It was about time to
get rid of the original rubber bushes that had taken the beat at the track and
resisted the wear and tear of road use for 23 years. I installed a complete set
of Energy Suspension poly urethane bushes during the winter. The job was quite
straight forward and I could complete it in my ordinary garage. It took some
time but I was not in a hurry.
I also wanted to
replace my old Koni Sports Kit with something more suitable for racing. Most of
the track oriented guys here in Finland have opted for BC Racing. They seem to
work nice and customers are satisfied. I must admit having an issue with
BC-racing shock coming from Taiwan. I also don’t like the high spring rates
they use. I know, they are not all bad and BC’s kits evidently work nice.
Another issue was money. Bilstein, Öhlins, KW, AST, JRZ and Koni all make
excellent shocks and complete kits, but they come at a price – too high for me.
So, after some
consideration I took my old shocks to the local Koni importer who offers an
inspection service for all of their products – free of charge. And guess what,
they were as good as new! After a short chat with the mechanic I decided to
keep them and try to find adjustable perches with slightly stiffer springs. It
did not take long to find out that Ground Control Suspension Systems in
California had what I needed. I was more than happy that a set of Eibach racing
springs was included in the kit. I went for 6,6 kg in the front and 4,4 kg in
the rear, which the Koni mechanic recommended was a good starting point. Shocks
could be revalved afterwards if stiffer springs were needed. I must emphasize
that at the Ground Control the quality of the service was as excellent as the
quality of the kit – I have nothing but good feedback to give!
While I was waiting
for the GC-kit to arrive I made some basic research and measured Miata’s camber
gain. Both front and rear were first set to a reasonable suspension height (
310 mm front and 325 mm rear from the wheel hub center to the fender flare).
Then I simply jacked the wheels up while the car was on four jack stands and
measured the change of the camber angles. The gain is roughly 0,5 degrees per
10 millimeters of wheel travel, both front and rear.
I could not be
happier with these two simple mods. Combined with increased chassis rigidity
and more aggressive wheel alignment the car really has started to take corners.
I was able to shave of almost two seconds from my best lap time at the first
visit to the Ahvenisto racing circuit this spring.
The car feels more
planted, steering inputs are more precise, front-rear weight transfer and body roll are reduced
and the overall driving experience has become more effortless. This is a good
start for the season 2014!
