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Flywheel balance
is critical for maximum power output and engine durability.
The second big issue
with your flywheel is balance. Approximately
one out of twenty flywheels we produce balances out to our specification
of 1/2 ounce inch maximum imbalance with no balance drilling required.
The other nineteen are going to have drilled areas to bring them
into balance.
So, if 95% of all
flywheels require the balance drilling (See photo), the odds are pretty
good that whatever flywheel you purchase should have some drilling.
Take a look at the flywheel you are buying. Few competitors have
the capability to balance to the 1/2 ounce inch specification and some of
them don't even manufacture their own flywheels or have any in house
balancing capability. One
manufacturer is honest enough to state their flywheels are 'rough
balanced' (Which means not balanced) and it is your responsibility solve
that problem. Strangely,
these are the highest priced flywheels on the market.
The balance situation
gets more interesting when the flywheel must be balanced to an
external balance specification. External
balancing requires putting a specified ounce inch imbalance within
a one-degree radial on the flywheel.
This is nearly an impossible task without some pretty sophisticated
and expensive balancing equipment. We
can show you our balancing equipment.
Most others can't.
If your flywheel
manufacturer or non-manufacturer supplier does not have the precision
machine tools, precision grinding, precision balancing, and complete
control of the manufacturing process in house, why would you consider
purchasing their product?
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Most flywheels require some balance drilling. |
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Flywheel design
and materials
Performance
manufacturers participate in the Safety Foundation Inc. (SFI)
certification program. SFI
certification is required by most racing organizations and tracks for
racing components for vehicles running 11.99 or faster before you are
allowed to participate. SFI dictates the type material and mechanical
properties minimums required to meet the specification and the
manufacturer must submit product samples for testing in order to qualify
for SFI product certification.
What SFI material
specifications do not take into consideration, and many manufacturers do
not know, is how the product is actually used and the abuse it must
withstand under actual racing conditions.
Aluminum flywheels
typically have a steel insert for the friction surface. This insert must
be substantial enough to handle the heat from clutch slippage (Intended or
not). Some manufacturers use
inserts as thin as 1/8 inch. That just won't take enough heat without
distorting. RAM flywheels
have a 0.235" thick insert on flywheels for 8 cylinder engines and
0.180" for Sport Compact flywheels.
This provides adequate mass to take the heat from racing and enough
thickness to allow resurfacing as necessary without replacing the insert.
Without a thick enough insert you can't get the performance or
service life you want from your clutch system.
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| Thicker
RAM flywheel insert |
Competitor's
thin flywheel insert |
The flywheel buyers
checklist
Insist on a SFI
certified flywheel.
Be sure the flywheel has
a 0.225" minimum thickness insert if aluminum. (Sport Compact 0.175"
minimum.)
Be absolutely certain
the flywheel is surface ground perfectly flat and parallel to the
crankshaft flange surface.
Insist on certification
from the manufacturer that the flywheel is dynamically balanced to within
1/2 ounce inch minimum of specification.
Ask if the manufacturer
makes the flywheel in house and has complete control of the manufacturing
process.
Resist the temptation to
buy a bargain flywheel. The above features will be absent.
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