Brake fade at CMP

RN SHARK

So last weekend at Carolina Motorsports Park I experienced brake fade for the first time on track. The pedal went to the floor and had very little braking ability. This happened a few times near the end of 25-30 minute sessions. I am trying to figure out why this happened and if I can prevent it. Air temps were mid to upper 80's.
My setup is Carbotech XP10 front, XP8 rear, front RacingBrake 2-piece rotors, rear stock rotors, Stillen brake cooling ducts, Motul 600 fluid, SS brake lines.
The pads were new for this weekend and the fluid was recently flushed in April. I did not have any fluid flow out of my bleeder screws. The only thing I can think of is that this track is hard on the brakes with straights just long enough to build up speed, but not long enough to effectively cool the brakes. After the sessions I would drive down the street about a mile each way and the pedal would come back a bit. By the time the next session started, the brakes felt solid again, until 20-25 minutes into it. For reference I was running 1:55 to 1:54 lap times.
I have not had this happen anywhere else. I've been to AutoClub Speedway many times in the summer, Big Willow, VIR, and Roebling Road.
Any thoughts?

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'09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare
'14 SRT Grand Cherokee; '08 TL Type-S

street2soul

by the description of pedal going to the floor, only thing i can think of is the fluid boiling even though it's RBF600, and if maybe a leak in the brake booster/master cylinder. If there is no leak whatsoever, and assuming the brakes were bled properly and it sounds like you have done this, probably the overheated brake fluids.. good idea to bleed it again to see if there were any massive amount of air traps. Was this track short, technical and alot of braking? I've been to 7 tracks total, and Shenandoah is the only track that will cook my brakes and give me brake fade.


EDIT: do you have a aftermarket SS brake lines? i dont have any experience with them, but could be possible that they might be expanding.

RN SHARK

I do have aftermarket SS brake lines. Not sure if they are expanding/failing on me. I would say the track is on the shorter, more technical side. I did not see a leak in the master cylinder, but I will double check everything when I swap out my track pads back to street and bleed the brakes again. I did add the Z1 brake master cylinder bracket, but that only stabilizes the unit and would not cause a leak.

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'09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare
'14 SRT Grand Cherokee; '08 TL Type-S

street2soul

yes please let us know, i'm curious of what you find.

but i agree with you on this one, i think the brake fluids just got too hot because of the nature of the track configuration. It is mind boggling, but brakes do get super super hot shorter, technical tracks. For example, at COTA brake feel is solid even after a full weekend, but eating through pads and rotors. shorter tracks with alot of 100-50 braking zones seems to cook even RBF600 with our shitty brake cooling design on the 370.. even brake ducts may not provide as much alleviation according to some guys on the 370z

BGTV8

You require supplemental brake cooling (ducting)

RN SHARK

I already have the Stillen kit. So you are saying more than that?

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'09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare
'14 SRT Grand Cherokee; '08 TL Type-S

echoshotz

Maybe you're just getting fast enough to begin reaching the limits of the XP10/8 combo by the end of a session.

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2014 Solid Red Nismo 370z
Motordyne|Synergy Composites|Stance Suspension|Recaro|RJM|EVOR

cv129

Curious, how old (length of time and miles) is the brake fluid? Would something like Castrol SRF or Torque RT700 help? How about Titanium brake pad shims to buy you a little more time before boiling the brake fluid?

Edit: reading fail, OP said fluid recently changed.

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Setrab | RE-71 | SPL | JRZ | Nismo | ARK | Whiteline | RacingBrake | CJM Oil Pan | Ti shield

BGTV8

Stillen kit is only 2" hose ... I reckon you are creating more heat than this kit can cope with and 3" or 4" hose is required.

Rusty

You are to the point where you need more cooling on the front rotors. You're boiling the brake fluid. I run the same set-up. Racing Brake rotors front and rear, 10/8 combo, Hard Racing Ti heat shields on the front calipers, Z1 stainless lines, Motul 600, Nismo RC brake ducts. I've had my bleeders leak.

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浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
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RN SHARK

Well damn. I guess I'm just getting faster. I'll have to look into larger diameter brake duct hosing. And I just bought and installed all new 2-ply hoses this track season. Maybe those Ti shims too.

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'09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare
'14 SRT Grand Cherokee; '08 TL Type-S

Eagle

You are probably getting faster. You could also try going to yet a higher temp brake fluid, Motul offers an RBF 660 which I ran without any boiling issues. Other alternatives I've tried are the Brembo LCF (600+) and the HTC 64 which is meant for racing applications.

My rotors are OEM or Centric Premium replacements, pads are Endless MX72's.

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