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Faded brakes resulting in reduced stopping force remains a constant concern when attacking our favourite
tracks. Spongy brake feel culminating in heart stopping moments and inability to brake well, on the way
back from the local track are typical. We spend hundreds, if not thousands, of dollars on modifications to
increase the braking ability of our beloved rides and enjoy the results when tracking.
A moment of reflection leads us to ponder if this money was well spent. Could money saved on excessive
brake modifications be better used on items such as better suspension or even other safety equipment? This
article looks to examine and promote meaningful and practical discussion, by way of cost benefit analysis,
the effectiveness of current expenditure regarding braking modifications and their practical impact to track
day enthusiasts.
A simple understanding of the brake system is necessary for us to begin. The friction generated between the
brake pad and the rotating brake disc converts the energy of the moving vehicle into heat. The heat is lost
through the surface area of the disc to air when the car is moving. Build up of heat in the disc will mean;
generation of heat is at a rate higher than the ability of air to dissipate the heat of the disc quickly enough.
Faded brakes, spongy brake pedals, burnt discs & crumbling brake pads are all symptoms of a simple
problem of too much heat in the braking system. I will use a virtually stock Honda S2000 (unmodified
except for a bolt-on exhaust & sportier alignment) tracked at Sepang International Circuit as a reference.
Tracking the S2000 on stock brake components proved a bad idea considering the searing >50 Degree C
track temperatures. The stock brake pads quickly disintegrated with 80% thickness pads dropping to 10%
in one 3 hour track session. The stock brake fluids boiled after a few laps & remained dangerously spongy
even after a long rest in the pits. The brake discs turned a funny burnt tinge after a taxing session and
smoke could be seen pouring off them on entry to the pits.
Upgrades to address these issues soon followed by way of Ferodo DS2500 brake pads (which are rated
from 50-750 Deg C), stainless steel brake lines and Motul RBF 600 brake fluid for a total cost of about 800
SGD including labour cost (Note: Labour costs may vary from workshop to workshop). The rate of wear of
the pads was halved and sponginess was staved away. Brake fluid changes could be done after every other
track day although lapping the track was still limited to about 5 hot laps before the brake fade began to
worry the driver. The condition of the brake discs remained relatively unchanged.
This meant the heat experienced by the system had clearly not changed. However, certain components
were now able to handle the heat slightly better. A possible reference to how much deep braking was used
was that the confidence level to begin threshold braking for Turn 1 had grown so much so that the driver
was confident to brake just before the 100m marker to still make the corner for at least the first half of the
track session. Braking that late for the latter half of the session was risky as brake fade had begun to appear.
The next step, to most of the tracking community, would certainly be obvious. To increase lapping
longevity (to get as many hot laps per track session to maximize seat time), further brake modifications
were necessary. 4 pot monoblock calipers, even higher temperature brake pads and bigger discs, at least for
the front brakes, (at a cost ranging from 4000 to 6000 SGD from brands such as Project Mu or AP Racing)
would need to be fitted to generate more powerful & consistent braking.
There is no doubt on the benefits such modifications confer. However, would it be possible to have
approximately 80-90% of the benefits at a lower cost? Tracking isn’t the cheapest of hobbies and being
cheap on vital components, such as brakes, isn’t something most enthusiasts want to be seen doing and yet
the cost of a “proper brake” upgrade system is clearly prohibitive to many. Perhaps we should examine
more closely our desired brake performance objectives.
Upgraded stopping power is greatly desired. A simple explanation of braking “power” is that an increase in
the braking “power” can be defined as a small application of force resulting in a larger than typical braking
forces. One could upgrade the brake booster (master cylinder) to get this result or simply step harder on the
brake pedal. The S2000 test car with stock tyres achieved >1G of braking on the front straight without the
use of a big brake kit so clearly there was no lack of braking power, however, a big brake kit would greatly
improve modulation characteristics under threshold braking.
To address brake fade and a spongy brake pedal, another S2000 fitted a 4 pot big brake kit (including large
calipers & upsized discs) from a leading brake manufacturer and achieved good consistent braking but fade
still begin to rear its ugly head by the end of the 3 hour track session. Brake fluids did boil a little less, fluid
change intervals were slightly increased but 3 track sessions on the same fluids would probably the
absolute limit. A definite improvement, to be sure, but it was clear that the problem of fade still remained.
The S2000 test car was then modified with a commonly overlooked modification, namely, brake ducts. The
initial setup was with ducts channeling air by a regular piping to the calipers on all four corners, evolved to
add a funnel head on each pipe to concentrate air flow to the same 4 calipers and finally to a setup where
both front and rear brake discs and calipers are individually cooled with their own piping. The total cost for
ducting and fitting (all customized) was approximately 800 SGD.
Testing of the system was done over the course of a year with 7 track days at both Sepang International
Circuit & Johor Circuit and the results were: With the same Ferodo DS2500 brake pads & Motul RBF 600
brake fluid on the stock brake system, brake pad life was increased to at least double of the usual service
interval while discs ceased to smoke and exhibited no visible burn marks.
The result with the brake fluids was not only that sponginess was eliminated for all the track sessions and
not evident on the 300km drive back to Singapore, >5 laps could be easily done without a hint of fade,
braking could be done consistently on every lap at the 100m marker without fade appearing and no change
of fluids appeared necessary even after the 7th track day. The S2000 test car could now repeatedly do
multiple stints of >15 hot laps without fade on the stock calipers & discs which is clearly a huge
improvement in fade resistance over even usage of an expensive big brake kit.
An added potential benefit, which is not immediately evident, could be that of the heat being taken out of
the drive train components (such as CV joints and wheel bearings) thus reducing the heat stress on them
and possibly prolonging their lifespan. Usefulness of brake ducts is nothing new in racing (virtually every
race car has them) but strangely a search within some aftermarket brands concluded that you will be hard
pressed to find them selling an effective and comprehensive brake duct solution in their product ranges.
The downside of such a system would be some time spent to customize a proper system, maintenance of
the fittings and probably some hindrance to certain modifications as the ducts would require some space to
fit. The benefits are, however, numerous and obvious to the track enthusiasts. These would be namely, cost,
maximizing seat (practice) time, safety and prolonging the lifespan of various components in the car.
This article does not suggest one should replace a big brake kit with brake ducts, however, every track day
enthusiast should consider to have a brake duct system in place to complement their existing brake setup.
The actual cost and benefit derived varies car to car and with the type of brake duct system constructed.
More data will serve to cement the ideas listed herein and it is this author’s intent that such discussions will
serve to usher a more measured and practical approach to safely enjoying tracking as a hobby.
Written by Norman Souza Tan |
