[V8] Track F/R discussion

[QSHIPQ at aol.com]

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








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