Re: quattro-digest V4 #78

[Dave Eaton <dave.eaton@minedu.govt.nz>]

..>From: QSHIPQ@aol.com
..>Date: Mon, 13 Jan 1997 02:53:19 -0500 (EST)
..>Subject: Re: diffy q's
..>
..>In a message dated 97-01-13 02:11:26 EST, you write:
..>
..><< > Ok, but one the most tweeked of Urq's here in the states didn't 
..> > catch the M3 at the track here, rain or dry.....  M3 is not a 323 or a 
..> > 328.....
..> 
..> I find that difficult to believe. Not that I don't believe you. It's just
..>I'm very
..> surprised. BTW what are we really comparing here. If you want a real
..> comparison of the quattro advantage surely you have to compare 
..> basically identical vehicles one with quattro and one without. Just as
..> Audi did when it was first developing the urQ. I will post the article about
..> this tomorrow.
..>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
..>$ for what you get, is how I compare them, racing venue the M3 is exactly the
..>A4q counterpart, there the a4 does circles around the M3, NOT so in the Real
..>world, but there we have to compare to other cars?  

perhaps where you come from the m3 is the counterpart of the a4q, but not here
or in oz by a long chalk.

the m3 evo in nz (euro spec) is 320hp stock (is this high hp?) and costs $150k nzd.
there is no audi a4 in nz for sale that i know of for more than $100k.  i test
drove an mtm tuned a4q with 286hp which would have cost me $105k new.
apples and oranges?  the m3 and rs2 *are* in the same ball park pricewise.

..>Not sure I follow
..>this.....   I would even take the lowly 328i two door vs the A4q for a more
..>apples to apples....  Drive a 951, an RX7...  Weight, COG, Brakes, balance,
..>LSD rwd are all tough to beat without resorting to the hihp equation in a
..>stock car....  It' s just not there.....  Let me restate that, It's Not
..>there...  Believe it or not....  I urge you to drive these cars...  50/50
..>weight does wonders for offsetting the q advantage, so does good brakes....

yeah but these things are *not* changed in class 2 racing.  while suspension
and engine mounting can be changed these can't be changed significantly,
while brakes can.  so your cog argument doesn't apply.  the class 2 a4q
has the usual audi quattro transmission arrangement (motor out front, front
driveshafts exiting the bellhousing).  weight is parity by the rules except than the
a4q is 45kg's heavier than the bmws and 95kgs heavier than the volvo and
renault and fwd brigade.  hp is within a few percentage due to rev limiter (and 
less than the stock euro m3 or rs2 here in nz).

i'm also not convinced that the a4q hasn't run torsen.  the racecar engineering
article specifically mentions torsen centres.  i know that phil has personal
experience of a non-torsen car, but that doesn't mean that all class 2 cars are
not torsen, or that torsen is not run at some circuits.

i scanned the article and the relevant part of it is below:-

"Transmission

Compact packaging and a simplified driveline are crucial elements in the design of 
the well-known Audi Quattro four-wheel-drive system. A cast magnesium alloy casing, 
comprising three separate main sections, bolts onto the rear of the bell-housing flange. 
The forward section of the casing contains the front differential and front axle 
assemblies, the second the gear ratio set and the third, the centre differential. 
This unitary construction allows the ratio set to effectively form a cassette which 
can be removed and replaced within minutes. Similarly, the centre differential may 
be removed and replaced without dismantling the gearbox. A significant feature of 
the system is that drive from the central unit is carried forward to the front differential 
by means of a steel propeller shaft, running through a hollow lower gearbox shaft.

In the case of the A4 racecar, the forward differential unit is a viscous coupling. The
rear differential is driven by a carbon fibre propeller shaft. This is connected to the rear
flange of the central differential by a coupling formed by a Kevlar plate with a three-bolt 
fixing on either side which allows up to 2deg of misalignment.

The rear differential can be either a viscous coupling or a plate-type differential, and 
the central differential either a viscous coupling with torque-split or a Torsen unit, the 
choices being dependent on the circuit characteristics and driver preference. 

Torque splits ranging from 70:30 to 50:50 are available. After pre-season testing front:rear 
split options of 64:36 and 61:39 were selected for the BTCC.

The driveshafts are tubular steel, although titanium shafts have been used in the past. 
These are supplied by Lobro and are fitted with universal joints at their outer ends and 
tripod joints at their inners. The tripode inner joints allow angularity in  the driveline 
particularly in the front axle line where, due to the more rearward engine location of 
the racecar, the driveshafts are angled approximately 10deg rearwards from the uprights.
"

tally ho!

-dave
'93 s2
'90 ur-q