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In all the above scenarios your brakes would not have come back so quickly.
another possibility is play in the rotor or a slightly warped rotor that pushes the pads back on the straightaway so that when you apply the brakes you have to bring the pads back into contact with the rotor so pedal goes to floor.
not an unusual occurrence, many racers will do a left foot brake pump before their braking point on long straightaways to bring pads back into contact and provide a high hard pedal.
Brake rotors are pretty new and feel very solid. I don't notice any vibration with them. Although I can hear the brakes squeal a bit at lower speeds after braking, but once I get above 30mph that goes away.
Originally Posted by groundhog
Something to be aware of - higher mu brake pads as mu implies, have higher coefficients of friction. This imparts more brake torque at a higher rate and thus generates more heat more quickly - basically if you're rookie braking (threshold braking) you can cook the fluid in the callipers in one action. The symptom is loss of or partial loss of pedal - but it will come back on cool down and with pumping. Any doubt tap brake pedal before the braking point to see if its there. Bottom line is pads and rotors are on the small size for the base model. Try trail braking and optimising weight transfer whilst maintaining momentum - you will find you will go quicker, work the brakes less and better preserve the tires.
You may want to ensure your pads have the same friction material front and rear - if the front are higher mu than the rears the brake bias will have moved forward which can have all sorts of unintended consequences. Good luck.
Thanks for the advice. I had the same thing explained to me by the shop I got the brakes installed, he was saying they're just making too much heat for the stock rotors. I have the same pads front and rear, ME20s on new stock rotors. I probably was working the brakes too hard at this last session unfortunately, ill have to work on that.
I'm hoping the Girodiscs end up fixing these issues going forward, they should have much better cooling than stock...
Some things I've seen as potential solutions include adding in titanium shims, any thoughts on shims?
Also does any one know if there are any brake duct mods available? Either from the GT3 series or other? If this is a heat related issue, going with bigger rotors/calipers and better cooling are going to be the only fixes. I've ordered some high temperature paint to see how hot the rotors are actually getting.
If the girodiscs don't totally fix the issue, my next step is to get the 6 piston calipers from the Carrera S, Suncoast will sell the calipers only for ~$1365.
You must have been really working those brakes, even the steel brakes on the GT4 are way overkill and over engineered for its weight.
I will echo others though, Castrol SRF is great stuff. I have it in my SS 1LE and unlike most DOT 4's, it doesn't absorb much more moisture than regular DOT 3. I have had mine in for 1.5 years of street driving, and the pedal is still very solid and I have NEVER once gotten a soft pedal when pushing it in the mountains/canyon roads and my car weights almost 3800 lbs.
I noticed no one mentioned anything about the fact the car is a base C2. My impression was that the smaller diameter 4-pistons on the base were overengineered for the street but not suited for heavy track use... but I guess what we're seeing here is what defines "heavy track use". I've seen (and done) some pretty awful braking techniques on track... I'd have to think that not great technique + a brake-heavy track = heavy track use, no?
Anyway, it seems that the solution here would be to upgrade to the S brakes?
Last edited by manifold danger; 01-19-2021 at 03:19 PM.
I noticed no one mentioned anything about the fact the car is a base C2. My impression was that the smaller diameter 4-pistons on the base were overengineered for the street but not suited for heavy track use... but I guess what we're seeing here is what defines "heavy track use". I've seen (and done) some pretty awful braking techniques on track... I'd have to think that not great technique + a brake-heavy track = heavy track use, no?
Anyway, it seems that the solution here would be to upgrade to the S brakes?
I will tell you the standard C2 brakes are not 'great' on track, just having completed an HPDE weekend with them. On my 996 I had the big red brake kit, and that was a WORLD of difference than the small, stock 'grey' C2 brake setup, despite being 10 years older. I had a good bit of undulations in the braking especially coming out of straights, hitting 105-115mph, that had me worried a little bit. I just held back on flooring it for some of the turns off said straights, and it was a little better but it certainly made me nervous a few times. They really needed to be warmed up too, and improved as sessions went on (20 mins. per session).
When I hit COTA later this year I definitely plan to put on some more race/track-focused pads, as these would get melted thru pretty quickly.
But yeah, they leave a good bit to be desired and if I end up doing more track work, I'll spring for the Big Reds absolutely, if better/more suited pads/rotors don't fit the bill.
You beat me to the punch before I could respond! The hydraulic brake system is a closed loop, and brake fluid is not compressible. When you press the brake pedal, fluid just shifts from one place to another. If the pedal is going to the floor, one of two things is happening:
You have a leak somewhere in the system- In this case you found your leak. More often than not it is a loose bleeder screw on a caliper, and if the calipers are worn, it could be fluid slipping past a piston seal. The best way to check for a leak is with two people: one pressing the brake pedal and the other working his/her way around the car examining all potential leak points...caliper bleeder screws, brake hose connections, brake fluid reservoir cap.
If you don't have any leaks and the pedal is going to the floor, then something in the system is compressible. The most common occurrence is that the brake fluid has boiled and created compressible air bubbles. You press the pedal, the calipers clamp, and the tiny air bubbles in the brake lines and caliper squish, allowing the pedal to drop. The solution is to bleed the system to get rid of any and all air bubbles. Boiled fluid is caused by too much heat. That heat begins with the discs and pads, and migrates into the calipers. Solutions are larger, more efficient brake discs that flow more air and run cooler, calipers with features that prevent heat from reaching/boiling the fluid, and fluid with a higher dry boiling point.
If the pads were the primary culprit/failure point, the pedal typically doesn't go soft. When pads fade, the brake pedal remains hard but the car doesn't slow as anticipated. The pads simply exceed their ability to generate friction.
I would definitely suggest our AP Racing by Essex brake kits over the Suncoast OEM 'upgrades'. If you're on a budget (like me! ) you'd be far better off just getting our front Road brake kit and leaving your rears stock than you would be putting C2S parts on both ends of the car. Even on a rear engine platform like the 911, the front brakes take considerably more abuse than the rears as the weight shifts to the front of the car during a stopping event. You can keep running your OEM rears with race pads, and that setup will mate to our front BBK. We have numerous 991 clients on our front-only brake kit and they work great.
The S brakes are frankly not very large or efficient. You're going to spend $2650 on the Suncoast kit, and you'll still be on inefficient OEM discs that don't have much thermal mass, don't flow much air, and have drilled holes that will crack. You'll also still need to buy suitable pads for both the street and track for the new S calipers, which are a different shape than the base car pads. So figure $500 for new front track pads in the S shape (the Suncoast kit comes with OEM road pads). Now you're in for $3150, and you're still on OEM parts. As for the rear OEM parts from the S, they again aren't going to gain you much. In their description of their $1895 rear kit, Suncoast even says, "This is more of a visual upgrade than a performance upgrade." So you add the rear, and again some track pads in the S shape for $400, and you're now at $5,445 ($3150 front, plus $2295 rear). With that setup you're not going to have any more brake headroom than a stock S.
A far more effective choice for $5k is to get our front Road Kit: https://www.essexparts.com/ap-racing...mm-porsche-911
Our system has a massive 380x36mm, 72 vane AP Racing J Hook disc. This disc is a tremendous upgrade over both the Base and S OEM discs. It has far more thermal mass, will run far cooler, and will last much longer. Since our discs are so much larger, your brake temps are going to be much lower. That means you'll be going through spare pads and fluid at a much slower rate. Our system also comes with a set of Ferodo DS2500 pads, which some people run on both the street and the track. If you wanted a set of race pads for the front, they'd also be in the $500-$600 range, bringing the total cost to almost exactly what you'd pay for the OEM S parts.
The other great aspect of our kits is that they retain their value extremely well. You can run them for a few years until you move onto your next vehicle, and sell our kit for 65-70% of it's purchase price. The same can't be said for the OEM parts. They typically trade hands for a few hundred dollars, so your original investment usually evaporates both literally and figuratively as you burn them up over time.
If you decide later that you want to add our matching rear brake kit for either performance or aesthetic reasons, that option is always there.
Finally, our system is going to fill your wheels up and look MUCH better than a 350mm OEM setup!
Thanks for your consideration, and feel free to reach out to me if you'd like more info/have more questions.
ps Here's the difference in how our kit looks vs. stock.
Originally Posted by SpeedZ
The culprit was a loose hose connecting to the brake fluid reservoir. Not sure how it got loose; but once it did it let air into the system.
Im still planning to go for a big brake kit though in the near future, debating on the C2S brake kit from sun coast or the AP Racing road brakes.
__________________
'09 Carrera 2S, '08 Boxster LE (orange), '91 Acura NSX, Tesla Model 3 Performance, Fiesta ST
Jeff Ritter
Mgr. High Performance Division, Essex Parts Services Essex Designed AP Racing Radi-CAL Competition Brake Kits & 2-piece J Hook Discs Ferodo Racing Brake Pads Spiegler Stainless Steel Brake Lines
704-824-6030 jeff.ritter@essexparts.com
Can you run a 19 inch wheel with your brake kits? The ones posted above?
It depends on the wheel. Your best bet is to check the wheels you intend to run with our wheel fitment template which can be found in the links below. Print the template and make sure it printed to proper scale by checking one of the listed dimensions. Then you glue or tape the printed template to a manila folder or cardboard, cut it out, and place it inside the wheels. That eliminates the guesswork and prevents costly mistakes. Thanks!
I would definitely suggest our AP Racing by Essex brake kits over the Suncoast OEM 'upgrades'. If you're on a budget (like me! ) you'd be far better off just getting our front Road brake kit and leaving your rears stock than you would be putting C2S parts on both ends of the car. Even on a rear engine platform like the 911, the front brakes take considerably more abuse than the rears as the weight shifts to the front of the car during a stopping event. You can keep running your OEM rears with race pads, and that setup will mate to our front BBK. We have numerous 991 clients on our front-only brake kit and they work great.
One of my friends has a 991.2 GT3RS with the AP Racing brake kit, I did a session with him @ Laguna Seca with those brakes and I can still feel the seatbelts. My dilemma is after a certain point of $$ spent it starts to make more sense to upgrade to a GT3/GT4 from my current car.
I guess the other question is, Road vs Radi-CAL kit? Main difference I see is that the Road kit has dust boots and the Radi-CAL weighs less. Won't those dust melt during repeated track use? Also is the Radi-CAL kit available for the 991.1 C2?
06-01-2019, 02:42 AM
