Coilover spring rates

I have had AGX shocks (two sets - one for springs and one for Ground Control
coilovers) on my '94 miata for several years and I like their adjustability.
However, I am still looking for the best compromise of spring rates. I had
several of standard-type springs and I have also had several sets coilover
springs installed and I have never been satisfied that I arrived at the best
compromise. The car is driven daily, summer and winter, and occasionally
autocrossed in the summer (pavement) and winter (gravel occasionally with
snow and ice). The car has suspension braces front and rear. The car has FM
rear shock mounts, stock sway bars and urethane bushings. The front
suspension brace made the most dramatic improvement in the car but good
tires really do matter.

The OEM springs were Front:153lb, Rear:94lb - considerably too soft for any
performance driving. The Eibach Pro-Kit springs were Front:228lb,
Rear:137lb - too low, poor suspension travel, really harsh particularly in
the rear and not particularly compliant. Flying Miata springs were
Front:342lb, Rear:228lb - overall not too bad, maybe a bit too firm in rear
for racing on gravel and I did not want to lower the car more than 1/2" or
3/4". The coilovers have had 6" long front 400lb and 7" long front 350lb
with 7" long rears of 250lb, 200lb and 150lb. I also tried 10" long 125lb
rears. The 10" springs are a bit harsh due to preload, but you eventually
find that they are too soft. I am reasonably happy with the front 350's. I
am about to order another rear set and I am going to try a combination of
linear springs with 4" 250lb springs (Eibach No. 0225.250.0250) coupled to
4" 150lb springs (Eibach No. 0225.250.150) on each rear wheel. Hopefully
this combination will seem somewhat progressive by being initially quite
compliant, firm when driven hard but will not be vulnerable to any
bottoming. Then again it might just be another $300 experiment.

Brian Minto, Calgary, Alberta, Canada

In article >,
"Brian Minto" > wrote:

> The car is driven daily, summer and winter, and occasionally
> autocrossed in the summer (pavement) and winter (gravel occasionally with
> snow and ice).

Maximizing performance over that spectrum of surfaces is a tall order,
no?

FYI, FM has revised their springs. Current rates are 318 front and 233
rear, with less drop. The goal is to keep the car off the bumpstops. FM
prefers Illuminas, but I'm sure with a phone call you can find out how
they work with AGX.

Or, if you are willing to spend the money, Keith Tanner did very well in
this year's Targa Newfoundland with his AFCO setup.

--
Lanny Chambers
St. Louis, MO
'94C

I am not trying to "maximize performance". You may notice that I used the
word "compromise". I use AFCO coils on all four corners already. For
example, I have had a set of Eibach 350's and I have had a set of AFCO 350's
for the front. I use the AFCO's because they begin moving more smoothly.
Although they are the same length and same rate, the Eibachs hit the bumps,
while the AFCO's absorb the bumps.

"Lanny Chambers" > wrote in message
...
In article >,
"Brian Minto" > wrote:

> The car is driven daily, summer and winter, and occasionally
> autocrossed in the summer (pavement) and winter (gravel occasionally with
> snow and ice).

Maximizing performance over that spectrum of surfaces is a tall order,
no?

FYI, FM has revised their springs. Current rates are 318 front and 233
rear, with less drop. The goal is to keep the car off the bumpstops. FM
prefers Illuminas, but I'm sure with a phone call you can find out how
they work with AGX.

Or, if you are willing to spend the money, Keith Tanner did very well in
this year's Targa Newfoundland with his AFCO setup.

--
Lanny Chambers
St. Louis, MO
'94C

In article >,
"Brian Minto" > wrote:

> I use AFCO coils on all four corners already.

Sorry, I meant AFCO coilover units, not just their springs.

http://www.flyinmiata.com/index.php?...stocknumber=13
-16200++STANDARD

--
Lanny Chambers
St. Louis, MO
'94C