Mean
07-01-2002, 07:58 PM
Found this while searching the Mailing List archives and thought it was good enough to repost here.
Gene
Matthew wrote:
>Can anyone offer an explanation why we have seen recommendations for GC
>coil overs with spring rates of 300 front 200 rear? I am ATTEMPTING, as
>are some others on the list, to emulate the success of the Allen's who
>won the SCCA Solo2 Street Touring (now termed STS) championship last
>year in an Integra GS-R. They used a CG set up that employed spring
>rates of 375 front 450 rear, quite a bit stiffer. The Trunk Kit for
>SCCA Showroom Stock class that the Mazda Protégé uses has spring rates
>of 325 front and 600 rear. Now, these cars weigh approximately the same
>as a SE-R, so why the bias towards tremendously stiffer rear springs?
>Is this the correct way to maximize grip at both the front and the
>rear? It must work on both the road course and at autocrosses, so I
>doubt that it is just a way to gain oversteer characteristics. Anyone
>out there with a similar set-up on an SE-R care to comment, and will
>GABs (or even KYB-AGX or Koni inserts) survive such stiff spring rates?
>Any opinions are appreciated.
I came up with these spring rates as a compromise setting that would work
much better than any of the typical aftermarket street replacement type
springs that are typically only about 20-30 percent stiffer than stock. The
original recommendation was from Jay Morris at Ground Control which was
verified by me through testing a few different spring rates through street
driving and track driving on my car and other peoples cars. I am not an
autocrosser so I personally did not test them in autocross but Geogre
Pereinis won the Pro-Solo national championship on these rates.
I recommend these rates because they give a slightly more neutral balance to
the car. The car will 4 wheel drift, leading with the front wheels. The
car will tighten the line under lift throttle and will oversteer under trail
braking. I feel that this is good, safe, predictable handling for most
people. Naturally many drivers will like there car looser and have a fwd
car rotate more aggressively.
As for what spring rates work well on other cars, there is a huge difference
between the spring rate and wheel rate. Different suspension designs have
different motion ratios and wheel rate curves. The rate at the wheels can
vary depending on how the springs are mounted. Wheel rate and the wheel
rate curves are a function of how much lever arm and the pivot locations of
the suspension. In a real rough example a spring that works directly on a
wheel will need to be doubled in rate to maintain the same wheel rate if it
is mounted half way inboard on the control arm, or if it is canted inboard
by a lot. It is not exactly this but it will help you visualize what I am
talking about.
An example of this in a car that I know about would be a 280ZX or a 510 with
semi trailing arm inboard springs. You often run a higher rate rear spring
with these because of the suspensions motion ratio. The Integra with it's
multilink suspension runs the springs more inboard than a strut type SE-R so
the higher spring rate does not necessarily mean a higher wheel rate.
The beauty of the coilover conversions is that you can fine tune your spring
rates because of the wide availability of rates available, an option you
don't have with street springs.
Now some people have had success with running 250 in/lb rear springs and a
few run even higher. I my self don't like the car so tail happy but you
should not be worried with experimenting. ERS springs are cheaper than
regular street springs. Building a competitive car is all about testing. I
also feel that if you go much stiffer than 250 in/lb in the rear, the car
will hop around in rough corners and lose traction. I have experimented
with as high as 300 in the rear and that was my impression. I currently run
350 front and 250 rear but that is getting to be on the edge of what I
consider to be streetable. 300/200 rides quite nicely, better in my opinion
that typical street lowering springs as these tend to let the car bottom too
much.
Mike
Gene
Matthew wrote:
>Can anyone offer an explanation why we have seen recommendations for GC
>coil overs with spring rates of 300 front 200 rear? I am ATTEMPTING, as
>are some others on the list, to emulate the success of the Allen's who
>won the SCCA Solo2 Street Touring (now termed STS) championship last
>year in an Integra GS-R. They used a CG set up that employed spring
>rates of 375 front 450 rear, quite a bit stiffer. The Trunk Kit for
>SCCA Showroom Stock class that the Mazda Protégé uses has spring rates
>of 325 front and 600 rear. Now, these cars weigh approximately the same
>as a SE-R, so why the bias towards tremendously stiffer rear springs?
>Is this the correct way to maximize grip at both the front and the
>rear? It must work on both the road course and at autocrosses, so I
>doubt that it is just a way to gain oversteer characteristics. Anyone
>out there with a similar set-up on an SE-R care to comment, and will
>GABs (or even KYB-AGX or Koni inserts) survive such stiff spring rates?
>Any opinions are appreciated.
I came up with these spring rates as a compromise setting that would work
much better than any of the typical aftermarket street replacement type
springs that are typically only about 20-30 percent stiffer than stock. The
original recommendation was from Jay Morris at Ground Control which was
verified by me through testing a few different spring rates through street
driving and track driving on my car and other peoples cars. I am not an
autocrosser so I personally did not test them in autocross but Geogre
Pereinis won the Pro-Solo national championship on these rates.
I recommend these rates because they give a slightly more neutral balance to
the car. The car will 4 wheel drift, leading with the front wheels. The
car will tighten the line under lift throttle and will oversteer under trail
braking. I feel that this is good, safe, predictable handling for most
people. Naturally many drivers will like there car looser and have a fwd
car rotate more aggressively.
As for what spring rates work well on other cars, there is a huge difference
between the spring rate and wheel rate. Different suspension designs have
different motion ratios and wheel rate curves. The rate at the wheels can
vary depending on how the springs are mounted. Wheel rate and the wheel
rate curves are a function of how much lever arm and the pivot locations of
the suspension. In a real rough example a spring that works directly on a
wheel will need to be doubled in rate to maintain the same wheel rate if it
is mounted half way inboard on the control arm, or if it is canted inboard
by a lot. It is not exactly this but it will help you visualize what I am
talking about.
An example of this in a car that I know about would be a 280ZX or a 510 with
semi trailing arm inboard springs. You often run a higher rate rear spring
with these because of the suspensions motion ratio. The Integra with it's
multilink suspension runs the springs more inboard than a strut type SE-R so
the higher spring rate does not necessarily mean a higher wheel rate.
The beauty of the coilover conversions is that you can fine tune your spring
rates because of the wide availability of rates available, an option you
don't have with street springs.
Now some people have had success with running 250 in/lb rear springs and a
few run even higher. I my self don't like the car so tail happy but you
should not be worried with experimenting. ERS springs are cheaper than
regular street springs. Building a competitive car is all about testing. I
also feel that if you go much stiffer than 250 in/lb in the rear, the car
will hop around in rough corners and lose traction. I have experimented
with as high as 300 in the rear and that was my impression. I currently run
350 front and 250 rear but that is getting to be on the edge of what I
consider to be streetable. 300/200 rides quite nicely, better in my opinion
that typical street lowering springs as these tend to let the car bottom too
much.
Mike