[V8] Track F/R discussion

[QSHIPQ at aol.com]

I started my experience with a A1 scirocco, then made a rally car out of  
one, then built one with a GMP 2liter motor.  Little did I know it would  become 
a good jumping point for understanding these big understeering  pigs...
 
I think you are onto something with the DTM cars David, Audisport lists the  
track as 1501f, 1542r  1990 and 1505f,1542r in 1991.  I believe that  was on a 
19x9 wheel too, and it's only 2650lb...  However, DTM is quite  limited as to 
what they were allowed to do with the suspension design.  I  believe that 
includes bar diameter...  I don't think they increased or  reduced it, I think 
they just used the stocker by rules.
 
On the v8, starting at the back to address the front doesn't work  IME.  
Carroll Smith quick tip would be if the front washes out, it's a  front swaybar 
first....  The problem I have with increasing rear bars is  their tendency to 
lift wheels ala vw, and (T44) add front inside wheel lift from  a combination of 
chassis flex and the front swaybar relocating the inside  tire.  Understeer 
is safe.  I also learned long ago, that a front  heavy fwd/audi awd car 
understeers, live with it and optimize it's  predicatability.  Buffum actually 
references driving the quattro in his  book with a similar slant.  And Blomqvist was 
one of the most successful  drivers of the quattros because of his previous 
experience with understeering  saabs.
 
I see a lot of frustration trying to make any front heavy quattro  
'oversteer' .  Stasis has had success doing it with the high TBR  center torsen.  Drive 
anything less than a full race car at the  limit, that mod is a bit of a 
handful IMO.  And don't forget that  audi had a lot of success in racing (rally and 
tarmac) just locking the center  diff.  I shifted the perspective to living 
with understeer, and make it the  best handling understeering pig on the track 
or street.  Really want  to change the perspective, raise the car up .75in and 
run all the suspension  settings on the alignment rack, then drive it on the 
street.  Part of the  quattro advantage IME, is keeping those 4 drive wheels 
on the ground.  I  just built a 91 200tq steamboat car for a guy to that 
philosophy, it's a  fantastic street car too!
 
I guess I've become old to the school of lowering quattros, especially type  
44.  It all comes down to that darn triangulated swaybar design.  On  the LT1Q 
project, we were really close to just building a traditional control  arm 
setup.  
 
I guess my perspective is that you waste a lot of time trying to catch up  to 
a lowered type 44.  Time that could be better spent on a lot of more  
rewarding endeavors.
 
All that said, track is a good thing, and after driving Stuckey's wide  
front/narrow rear tire combo on his 5ktq, I liked that approach too.  I  just don't 
see the numbers working after .5in drop on the type 44.
 
YMMV
 
Scott Justusson
 
 
 
In a message dated 4/17/2007 11:05:51 A.M. Central Standard Time,  
David.Coleman at blackrock.com writes:
Al, I didn't mean to offend -- a pet  peeve of mine is folks hearing but not 
listening, and I thought this was a  critical discussion, not a criticizing 
one...  Re: the odyssey, it's got  nothing to do with a lowered V8.  My 
good-humored and muted point was that  bump steer is a lesser priority than the other 
parameters that are in  question.  Find what works, then tweak bump steer as a 
final measure to  smooth out transitions in specific areas of turn-in.  As a 
more direct  answer (or educated opinion), any deviation from a stock 
suspension will have an  effect on bump steer, typically adverse, assuming it was 
optimized in the  factory development.  I doubt there's any one rule of thumb in 
that  specific respect.

And Scott, my hilarious Pobst remark was followed by a  wink and a smile, 
since I'm unfamiliar with the 5kqt racer and its equipment --  I KNOW your stuff 
more than anyone I know (including the Stasis outfit) is  backed up with an 
intimate knowledge of what makes these things ungainly cars  tick.   I tend to 
skip to your posts first, then supplement with  others.  I may disagree, but 
more because of being a one-trick pony -- I  don't profess to know enough about 
the T44 to know what's right or  wrong...

It's becoming clearer to me that Audi erred a bit to far in the  direction of 
understeer, and the benefits of widening the front track a *tad*  could 
alleviate the tramming and twitchiness of a lowered car.  As I  mentioned, I did 
just that on the Mk1 racer.  I'd LOVE to see up close and  personal how a DTM 
car got that front so low with a stock front bar setup (i.e.  mounting points, 
not diameter).  In fact, I wonder if they, or someone  else, might consider a 
*smaller* front bar in the hopes to minimize ancillary  effects you mention, 
and reduce understeer.

>>"Rear track, rear  bars, rear spring rates before front tends to cause more 
front problems than it  solves at the back."<<

Agreed--this is why I start at the back and  work forward.  Or else I'd have 
an old school neuspeed front bar on the VW  and a steel I-beam in the back... 
of course then I work backward, then back  forward again, then have a beer, 
then backward...

I know some of what I  say goes against convention, but I have had great 
success with combinations that  others dismiss out of hand.  Doesn't mean I'm not 
listening to them though  -- Just because something works well doesn't mean 
it's optimal.    Perhaps if I had a better understanding of what "arc" and its 
effects refers to,  I'm sure my thought process would change.  To beat the DTM 
drum to pieces,  they didn't have to go that low and instead just used a 
deeper air dam instead  -- so how and why did they then?  H&R may not have wanted 
to be liable  for smashed oil pans on street cars, but if they're not 
progressive springs,  what's the huge give-up with losing another 1/2"?


-dc-
 



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