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Old 08-24-2011, 09:24 PM   #348
RandR
Scooby Newbie
 
Member#: 292132
Join Date: Aug 2011
Location: Australia
Vehicle:
2015 WRX STI
WRB

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There are many points I agree with and in particular the importance of tires.

However, if you have high quality tires and add higher quality, higher coefficient of friction brake pads with slotted rotors you do improve stopping distance.

Why, the high coefficient of friction brake pads "bite" (increase brake torque) and hold the brake rotor better than the lower coefficient of friction OEM pads (brake torque is proportional to coefficient of fiction for any given brake pad), moreover as pads of this type are designed to work better at higher temperatures they will maintain the bite in an emergency stop situation. Furthermore, the gas and debris generated in this type of situation will be removed by the slots in the brake rotor again ensuring maximum bite.

The change in stopping distance with my setup (Advan Neova 08 tires, Ferrodo DS2500 pads and DBA 5000/4000 rotors) is about 20 ft shorter from 60 mph than stock. Obviously this is a life saver. I know because I have measured it.

Some test results: - 4 cars tested under the same conditions, at the same location on the same day (stopping distance from 62 mph, specifications and results as published in Motor Magazine, 08/11 - note this test was conducted in Australia with Australian spec vehicles)

1) 2011 STi - 125 ft, brakes 365f/324r (mm diam front/rear), rim width 8.5 in, Dunlop SP600 (car weight 1.515 tonnes)
2) Focus RS - 135 ft, brakes 336f/302r, rim width 8.5 in, Continental Sport Contact (car weight 1.493 tonnes)
3) 2011 WRX - 136 ft, brakes 294f/286r, rim width 8.0 in, Dunlop SP01 (car weight 1.410 tonnes)
4) Megane RS - 138 ft, brakes 290f/290r, rim width 8.5 in, Continental Sport Contact (1.387 tonnes)

The car with the largest diameter front brake rotor stops in the shortest distance (or total effective diameter, note: the reason it stops in a shorter distance will be a combination of tires, pads, suspension and rotors) the same is true where the rim width and tire type is the same (e.g. Focus Vs. Megane)

Wider tires can be dangerous when roads are inundated with rain water.

Why, because they have a larger surface area and are therefore more prone to aquaplaning (lower surface contact pressure - if the wicking doesn't cope with the amount of water under tread).

Towing - improved brakes are recommended for towing as this puts extra load on the brakes - braking whilst towing generates a substantial amount of heat in the brake rotors - high - C or larger rotors dissipate the heat more effectively - protecting bearings, pads and rotors.

Bottom line, brakes can be upgraded leading to better stopping distance and improved long term performance especially if you have high performance tires. By the same token ensure you have the right tires for the conditions you most commonly encounter.

Key points: performance
(1) Buy high quality tires (this improves grip) - with OEM pads - shorter stopping distance
(2) Buy high quality, moderate to hi-t, higher coefficient of friction brake pads = higher brake torque - even shorter stopping distance than (1)
(3) Buy replacement high - C, ventilated slotted rotors - they can improve brake torque due to gas release and clearance of pad surface - even shorter stopping distance than (2)
(4) Buy larger replacement high-C, ventilated rotors if you do a lot of braking e.g. hilly areas, towing, motor sport - the high thermal mass effectively stops overheating of the brake components and fluid - e.g. your brakes do not go off
(5) In my view cross drilled rotors are largely cosmetic, they substantially reduce brake surface area and are not suitable for hi-t applications e.g. motor sport or towing.

key points: feel (feel does not equal improved equipment performance although it can improve driver performance)
(1) Use low compressibility, hi bpt brake fluid
(2) Fit brake master cylinder support
(3) replace brake lines with braided stainless lines - these must be high quality with high quality fittings to minimise chance of failure
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Last edited by RandR; 08-29-2011 at 10:52 PM. Reason: Another point
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