Shocks/springs/ride height

[Todd Phenneger]

If the shaft in a oem shock on an oem car were an inch longer
then of course it would still compress it.  But would compress
it an inch less before the shock bottomed out.  NOt a good thing
for shock longevity.  Thats why the bump stops are there. 
  Now, you talk of shortening the shock when you lower a car. 
This is true in theory, but in practice rarely happens.  Take a
look at the technical drawings for Bilstein shocks for the 4000q
and ur-q.  The sports are the same length compressed and
extended as the HD's are.  And for the rear actually have the
same dampening rates.  Roughly 110/55 if memory serves.  Now
look at them for the 5ktq.  On this car there is a difference of
about .5" between compressed and extended lengths of the HD's vs
Sports.  BUt that difference is only at the top of the travel
while extended, Not on compression.  WHat this means is that if
you have the HD's and lower your car, thats FINE.  But if you
have the sports and return the car to stock height then you may
have troubles with the shocks reaching their limit on extension
going over large holes, up hills, etc.  I currently have this
problem with the 10" springs in the rear of my Coil-over
equipped 4ktq.  It needs 10" springs to get the travel needed by
a rally Car.  But finding a shock with enough travel has not
been easy.  But the 5ktq front Bilstein HD has over an 1" more
extention than my current 4kq/urq Bilstein.  It should fit the
bill nicely.
  BTW...I am NOT in ANY way saying you should lift a car by
lengthenign the shock shaft.  I saw mention to that in your post
and want to be clear that I am NOT saying that.  Dont know where
that came from.  But I've been on the phone extensively with the
Bilstein Shop (their technical and race dept) looking at
different shocks I can use so I have way to many numbers dancing
in my head.  But in the process have learned some interesting
things about the Audi Lineup of Bilsteins.
  BTW....try this some time.  Replace a set of shocks with the
same shock but valved to be much stiffer.  SURPRISE...your car
now sits higher.  Not much but its higher.  NOw low pressure
shocks wont do this, but a High Pressure Gas shock will as it
exerts outward force ont he piston Rod.  This pushes up on the
car and it will lift it a bit.  KYB"s are High Pressure and can
lift the car a little.  
  As for the mounts, whats the recent confusion you speak of? 
Its pretty well documented what happens when you put Blue mounts
in front or black ones in the rear of a 4kq.  The black ones DO
make the car sit higher.  If you dont believe me then go try it.
 I have many times.    However, there are 3 different PN# of
blue upper strut mount.  All three will have the car sit lower I
believe but only one or two actually have the beefier bearingh
in them.  Dont have the numbers handy though.  Sorry.
 l8r
    Todd

--- John Larson <j.d.larson at verizon.net> wrote:
> If the shaft of the shock were an inch longer, or even 2",
> what would
> prevent it from compressing?  A frozen shock is one thing, a
> shock of
> improper length is another.  When you shorten a spring to
> lower the car, it
> requires a corresponding reduction in length on the part of
> the shock to
> preserve the effectiveness and range of its operation.  You
> cannot lengthen
> a spring to achieve a higher ride without lengthening the
> shock (which
> limits the overall increase in height by acting as a stop at
> full extension)
> to allow an increase in the height limit. Failure to do so
> only makes the
> spring effectively stiffer, it doesn't increase the height.  I
> agree with
> you on the mounts, although we've recently had conflicting
> reports of ride
> height direction and extent.  John
> ----- Original Message -----
> From: "Todd Phenneger" <tquattroguy at yahoo.com>
> To: "John Larson" <j.d.larson at verizon.net>;
> <duncan at systemcontrols.co.nz>
> Cc: <quattro at audifans.com>
> Sent: Friday, May 18, 2001 11:56 PM
> Subject: Re: Shocks/springs/ride height
> 
> 
> > I seriously doubt that its to long a shock.  If that were so
> > then in driving you would get no compression at all.  Ever
> > driven a car with a Siezed shock, its bad.   Shocks can
> affect
> > ride height, just not that much.  Its common for Bilsteins
> to
> > raise a car a touch.  While they wont support the car, they
> do
> > exert force outwards.  To keep a shock compressed takes
> force
> > (maybe 100lbs)  A stiffer shock can raise the car because it
> > takes more weight to compress the spring and shock package. 
> But
> > usually we are talking more like 1/4" not 1".
> >   I wonder if possibly he used the wrong upper strut mount. 
> Its
> > Fairly common knowledge that the blue ur-q mounts will make
> a
> > car sit 1/2"+ lower than the 4kq front mounts.  If he put in
> > 4kq/90q front mounts and had rear or ur-q mounts in before
> (or
> > worn 4kq units) then that could accont for the raise.
> >   l8r
> >      Todd
> >
> > --- John Larson <j.d.larson at verizon.net> wrote:
> > > Let's think about the ride height question.  You can
> compress
> > > KYBs, and even
> > > Bilsteins, by hand.  Let's say the car weighs 3600 pounds,
> > > that's 900 pounds
> > > per corner.  That's gonna compress them right to the
> limit.
> > > You have
> > > springs, held in check only by the shock absorber (or
> insert).
> > >  See where
> > > I'm going?  The spring holds the car up, and it's length
> is
> > > controlled by
> > > the presence nut on the end of the shock.  Take the nut
> off,
> > > releasing the
> > > end of the shock, and the car could theoretically rise
> until
> > > the spring
> > > reached it's unrestrained length.  The sheer weight of the
> car
> > > prevents
> > > this, however.  What you have is a problem with the length
> of
> > > the piston,
> > > not the pressure of the gas inside the insert (shock). 
> You
> > > need a shorter
> > > shock.  HTH, John
> > >
> >
> >
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