[V8] Track F/R discussion

Tue Apr 17 13:05:10 EDT 2007

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-

________________________________

	From: 32vquattro [mailto:allanvega at adelphia.net] 
	Sent: Tuesday, April 17, 2007 11:07 AM
	To: Coleman, David; QSHIPQ at aol.com; ingo.rautenberg at gmail.com;
jward.v8 at gmail.com
	Cc: v8 at audifans.com
	Subject: Re: [V8] Track F/R discussion

	This is my last post on the subject. Too many of you hear what
you want to hear, rather that what I'm typing. 

	Now Dave, what does your wifes Odyssey have to do with a lowerd
v8? the last line I posted was " On a lowered car, which is more
susceptible to bump steer? the one that rides smooth (or semi smooth)
race track, or the one that rides down your typical public road or
highway?"

	Please read "lowerd" and "more susceptible".  I didnt ask if was
more imortant or that it matters more on a track verses  the street.
Symply that you will experiance it more on the street than the track
with a lowerd car. But I guess you didn't get that. Al

	'

		----- Original Message ----- 
		From: Coleman, David
<mailto:David.Coleman at blackrock.com>  
		To: QSHIPQ at aol.com ; allanvega at adelphia.net ;
ingo.rautenberg at gmail.com ; jward.v8 at gmail.com 
		Cc: v8 at audifans.com 
		Sent: Tuesday, April 17, 2007 10:40 AM
		Subject: RE: [V8] Track F/R discussion

		Excellent mediating points Scott -- I too am following
with interest, and don't see a pissing match -- just the airing of
opinions to uncover the facts.  I am try to find the commonality between
the full-race track setup on my inherently disadvantaged yet track
record setting, championship-winning fwd Mk1 VW touring car, and a
mildly tuned street V8.   "Flipping front tie rods"?  Hmmm.  I'd like a
before/after session for that mod alone to convince me, with all the
slop in other areas, that this would make a notable difference.  Not
doubting, just need more info.. Jack's contribution has been worth my
study, even if I'm not sure it applies to non-rwd chassis 100%.

		My scca racer has a widened front track, and the front
coil-overs set to lower the front end enough so that, viewed from the
front, the control arms rest a few mms past parallel to the track
surface (i.e. ever so slightly inclined toward the hub away from the
pickup point).  Very heavy front springs, no front sway bar.  -2.5 to
-3.25 deg camber.   Out back, less heavy 400# springs, fat sway bar, and
about an inch lower than the front, with zero (-0-) deg camber.
Corner-weighting sets actual corners a tad catty-wampus in relation to
one another, but overall this setup is the result of 3 seasons of much
trial and error.  If I want better still, my next move is to take 100#
out of the front springs.   Point is -- it works well, and I love it on
track, but it'd be extremely impaired/undriveable on the highway..

		....  The V8, on the other hand, is a different car in
nearly every respect, and I'm not chauffeuring bank CEOs on a daily
basis.   But I do drive it on the highway, sometimes for exended periods
of time with a passenger or two.  So I want crisp, *predictable*
handling that will respond to an on-track mentality, but not require
enough concentration to miss a roadsign or a witty observation from the
passenger area...  An RS6 provides to me about the ultimate feel, but to
achieve that would require changing every single part on my car to that
from an RS6...   8-)

		With koni/H&Rs installed, and the hunt on for a rear
bar,  I'm about there... would like to hear real-world experience in
adding a turn of stiffness to the front struts, but they're
rebound-only, no?   And as Scott describes it, the sucky front
suspension geometry is familiar to me and can be worked around.  I like
the appearance of the V8 lowered, and would even like to see my front
dropped another 1/2".  Hey, the DTMs were lower in front than the
rear...maybe it's time to hack a coil off my H&Rs!   And not to be
flippant, but Scott, your Pobst-approved track car has no competition
(H&R/etc) springs?  Maybe Randy was just being congenial??    ;-)

		This whole discussion came about from optimal wheel/tire
setup, which is highly subjective.  I want to be able to rotate the
tires without breaking beads, so all four wheels and tires must be
equal.   And I would first and foremost add wheel width by way of offset
rather than spacer, but am not opposed picking up some 10mm and 15mm
spacers, if for no other reason, to use as tuning tools.

		Sorry for the epic novel -- if you made it this far,
you're not working hard enough.

		-DaveC.

		PS:  bump steer matters far more on a race track  (I've
yet to see an aftermarket modification to tune the bumpsteer on the
wife's odyssey)

________________________________

			From: QSHIPQ at aol.com [mailto:QSHIPQ at aol.com] 
			Sent: Tuesday, April 17, 2007 9:12 AM
			To: allanvega at adelphia.net;
ingo.rautenberg at gmail.com; jward.v8 at gmail.com
			Cc: v8 at audifans.com; Coleman, David
			Subject: Re: [V8] Track F/R discussion

			Watching this thread with some interest, and I'm
pretty sure Jack has a firmer handle on this than Al may give credit.
IME, type 44 (and most early quattros for that matter) take to *raising*
chassis height a lot better than lowering chassis height - a tribute to
the quattro being a rally car first.  On the type 44 (5ktq) race car I
set up, I found that the best compromise in the front was to drop
~.5inches, and then address all the other ways to optimize the chassis.
I have since dropped it a bit more, but have had to totally rebuild the
suspension setup, from bar rate to spring rate.  For wide track
modifications, I see the best benefit on a type 44 by dropping this
.5in, and adding as much track as you can.  For better handling, I'd go
after wider tires front than rear (adjusting tire size for equal rolling
diameter).   Since Al hasn't indicated what the setup is for, this may
be extreme.  However, what I will say is that a triangulated front
swaybar/control arm just plain sucks.  Compared to the artistically
crafted rear multilink suspension in a type 44, it's a sin to put the
front together like that.

			As such, accept the fact that the front isn't
optimal, and optimize the rest of the car.  Spacers are one of the best
modifications, and the v8 wheel wells can accomodate the widest
additional track without mods other than the RS6.  Al, I looked at
swapping ball joints, but I really don't see the benefit.  I would
encourage you to really watch chassis loading on a alignment rack before
you go too far here.  IME, you can see the slop in that front suspension
which (to me anyway) dictates that you go after a lot of other avenue
before you drop and tweek arcs.  

			In my personal chassis tuning experience my
highest 'n'  is in the 44 and C4 .  Mostly from having to work with a
lot of the nasty effects on handling a triangulated swaybar does to the
suspension under load.  I know from simply a geometry standpoint, beyond
.5in drop on a type 44, better suspension dynamics under load can be
found elsewhere in that chassis.  One of the first and best is wider
track front.  I also don't find wheel bearing loads to be excessive with
spacers, that IME is usually more associated with drop, not width.

			Backing off my pulpit a bit, my first question
is 'what you doing with the car?'  If you want better handling, there
are a lot of stock ride height options that have better potential
handling without the compromises.  If you are doing a full out race car
(btdt), weight and chassis stiffening is one of the higher priorities.
When I read H&R and swapping steering tie rods, I think wow, I didn't
even do that on the race car yet?  And when Randy Pobst drove the beast
with me shotgun, there is no doubt that whatever I did passed good
muster ( we did have a rear brake issue, which he blamed on the caliper,
I blamed on trying to ditch that SQ behind him)

			When I read widening front track, and tire
sizing the front/rear, I think you guys are onto something good.  Al, I
guess I'm not really clear on what your objective is.  My cumulative
experience on type 44 and C4 chassis can be summed, don't be too quick
to drop, you spend a lot of time fixing something that audi already
compromised on when they shot the end of the front bar thru the control
arm.

			HTH and my .02

			Scott Justusson

			In a message dated 4/16/2007 9:21:03 P.M.
Central Standard Time, allanvega at adelphia.net writes:

				Sorry Jack, but Ingo never stated that
spacers affected how the suspension works. His exact quote was
				"Careful there, buddy! When you're
adding spacers, you're effectively
				changing the suspension geometry, even
if only slightly."

				to which my response was "......Simply
widening track doesn't affect anything 
				but the load on the wheel bearings....."

				Perhaps I should have said widening the
trac has no "ill" effect on the suspension,cept for the wheel bearings.
But since we were already talking about ill effects, I guess I felt
everyone knew what I meant. My bad. No where did I state that widening
the trac had no affect on the handling.  I mean come on man, why would I
have purchased them if they didn't improve the handling. The H&R race
springs with a spring rate of 350lbs front and 300lbs rear should negate
any spring rate loss do to the lever action of the spacers. As for
flipping the tie rods, well you got me there. It was something I didn't
put a whole lot of thought into, but it did seem logical. I guess i have
a few options. 1 Fill tapered hole with weld and re-taper from the
bottom (hard way) or 2. bore out the taper, and use none tapered tie
rods from later Audi's found  here---->  

http://www.ecodetuning.com/shop/cart.php?m=product_detail&p=102 

				Don't know if this will work, but I will
let the list know if it doesn't. Al

				  ----- Original Message ----- 
				  From: J123fs at aol.com 
				  To: allanvega at adelphia.net ;
ingo.rautenberg at gmail.com ; jward.v8 at gmail.com 
				  Cc: v8 at audifans.com ;
David.Coleman at blackrock.com 
				  Sent: Monday, April 16, 2007 9:03 PM
				  Subject: Re: [V8] Track F/R

				  I'm not sure I agree Ingo.  Simply
widening track doesn't affect anything 5/2007 6:43:10 P.
				  but the load on the wheel bearings.
Lowering a car would (and does) have an 
				  effect on the front control arm,
steering arm,and axle's. I have been 

				  Sorry Al,
				  Ingo is correct. Widing your track
DOES affect how the suspension works. 
				  You are correct, it does not effect
the static geometry, but as I have an effect on the roll center of the
car......and to say it does not effect the handling on the car is
factually incorrect. 
				  It also makes the front springs
effective rate lower by a fair bit, as you are making the lever arm
acting on the struts and springs longer. This too also effects handling.
				  I had an interesting off list exchange
about this recently, and in the middle of the MASSIVE Northeaster we
where getting here on Cape Ann ran the numbers on SusProg3D, while
watching it gust to over 70 mph on the anemometer. 
				  On our cars changing the track 25 mm
lowers the roll center 4%. Dropping the car an inch or so does about the
same thing- but you then tempt the pothole gods. This can and does
effect the suspension. I could not accurately figure out the spring rate
change as it was way too S#$%^tty to venture outside to measure the
control arm- (VW rabbit/Porsche 944/944tT control arm - same length and
articulation angles already in my database) but on a car already in the
database changing the track 25 mm changes the effective spring rate by
7+%. Not chickenfeed numbers wise. You COULD argue that it's not apples
to apples, but the Audi C-Arm IS longer, so I bet the numbers are even
higher.
				  I would be worried about the CV's- I
have seen every brand of car racing with lowered springs decrease the
life of NEW CV's by 75%+. The issue isn't the static position, but as
the suspension goes through it's range of motion and it runs out of
length. Most guys who change their geometry, change the length of the
axles also. You HAVE to.
				  I would like too see the tie rod end
inverted- this makes a LOT of sense when it comes to bumpsteer on an
lowered car with such a highly mounted steering rack, but will it work?
				  I just replaced a split braided brake
line (yes it happens, thankfully I was going slow) and spent a good deal
of time planning my subframe upgrade along with tie rod ends, ect while
replacing the hose, and I'm not too sure you could reverse the taper on
the strut arm without welding and re-machining the thing to accept the
tie rod end upside down. Do you know something I do not?
				  Jack

________________________________

			See what's free at AOL.com
<http://www.aol.com?ncid=AOLAOF00020000000503> . 

THE INFORMATION CONTAINED IN THIS MESSAGE AND ANY ATTACHMENT MAY BE PRIVILEGED, CONFIDENTIAL, PROPRIETARY OR OTHERWISE PROTECTED FROM DISCLOSURE. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, copying or use of this message and any attachment is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and permanently delete it from your computer and destroy any printout thereof.