I suspect this is going to be as hoary as the proverbial question of what brake pads people use at the track. However, nothing ventured... I have been through 4 types of fluid: - "stock"/regular DOT 4. Boiled within 3 laps of Blackhawk - "Castrol LMA". Coupled with Porterfield R4S. Fade. - Motul and R4S (street/track pad): down to backing plates after one weekend at Road America. No Fade. - AP550 and Carbotech 1108 (race pad). Better. - Motul and Carbotech 1109XP (current - race pad). No fade, higher initial bite. 3 track days and the fluid still boiled at 536 degrees. Tons of pad life. Not too hot on a cool or wet day with occasional use The BMW guys seem to swear by ATE Super Blue (with Hawk pads). Certainly the M3 lightweight I rode in around RA (2:35 laps) braked extraordinary well. Anyone used the fluid or the combination on their Ferrari (308)? Philip
Not surprised. LMA has a dry boil of less than 500 degF. For your hard lapping, R4S is too soft of a compound. As you found, Motul has a higher dry boiling point. AP550, Motul, ATE blue all have similar properties and high boiling points. What's your data acquisition system for fluid temperature? Using the stick-on temperature strips? If your fluid is indeed reaching 536 degF, your caliper seals are taking a beating, and I guarentee your rotors are glowing orange at 1100degF. The seal material heat fatigues, gets less pliable, lets in air. You can also monitor rotor temperatures with paint available at race supply stores. ATE is a good fluid, and it works for them. Brake system component life is influenced by driver technique, too. Philip, I know your style and skills are very sound, so I have some questions: 1. How often are you bleeding brakes? I bleed at least once a day, even on a Honda. I've had Ferrari guys that required a bleed every session, but they were 'King of the late brakers'. 2. When were your caliper seals replaced? I do this every 10-12 days of track use (and ALWAYS before a track like Montreal). For most, this is a year or more, for some, this is three times a season. Higher temperature seals are available, email me you size in mm. 3. As for fluid, (we just had this discussion in 'General' last week), get the manufactures specification for dry boiling point, don't go off of DOT3/4 minimum specifications. The ATE, Motul, AP fluids are all good. IMHO, there are only two brake fluid choices: Ford Heavy Duty/ Willwood 570/ Performance Friction Z Rated (all Dow Corning) . This is all the same stuff brewed by Dow, and repackaged. Dry boiling point is 568 degF. A pint is about $6 at any and all Ford dealers. The only other choice is Castrol SRF, dry boil is about 600 degF, cost is $60 per liter. You best be ducting plenty of air into the center of the rotor and life the caliper seals. (For additional specifications and discussion, here's the other post: Anyone use Agip brake fluid?. I know you're ducting air into the rotor center, your next modification is an evaporative cooling system. Tilton manufactures a simple and effective system you can easily adapt. In summation, the key points are: High dry boiling point, at least 500degF Bleed brakes often, at a minumum of just before a track day Change caliper seals anually if you do more than eight days a year (track and driver dependent) High temperature, hard pads (1000 degF capabilities) Best regards, Rob Schermerhorn
Yet another excellent, informative post by Rob. Philip, from this amateur's point of view, either you need to upgrade your rotors/calipers to something bigger and heavier to help dissipate heat better, or modify your braking techniques. On some track days, two friends in nearly identical 355 Challenge cars, running the same number of laps: one would barely use up any pad material, while the other would wear out a set of pads and boil the fluid. Guess which guy was running faster lap times - surprisingly or not surprisingly, the guy who braked later and harder and used LESS pad material. Why? My theory, and I could be TOTALLY WRONG about it, is that the faster guy just hit his brakes later but HARDER, and then got off the brakes quickly, giving them time to cool. The slower guy would brake earlier, carry the braking for longer, and would have less time during the lap to let the brakes cool. Just my $.02. vty, --Dennis
In general, the fastest guys will tend to be at the grip limits of their tires at all places (braking, braking + turning, or just turning). "Threshold Braking." This comes from some track experience and a lot of research. The guy who brakes hardest, shortest is faster because they have the highest average speed through any given braking segment (assuming that mathematically, they brake JUST enough to achieve a certain maximum speed that they can hold for the line they've chosen). I'm not sure how the speed of braking affects it; from an energy standpoint, you're absorbing the same amount of kinetic energy from the car by reducing its speed from x to y (1/2mv^2, velocity is the variable in this case)... Perhaps hard, late threshold braking also has a benefit of being more effective for cooling your brakes; fundamentally, though, it's a technique employed by fast drivers (something I am not very). --Mike
All, thanks for the responses. One point of clarity, Rob, we took a sample of brake fluid (on its third track day in 3 weeks) from the master reservoir at Gingerman. One of the techs had a tester - a probe which heated a sample to boiling point and measured the temp. This was where the reading came from. If I'd have heated the fluid to that temp on the track...well my guess is I'd have bent metal! Your point on changing seals is noted. Winter job. Will email you the spec when I get into the job. Thanks On the technique point raised by Dennis, absolutely concur. Found this out in spades at RA in May last year. "Use less, but use more when you use it!" Actually with the ducting, new rotors (well, new at the begining of last season), race pads and good fluid, the brakes work pretty well when you press HARD on the pedal - say coming into the Hurry Downs at Road America or 5, or Canada. But you do have to press hard!
Does anybody have a procedure for doing this? Is it easy for the technically challenged to do? I have changed my brake pads, but never replaced any caliper seals. Dom
Ferraridriver: Yes, blue can. Dom, if you can bleed brakes and have access to compressed air, you can replace caliper seals. I'll post in new thread. Philip, I highly recommend investing in some temperature paint and temperature indicating strips. You seem to enjoy gathering data, which I really appreciate, and will help gauge your system's effectiveness. You can get them at your favorite source. Pegasus has always been quick for me. Rob
Rob, good thought. Will do, and, when weather and conditions next permit, will post the data. BTW, on another thread, the WB O2 is nearly built. We have a couple of remaining questions for the supplier.
Typically on 348's the rotors were consistently over 1000degF, and calipers just over 450 degF. Rears frequently higher than front when the driver relied heavily on ABS, which is biased to the rear when running slicks. F355 and 360 Challenge, with much larger rotors and calipers, were ever so slightly cooler, depending on the driver, but still flirting with 1000 degF rotors and 400+ degF calipers. Montreal was always brutal. Trans Am cars, with proper ducting, again 1000+ degF on the rotors, 450 degF on the calipers. A Honda Civic I ran many years ago (stock rotor/ caliper): 1000 degF on the rotors, 400 degF calipers. The temperature paint helps with setting bias if the driver has difficulty with giving good feedback. It also helps with confidence in the brakes if you're only going up to 800 degF (hit 'em harder). F40 will only survive a track like Blackhawk is with brake ducts modified to force air into the center of the rotor and add the evaporative cooling system. Otherwise, three laps and you're done. What it comes down to is heat management via air ducts, or in extreme situations, evaporative cooling system. Bleeding brakes every day is good insurance, or may be mandatory. Rob
Rob: Your 348 Challenge drivers were using the ABS? I'd been under the impression that most ran without it, and have it disconnected on my car (used solely for track events, and driving to/from). Your thoughts? THANKS. Ira
I have been very happy running ATE's Racing Blue. I have used it for 2 years and 7-8 track events with great results.
