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

[Brandon Rogers]

Whats the difference bewtween how the grooves work and coilovers - don't
coilovers just use threads to alter the perch location only?  

If it is that stiff at lowest settings - I'd be curious what its like
when you raise the car - would adding preload, thus raising car, change
your spring rate?  Actually as a think about it - the I guess the spring
rate would not change if they are linear rate springs, but _could_ if
they are progressive depending on where in the stroke it sits....?

Brandon 

-----Original Message-----
From: a4-bounces at audifans.com [mailto:a4-bounces at audifans.com] On Behalf
Of thejimrose
Sent: Monday, January 08, 2007 3:30 PM
To: quattro at audifans.com; a4 at audifans.com
Subject: [A4] suspension theory thoughts, questions, etc - grooved
shocks


hey all - i've got a question and some thoughts and btdt i'd like to
throw out for collective rumination, enjoyment, infotainment and maybe
edification. i installed a suspension kit on my a4 from neuspeed [got it
used, cheap] that includes bilstein sport shocks and neuspeed sport
springs [a bit lower and stiffer]. the shock bodies are grooved and
include a big C clip which the lower spring perch sits on, to allow the
ride height to be 'adjusted'. it's nothing new, but i'm suspicious of
its merit.

what i don't understand is how raising / lowering the lower spring perch
on the shock body will adjust ride height? all it seems to do is preload
[compress] the spring, since all it does is shorten the distance from
upper to lower perch. it doesn't change suspension geometry at all. i do
understand that, as a byproduct of this preload, that the car
could/would/should sit a little higher since the spring is pushing
harder against the body, which is more likely to give than the road.. =)

the question comes because, in installing them it was almost impossible
to get the springs compressed enough to squeeze into the 'highest' ride
height setting - aka the uppermost lower spring perch setting aka the
shortest distance between the perches aka the most preloaded spring. set
this way there is virtually no room between several coils - they touch,
so there isn't much room to suspend if the spring coils are touching at
that point it's a sleeve not a spring =]. the NS springs have far more
windings than the stock sport springs do.

as a review, i'm not thrilled with the setup so far. it does handle like
a gokart [for good and bad], its a load of fun but very bouncy and the
car wants to launch itself when the suspension unloads over bumps. there
is NO dive or squat or sway. it's a crapload of fun in the turns but is
unsettled easily. when i installed it all i planned to set the perches
at full high, but i ended up installing them full low, partially because
i figured it better to have the least preloaded spring, which i thought
would ride better vs a higher riding, but more preloaded spring. i was
also forced to install them full low because the crap compressor i have
wouldn't allow me to physically compress the springs enough to squeeze
them between the perches [at the highest setting]. ideally i would want
slightly higher ride height, but i'm afraid of preloading the spring
more and losing what little ride compliance there is. [i have a feeling
that i just asked the suspension holy grail question and the only answer
is $$$$$$$$$ =]

so i guess my questions are; is my understanding of the adjustability
and function accurate? i'd like to validate my suspicions before i make
more changes. what i'm thinking is to install my stock sport springs on
the bilsteins but i'm worried it would go the other way [overdamped -
soft but harsh]. ive heard this setup works well on non-grooved shocks.

did any of that make sense? =)
thanks all!
jim
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