[V8] Track F/R discussion

Tue Apr 17 10:52:56 EDT 2007

Oh, and to focus on alleged "inaccuracies" in the track widening --
sometimes it helps me to think in extremes, as if you had 20-foot
spacers on the front wheels and tubbed the rear.   TONS of front
cornering grip, but (a) it's be nearly impossible to rotate the back end
around, and (b) the effective lower CG and weight displacement as a
result would definitely affect the suspenstion geometry -- I mean, would
shorter springs  really have as much effect with this (obviously
hypothetical and absurd) track setup?   This is part of the thinking
that makes me doubt the benefit of spacing front track without spacing
the rear the same amount on an AWD or RWD car if you want to kill
understeer and make NO other adjustments.

whatever,
DaveC.

________________________________

	From: 32vquattro [mailto:allanvega at adelphia.net] 
	Sent: Tuesday, April 17, 2007 10:21 AM
	To: QSHIPQ at aol.com; ingo.rautenberg at gmail.com;
jward.v8 at gmail.com
	Cc: v8 at audifans.com; Coleman, David
	Subject: Re: [V8] Track F/R discussion

Steve, not looking to get into a pissing match here. You and Jack both
obviously have allot more experience tuning suspensions than I do. That
said,I was merely responding to some inaccurate quotes that Jack made
about what Igor said about widening the trac affecting the suspension
geometry. From there, I explained how I am going to address some of the
ill affect that come with lowering a car. Bump steer is one of those
problems that arise when lowering a car. Jack seems to agree with me
that its logical to flip the tie rod to accommodate the drop. His
question to me was "will it work?" In theory, I believe the answer is
yes. will the steering arm need to be modded? Yes. How would you address
the bump steer for a 1.5" drop? (not saying you would drop your car that
low....but if you did) I'm just addressing problems as they arise. As
for how I will be using my car,let just say it will never see the track.

Question to both you and Jack. 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?

		----- Original Message ----- 
		From: QSHIPQ 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: Tuesday, April 17, 2007 9:12 AM
		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.