Locking Torsen

[Jens Rösner]

Hi Lawrence!

I have posted some kind of FAQ dealing with all that some weeks ago, I
hoped this was not CWOB...

> Any Quattro (not including the TT) is full time all wheel drive
And not including the A3/S3: All "quattros" with transverse mounted
engine.
BTW: The Haldex is IMO between full-time and part-time, I don't want to
revive that discussion.

> is full time all wheel drive, which 
> means that approximately 50% of the torque is directed to one front
axle,
> the other 50% is directed to one rear axle. 
As long as there is no serious slippage on the axles.

> Any non-limited slip front or
> rear drive car has approximately 100% of it's torque directed to one of
> the two driven axles at the end of the car that is driven. Hence the
Now, where did you get that from?
And what do you mean with "non-limited slip front or rear drive"? Do you
mean the diffs in the axles or "front and rear _wheel_ drive"? These have no
influence in torque distribution front/rear axle per se. Honestly, I don't
understand your sentence. 

> quattro system has an even distribution between front and rear axles and
> at least two driven wheels at one time (vs one driven wheel for FWD or
> RWD).
If slippage occurs, the equal torque distribution changes.

> The purpose of the locks is to guarantee the front rear distribution. 
> For quattro 1 <snip> this is accomplished by a true mechanical locking 
> mechanism, as the center diffy is an open diff, so in extreme
situations, 
> it is possible to one wheel drive even a Q1 without the lock. 
I think early quattros have two diff locks, one center one rear, right?
You need two diff locks to always get out of µ-split. If left is pavement
and right is ice, only a locked center diff won't help you very much, the
right wheels would turn on the ice. With an additional left-to-right
diff-lock, your car will start to move. If of course three wheels are on ice, and
only one on pavement, you'd need three diff locks to start moving in all
circumstances. And if all four are on ice, well...
(wet ice has about µ=0.1 and below, down to 0.05, dry asphalt has up to
1.2, motorcycle tires are capable of reaching 1.4)
...you will start moving slowly, very slowly.
 
> In later quattros, (excluding
> your V8Q) it's accomplished with a viscous coupling called T_rs_n, 
This is NO viscous coupling!! It is purely mechanic! That's why it is so
great, IMO.

> which
> "senses" slip at one end a redirects torque to the other end up to a (I
> think, list may correct the %ages) 30-70% or 70-30% split. 
AFAIK, some are 30/70//70/30, some different?!

> As for your V8Q auto, there is a slightly different function (V8 owners,
> or V8listers help). AFAIK, the center diffy of the autobox V8Q's has an
> electronic center lock that senses slip via the ABS sensors, and a
T_rs_n
> rear diffy lock, making the entire system automatic at all times. There
> is no decision making for the driver to do. Again, both the front and
> rear axles of the car are (attempted to be) driven at all times, and
> again there are no factory controls designed so that the car could be
> made an on demand FWD car. 
100% correct, I would say.
Having a manual V8 would change the center diff to Torsen.
(Yeah, I said Torsen, not T-thing or T_rs_n or Nesrot, simply Torsen like
in TORqueSENsing) 

CU
Jens

http://www.AudiStory.com
Member of the AFOSAT
(Association for open speech about Torsen)

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