[BiturboS4] suspension upgrade

Todd Sager todd at awe-tuning.com
Mon Sep 9 20:16:38 EDT 2002


> 2) I'll pose a question: can we agree that, theoretically, a well matched
> H&R-spring/Bilstein-damper setup would handle identically to a H&R coilover
> setup w/the same specs, and would cost the consumer less? If so, great. If
> not, why?

The advantage of a coilover kit for a street car lies in the fact that
it is a fully tuned package, rather than relatively compatible

The shock valving in a proper coilover kit is tuned to a narrow spring
rate spread, maximizing compression and rebound control.  This allows
the use of a stiffer spring while minimizing ride quality sacrifices.

A typical shock and spring combo works in more general ranges.  For
example, the spring rate of the H&R sport springs are ~400 lbs/in front,
yet the S4 specific Bilstein strut is designed to work with springs in
the 325-450 range.  Thus, the relationship between spring rate and shock
valving is not optimized like in the coilover kit.

However, some fixed height suspension tuners are putting together
specially valved shocks with their spring choices, which should, in
theory, result in performance similar to coilovers.  The downside is
that their markets are smaller, and pricing on their kits approaches the
coilover costs, which have height adjustability as an advantage still.

I still do not think a shock only upgrade for the S4 will satisfy most
of the enthusiast market.  I'm glad to read that it worked for you, but
it would fall short of expectations for most of the rest of the market
in my opinion.

A.W.E. Tuning
Orderline 888-565-2257

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