, and
> >> also 'fine for 9/10ths of driving'.  Go to the track, hit the 'predictable
> >> understeer' button, then unlock and drive home.  After 32 years of FWD/AWD
> >> cars, I fail to understand such a grand fight of the laws of physics.  I
> >> have no problem with understeer, make it really predictable - that's the
> >> goal.  The unfair advantage to a locked center then, is much better braking,
> >> especially in the non-abs cars.
> >>
> >> my .02 arbitraged thru the peso
> >>
> >> Scott J
> >> Torsen 4kq
> >> Locker everything else
> >>
> >> -----Original Message-----
> >> From: afinn1 <afinn1 at gmail.com>
> >> To: urq at audifans.com
> >> Sent: Wed, Apr 6, 2011 12:13 am
> >> Subject: [urq] 01E Madness
> >>
> >> With all this talk about torsens it has me worrying that the 01E that I
> >> had planned to install in the urq v8 will disappoint. I really rely on that
> >> locked center dif in my 016 as a poor mans antilock. Is there a lockable
> >> center dif for the 01e? Anyone tried the wavetrak differential? It claims to
> >> be preloaded. Would it lock under braking? Any thoughts appreciated. Sorry
> >> if this is a duplicate post. I think my last posts got lost in the server
> >> hiccup.
> >>
> >> Andrew Finney
> >>
> >>
> >>
> >
> _______________________________________________
> Audifans torsen mailing list
> Send posts to: mailto:torsen at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/listinfo/torsen
> 
> You can help keep the audifans site running by shopping at http://audifans.com/shop/



More information about the urq mailing list