Re: U/S Torsen

[Eliot Lim <eliot@u.washington.edu>]

On Mon, 8 Jan 1996 ScharfR@aol.com wrote:

> Be careful when you call VC based all-wheel drive "a cheap and ugly hack".  I
> think they are rather elegant and that the systems (i.e., Volkswagen Syncro;
> as used on the late, lamented Eurovans) are extremely capable.

the VW syncro is a part time 4wd system using a VC to automatically engage
4wd.  the latest porkers are the same way.  

VC's are cheaper than torsens, so the first part of my comment is true.

ugly?  i think so.

during development of the syncro, they had to install a disengager
so that the VC would not cause rear wheel lockup, something caused
by its exponential characteristics.

then they realized that the disengager didn't know the difference
between overrun and reversing, thus you only had 2wd for reversing.

at this point my memory fades, i don't remember how they got around
that, but the fact that they had to engineer all these extra bits
to accomodate an uncooperative device to me makes it ugly.

as i said, on the full time systems you have to slacken the couplings
so that abs can work.  which means that you do not have as much 
limited slip capability as you can get from the other systems.

early mitsu eclipses could not be gotten with rear VC and ABS.  these
were mutually exclusive options.  ugly?  i still think so.
 
> I've owned Audi quattros and Syncro Eurovans, and loved driving both.  The
> real testament is that you won't find anybody on the planet who says that
> they loved driving a Eurovan unless it was the Syncro version.

i'm sure the final results are highly effective and i will probably
get attacked again for worrying about design rather than looking at
the final outcome...  think of it as trivia if you will...
 
> Final comment.  The Audi TT/TTS concept car will become reality in 1998.
>  Guess what kind of "quattro" system this car will use?  I'll give you a
> hint.  The TT/TTS is based on the next generation Golf platform and it uses a
> transversly mounted engine.

that's fine and dandy.  for the record, the syncro automatically
engaging part time 4wd concept was originally dreamed up by audi
engineers but rejected and subsequently picked up by VW because it was
cheap and simple.  if the choice is between a syncro and a fwd with TC
it is a no brainer which i would take.  the new golf IV will not get
the A4's new multilink front suspension, so i would tend to be less
enthusiastic about it.

i used to be a staunch advocate of full time systems, but seeing that
you can use lighter driveshafts on a part time system i will probably
weigh that in more heavily, seeing how much inertia the traditional
quattro system has.

the same engineer that did this system went out and started his own
little consulting company.  this led to 4wd minivans and a very
diverse range of other makes and models with this concept, including
the lambo diablo VT and the latest porkers.

let me put all this into perspective:  a VC system is still light
years ahead of traditional f*** truck 4wd.  there is some progress
being made in that world, but it is moving as quickly as icebergs.


eliot