[A4] suspension theory thoughts, questions, etc - grooved shocks

[LL - NY]

Until you run out of travel in the shock, when you move the spring perch on
any (fixed upper mount or adjustable) adjustable coil over set up, pre-load
is
not affected, and all you do is adjust ride height.

With the Tien's that Taka mentioned, by varying the distance BETWEEN the
adjustable upper and lower perches, you can increase the preload (shorten
the distance btw perches) or decrease the preload (extend the perches), then
ride height is dictated by where along the shock body the top perch is
positioned.

On the H&R's that Taka mentioned, if you raise or lower the adjustable lower

perch, pre-load is unaffected until the shock either tops or bottoms out,
lower
until the shock is fully extended, and pre-load is decreased (but car is
sitting
on the ground and shock is well past it's designed travel (it's bottomed),
seals
may fail, etc),  raise the perch to compress the spring and the shock is
topped
out and car looks like a Baja runner. In either case, the shock is at its
full travel,
hence it's no longer acting like a shock, it's now a rigid suspension
member.

Grant's summary is really quite good. Just adding further fuel to the info
fire, here.

LL - NY

On 1/11/07, Taka Mizutani <t44tqtro at gmail.com> wrote:
>
> By having adjustable upper and lower perches, you can move the entire
> spring physically lower to the ground in order to lower ride height. You
> can't
> do this with the cheaper coilover setups- compare Tein Basic to Tein Flex
> and you'll see what I'm talking about.
>
> With the cheaper setups (like the H&R coilover setup I had on the A4), you
> lower ride height by scrunching the lower spring perch up and compressing
> the spring to shorten the distance.
>
> Sorry if I'm not using the correct terminology, but if you take a look at
> the two
> products I mention above, you should be able to see exactly what I'm
> talking
> about.
>
> The advantage as I understand it, is that you do not change the effective
> spring rate
> if you can move the entire spring body in relation to the shock body
> rather
> than merely
> compressing the spring to lower the car.
>
> Taka
>
>
> On 1/11/07, Grant Lenahan <glenahan at vfemail.net> wrote:
> >
> > What, precisely is adjustable about the top perch, and how can you
> > preload a car spring?
> >
> > Grant
> > On Jan 11, 2007, at 7:16 AM, Taka Mizutani wrote:
> >
> > > Adjustable lower and upper perches definitely do exist- they're pretty
> > > common
> > > on the coilover setups for the Japanese cars- I know I'd get that type
> > > of setup if
> > > I were to go coilover on the STi. Allows you to separately adjust
> > > spring preload
> > > and ride height, which is really nice. Add two-way adjustable damping
> > > and camber
> > > plates and you have a really trick setup that's way too adjustable for
> > > 90% of people
> > > who buy these things. Takes way too much tweaking to get right unless
> > > you have
> > > a baseline setup already developed for the car.
> > >
> > > Taka
> > >
> > >
> > > On 1/10/07, Grant Lenahan <glenahan at vfemail.net > wrote:
> > >> > in looking at 'real' "coilover" designs [i too have always thought
> > >> it
> > >> > funny that they're called coilovers when pretty much every
> > >> suspension
> > >> > i've come across is a shock inside a spring] they do all use the
> > >> same
> > >> > principal - an adjustable lower perch. with the exception of the
> > >> > stasis motorsport coilovers, these look like they have an
> adjustable
> > >> > upper perch as well. and they outta at 4grand.
> > >>
> > >> I have never seen an adjustable upper perch. What you may have seen
> is
> > >> a camber plate, whcih allows you to adjust CAMBER, but not ride
> > >> height.
> > >> Its a slotted plate you attach the strut top to.
> >
> >
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