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? Let’s examine, by way of cost benefit analysis, and discuss 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. Buildup of heat in the disc will mean that the generation of heat is at a rate higher than the ability of the braking system to dissipate the heat of the disc.
Faded brakes, spongy brake pedals, burnt discs and crumbling brake pads are all symptoms of a simple problem of accumulated heat overloading the braking system. I will use a virtually stock Honda S2000 (unmodified except for a bolt-on exhaust and slightly more aggressive alignment) tracked at Sepang International Circuit in Malaysia as a reference.
Tracking the S2000 on stock brake components proved a bad idea considering the searing 50°+ C (122°+ F) 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 and 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° C to 750° C), stainless steel brake lines and Motul RBF 600 brake fluid for a total cost of about 800 SGD (equivalent to about $662 US) 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 continuous lapping on the track was still limited to about five hot laps before the brake fade begin to significantly impact driving. The condition of the brake discs remained relatively unchanged.
This meant the heat overload experienced by the braking system had clearly not been significantly addressed. 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 was that the driver was confident to brake just before the 100m marker while still being able to make the corner for at least the first two or three hot laps of a full five lap outing from the pits. Braking that late for the remainder of the five laps was risky as brake fade had begun to appear and by the second half the entire three hour track session it was increasingly difficult to have more than one or two hot laps before the brakes began to feel extremely spongy.
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), extensive brake modifications were necessary. 4-pot monoblock calipers, brake pads exceeding the current already high temperature ratings and bigger discs, at least for the front brakes (at a cost possibly ranging from 3000 to 5000 USD from brands such as Endless or AP Racing), would need to be fitted to generate more powerful and 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 over 1G of braking in straight line 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 and upsized discs) from a leading brake manufacturer and achieved good consistent braking but fade still began 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 three track sessions on the same fluids would probably be the absolute limit. A definite improvement, to be sure, but it was clear that the problem of fade still remained. Some other S2000s fitted with aggressive street brake pads and no ducting or only basic brake cooling setups tended to crack rotors much like the picture below.
The S2000 test car was then modified with a commonly overlooked modification, namely, brake ducts but remained entirely stock elsewhere with the exception of the brake fluid and brake pad changes as stated earlier. 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 four calipers and finally to a setup where both front and rear brake discs and calipers are individually cooled with their own piping.
Here is a picture of the front funnel setup:
Here are some pictures of the funnel setup leading to the caliper and disc:
Testing of the system was done over the course of a year with seven track days at both Sepang International Circuit and Johor Circuit, also in Malaysia, and the results were: With the same Ferodo DS2500 brake pads and 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, over five 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 seventh track day. The S2000 test car could now repeatedly do multiple stints of over 15 hot laps without fade on the stock calipers and 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.
Every track day enthusiast should consider having a brake duct system in place to complement their existing brake setup. The actual cost versus benefit result derived varies from car to car, the class of competition that the enthusiast is running in and with the type of brake duct system constructed.
What brake modifications have you performed on your S2000? Has that improved your braking performance?
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on Sep 10th, 2011 at 11:19 pm
Was there any difference in high speed stability and cornering? This may be the only downside to brake ducts.
on Sep 11th, 2011 at 1:17 am
Where can I get brake duct funnels like those? I just have exposed hoses coming out of the faux ducts (circles cut out just slightly smaller so the hoses actually stay snug and still when on track).
on Sep 11th, 2011 at 2:00 am
What an amazing write up. This would be useful even outside of track days as I get a lot of break fade in regular in town driving. I now just need to know in more detail how they ran their hoses and with what they were built with.
on Sep 11th, 2011 at 5:34 am
Do you have a write up of the tested setup?
on Sep 11th, 2011 at 6:25 am
can you PLEASE post DIY on how to do this?
it would be GREAT!
on Sep 11th, 2011 at 8:01 am
@nikolas: Friends of mine and I did not feel any percetible downside to high speed stability & cornering so all is well
@Cody red: it was custom made in fiber. Check some of your local shops & I’m sure that they can come up with something for u.
@Daniel: sorry I don’t have a DIY tutorial on it as I had a shop customize it for me since I’m a lousy handyman. Do check out s2ki.com forum as I remember a thread on this. I think it was called: DIY brake duct tutorial.
on Sep 11th, 2011 at 8:07 am
@Marcus: Thank you. Would you like to leave an email so I can get back to u with more info or pics?
@S2000Beers: this was originally written as a piece for my local tracking club but I decided to dedicate this to s2ki. This article was edited together with the s2ki news team so I would consider this a joint effort. When you say writeup, is there specific information u need? Would be glad to help if possible.
on Sep 11th, 2011 at 8:49 am
This is one of the best articles I’ve ever read here on S2KI. Thank you.
on Sep 11th, 2011 at 9:05 am
#3Marcus
on Sep 11th, 2011 at 2:00 am
What an amazing write up. This would be useful even outside of track days as I get a lot of break fade in regular in town driving. I now just need to know in more detail how they ran their hoses and with what they were built with.
^^^^^ where the hell are you driving?
on Sep 11th, 2011 at 1:56 pm
surprisingly lowe’s or home depot have some pretty nice tubing like that in the plumbing/hardware sections.
on Sep 11th, 2011 at 3:34 pm
I arived at the same conclusion the first time i ran a competition tire at a track day. I only had to replace 550 dollars worth of rotors once before i went down to the hardware store and bought a shop vac hose kit and fasioned some ducting of my own. 18 bucks and 2.5 hours of work sure beats 550. Did the mod 3 events ago with no rotor problems or melted cheap hoses.
on Sep 11th, 2011 at 4:23 pm
And yet the fastest guys on the track with this car elect NOT to run brake ducts.
on Sep 11th, 2011 at 5:41 pm
c32b- When I said write up, I meant a DIY write up. But you answered my question above.
on Sep 12th, 2011 at 4:02 am
Hi JJ, do the fastest guys you know run a big brake kit? Would they be in autocross, time attack or would you know how many laps at a stretch they need to run for example a 30-50 lap race?
For discussions sake, I’d like more real world experiences to maybe help people consider if a brake duct system is necessary for their specific purpose.
on Sep 12th, 2011 at 9:52 am
Awesome write-up! Here’s a DIY that I had bookmarked for when I’m ready: http://robrobinette.com/S2000BrakeDucts.htm
on Sep 12th, 2011 at 11:56 am
c32b – Krazik has been dead set against them and he road races the car with the extra power of a turbo. The racing section of this site is full of road racers who don’t use them. (I can’t imagine why an auto cross or time attack car would even need them).
on Sep 12th, 2011 at 1:22 pm
JJ- definitely time attack and autocross won’t need them. Krazik’s car is pretty light being a all out race car however I’m not sure what brake system he employs. Perhaps his setup doesn’t need ducts as his braking system isn’t overloaded by what heat it generates?
on Sep 12th, 2011 at 1:49 pm
c32b – I would guess that his system is incredibly overloaded as he goes through rotors at a very high rate. However, he doesn’t seem to think there is a need to cool the brakes in order to keep them performing at an optimum level. I’m 99% sure he runs the stock brake system and not a big brake kit. The only problem with the oem brake setup is the rotors are prone to cracking, but many folk who vent their brakes report they crack more frequently with the added cooling.
on Sep 12th, 2011 at 2:10 pm
JJ- not sure what setup he runs so I couldn’t say. I don’t really know what exactly results in cracked rotors, some say uneven cooling throughout the stock disc, but let’s keep this discussion alive as I’m very interested in what contributes to the lack of necessity to run ducting.
on Sep 12th, 2011 at 5:08 pm
“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, over five 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 seventh track day. ”
I don’t understand how creating better airflow to cool the discs/pads can improve the brake fluid sponginess and feel. Please explain that. Is it perhaps you are now better accustomed to the circuit and are a better driver – less braking, higher speeds into corners, or even instinctively know to be easier on the brakes?
on Sep 12th, 2011 at 5:54 pm
Wait – so you’re saying you upgraded the pads and fluid and then tracked the car and took measurements of brake efficiency? Then you installed the ducting, took measurements of brake efficiency and found that is was significantly better than without ducting? If so, that is something that I don’t think anyone has found before. I think most people who run ducting do it without being able to tell it is in place. Even the guys who run the Nurburgring don’t tend to run ducting.
on Sep 12th, 2011 at 7:23 pm
Awesome right up !!!
Beautiful details and alot of useful info.
on Sep 12th, 2011 at 8:13 pm
JJ – i would have to disagree with you about brake ducting and Krazik’s car.
Here’s a recent picture of his car in action
[quote name='krazik' timestamp='1315595572' post='20958490']
[font=arial, verdana, tahoma, sans-serif][size=2]Some pics:[/size][/font][font=arial, verdana, tahoma, sans-serif][size=2][img]http://posterous.com/getfile/files.posterous.com/temp-2010-12-23/uHvbzoqnbwxkhnDqHJedmHkqBGdGmaqcrGtaqiaacIICuCoCFBFtkCddAczk/030.JPG.scaled1000.jpg[/img][/size][/font][font=arial, verdana, tahoma, sans-serif][size=2]
[/size][/font][font=arial, verdana, tahoma, sans-serif][size=2]More Pics:[/size][/font]http://www.rylan.org/help-me-choose
[/quote]
there are clearly holes for brake ducting.
on Sep 12th, 2011 at 8:15 pm
^^^ FAIL….
anyway, go here instead. http://www.rylan.org/help-me-choose
His car clearly has brake ducting. Also, he’s running stoptech 4pot piston calipers.
on Sep 12th, 2011 at 8:18 pm
also, for those wanting a brake duct kit and too lazy to put it together themselves – mix and match to your level of expertise…
http://www.lapponline.com/index.php?main_page=index&cPath=65&zenid=1d4923ab3f56d2b0874475e8428893d0
on Sep 13th, 2011 at 6:17 am
Don’t you guys have google on you puters? Here’s a thread I found in five seconds: http://www.s2ki.com/s2000/index.php?act=ST&f=11&t=709140
“Also for what its worth, I have almost 500 hp and do 30 minute sprint racing at places like laguna seca which is very hard on brakes haven’t run ducts in years.
-Ry”
on Sep 13th, 2011 at 4:49 pm
@ncmx5: “I don’t understand how creating better airflow to cool the discs/pads can improve the brake fluid sponginess and feel. Please explain that.”
Glad to
. I had piping run both to discs and calipers on all 4 corners. this created cooling airflow that attended to the main culprit of this issue, namely fluid fade. It was related to the extremely high track temps for that particular track (mid 50 Deg C) and not relating to my familiarity with the track.
on Sep 13th, 2011 at 4:51 pm
@Bullwings: are we able to find a pic of brake ducting krazik runs if he does run any at all? Hoping he would be keen to contribute his thoughts to our discussion. I can see it blacked out on the AP1 bumper in the pics but I am not 100% sure that is ducting.
on Sep 13th, 2011 at 5:12 pm
@max: Thanks!
@JJ: Apologise if the article is not clear enough in its description as I had to keep it concise but detailed enough. Here is a step by step:
1. tracked car on stock fluids & pads.
2. tracked car on motul RBF & ferodo ds2500 without ducting. Pads wore quick, discs smoked and fluid fade appeared although less serious a problem than stock brake fluids.
3. Installed ducting and the fade issue from fluids and likely pads as well was addressed. Pad longevity increased. Brake efficiency was compared by cross referencing data logging of pre and post ducting of braking G (braking G tapered off much earlier on a pre ducting setup than a post ducting setup) and as the driver I could feel the fluid getting extremely spongy for the pre ducting setup on just 4-5 laps versus the post ducting setup which had a solid pedal even after 15~20 hot laps.
I’m not sure Nurburging is a direct comparison as different tracks have different track temps, braking needs, straights to cool the brakes, ambient temps (blowing 35-38deg C air to cool the brakes would likely cool the brakes less than blowing 20 deg C air). krazik may have a good setup that doesn’t require ducting but I’m not sure that can be applied across the board to all cars so if we know more specifics we can maybe begin a detailed look into why cracking happens. Going through rotors at a high rate may not point to rotor overload but maybe could be attributed to a higher friction coefficient. I’m not an expert by a long shot so I would value all discussion as part of my learning process. Keep the discussion going
on Sep 13th, 2011 at 5:13 pm
@Bullwings: btw, if he has stoptech calipers, he may still run OEM/Centric rotors? It would be interesting to know if he and other drivers run fade free including details such as how often fluids are change, was the heatshield removed entirely, i read krazik’s car was 2600lbs with driver but am not sure if that is accurate since car weight might reduce braking demands and more micro details such as how much the track demanded of him under braking if he was competing with slicks. This discussion is looking very lively and thank you for your contribution
on Sep 13th, 2011 at 6:26 pm
You got a benefit from ducting that no one else has.
on Sep 13th, 2011 at 6:51 pm
Sorry, I don’t have the FULL details on Krazik’s car, but you can check out what he’s posted over here
http://www.s2ki.com/s2000/topic/895602-my-turbod-race-car/
since it’s now possibly up for sale.
As for me, I know that one of my next 2 upgrades will likely be brake ducts.
on Sep 13th, 2011 at 8:23 pm
@ JJ: gee. I didn’t realize no one else u knew had no benefits to ducting? The people I know who run ducting locally do get at least some benefits.
@Bullwings: thanks for the link. Do share your experience after the ducts are fitted
on Sep 16th, 2011 at 7:36 pm
I’ve wondered where there’s not an aftermarket solution for this. The faux ducts on the AP2 or AP1 bumpers would be perfect, and I’m sure the value would be a bit higher than the cost of materials…
Hint, hint!