JVL
Elite Detailing Full Car Detailing, Interior Clean, Exterior Clean,
Paint Protection, Race Equipment Specialists, Weight Balancing Setup Specialists.
JVL is Coffs Harbours most exhilarating car detail care units. John is
dedicated to ensuring that the passion YOU have for YOUR car becomes HIS
PASSION to deliver to you - an impressive result and satisfying experience
EVERY TIME. The presentation of the workshop care unit and lounge area
emulates the perfectionist standard that John operates under. Coffs Harbour
NSW 2450 Australia.
Full Wash Detail
Interior & Exterior, rims, wheels, tyres - All cars
Local Area Pick-up and Drop-off available by appointment only.
Racing
Australian
First Being exposed to motorsport at an
early age is part of the reason why John is crazy about anything
with 4 wheels. Trying his hand at race karts and working on the
now defunct super tourers, learning the race craft with Team Mondeo
over a couple of years. It was all a stop-gap until the desire to
build his own race car, became a reality. Being the first Tube Chassis
VW Race Car in Australia with an EJ20T Subie Motor, the car at it’s
first hit proved 2 seconds behind the fastest car of the day. Not
bad for a first effort.
The first Tube Chassis
VW Race Car in Australia
with an EJ20T Subie Motor
Now converted to a VR6 2800cc Motor
Videos
Racing in an R32 against a porsche.
The R32 whips the Porsche. Oran Park Speedway Sydney NSW Australia
(Late 2007). 18 second video.
Achievements
x10 Australian Motor Show Foundation (AMSF).
Street Machine Trophies, Top 12 Turbo Calender Cars,
and Cover of Zoom Magazine with a four page write up. Numerous Magazine Appearances over
the years.
More
Photos
JVL Elite Detailings Picassa Web Album
Understanding
Corner Weights
Important Aspect One of the most important aspects of car
setup is the static weight distribution and the cross-weight percentage.
Why?Picture
the following... Your car is really fast in right-hand turns,
but understeers in left turns. If you get the car neutral in left
turns, it oversteers in right turns. The situation is frustrating.
You’ve tried springs, shocks, different bars, neutralizing the
anti-roll bar, and nothing seems to work. Even on a track with mostly
right-hand turns, the problem in the left-hand turns cost a lot of time.
While several different setup parameters could have caused this situation,
a likely cause is excessive cross-weight.
Static Weight Distribution Static weight distribution is the weight resting
on each tire contact patch with the car at rest, exactly the way it
will be raced. This means the driver should be in the car, all fluids
topped up, and the fuel load should be such that the car makes your
minimum weight rule at the designated time-usually after a race. The
car should be at minimum weight, using ballast as needed to make the
proper weight. When working with static weight distribution,
we use two percentages to analyze the car’s corner weights:
Left weight percentage and rear weight percentage. These tell us all
we need to know about the setup relative to the weight distribution.
The left weight percentage is found by adding the LF weight to the
LR weight and dividing the sum by the total weight. The rear
weight percentage is found in a similar manner: Add the LR and the
RR weight together and divide the sum by the total weight. Many electronic
scales will perform the calculations for you. For road racing
and auto crossing, the ideal left weight percentage is 50 percent.
This makes the cornering force balanced from left to right and offers
the best performance overall. However, many cars cannot make the 50
percent left-side weight percentage due to driver offset. Still, it
is a worthwhile goal to strive for 50 percent left-side weight.
Rear weight percentage for road racing and auto crossing is less definite.
The more power a car has, the more that static weight over the drive
wheels helps acceleration off the corners. Additionally, it is much
more difficult to change rear percentage much, since rear weight is
mostly a design function. It still pays to be thoughtful about weight
placement fore and aft in your car. The only way to change the
static weight distribution percentages is to physically move weight
around in the car. Jacking weight will not alter the left side or
the rear percentages.
Cross-weight
Percentage
Cross-weight percentage compares the diagonal weight totals to the
car’s total weight. To calculate cross-weight percentage,
add the RF weight to the LR weight and divide the sum by the total
weight of the car. Cross-weight is also called wedge: If the percentage
is over 50 percent, the car has wedge; if below 50 percent, the
car has reverse wedge. More wedge means that the car will likely
understeer more in a left turn. The advantage to wedge is that the
left rear tire carries more load, so the car drives off the turns
better. But in a right turn, the opposite occurs and the handling
is worse. In almost all cases, the loss of cornering performance
in one direction is greater than the gain in the other direction.
On oval track cars, cross-weight is usually used in conjunction
with stagger (where the right rear tire is larger in circumference
than the left rear tire) to balance handling. More stagger usually
loosens the handling in left turns, so more cross-weight is used
to tighten it up. But stagger is not a good idea on a road course
or autocross either, where the ideal is 50-percent cross-weight
and no stagger. One of the problems with cross-weight is that
it will change the handling balance from a left to a right turn.
This can make maneuvering in traffic difficult, even dangerous.
On a road course, the cross-weight percentage should be very close
to 50 percent, within a half-degree either way, to keep the handling
balance similar in a right-hand turn compared to a left-hand turn.
In the example at the beginning of the article, this was the problem:
a cross-weight percentage that was less than 50 percent, and probably
off by at least two percent. One of the keys to obtaining a
good setup is using the correct procedure to weigh your race car.
How
to Weigh Your Race Car
Here are some points to remember when weighing your race car:
Make sure the floor is perfectly level; use
shims under the scale pads if needed. Small angles can throw off
your readings significantly.
Set tire pressures first.
Check stagger at each tire, even if using radials.
Put the driver weight in the car, preferably
the driver.
Use a load of fuel for where you you want the
car balanced, either at the start of the race, the end of the
race or an average between the two.
Disconnect the shocks, when possible, and
the anti-roll bars.
Use blocks the same height as your scale pads
to move the car off the scales to make adjustments.
Bounce the car at each corner to free the
suspension from any bind, then roll the car onto the scales.
Make sure the tires are centered on the scales.
Recheck Air Pressure often to assure ride
heights stay consistent.
Setting Static Weight Distribution
Check static weight before working on cross-weight. The only way
to change static weight is to physically move or ballast in the
car. To increase left-side weight, move weight as far to the left
as possible. To increase rear weight, move weight as far back
as possible. Move ballast first, since it’s easier. Then
move components like the battery or fuel cell. It is best to get
50 percent left-side weight when possible. Get the rear percentage
as close to the manufacturer’s specs as possible.
Setting Cross-weight
Once static weight percentages are set, work on cross-weight percentages.
You cannot change the left or rear percentages by jacking weight
around in the car, although this will change cross-weight. Changing
the ride height at any corner will change the cross-weight percentage.
If you raise the ride height at a given corner (put a turn in
or add a round of wedge), the weight on that corner will increase,
as will the weight on the diagonally opposite corner. The other
two corners will lose weight. If you lower the ride height at
a given corner, that corner will lose weight as will the diagonally
opposite corner. The other two corners will gain weight. This
will not change the left-side or rear weight percentages.
To add weight to a given corner, raise the ride height at that
corner or lower the ride height at an adjacent corner. For example,
if your initial setup is 52 percent cross-weight, and you want
50 percent cross-weight, lowering the right front or left rear
corner will decrease cross-weight percentage. You could also raise
the left front or right rear ride heights to do the same thing.
It is best to make small changes at each corner, instead of a
big change at one corner. This keeps the ride heights as close
to ideal as possible. In the above example, to go from 52 percent
to 50 percent cross-weight, try lowering the right front and the
left rear one-half turn on the weight jack bolt or spring perch
while raising the left front and right rear the same amount. Always
record the cross-weights and ride heights for reference at the
race track in case changes are needed.
Measure control arm angles after each change. The angles are another
way to set the suspension for the desired ride height and cross-weight
percentage. The distance from the ground to an inner suspension
arm pivot point will also accomplish the above goal.
Remember that changes in stagger, tire pressures
and springs will change the ride height and alter the cross-weight percentage.
Change at the Track
Make small changes at the track, and make only one change at a
time. If the car understeers or oversteers in only one direction,
check the cross-weight percentage.
One of the most important aspects of racing
is having a good handling balance. Setting static weight distribution
and adjusting cross-weight percentage is one way to assure good
handling. Taking the time and making the effort always ay dividends.
