[s-cars] Spring Measurements: Eibach/Stock/Audi Euro Sport

[Voits]

In the working range they are linear.  In the pre-load range the rears
especially are non-linear due to the inactive coils that get compressed
together by about 300-500 lbs force.  Above that point they are linear.
S.
  -----Original Message-----
  From: Mark Strangways [mailto:Strangconst at rogers.com]
  Sent: Monday, July 26, 2004 8:57 PM
  To: voits at comcast.net; s-car-list at audifans.com
  Subject: Re: [s-cars] Spring Measurements: Eibach/Stock/Audi Euro Sport


  Very nice...
  But I thought the Eibachs are a progressive rate spring.
  Mine sure look that way.
  Mark S

    ----- Original Message -----
    From: Voits
    To: s-car-list at audifans.com
    Sent: Monday, July 26, 2004 11:49 PM
    Subject: [s-cars] Spring Measurements: Eibach/Stock/Audi Euro Sport


    S-Heads:
    I have benchmarked spring rates for decision purposes, and list the
results
    below.  The reason I did this is because the data I've seen online/from
    vendors/word of mouth/urs4.com  did not add up to a coherent picture.  I
    wanted better data.

    Measurements were taken using the QA lab at Curran Coil Spring,
Wilsonville
    OR, in May.  Curran manufactures coil springs for OEM applications and
they
    do spot testing on their product using this facility.

    The setup allowed for precise measurement (+/- .005" est.) of spring
length
    with simultaneous force readout (guessing +/- 5lbs est.)on an automated
    press set-up designed exactly for this purpose. Our process was to begin
    taking measurements at approx 500 lb load, and then to plot two or three
    data points up to about 1100 lbs.

    The contestants:
    (A) Stock springs from my 1995.5 S6
    (B) Audi sport springs (euro OEM option) purchased from Alex Van Gerbig
at
    Europrice (802)324-8407
    (C) Eibach springs (purchased from shox.com)
    Front: the correct sedan spring 1527.001VA
    Rear: the avant spring 1517.002HA  This is the culprit in so many
'wrong'
    shipments because orders for the correct sedan 1529.140 box were
mistakenly
    fulfilled with the 1529.140E box, the latter from a parallel european
part
    numbering system intended for the avant and filled with the 1517.002HA
    spring instead of the correct 1516.002HA part.  I went ahead and tested
the
    avant spring for 2 reasons: a) its what I had on hand, b) I'm told the
only
    difference b/w the sedan and avant spring is 1 full inactive coil
length.  I
    decided to emphasize results from the fronts in any conclusion.

    FRONT:

    Stock Front (labeled silver, silver, yellow)
    Rate: 167 lb/in
    Comments: linear in nature

    Audi Sport Front Spring (silver, pink, pink)
    Rate: 194 lb/in  (+16% over stock)
    Comments: linear in nature

    Eibach Front (labeled 1527001VA, part of 1529.140 <note: not 1529.140E>
kit)
    Rate: 200 lb/in (+20% over stock)
    Comments: linear in nature

    REAR:

    Stock Rear (labeled pink, green)
    Rate: 220 lb/in
    Comments: linear in nature

    Audi Sport Rear (labeled blu, blu, blu, yellow, also p/n 4A5.411.115 AG)
    Rate: 232 lb/in (+ 5% over stock)
    Comments: linear in nature

    Eibach Rear (labeled 1517002HA **see note above** part of 1529.140E kit)
    Rate: 249 lb/in (+13% over stock)
    Comments: linear once the car's load collapses the initial inactive
coils


    SPRING RATE CONCLUSIONS:
    Even though the test arrangement was precise in nature I chose to focus
on
    bench mark type results.  The spring constant of the Audi Sport and
Eibach
    springs are similar to one another.  My conclusion is that one should
select
    one over the other from a ride height point of view.

    RIDE HEIGHT CONCLUSIONS:
    Since the spring rates are neraly the same, you should choose springs
based
    on the ride height.  Eibachs deliver 1.5" drop and the Audi Sport
Springs
    are advertised to provide 2 cm drop, or less than an inch.

    EIBACH RIDE HEIGHT OBSERVED:
    I installed the correct Eibach 1529.140 kit (1527.001VA Front,
1516.002HA
    Rear) and I have *exactly* 1.5 drop in both the front and the rear.
Despite
    this exact drop the rear looks a touch low to my eye > so I thought I
needed
    to install the 1529.Perch assembly ("spacers") from Eibach which I own,
and
    would raise about 3/8 inch.  Before proceeding I placed a bottle jack
under
    the center rear body and raised the rear by this amount.  Too high!  I
    decided that the aesthetics are such that one might want to raise the
rear
    by 1/8", but the Eibach did lower the car evenly front to rear and that
the
    spacer is too much to add.

    ON THE ROAD EXPERIENCE:
    I initially panicked when I installed the Eibach Bilstein setup as it
was a
    dramatic change. But after a few weeks have learned I love the
trade-offs.
    It remains a bit harsh at low speed on potholes, etc.  but works very
well
    at speed and has given the car an altogether safer, more precise &
    commanding feel.  Even the stock brakes feel more sensitive because
their
    function is not lost to body squat.  I installed the 2Bennett camber
plates
    and aligned to factory specs and tramlining has disappeared.

    I'm convinced the Audi Sport springs would deliver the same experience
    described here, but with more ground clearance. (contact me if you want
to
    buy my extra set)

    Steve Voit
    voits at comcast.net
    95.5 S6
    Seattle




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