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First off... Congratulations on your purchase of the Ultramax
Racing Chassis! And welcome to the Owners & Setup Area of
the Ultramax website.
We'll help you get started off with your chassis the right way.
Even if you are an experienced racer, you should be able to
go even faster! |
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Owners
Manual Page 5:
Setting Your Weight Percentages
continued...
Nose weight is also
proportional to the amount of bite in a track as
well as front-end settings, rather than driver size.
For a track with a lot of bite and speed you can
generally get by with the least amount of nose weight
that we recommend, 43.5%. This is due to the strong
influence of the high biting track conditions on
the front end of the kart. On the other end of the
spectrum, a track with a low amount of bite can
generally take on a little more nose weight, 45%
or so, due to a lack of track bite to help the kart
turn. In this case, you will generally have to tighten
the kart up a bit to keep the rear end underneath
you at the apex of the corner however, once this
is done you will generally have an overall better
handling kart. We are now ready for the always debatable,
cross weight setting.
Over the last
several years cross weight has become an increasingly
complicated topic that has had many different cases
of debate to go along with it. So for this section,
we will primarily give you a set of constraints
that we feel are a safe range to stay in. This is
an area of chassis setup that you will just have
to play with and learn what you and your driver
likes for different situations. For the 2003 Blaze
we recommend a minimum of 55% and a maximum of 65%
cross weight. Yeah, I know, we really helped you
out there didn’t we? This is simply one of
those areas that you are just going to have to work
at and see what works best for you. We have found
that generally a track with a lot of bite and high
speed tends to like a lot of cross weight for two
reasons: 1) excessively loading the right front
tire making it carry all of the work and thus, pivoting
the kart very quickly in the center of the corner
and 2) relieving the right rear tire from excessive
tire temperature and stress. Given the previous
two reasons, it should be obvious to you that cross
weight is very dependent upon other settings in
the kart such as front end geometry (remember, we
said that a lot of cross weight loads the right
front tire excessively) left side weight, as well
as and most importantly, driver preference. With
this brief explanation of weight percentages we
are now ready to go to the track and tune on those
miscellaneous chassis settings.
7 – At the Track Tuning
In this section we will
simply discuss several different chassis tuning
techniques such as axle lead and air pressure. This
section is simply designed to familiarize you with
the rest of your 2003 setup options.
Axle Lead
Axle lead has become
quite a hot setup-tuning tool over the past several
years for all of the top karting manufacturers and
riders. Your chassis is leading the way of top manufacturers
by giving you that same tuning tool. Axle lead is
designed to assist the kart in turning from the
apex to corner exit much like a fork lift turns.
Maximum axle lead will generally be ran during those
fast hard biting track conditions where the kart
tends to get tight from the apex to corner exit
and becomes very hard to steer under other karts
to make that all important pass getting into the
next corner. Be careful with axle lead, as it will
tend to give the driver a sensation of spinning
out on corner exit. This sensation varies depending
on track size and condition but is definitely something
that takes a little getting used to. We recommend
running no less than the standard axle lead of 1/8"
for most all track conditions.
Tire Pressure
Tire pressure is yet
another thing that greatly depends on track conditions
and situations. However, for dirt and pavement we
recommend starting with 1psi less air pressure in
the left side tires than the right and working on
your own from there. On dirt, race air pressures
can vary anywhere from 5psi to 11psi depending on
the amount of speed and bite in the track. The more
bite a dirt track has, generally the more air pressure
you need to run to keep the kart free. On pavement,
we recommend starting around 10psi for most all
track conditions. Going up in air pressure will
tighten the kart along with making it "come
in" quicker (which is good for qualifying)
and having the long lasting effect of "locking
down" late in a run. We recommend going no
lower than 9psi and no higher than 13psi for most
pavement conditions.
Tire Selection
This is a touchy subject
that can rarely be simplified as we are trying to
do here. However, We will lastly try to give you
an idea of what to do when you see that dirt track
go through a "face lift" or that pavement
temperature go up or down 25°.
A dirt tire is primarily dependent on two things;
spring rate and rubber thickness, both of which
tie into one another. The thinner the rubber the
less natural spring rate a tire has and the more
air pressure you would have to run to get "x"
as a desired spring rate. Likewise, the thicker
the rubber on a tire the more natural spring rate
a tire would have requiring you to run less air
pressure to get the desired spring rate "x."
Now, we aren’t saying that you have to calculate
spring rates and rubber thickness for every track
condition; we are simply trying to give you an understanding
of the basis behind the following statements.
The more speed and bite a racetrack has, the more
tire temperature that will be developed which will
require you to run a thinner amount of rubber to
dissipate that excessive temperature build up. Running
a thinner amount of rubber will require you to run
a little bit more air pressure to get the necessary
spring rate needed for that particular tire and
those particular track conditions. As speed and
bite decrease in a track, tire temperatures become
less and less and you need more and more rubber
on a tire to create bite in the tire. Because of
the larger amount of rubber, you need to run a little
less air pressure to get the desired amount of spring
rate for those particular conditions. The more speed
and bite that is produced in a track, the harder
the track is on tires requiring a harder tire selection.
This can be compared to sand paper being rubbed
on bare skin versus sand paper being rubbed on wood.
The bare skin, like the soft tire, is too soft for
the sandpaper and just gets ripped away while the
wood is harder and therefore cannot be torn up by
the sandpaper as bad. In the same way, the harder
tire can resist the harder biting track conditions
better than the softer tire, producing better overall
grip.
Pavement tires have all of the same conditions as
mentioned above. However, the one thing that is
generally most important on pavement is a new tire.
With this being the case, we don’t have near
as much influence over the spring rate of one tire
versus another due to each new tire having roughly
the same thickness of rubber as the other. This
is an issue that many tire manufactures has already
taken care of and calculated for while building
their tires for pavement conditions. So, that leaves
us with the easier, yet in some financial ways harder,
job of just bolting on a new set of tires and picking
the right air pressures.
For most pavement conditions, either Firestone YGF’s
or YGH’s will be ran with the F being the softer
of the two. The more rubber that is laid on a racetrack,
the less and less abrasive the track becomes, allowing
you to generally run the softer tire. This is likely
opposite of the way you would think it would be.
With this being said, for most pavement conditions
we recommend running the YGF with a DAM Dunlop on
the left front and a DAH Dunlop on the left rear.
In closing, we would like to thank you for your
purchase of the Ultramax chassis and hope that you
get as much out of it in your racing seasons, as
we have put into it. We hope that in some way this
setup tutorial has helped you become more familiar
with your chassis as well as becoming better acquainted
with chassis preparation and analysis in general.
Here at Ultramax Racing Chassis, we try very hard
to give you the very best product and customer support
that we can and we look forward to helping you in
any way that we can for the 2003 racing season and
beyond.
GOOD LUCK from, Ultramax
Racing!
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