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

[Taka Mizutani]

That doesn't sound right, Larry.

The TEIN (note spelling) Flex and similar are not intended to just vary
preload-
the whole point of having two adjustable spring perches per shock is so that
you
can change the ride height _without_ affecting preload. If and only if you
need to
change the preload, you can tighten the actual distance between perches.

The H&R coilovers strictly adjust ride height and preload together, as there
is only
a threaded lower spring perch and a fixed upper perch. Hence the
disadvantage of such
a setup. Preload is most definitely affected any time you adjust the spring
perch on
a single adjustable perch setup like the H&R.

Taka


On 1/11/07, LL - NY <larrycleung at gmail.com> wrote:
>
> 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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