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Kev here is some information that may help you out and safe you some money.
Regarding which brakes are better stoppers......
Why Big brakes!
* The ability of the caliper to apply enough clamping force to overcome the rotating rotor.
* The ability of the caliper pads to maintain adequate friction properties even with the heat
generated by continuous application of pressure from the caliper.
* The ability of the rotor to absorb and dissipate the heat.
* AND the necessary traction from the tires to allow the brake system to be effective.
Larger Rotors
The distance from the center of the rotor to its edge (radius) can be thought of as a lever and
the caliper in effect pulls on the lever to slow the vehicle. The bigger the rotor, the longer the
lever. The longer the lever the more effective the caliper. It is easy to understand then that
larger rotors increase braking capacity. If the rotor is also well ventilated, its ability to dissipate
heat is improved, allowing the caliper pads to operate at a lower temperature and endure the
torture to which they are subjected.
Assuming all the other variables remain unchanged, cross drilled and slotted rotors will
almost always deliver better braking figures than other types. The improved cooling effect
of these rotors allows effective use of the brake system under extremely severe conditions
(as might be seen in racing). The down side to this design is that when these rotors are
forced to work to capacity for prolonged periods, they are subject to cracking around the
drilled holes as a result of constant overheating and cooling. Until they destroy themselves
these are the most efficient. For street use (long track racing), cross drilled rotors are
perfect most of the time as the system is seldom used to capacity. The rotors should last a
normal life span.
If the rotor is of only marginally adequate specification for the vehicle weight or use, cross
drilled rotors can be problematic and require frequent "crack checking" and possible
frequent replacement. Under these conditions, slotted only rotors are more desirable.
Slotted rotors are less prone to cracking under severe service than drilled. What they lack
in efficiency (if any) they make up for in longevity. You will seldom find a high performance
short track racecar with drilled rotors, these cars are almost always fitted with slotted
rotors for the reasons listed here.
If we had to stop hard one time from high speed, we would probably select a drilled and
slotted rotor. If we had to do it over and over, we would almost certainly use slotted
rotors.
High Performance Brake Pads
Probably the least expensive, single most effective upgrade one can perform is a brake
pad upgrade. This is an area where one definitely does NOT fit all. There are as many
pad compounds as manufacturers of pads and each has its particular niche. For the sake
of simplicity, we have broken pads in three basic categories; High Performance Street,
High Performance Street / Race combination and Race Only. Street pads have to be able
to work well at low to moderate temperatures because street vehicles are driven cold and
under normal circumstances don't generate high temperatures. Usually in this category,
the pads work well cold and their effectiveness decreases as their temperatures increase
until breakdown of the compound bonding agents cause brake fade. Repeated hard brake
applications as in most types of racing will quickly overheat these pads making them
useless.
Combination pads usually incorporate some degree of compromise to incorporate this
flexibility of use. For the street they have to work well enough at low temperatures to be
safe and must also be competitively functional at moderately high temperatures under
racing conditions. These pads usually increase in effectiveness as they heat up through
their upper operating range then fade with overheating. They usually don't work as well
cold as a street pad and they don't work as well in the upper temperatures as would a
racing pad, the trade off for an "all around" pad. There are many circumstances where
these are the best pad for the application.
Race only pads do not work cold, period. Do not use race only pads on a street vehicle
thinking "If they are for racing they must be great pads". You will be in for a huge
surprise the first time you go to stop at a street light and sail right through the
intersection as though you had just hit the gas! They do not work cold and must be
warmed up before they are at all useful and in most circumstances require certain driver
skills to optimize their use.
Tires
All the brake improvements in the world are not going to help if
there is no traction available between the wheel and road.
Ultimately, your tires will determine how well your car stops. A
brake system of given efficiency will be most effective with the
smallest possible diameter tire. In the same way that the larger
rotor offers the caliper a longer lever, the smallest diameter tire
offers the vehicle a smaller lever. While different (smaller) wheel
and tire diameters are frequently an option for racers, most street
vehicles are limited to near standard tire diameters for a variety of
reasons.
Fortunately the trend in recent years toward larger diameter rims
and low profile tires has opened up many options in the area of
big brakes. In many cases, increasing rotor diameter will require
an increase in rim diameter to make room for the rotor.
Fortunately, low profile tires keep the outside diameter the same
or near the same as the original equipment so increasing the rim
diameter usually has no ill effect on braking. Conversely, modern
low profile tires are typically of a higher traction rating (or at least
high traction ratings are available) which will aid braking.
Hope this helps!!
_________________
Eddie @ formulaimage.com
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