Soft brake at track

Hello, I need some help diagnosing I had my first track event this year yesterday, Stock pads. ATE Typ 200 changed 2 weeks ago, full system flush. My braking performance was poor at best. 15 min into my third session, coming hot into a turn, I hit the brakes and my foot went to the floor so I went strait off track. My brakes were sub-par all day, poor stopping power. I checked the pads and they are fine, like 5mm all around, a little more in front. After I changed and flushed the fluid, the pedal was firm from the top of the range of motion. Now, after the event the pedal is non-existant until about halfway down. The braking performance is poor. There is no leaking anywhere. One thing that might be helpful, a few bleeders were clogged. Any recommendation? I am going to flush again, to see if that fixes it, If ot. I really don't know what else it could be, so does anyone know what I should check? Thanks

Sounds like air bubbles somewhere in or near the calipers. Heat causes the air to expand, making the whole system unpredictable. Otherwise, its possibly time for a new master cylinder.

AIR, With out a doubt. You need a power flush.

I have boiled both ATE T200 and Pentosyn SuperDot4 on the track. Neither of these times resulted in any change in pedal feel after the brakes cooled. I now run Castrol SRF which is the best (almost twice the wet boiling point), but expensive. I would recommend you consider it. It's possible you damaged the seals in the master cylinder by cycling the brake pedal to the floor which could result in the symptoms you have. Or as said above there could be air in the calipers but unlikely there is air beyond the caliper area after boiling out. If you do end up needing a new master cylinder the 997 GT3 M/C is a NICE upgrade. See my thread about the installation.

Thanks, guys. Yes I was pretty sure it is air, at least it feels like it. I just didn't realize that I could possibly boil brand new fluid. This track is super hard on brakes though, so it makes sense.

type of pads could also be the culprit. if your pads are not aggressive enough for track use, you'll put more stress on the fluid and hence overheat it.

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+1. My brake caliper temps are remarkably lower running Ferodo DS11.1 vs the Hawk Pro+ I was running before. Checking w/ an infrared thermometer after coming off track.

When I first got my 996 I had the same issue. Thought it was air bubbles. Bled, Bled, Bled, and rebled. Also made sure to bleed the clutch slave cyl.. I even purchased the Durametric so I could cycle the ABS pump. All of that did not work. I would make it 10 minutes into a session and the brakes would go soft. I was running stock pads at the time. At a loss of what else to do, I upgraded the pads, and that did the trick. Not sure if the pads were getting so soft it was creating the fade, or cooking the fluid, but either way, upgrading the pads from stock eliminated the problem.

Please do not run stock pads at a track, no matter what others say. They will just fade as you experienced. Get dedicated track pads and this will most likely cure your problem and you'll never run out of brakes again. Additionally, learn to use LESS brake at the track. I once brought my 968 to the track without dedicated track pads and after about 5 laps.....OMG, no braking power!!! What did I do? On the next session, I learned to use less brake, come off the throttle earlier, don't brake hard, use more momentum, guess what happened? My lap times went down using less brake! Imagine that! ;-)

You might also investigate whether any of your calipers are dragging and causing excess heat to build up and boil the fluid. If any particular wheel is much hotter than the rest it would suggest a localized sticking problem like this. If everything is more or less equal temp, it suggests it's a mismatch between your pad compound and your driving style. I run stock pads and Ate Typ 200 at the track all the time and have no issues, so there's nothing fundamentally wrong with that setup. I have had other brands of pads cause a soft pedal exactly like you describe, and I'm convinced its because they built up more heat and cooked the fluid.

Paul W is right, learn to drive a 996 as a momentum car. Proper pads and better brake usage will eliminate your problems.

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Hey Paul W, I am running at Blackhawk, pretty sure you might be familiar with it? It is pretty notoriously hard on brakes, especially in door-slammers. Can you give me some tips for using less brakes at that track? I just realized that I am hi-jacking my own thread...

Definitely air in the lines. Upgrade your fluid to Motul600 or Castrol SRF, run track pads for the track, and make sure you have front brake ducts. Tracking these cars is amazing, but it requires a little prep.

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Thanks, Slakker. I have been recommended SRF. Which do you prefer? Also, I have been recommended Pagid yellow, which I may bite the bullet and buy. I was thinking about temp-painting my rotors and basing new pads on empirical data,as a few people recommended blacks in the rear for the 996. Do most people use the larger GT3 front ducts? Definately feel I need to do some brake upgrades, at least fluid, more likely pads as well. I did a full suspension overhaul this winter (coilovers, links, bars, sport alignment settings) and I was running a lot faster at the track, so I assume this is why I had brake problems now, where I have not had problems in the past.

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Here's my story from Blackhawk with the 968..... https://rennlist.com/forums/968-foru...t-weekend.html I also drove the 996 there once after I got it, had track pads for it.....man, absolutely NO ISSUE with braking.....once you get track pads, you'll never go back. However, I saw my oil pressure fluctuate on the back side of the track on the long left hand sweeper after about 3-5 laps and decided to bring the car in and not chance an oil starvation issue. https://rennlist.com/forums/showpost...8&postcount=37 I have decided not to track the 996 and just use it as a street car. Sold my track pads to murphy'slaw, who happens to live the next town over, he used them at Road America and had incredible brake all day long!

The last time I ran street pads at the track was in early 2000... after 8 laps in my corvette... I ended up using a new porsche 996 4s as brakes. She was a nice enough lady. Creamed her car. The Hawk autocross pads (blacks) I was using just cracked, fissured and came away from the backing plate in chunks. Use dedicated track pads, or drive something slower. slacker is right: module 600 and track pads (I like either pagit's or hawk dt60).

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Need moar details and pics! Holy Cow Batman!

I've run both SRF and Motul 600/660. One time I had issues with Motul 600 - it was on the 3rd weekend with the same fluid at Sebring in the summer. Completely my fault. Either of the fluids are a HUGE step up from what you're running now. Combine with some PFC, Pagid, or Ferrodo pads and you're set to go.

I was running SRF with stock pads. It does not help. You have to run track pads (providing you are not a first time person at the track, and even then, you should probably change them out). Of course, braking less also helps. If you don't want to throw big money at Hawks, you can use the StopTech street/track pad. While the bite is not as good as a true track pad, they don't fade like the stock pads do, and you can get them for under $200 for all four corners.

Man, everybody else here must be braking a lot harder than me, or else I just have some kind of miracle setup I run in the advanced/instructor group with OE Textar pads, cheap-o Meyle rotors, and Ate Typ 200 fluid and I've never had a single instance of fade with this setup. The pedal is rock solid every time, perfectly consistent, lap times within a tenth or two if there isn't traffic, and I always have enough power to engage ABS (running street tires). I do about 10 track days a year, and will bleed my brakes once a year. I used to do it more often, but could never feel a difference, never saw dirty fluid or bubbles come out, so I figured what's the point, I'm just wasting fluid. I do have the GT3 scoops in the front and 997 Turbo scoops in the back. i.e. the cheapest scoops you can buy at both ends. Before anybody says it, I am NOT holding up the group, if you know what I mean. I'm not the fastest car out there, but I'm definitely not in the way either. And frankly although I feel like I take it pretty easy on my brakes to create a smooth transition into the corner, I tend to make up a lot of ground on people into braking zones, so I really don't think I'm babying my brakes unreasonably. My ONLY complaint is that the pads wear fast. I will get roughly 4 track days out of a set of pads. But when I can re-pad the entire car for about $160 and 30 minutes of my time, there's not a very strong argument for me to upgrade to something that costs ~3x as much!! So anyway, just putting it out there that it IS possible to track a 996 on stock equipment!! If you are getting fade 15 minutes into a session with the stock setup, I think either something is wrong with your car, or you should think about braking less. I'd rectify any problems and adjust driving style until a ~20-25-minute DE session can be done successfully without fading. THEN think about buying more expensive components to start destroying. Just my 2 cents!

Agree with Blue Chip. I like SRF better but if a car has Motul I generally won't bother switching it. I ran motul600 in my ~550hp 996TT yesterday and it definitely got tested. As for track pads, I generally run whatever I can pick up cheap and usually used. PFC, Pagid, Ferodo, Carbontech all work great. If I'm buying new, I'll get Hawk DTC-70's as they are less expensive and have amazing bite. And the best thing you can do for your braking system is to make sure you are looking at the apex when you are breaking, NOT your turn in marker. I was pretty rusty yesterday and made that mistake a few times. Once I corrected, my brakes "felt" totally different. Lastly, brake hard initially, and then feather off until you are ready to go to throttle. These cars react poorly to coasting. On low speed corners, I typically brake all the way to apex using them to help rotate the rear end (trailbraking). And the feathering allows you to gain consistency in your cornering speeds that threshold braking until turn in doesn't allow.

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Bingo. So many drivers that I coach stare at some mysterious braking reference point then jam on the brakes until they hit the ABS because some knucklehead told them to threshold brake in every single turn. Fill your brain with the right inputs by looking way into the turn (like at the apex) as you brake and you�ll speed up, gain entry and mid corner speed, trail brake naturally to hit the apex, and get better longevity out of your braking components. Plus you�ll start closing on GT3�s in your basic old 996 BTW, big fan of the ferrodo ds1.11s. I run those with sebro slotted rotors and ATE 200 with complete confidence for dozens and dozens of track days each year.

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You are right in a way, I was on the brakes hard in a couple places on this track, more laps with my new setup are definitely needed to adjust my driving style. However, as I mentioned I am not on stock equipment. I have run successfully on stock equipment as well, but i have upgraded my entire suspension which I am sure was also was a factor, as I was running a lot faster in all sections of the track, hitting my normal braking points in fast spots 20-30mph faster than before. Probably not a good idea to upgrade the go-faster parts without upgrading the go-slower parts....

Congrats on the new found speed. And yes, braking, suspension and tires need have some balance between them performance wise. So now you just need a set of RE-71R's to go with your braking upgrades. After that, your car is good (assuming you have safety) and it will be time to poor all of your discretionary income into track days and professional instruction.

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If your pedal was firm initially, then it's more likely you boiled it than had air in there from the get go. Yes better fluid is crucial, but better to prevent the heat in the first place. For that, your best option is the cup brake ducts at all four corners. They are ridiculously expensive for pieces of plastic, but they work.

The problem with the cup ducts is they channel the air where the rotors would be if you had cup rotors. On our cars, that ends up being below the rotors.

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What tires are you running? They symptoms you describe appear to be boiling the fluid in at least one caliper. I suspect the front. Folks have identified a bunch of different potential causes in this thread. Having done tons of upgrades to my 996 back in the day, I suspect that it's the wrong combination of tire/pad, coupled with lack of cooling at the front. IMO, there is no meaningful or worthwhile way to cool the rear brakes, especially given the brake bias of the 996. Stock pads have a very specific operating range. They work awesome in low to medium temp scenarios. They have good cold bite, but after they get over their optimum operating temps, they lose efficiency. And this is where boiling fluid with a street setup starts. The high temps cause the brakes to have less braking torque, so you try to brake more. But that increases the temps making them brake still less. And, much of that extra heat gets pushed into the calipers. A second symptom the lower operating range is a longer braking zones. The longer the zone, the longer heat will be generated. That's when you start to see boiling fluid. One caliper of boiled fluid will result in a soft pedal. [note: you can simply pump, pump, pump the brakes because the other corners still have some braking force left. It just might save your car. (The common statement that you have "no brakes" with a soft pedal is an overstatement because you do, just not what you expect)] One solution for all of this is to simply upgrade to a pad with a higher operating range. The brakes will still generate heat, but they won't get into the same "meltdown" mode as street pads. Endurance pads are an optimal choice because they have a broad operating range as well as decent initial bite. Different pads have different heat/torque as well as release characteristics. But at your level, you probably won't be able to tell the difference, honestly. [For example, this manifests itself in long braking zones where the heat curve rises significantly, which might also increase torque with certain pads. In some instances, this will result in front ABS kicking in although you haven't increased pedal pressure. So, you need to reduce pedal pressure in the braking zone slightly to have the same amount of braking force without triggering ABS. Some folks don't like this and would rather have a more consistent braking feel in one zone. Similarly, the same concept plays out with trail braking because the torque curve is impacted by pedal pressure. That is, the timing/cadence of your trail braking can be impacted by pad choice. But, like I said, most novice and intermediate drivers, and even many advance drivers can't tell the difference between pads. They just drive what they have. And there's nothing wrong with that.] Another way this can manifest itself is when your "track" pads are not aggressive enough for your tires. For example, a set of "OK" track pads will suffer the same issues as above when you have sticky R-comp tires. That is, the tire will just roll and roll and roll in a braking zone because the brakes can't generate enough torque to slow the car quickly enough. Upgrading to a more aggressive pad can solve this issue as well. Conversely, if you get a pad that is too aggressive, or one that outmatches your tires, you'll hit ABS in lots of braking zones. This is a different issue altogether, but still one that needs to be addressed. Bottom line, the pads and tires are a system that need to be considered together. So, my $0.02 is that you should try to pick a different set of pads that are more track oriented. There are a lot of good recommendations in this thread. I always used Pagid or PFC in the past, but have switch to PFC exclusively now. -td PS: Personally, I wouldn't worry about the fluid. Any DOT 4 will do the job. If you want track specific, try Motul600. When you have the right balance of tires and pads, you won't boil this stuff for a LONG time. And when you do, you can check out my other threads on brake cooling to solve that issue as well.]

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I sure did. I also used the pads for Autobahn Country Club in Joliet, full track, full day. So I think between both days, it was probably nine or ten 30-min sessions on those pads. They were very good. I was actually out braking a lot of folks, and like you said in your 968 posts, Paul, next time out I will learn to brake a little less and carry more speed through the corners. But track pads and good fluid are important for a successful track event.

Just another data point in support of the idea that you don't need expensive equipment to track: 2 days of HPDE at Watkins Glen this weekend, ran 8 sessions in the Advanced/Instructor group lapping in the ~2:17-2:19 range, and 2 sessions at ~70% in the B group to show my student around. OE Textar pads and Ate Typ 200 fluid. Zero instances of fade, deadly consistent pedal every single time, can tell zero difference between braking on lap 1 and the end of the session. Used about 40% of the pad life this weekend.. Will be good for 1 more weekend and then they'll go in the bin and be replaced for $160. To each his own, but cheap and reliable is the ticket for me!

Echoing dkraige's comments. I drove about 70 laps at Grand Bend this past weekend. The course has two straightaways that require threshold braking from ~180km/h to ~60km/h (~110mph to ~40mph). The temperature of my rotors measured almost 400 degrees Celsius when I got off the track. No problems at all using street fluid (ATE 200) and pads. I used to run the OE textar pads, but this time I was on Cool Carbon pads. I didn't notice any brake fade or decrease in braking performance during any of the 15 minute sessions. I would probably consider switching to race pads if/when I upgrade to racing tires, but with street tires the OE pads are fine (and cheap).

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The new to me 1996 BMW z3 I am trying to get kinks worked out on, had a similar issue. Not sure what pads were put on last, but they looked cracked on visual inspection before my first track day. Took the pad out and they crumbled in my hand. Literally came off the backing plate, and had cracks throughout. These pads looked brank new, full thickness. I suspect inexpensive pads were put on prior to sale? Not sure. But never saw that happen before. I was really glad I checked... Cheap pads on a race track is a bad idea..

Thanks for all of the input guys. Just o follow up for anyone who reads this in the future, I re-flushed my entire system with new ATE Typ200, and the pedal feel is back. I pushed out a few small bubbles, but only at first. I am pressure bleeding. My fluid came out pretty bad looking. I had blue in there from last time, and the fluid came out amber when I originally flushed. The reservoir and the lines were filled with green fluid. Kinda wierd. I didn't flush the clutch last tie, but I don't think that should make a difference. Correct me if I am wrong about that... Definitely need a lot more practice at the track, especially as I underestimated how much difference the suspension would actually make. I tend to be hard on the brakes, probably a novice thing. Everyone in my club uses Pagid yellows, so I may switch to them. In a way I kind of want to want to go back and run stockers again to see if I have the same issue. I can always end the day as soon as I feel the brakes fade.

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Could have just been really old pads. Some people don�t brake very hard in normal driving. That said, brake pads do fail like this, which is why some folks have spare pads at the track.

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Generally, it�s best to replace ALL the fluid twice a year or so. Maybe the prior owner didn�t do that, which could be why you had such a problem the first time around. Hard on the brakes (practicing threshold braking) is one of the first things beginners should practice at the track, so it�s not bad that you did that. The next thing to practice is to master the line so that you can carry a bit more speed in the turns and try to get slow-in/fast-out and get on the throttle sooner. You should still brake very hard at first, but then release the brake a little sooner before the turn. The idea of going back to stock pads would be similar to going back to all season tires rather than running extreme summers. You can, but remember that these have two different use cases. Street pads are meant to bite harder at first, produce less dust, not squeal, etc. Track pads don�t really always work that well until you get some heat in them and they may produce a lot more dust. Initial braking when they aren�t hot might actually result in longer stopping times.