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

Voits voits at comcast.net
Mon Jul 26 23:50:08 EDT 2004

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.


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


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

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.

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.

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.

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

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