Re: New to Audi's: Basic Questions

[dan_masi@MENTORG.COM (Dan Masi)]

On Oct 8,  9:37am, tlazay@ultranet.com wrote:

> Anyway, I am new to Audi and currently have a silver 97 A4
> quattro coming in a few weeks from now.

Congrats!

> 1) Electronic Differential Lock: What is this? How does it
> help? When does it engage?

I'm not entirely sure what the technology is, as I've heard
two different stories.  Anyway, this is basically what makes
the quattro a 4-wheel drive car.  In a "regular" car, power
is sent from the engine to a differential (in the front or
rear, depending on whether it's FWD or RWD).  The diff then
sends power to one of the two wheels, right or left.  Standard
diffs will send power to whichever wheel spins easiest;
thus, it's a one-wheel-drive car, and worse, the wheel that
gets the power is the one that's sitting on ice.

An AWD car has two diffs, one in front and one in back; plus
a center diff.  The quattro uses a Torsen center diff, which
won't just send power to the "easy" side.  So now, both the
front and rear diffs have power, and if each of them sends
power right or left, you've got a two-wheel-drive car.

The diff is necessary because it allows each tire, left and right,
to rotate at different speeds (e.g. for turns).  But in really
slippery stuff, and at low speeds, there are times when you'd
prefer to "lock" the diff... that is, force both wheels to
spin at the same rate, locking them together and delivering
power to both.  Do that front and back, and you've got
true 4-wheel drive.  That's where the ELD comes in.  At low
speeds, if the A4 detects wheelspin between left and right
on either diff, it will lock that diff.  I had assumed it
did it with an electrically-activated clutch of some sort, but
I've also heard that it does it by selective brake application
on the spinning wheel.  Anyone know?

> 2) CD Changer: Do you really have to pay the dealer $600 to
> install a changer that one could install by themselves for
> $300? Could one install an "off the shelf" changer from
> Crutchfield or any other similar outfit?

The Audi changer is an Alpine with modifications.  The control
signals have been altered; there is no off-the-shelf CD changer
that will talk to the Audi Delta head unit.

There is a company called Precision Interface Electronics (they
have an 800 number) that has been working on an adapter that will
allow you to use the standard Alpine changer off-the-shelf.
As of June, they didn't have the adapter ready for sale yet;
you might want to check.  As I recall, the adapter was going to
be somewhere around $100, and the best street price on the Alpine
changer is somewhere in the low $300's.

Consider, too, that paying $600 for the dealer-installed Audi
changer also buys you warranty protection for 3 years / 50000
miles.  I decided to get the Audi unit, and am quite pleased
with the performance.

Your other option would be to install your own aftermarket
changer AND head unit.  Be aware that the dash has a wider-than-
standard-DIN opening, so while a DIN-mount head unit will install
there, there will be a gap on each side between the faceplate
and the wood dash trim.

> 3) Tires/Snow tires: Do you recommend snow tires for this car?

I'd like to hear some answers on this, too.  I'm in NJ, and
even though we had some wicked snow last year, I'm planning
on going year-round with all-season tires.  I assume that
the decision to put snows on the car is not so much for
snow performance, but to allow one to put higher-performance
tires on in the "dry" months.  I'm not taking exit ramps
at 80mph, and I think that today's high-performance all-season
tires are quite respectable for their dry performance.

> 4) Performance Upgrades: Are there any chips or air filters
> which would increase the 172 hp?

Schaumburg Audi (Chicago) sells a modified throttle body.
They take the stock throttle body and bore out a restriction.
It doesn't increase peak hp, but seems to improve torque at
middle rpm (2000-3000 or so).  It costs about $300.  The
change is very subtle, but at least it's something.  They
also recommend replacing the paper air filter with a K&N
panel filter.

Dan Masi
'96 A4Q