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Discussion Starter #1
Hey,

question to guys who are often on track.
My setup is like: DBA T3 4000 + DS2500 + RBF660 + Goodridge Stainless Brake.
I thought such improvements would get rid of the unpleasant effect. But it's still there, so I don't trust the car when it brakes. The problem is that after two hard brakes, for example from 130 to 60kmh, during another strong braking, my leg gets into (fall into?) the pedal, the braking force decreases and I almost have a heart attack. What can this be a result of? The effect of overheating of discs/pads is not going to be such a thing?
 

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Pad fade does not cause a soft pedal; pedal pressure is normal, but braking force is reduced when that happens.

If your pedal gets soft, it means that the brake fluid boiled or you have air in the system, so you have gas in the calipers. The pedal goes to the floor because it's easy to compress a gas. Doing a full brake fluid flush to get all the air bubbles out will fix this problem. The high temperature brake fluids need to be changed more frequently than normal brake fluid, maybe twice a year, since they absorb water more easily, so also change it if it's old.

I would not recommend DS2500 for track driving in this car. The brakes get really HOT, and I've had DS2500 catch on fire in my track car. They're a good pad for aggressive street driving, or auto-X, but they can't take consistent heat.

(Powodzenia! Hamulce są na pewno zapowietrzone)
 

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Discussion Starter #4
Thanks. Maybe I used wrong words, but my problem looks like this flow:
WOT --------> hard braking --> [good hardness] --- (still braking) --> [good hardness] --> NOW, my foot fall into floor --> release -> brake again with good hardness but not as at the breaking beginning.
@OppositeLock - wymiana płynu miała miejsce, max 4tyg przed wczorajszym eventem, ale wczesniej też miałem ten problem. Maybe is RS's characteristic?
 

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You are describing _exactly_ the problem of air in the braking system. Trust me, I've been doing this for many years and many thousands of track miles :) This is not normal, it is dangerous, and it needs to be fixed. Our cars are very heavy and very hard on the front brakes. Did you bleed air from both bleeder screws on the front calipers? Each caliper has a bleeder screw on the inside and on the outside.
 

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Easy? Yes.
Depending on your tools and process, it can sometimes be hard to know for sure you've bled all the air successfully. From my own experience if I thought confident I did it right and yet *still* had an obviously soft peddle, I'd start the process again from the beginning.

For folks who have done this on various cars, we also know the FoRS is still a tad soft when bled correctly. I just live with it... but never had my peddle drop to the floor ( including many track days/miles).

Good luck!

I don't have a link handy, but I bet there are plenty of videos online to educate someone who is unfamiliar with the procedure. I watched someone in person first, before doing any of my own. That was before YouTube, but the idea is the same.
 

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I use a Power Motive bleeder with appropriate metal adaptor for the brake reservoir (can't remember the part #) Loosen the bleeder screws just enough and bleed very slow so don't get air in. Works great. I'm using G-loc R16's front and rear and Motul 660. 20-30 minute sessions and no significant fade for a weekend.
 

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I'm really happy with the combo we converged on after trying several things. Agreed with Oppositelock - soft pedal, if stainless lines are intact, is likely to be fluid related. It pains me every time I do it, because it is so expensive, but the track day is a loss if brakes aren't perfect, so we now only use Castrol SRF ($70/qt). I have it changed after every event (usually two day track days max), and special care has to be taken to make sure there are no bubbles. I'm not a mechanic, but apparently moisture is the big problem, so I believe once a quart is opened, you should use it or toss it (more ouch). Don't quote me on that last one, just what I recall.

We use stock RS calipers, same rotors as you: DBA T3 4000, and Ferodo DS1.11 pads. My son and I shared the car at Buttonwillow a month or so ago for two days, and the brakes were perfect. We hope we've fixed an engine cooling problem that was limiting us to about 8 laps a session, by switching from our Mishimoto oil cooler to a Cooltech with Setrab core (and we added a real oil temp gauge) but we won't know until Thunderhill in a few weeks. Hope that helps.
 
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