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Some details; yesterday I drove the full course Autobahn Club circuit as my first time on this track so I am not sure if harder on brakes then my normal tracks (Mid Ohio, Gingerman, Grattan, Waterford Hills)

I was in the Advance group running a faster pace then most. I was on new front pads (Carbotech XP12s) and New BOE floating rotors in front. Before event I thought I correctly bedded the Pads and Rotors. I have ATE racing brake fluid (rated 280 dry and 198 wet boiling point) and I bleed after every track event with 10% fluid change and complete flush between blue and clear every year. (I do about 8-10 track days a year)

15 minutes into my 2nd 25 minute session brake pedal went soft to the floor. In the pits I changed ~60% new ATE brake fluid and bleed brakes again. Next 25 minute session no issues and out braking passing most in advance group. Next session 15 minutes in session pedal goes soft again and I call it a day. This morning I drove Lotus down the street with cold brakes all is fine again. Looking at my front pads they are solid white and must have been supper hot at track.

Did I broil my brake fluid and need a complete flush with something better then ATE brake fluid? I am starting my after track day typical maintenance/inspect/clean (My idea of a vacation day from work) I plan to take pads out and see if glazed, but thinking I cooked the brake fluid?

Picture of white pads;
 

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ATE blue is a decent fluid but not all that great. If the petal went soft and went to the floor that is typically boiled fluid. A glazed pad in my experience still has a solid petal but just doesn't provide the stopping power.

I would definitely swap to a better fluid. Great cheap insurance. IMO RBF600 is a great fluid for the price, and if you are willing to get spendy I have only heard good things about Castrol SRF.

What exactly do you have for brakes? If you don't already have ducting and different pistons you will likely want to do those as well.
 

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I can't help but I am curious - what kind of times were you running?
 

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Yes you got the pads quite hot. The rotors are fine. You're probably over braking a fair bit, but that all fixes itself in time...

Will have to step up to a better fluid and /or consider the vented SS pistons. If you've already done the pistons, then better fluid will certainly solve the issue. Motul 600 typically works and then Castrol SRF always works... If the pedal goes to the floor, you boiled the fluid...

Cheers,

Phil
 

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Discussion Starter #5
I can't help but I am curious - what kind of times were you running?
Hello, well I can say for sure I have very much to learn on this track and was likely over braking as I learned the new track. Many corners are very late Apex's and I did not get this at first.

I had 4 sessions total (two cut short) My times where best 2:49 with most 2:50 - 2:52 on full 3.56 mile circuit. I believe if I was not over braking I would have had better (smooth) times and less likely to have boiled my brakes.....:eek:
 

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Discussion Starter #6
Yes you got the pads quite hot. The rotors are fine. You're probably over braking a fair bit, but that all fixes itself in time...

Will have to step up to a better fluid and /or consider the vented SS pistons. If you've already done the pistons, then better fluid will certainly solve the issue. Motul 600 typically works and then Castrol SRF always works... If the pedal goes to the floor, you boiled the fluid...

Cheers,

Phil
Phil as usual I am sure you’re correct, I was learning a new circuit and I am sure I was over braking for sure. I will try better brake fluid…. Never fails, I had bought a case of ATE fluid too
 

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Discussion Starter #7
Yes you got the pads quite hot. The rotors are fine. You're probably over braking a fair bit, but that all fixes itself in time...

Will have to step up to a better fluid and /or consider the vented SS pistons. If you've already done the pistons, then better fluid will certainly solve the issue. Motul 600 typically works and then Castrol SRF always works... If the pedal goes to the floor, you boiled the fluid...

Cheers,

Phil
OK Phil, just put in a order for BOE SS pistons and Castrol SRF. I have long weekend at Mid Ohio oct 27-28
 

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If the pads turned white...they are cooked, period and probably glazed. You can prep the surface again but I think its a waste of time. I have been there and done that and it lasts only a session or two, maybe.

I also run the carbotech xp12 but with AP Racing PRF660 Brake Fluid.

I am really pushing the car in tt format so I find at some tracks that I need to do a brake bleed every few sessions and at end of day in prep. XP12's have a technique to them...they have fantastic initial bite, so slam on them to get that initial speed down then feather off to a trail brake. I find that if you push harder past that initial bite they cook and pedal does go down as your describing.

At a track like Road America, I will bleed between each session as that track is a brake cooker.

I have been a fan of them but have been testing out performance friction brakes and seem to like the range of feel so far.
 

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I agree that you boiled your brake fluid. Sorry....but super blue is crap. I ran showroom stock for 14 years, so know all about boiling fluid. You need to look at the dry boiling point of fluid you'll consider. You also need to change the fluid completely before each event. Most HPDE and racing organizations will say that right on their tech form. I wrote a thread "the brake fluid thread" on nasioc years ago after researching brake fluids. It's pretty old, but gets the basic point across. You don't want to be using a 535F fluid. 595-600+ will be better.

You can also devise brake ducts. Back in the day, I would run temporary hoses exiting behind the brakes tied on with zip ties and then cut the ties before the time trials. I got the cooling during practice and became legal for the time trials.

The pads should be fine once you square away the fluid. If the pedal goes away during a run, you can pump it back up and then "nascar brake". This involves braking early and lighter to spread the heat and give the brake components more time to dissipate. I've had fluid boil and been able to cool it down enought with this method to finish the session.
 

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You experienced fluid boiling, that's why the pedal goes to the floor.

Your pads are shot too. i used to do this to Pagid RS14's, and after they turn white like that, they'll start to crumble in a few days time, since the binder effectively burned up.

BOE's stainless steel pistons fixed my fluid boiling issues (I'm now running super cheap ATE super-blue)

CL RC6 pads have an insanely high max temperature, and they're actually reasonably streetable, so I run those now.

Braking issues are completely solved. Don't run CL pads without the SS pistons, since they actually transmit more heat than non-metallic pads, so they'll make your boiling worse.
 
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