RE: Dan Bubb's long winded subject killing response to Re: dead horse spring question

["Fry, Larry" <LEF@chem-tronics.com>]

I'll buy that.

Larry  sandiego16V

-----Original Message-----
From: Dan Bubb [mailto:jdbubb@ix.netcom.com]
Sent: Monday, October 29, 2001 3:57 PM
To: Fry, Larry; Chris DeLong
Cc: ethos101@netzero.net; scirocco-l@scirocco.org
Subject: Dan Bubb's long winded subject killing response to Re: dead
horse spring question


Is everyone really tired of this subject yet??
OK...Here I go!
In order for a car to ride reasonalbly well the front and rear spring rates
need to be a certain ratio to each other. What is of importance is the
suspension frequency (i.e. the weight of the supported mass at one end of
the car divided by the spring rate at that end of the car) and not just the
spring rate by itself. In practice a car will seem to ride well if after a
bump the car "lands" horizontally. This means both front and rear hit the
low point of their strokes after the bump at the same time. Think in terms
of hitting a bump with low front frequency; the front is slow to rise, the
back kicks up and lands before the front settles. The back is hitting its
second occilation before the front has completed it's first! Anyway, for a
good ride the rear frequency needs to be higher than the front frequency
since it hits the bump later than the front (unless you're driving
backwards). This ratio of frequencies is basically an equation based on
wheel base and the projected average speed of the car, in other words the
speed at which the car would be optimized for ride since it spends most of
its time there. A car with a longer wheel base needs a relatively higher
rear frequency since the rear hits the bump relatively later. Also,
optimizing ride for a lower speed again means a higher rear frequency.
So, what does all this mean???
If you add 200 lbs to a car and 90% is added to the front axle (ala 16V),
the rear spring rate may need to increase a little to maintain the same rear
suspension frequency.  The front spring rate needs to increase quite a bit
to maintain the same frequency. Ride height is irrelevant to spring rate and
suspension frequency! Pick a ride height, pick a frequency, design a spring
to meet these two requirements!
So, based on this information and believing that VW still cared about ride
and handling when they produced the 16V I'm pretty Godamned positive the
front spring rate is higher than the 8V. Adjusting spring height to get the
desired ride height while maintaining the desired frequency is just plugging
in the numbers. Also, did anyone notice that VW increased the rear sway bar
diameter for the 16V? Why? Because the front spring rate went up, causing
the front roll stiffness to increase which would make the car understeer and
to rebalance the car VW put on a stiffer rear bar.
NOW, that's why I keep saying don't put 16V springs on 8V cars or 8V springs
on 16V cars! The spring rates do not produce the proper front/rear ratio of
suspension frequency and roll stiffness. It's not just the resultant ride
height that matters!
Dan
PS. For what it's worth to anybody that's gotten this far, cars that are
dominated by their aerodynamics (F1, LMP 900) disregard all of the above!
Ride doesn't count, aerodynamic efficiency does. Typically this demands a
very stiff front suspension with the back having a little more resilience.
So, in this case the frequencies are reversed where the front is much higher
than the rear.

----- Original Message -----
From: Fry, Larry <LEF@chem-tronics.com>
To: Chris DeLong <green536@hotmail.com>; <jdbubb@ix.netcom.com>
Cc: <ethos101@netzero.net>; <scirocco-l@scirocco.org>
Sent: Monday, October 29, 2001 12:10 PM
Subject: RE: dead horse spring question


> Chris-  I've been trying, using your information, to figure out just how
the
> 16V obtains a lower ride height using springs that raise an 8V car.  But,
> all I've done is give myself a headache.
> What's your theory?  What is anyone's theory?
>
> Larry  sandiego16V
>
> -----Original Message-----
> From: Chris DeLong [mailto:green536@hotmail.com]
> Sent: Sunday, October 28, 2001 12:13 PM
> To: Fry, Larry; jdbubb@ix.netcom.com
> Cc: ethos101@netzero.net; scirocco-l@scirocco.org
> Subject: RE: dead horse spring question
>
>
> The VW brochure states that teh 16v is 10mm lower than the 8v. Although
the
> car might be lower I know that if the stock springs for a 16v are
installed
> on an 8v that the car will be lifted about 26mm.
>
> Chris DeLong
> ICQ#45030867
> Seattle, WA USA
> '80 16V 'Rocco ragtop
> '91 GLi 2.0 16V
> '77 Rabbit 16V
> '80 'Vert (parting out!)
> '61 17 Window type II
> '91 Vanagon
> '78 Rabbit
> '78 Rabbit (for sale)
> '87 GTi 16V
>
>
>
> >From: "Fry, Larry" <LEF@chem-tronics.com>
> >To: jdbubb@ix.netcom.com
> >CC: ethos101 <ethos101@netzero.net>, list <scirocco-l@scirocco.org>
> >Subject: RE: dead horse spring question
> >Date: Fri, 26 Oct 2001 07:27:00 -0700
> >
> >You are presuming that both 8 and 16V cars use the same spring rate, so
the
> >lower ride height (of the 16V) is the result of more weight.  I'm not
sure
> >this is the case.  On the other hand, I am presuming the stock 16V
springs
> >are shorter/stiffer than 8V.  How about a third opinion?????
> >
> >Larry  sandiego16V
> >
> >-----Original Message-----
> >From: Dan Bubb [mailto:jdbubb@ix.netcom.com]
> >Sent: Friday, October 26, 2001 7:25 AM
> >To: Fry, Larry
> >Cc: ethos101; list
> >Subject: Re: dead horse spring question
> >
> >
> >Actually, since the 16V is heavier, the car would ride lower.
> >This presumes that the 8V and 16V's would sit at the same height with
> >the correct aftermarket springs and that the 8V spring rate is lower
> >since the car is lighter.
> >Dan
> >
> >"Fry, Larry" wrote:
> > >
> > > Probably give you a higher ride height than with a spring designed for
> >the
> > > 16V, since 8V MkII's sit taller than the 16Valvers.
> > >
> > > Larry sandiego16V
> > >
> > > -----Original Message-----
> > > From: ethos101 [mailto:ethos101@netzero.net]
> > > Sent: Sunday, August 26, 2001 12:47 AM
> > > To: list
> > > Subject: dead horse spring question
> > >
> > > hello all,I found a set of nuespeed springs on a cabriolet in the yard
> > > today.I called to check the part # with neuspeed to verify its
> >application
> > > as my catalog did not show the exact number,( 55.10.01 F) .They said
it
> >was
> > > for  cabby(no suprise) or mk.2 scirocco  8 valve.Id like to try them
on
> >my
> > > 87 16V  .bad idea? TIA Robert
> > >
> > > ----------------------------------------------------
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