Panoz Esperante GTS, Инструкция по эксплуатации

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Panoz Esperante GTS
Panoz Esperante GTS Panoz Esperante GTS
RVP – Reliability / Value / Performance
Bias Bar Set-up and Technical Notes
The function of a bias bar is to allow the adjustment
of brake line pressure distribution between two mas-
ter cylinders. This is accomplished through moving
the bias bar pivot towards one master cylinder
pushrod or the other. If the pivot is perfectly centered
between the pushrods, the force applied to each mas-
ter cylinder will be equal. This is known as the “neu-
tral position” of the bias adjuster. If the pivot is moved
closer to one pushrod or the other then the master
cylinders will receive different pressures (proportional
to the distance between the bias bar pivot point and
the master cylinder center lines). This adjustment
gives the driver control over the braking characteris-
tics of the car, and to alter those characteristics to
account for changes in fuel load, track conditions and
handling characteristics of the car.
Setting Up the Balance Bar
The balance bar is one of the most overlooked, and
least understood components on almost any race car.
As with all aspects of race car assembly and prepara-
tion, careful attention to geometry of the balance bar
and brake pedal will yield great benefits. To start, we
need to look at the proper installation of the bias bar
adjuster.
First, we must insure that the bias bar pivot bearing is
free to move within the pedal tube. Often this tube
becomes distorted during installation. If this is the
case, then the tube may be honed, until the bearing
slides smoothly from one end of the tube to the other.
The tube must be clean and may be lubricated with a
light oil or dry Teflon spray.
Next we need to know the distance between the cen-
terlines of the front and rear master cylinders.
Typically, this is 2.5 inches, though this is not critical.
What is critical is that this dimension, whatever it may
be, is duplicated in the center-to center distance of
the clevises threaded onto the bias bar adjuster rod.
This insures that the master cylinder pushrods are
actuated properly, minimizing any side loads applied
the master cylinder piston and bore.
With the clevises set on the adjuster, measure the
distance between them and the bias tube itself. If the
clearance between each clevis and the bias tube is
more than 1.5mm. then shims must be added until
the proper airgap is achieved. This prevents the bias
bar from shifting while on the track and altering, in an
unpredictable manner, the brake bias of the car. With
the bias bar connected to the master cylinders, and
the brake lines connected, the brakes should be bled.
It is ideal that front and rear brake circuits be bled
simultaneously. This will allow both master cylinders
to use their full travel and prevent binding the bias
adjuster.
With the pedal tube and clevises squared away we
now look at the master cylinder push rod length. The
key is to set up the bias adjuster so that it is perpen-
dicular to the master cylinder centerlines with the
brake pedal under compression. Typically, this means
that the front master cylinder push rod will be 3mm-
5mm longer than the rear master cylinder push rod at
rest. This is due to the fact that the front braking cir-
cuit has a larger fluid volume due the larger piston
diameters in the front calipers. As a result, the front
master cylinder requires a higher feed rate than does
the rear. If push rod length is equal front and rear
then the feed rate of the rear master cylinder is too
high relative to the front. The result in this case is the
rear circuit “hitting “ before the front. With the push
rod lengths adjusted properly the bias bar will square
under compression and the front and rear circuits will
“hit” approximately at the same time.
There is more brake bleeding information at the
beginning of this section.