[V8] More Spring Info

[Carol, Dave, and Zach Weiss]

Hi, folks.  I’ve been quiet for a long time, but do check in occasionally,
and saw this thread.  Here are a few of my notes from 1996-97(!); hope they
are of some help.  I calculated the stock front spring rate as a check on
Hoppen and came out pretty close.  I think the Sport Wheels spring rates
were different because they measured them.

 

The Eibachs for the S4 were NLA at the time, and the Intrax were way lower
than I wanted to go, so I bought H&R.  They were comparable to the Eibachs
in the rear (but the dead coils are on the bottom, adding a little unsprung
weight), but stiffer than the Eibachs in the front, so you won’t dial out as
much push.  Despite the official specs, the H&R’s aren’t designed to drop
the car quite 1.5” (per Roland Graef) and the Bilsteins will add a little
ride height.  I put in the thicker damping rings, too.  Overall drop was
around ¾” w/ the Bilsteins; adjusted the rear drop to match the front.
Assuming a 200 lb driver, spring frequencies are 1.50 – 1.64 Hz front, 2.00
– 2.06 Hz rear.  Front damping coefficients are 43 – 47% of critical
(rebound), 39 – 42 % of critical (bump).  Rear damping coefficients are 55%
of critical (rebound), 35% of critical (bump).  Overall a little stiff, but
I like it.

 

I just got around to installing the ECS stud plates, and haven’t got an
alignment yet.  The install was straightforward— Keith put out a parts list
for the suspension bits from a 1992-97 100/A6.  You will need to cut the
dust rings a little, and you will have to take about ½” out of the outside
of each strut tower to make them fit.  ECS was great to deal with.

 

Dave

 

Front Springs

Stock V8  160 lb/in linear (per Hoppen)

Stock S4   194 lb/in linear (Eibach)

Stock S4   160-170 lb/in linear (Sport Wheels)

Eibach S4  250 lb/in (Eibach)

S4 Sport    217 lb/in linear (Hoppen)

H&R V8    270-320 progressive (APS)

 

Rear Springs

Stock V8   206 lb/in linear (Hoppen)

Stock S4    205-210 lb/in linear (Sport Wheels)

Stock S4    237 lb/in linear (Eibach)

Eibach S4  190-308 lb/in progressive (Eibach)

H&R V8    320-340 lb/in progressive (APS)

 

Bilstein Sport Shocks per Bilstein

Resistance vs. velocity linear

Front rebound 1195 N @ 20 ips (13.43 lb/ips)

Front bump 1070 N @ 20 ips (12.03 lb/ips)

Rear rebound 1250 N @ 20 ips (14.05 lb/ips)

Rear bump 800 N @ 20 ips (8.99 lb/ips)

 

Bilstein HD Shocks per Bilstein

Resistance vs. velocity linear

Front rebound 1100 N @ 20 ips (12.4 lb/ips)

Front bump 950 N @ 20 ips (10.7 lb/ips)

 

Koni Adjustable Sport Shocks per Koni

Resistance vs. velocity initially concave down

Front rebound 1350-2700 N @ 13 ips (23.3 - 46.7 lb/ips)

Front bump 800 N @ 13 ips (13.8 lb/ips)

Rear rebound 1050-2100 N @ 13 ips (18.2 - 36.3 lb/ips)

Rear bump 600 N @ 13 ips (10.4 lb/ips)