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RE: S1 and sport q data (long - complementing history)
Hans, great information, love to hear more. According to Stig hisself,
Walter was rumored to use the torsen center on pavement stages... Some
further documentation from my library and 95 FIA Groupe A S2 service btdt:
>The S1 weight distribution was somewhere between 55/45 and 52/48 with
>two people and a fully loaded tank, depending which sources you
>believe. The sport-q used conventional LSD's front and rear and no
>centre diff. I have no records which show that the sport-q ever used
>a tor*en in competition as a centre diff. But the S1 is a different story.
>From what I read and heard the S1 was run with the following configurations:
>front: VCrear: conventional LSD or VC or tor*en
Remember that audi was really smart during homog applications. You say "or"
you *never* have to use it. However, in the front and rear diffs, even the
95 S2 FIA rally car I service has the torsen available. The notes in the
logbook discourage it's (front) use. More specifically, they say try it, and
take it out if it isn't working for the "driver or the rally conditions".
Current advice from Bruno K, JB and AS contacts indicate that fixed or open
should be used. My driving experiece with the car: Any tarmac stages, go
open. Locked f/c/r is an experience not forgotten on pavement. It's like
driving a crab.
>centre: VC and a split torque center diff on gravel stages and a
>tor*en on asphalt stages and a Porsche 959 multi-clutch centre diff
>at the 1985 1000 Lakes
* Stig shared with me that the torsen was never used in the loose ( I
suppose that could mean it might have been used on tarmac). I never got up
the nerve to ask if there was a bonus for using the torsen, hazard pay as it
>At the 1985 SanRemo the rumours are that Walter Roehrl used a tor*en
>center diff in his winning S1 and a variable multi-clutch Porsche 959
>system has been used on the 85 1000 Lakes rally.
The variable torque clutch was the precurser to the active diff, however,
different from a torsen because it could be constantly split to rear bias.
I'd sure like to hear more confirmation about the SanRemo event. However,
let's put all this in perspective, the S1 itself (Homog approved 7/1985) only
ran the following rallyes (+ pikes peak 1986/87):
* 1000 Lakes - 1985 (Mikkola) - DNF loss of oil
* San Remo - 1985 (Rohrl) - Win
* RAC - 1985 (Rohrl) - DNF - went off
* Points 1985: 1. Salonen (debut year of 205T16) 2. Blomqvist 3. Rohrl
Stats: Audi S1 wins 1 of 12 (audi entered in 11/12, mostly Sports), 205T16
wins 7 of 12 (entered in 9/12)
* Monte Carlo 1986 (Mikkola) - 3rd
(Rohrl) - 4th
Stats: Audi S1 entered in 1 of 3 ran (before audi withdrew from groupe B)
So if one is to believe that the center torsen in the S1 was used only on
tarmac, those rumors could only apply to either San Remo and/or Monte Carlo.
>The 959 centre
>clutch should not be confused with the PDK gear box which had the
>main function of being able to change gears under full throttle.
Also a note that all the rallye audis used a electro-hydraulic clutch in
rallye since 1986, which enabled left foot braking and shifting while on
throttle (read: no need for the PDK). The advice we received during our
conversations with several in the know, was that if you were going for the
rally win, hook that puppy up, otherwise disconnect it. Disconnected on the
S2 I service. Also, interesting to note, Bruno didn't use it all the time,
Buffum did, currently the sprongls don't. It has a way of eating expensive
gearboxes. I also learned the hard way that you don't want your foot under
that when activated.
>Other sources say that with the introduction of the 6 speed gear box
>variable torque split center diffs were used for the first time. Not
>sure if the sport-q ever run a six speed box though.
"The Sport quattro was homogolated with a special 6 spd gearbox, which at a
later stage in it's development, gave varialbe torque split to the front a
rear axles, Mortimer's car is fitted wiht a 5 spd box, as used at the Sports
debut in Corsica in 1984" - "Audi Sport Quattro Road Test -Car South Africa
- Jan 87".
Also, interesting to note in the same article: "According to Jeff Mortimer,
the short car was developed mainly for use on tarmac stages in Europe, where
the longer Quattro was beginning to suffer from terminal understeer at the
pace it was forced to run against the new Groupe B challengers."
Same article on the handling of the S1 with locked diffs "The handling is
rather like that of a front wheel drive car in that it is an understeer, but
only at a limit a few drivers on earth are brave enough to discover. The
nice part is that if you do overdo it, you can back off the throttle and the
car will just slow down. Because of the 4wd, there is no sudden oversteer
when the throttle is lifted mid corner. To get the rear end to break loose,
you have to flick the car on the approach to the corner, then hold it in a
We can also tell from some research into the "Just for Sport" article in Cars
and Car Conversions Nov 1986 that the 6 speed was indeed used on the sport
with <no> (read locked 50/50) center diff as the car they tested. Also in
that article was the reference to the "new 6spd" transmission being
introduced at Safari 1985 (April), the first 6spd in WCR. This tested car
was fitted with "the competition quattro system- solid shaft centre, front
and rear diffs and a complete absence of cockpit diff locks (redundant) -
makes good use of such power."
>Another data point in the never ending tor*en debate from the
>"father" of the quattro system Jorg Bensinger quoted from an Autocar
>& Motor article 6 Sept.1989
>" Bensinger elaborates: The tor*en diff feeds more torque to the
>output that is spinning more slowly,so,when cornering,mote torque
>goes to the rear wheels. It reacts before you can even measure a
>speed difference, so on snow the car will go straight into
>understeer. With a fixed 50/50 split, sometimes the front wheels will
>spin so you get initial understeer then oversteer,which is less controllable.
>From the very beginning we looked at all 4wd forms available ,
>including viscous couplings, before opting for a 50/50 centre
>differential and manual diff locks. Had we known about the tor*en
>diff then, it would have been in the orignal Quattro"
I'm not with that thinking. If that was the case, let's fast forward to 1995
S2 FIA groupe a car (MTM prepped to AS specs) I'm intimately familiar with.
With the car came a couple of crates of parts including: Open, locked, VC or
torsen front diffs. Open, locked, VC or torsen rear diffs. Center? Fixed.
No locking ability from the cockpit, no extra parts, no torsen option. Given
groupe a rules, this doesn't make sense based on your quote above. I can
also share that the ex 200 trans am car that runs prorally runs fixed center,
as does the factory prepped 90q20v that runs prorally, as do the Sprongls.
I would also propose that Stig (see my post 8-2-99 - he signed his quote for
me too, btw :) disagrees with Bensingers statements of the locker vs the
torsen, so do the later groupe A cars (private entries), and the current USA
prorally cars. Any of the current and/or ex prorally/FIA cars running
*could* be fitted with a torsen center easily. Interesting to note that Stig
took number 2 drivers spot over Walter by 16points in 1985 (that's AFTER
figuring Walters only win at San Remo).
I can read the above and see that Bensinger doesn't see that the proper (or
improper) slip angle differences accross the axle can send all torque shift
to the front wheels during a turn. Regardless, audi rallye history continued
'after' his thoughts, well documented in application. Interesting to note,
if you read Jeff G's interview with Stan Chocholek himself, Stan agreed that
U-O-U.. was possible, and that Rover declined the center diff application
because of this possibility.
Thanks for the information Hans.