[s-cars] spring constants

[Trevor Frank]

These are all I believe progressive rate springs that are intended to be
pre-loaded, so your calcs are off. As with this type of progressive
wound spring, it is designed so that the coils will bind progressively,
meaning that the number of active coils decreases as it get's
compressed.  From looking at them there are probably at least two
different windings in these coils, so there may be a strait rate portion
after the first few bind. 

I have laughed when people have quoted like 3XX# spring rate for these
spring because, sure, but when?

-----Original Message-----
From: Richard Tanimura [mailto:richard at tanimuras.com]
Sent: Friday, March 19, 2004 12:11 AM
To: s-car-list at audifans.com
Subject: [s-cars] spring constants

First, I don't have an S4. My car is an S2 with a 3B motor and a B4
chassis.

I just bought a set of H&R springs for my car. I measured pretty
carefully
and ran the numbers through a calculator for spring constants. Does
anyone
have similar data for the stock or aftermarket S4 springs?

H&R, Front axel, S2:

Wire thickness: 0.54"
Winding outer diameter: 5.9"
No. of active coils: 6.5
Spring constant: 125 lb/inch

H&R, Rear axel, S2:

Wire thickness: 0.54"
Winding outer diameter: 5.9"
No. of active coils: 5.25
Spring constant: 155 lb/inch

-----------
I also have some MTM spec:d Eibach springs. I think they are for the
S4/A4.

MTM, Front axel, S4/A4?:

Wire thickness: 0.60"
Winding outer diameter: 5.47"
No. of active coils: 3.8
Spring constant: 419 lb/inch (Yowza!!)

MTM, Rear axel, S4/A4?:

Wire thickness: 0.31"
Winding outer diameter: 3.9"
No. of active coils: 8.7
Spring constant: 32.43 lb/inch (Very soft!!)

Something fishy here I think. Any ideas.

Richard
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