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Old 10-06-2015, 05:11 PM   #1
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Default Front Brakes Dragging When Hot

Looking for anything I may have missed so here goes.

My front brakes drag significantly after a 30 minute track session then slowly return to normal after 45+ minutes of sitting before the next session. The rear brakes are perfectly fine.

Here's what I've replaced:
Calipers - The issue is there with NA8 and Sport calipers
Brackets - Same as above
Stainless Lines
Hard Lines
Master Cylinder (15/16) - 3 times
Compound - Carbotech and Hawks - Same issues
Spindles
Hubs

I've adjusted the brake preload as well and that hasn't helped.

The only thing I haven't replaced is the Sport Booster and the Wilwood Prop Valve. I'd be surprised if either is the culprit but at this point one of them has to be. The prop valve only plumbs to the rear so I don't think that's it but what the hell do I know at this point.

Thoughts?

-Jason
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Old 10-06-2015, 05:54 PM   #2
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How tight are the pads going into the clips? I ended up grinding my pad edges slightly to get them to pop in. They were just way too tight. If yours are tight, with a slight bit of heat expansion, they might stick.
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Old 10-06-2015, 06:07 PM   #3
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The pads move without much/if any resistance. I did grind the pad edges slightly to see if that would help but it hasn't. Since the problem occurs with multiple pads I don't think the pads are the cause.
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Old 10-06-2015, 06:19 PM   #4
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Old 10-07-2015, 10:54 PM   #5
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I'm going to try to replicate the problem and pull the master away from the booster to see if that frees things up. If that doesn't work I'm setting the car on fire.
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Old 10-22-2015, 11:38 PM   #6
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Okay, i have just resolved the same problem......

Not sure if yours is the same cause but for the record..

I have the 11.75" Big BBK with Willwood dynalites and carbotech xp 12's.

I LOVE the pedal feel and the stopping power.

Worked well for the first few sessions but then noticed the wheels wouldn't spin after a session (I like to jack the front end and turn them to try and prevent cracking).

After the first few sessions of this setup i could barely turn the wheel by hand. Couldn't figure it out...

Subsequently cracked the left rotor ( seizing was worse on that side).

Replacing the rotor the other day i was looking at some old Padgid pads and noticed they had a cut out for the inner rotor curve.

Looking at the Carbotech ones they dont have the cut out and I had the perfect relief of the inner rotor (a cliff) on the pad and that had been wearing on the inner edge of the rotor. To the point where it had a nice radius on the rotor.

I haven't tested yet but am sure this is the cause of the problem for me. I spent some time on the bench grinder grinding down the inner curve as the padgids had as standard.

I am hoping this is the cause of the pads wearing so fast as well.....

I am not sure why this is suddenly a problem after using the xp10's on the normal BBK for the past 2 years....must look at the old p 10's to see if they have the cut out.....I have to admit that if it was the cause to being a bit disappointed with Carbotek/Supplier about it.
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Old 11-02-2015, 03:46 PM   #7
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For anyone that gives a ****, it looks like the problem was the booster. I swapped in a new NB Sport booster from Mazda and the problem went away. I believe the issue was with the actuating rod inside the booster.
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Old 11-02-2015, 09:50 PM   #8
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Thanks for the update
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