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Re: Koni sport shocks questions (long and technical)
TLidasan@aol.com wrote:
> I have a 1990 V8 quattro that currently has H&R springs and Koni sport
> adjustables.
> My questions are:
> Before I spend another 4 hours disassembling the
> suspension and adjusting the Konis to the softest setting, any lister
> out there have tried the Konis on the softest setting? How about
> Bilsteins HD?
>
> How are they compared to the Konis? Or am I tackling the problem the
> wrong way? Is it the H&R springs that's giving me the stiff ride? I was
> told by H&R technical help that the H&Rs are only 15% stiffer than the
> stocks, however the car right now feels like 50% stiffer. So I am
> leaning towards junking the Konis and replace with Boge Turbos or
> Bilstein HD (if available) - if I am going to disassemble the
> suspension again.
>From the data I've gathered so far (numbers and seat-of-pants), the
H&R's are hugely stiffer than stock for the V8. The 15% is understated
even looking at frequency, which is a square-root calc. Also, they
lower the car about 1.25", which is more than some of the Audi
suspension experts like, because of bump steer problems. Spring rates,
in lbf/in:
Front Rear Source
Stock V8 5-spd 160 206 Joe Hoppen
Stock V8 5-spd 153 228 Calc'd from spring dims
H&R V8 270-320 320-340 Roland Graef @ APS
The calculated rates are based on some quick measurements of the stock
springs, so I don't feel too bad about being w/in about 10%. The H&R
rates are the working range; the springs are somewhat progressive. The
front springs for the V8 AT might be a bit stiffer than for the 5-spd,
as I believe the AT is heavier in the front.
If you can get shock rates for the Koni's, you can compare them to the
Bilsteins. Shock rates for the unmodified Bilsteins, in N @ 20 ips,
are:
Front Rear Source
Sport, bump 1070 800 Scott @ Bilstein
Sport, rebound 1195 1250 Scott @ Bilstein
HD, bump 950 Monica @ Bilstein
HD, rebound 1100 Monica @ Bilstein
The 20 ips is important, as other manufacturers quote at a lower piston
speed (12 ips?). For quick damping calcs, divide force by velocity; in
rebound, the HD's are 8.99 lbf/ips. Also, the Bilstein sports are set
up for about 1" lowered suspension, and the fronts have internal bump
stops.
The spring and shock numbers quoted above are available for the asking.
I suspect that people who "improve" things might be more reticent, and I
would be loathe to disclose any tuner data. TAP sells unmodified
Bilsteins, whereas Abt and Sport Wheels revalve them. Expect the
Bilsteins to add to the spring rate due to the high pressure gas; ride
height increases about .25". They feel stiffer in cold weather.
Let me know what you come up w/! My car is out of commission now
getting new grooves for the split rings in the rear shocks, to install
coil-overs with adjustment down as well as up. Once it has a truly
adjustable rear height, I'll have more freedom to play. The corner
weights are also being set-- for the first pass we'll go for equal
diagonals w/o too much F:R change vs. stock.
BTW, how are the Konis set up to support the lower spring perch? And
what's the shock body OD? Who sells them? If you junk yours, may I
have them? ;-)
HTH,
--Dave Weiss
'91 V8 5-spd, K&N (+0.0*10^9 hp), H&R's, Bilstein sports, 16" Audi
5-spoke w/ 225-50-16 CZ91's, S6 (V-8) front brakes
'93 90CS UnQ
P.S. What brakes are you running? Hoppen's (Audi factory) conversion
works very well on mine!