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Old 08-12-2012, 07:01 AM   #1
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Default Bent caliper forks?

So I have this terrible brake pad wear issue. After a few trackdays my front pads look like this:

Outside (the right is the top of the pad, the left is the bottom [hub] side of the pad):


Inside (horrible photo, but it demonstrates even pad wear):


Front to back they are essentially even.

This is what I have ruled out:
-pads - I have tried several types, all with same result
-rotors - I had cheap aftermarket slotted rotors, and went back to OEM rotors with same result. **See below
-slider pins - replaced with brand new OEM ones, and lubed up nicely
-bracket - both would be wearing uneven if this was the case
-heat - trackday was super cold (like 10-15*C ambient), and pedal was firm whole time; no fade. Plus car is stock performance-wise

**
I recently got the OEM rotors skimmed and put new pads in for a recent trackday, and got this:

After 300km road driving to track


After first session


You can see that the inner most surface of the rotor is untouched

The only thing I haven't been able to eliminate is the caliper itself. I have rebuilt it myself, so all the seals and such are new, but the car has been through maybe 20 track days with these calipers. Is it possible that the two outside forks have bent outwards at their base? Has anyone ever experienced a similar issue? How was it resolved?
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Bent caliper forks?-p1030528large.jpg   Bent caliper forks?-p1030530large.jpg   Bent caliper forks?-7680305904_1a2042aa2a_b.jpg   Bent caliper forks?-7680306244_f0bbf16296_b.jpg  
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Old 08-12-2012, 07:20 AM   #2
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Search bro.

This is normal, they all do it.

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Old 08-12-2012, 07:23 AM   #3
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Very, very, very, very normal.

Only solution seems to be either continue replacing pad when they still have an average of 50% meat left on them, or upgrade to Wilwoods. Or stop braking as much.

You can try adding brake ducts, but I don't know that it'll help any.
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Old 08-12-2012, 07:24 AM   #4
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That's great, but I am trying to find out why they do it. If heat is causing them to deform, then will better cooling fix the problem?

I dont want to have to go down the road of Willwoods or similar (which is so far over kill on a car with not even 70kw that it's not funny), if it is a relatively simple fix
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Old 08-12-2012, 08:02 AM   #5
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Alright, it is a relatively easy fix then. Keep replacing the pads at half life.

Everyone suffers this problem, its a symptom of the single piston sliding calipers. The only way beyond wilwoods is stickier tires, better suspension, and a better driver.

Feel free to try and weld in reinforcements, bend the forks, forge new castings out of kryptonite, or anything else. They'll just be temporary fixes to a design that was never ment to be raced hard on.
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Old 08-12-2012, 08:07 AM   #6
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"The only way beyond wilwoods is stickier tires, better suspension, and a better driver."

What do you mean here?
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Old 08-12-2012, 08:16 AM   #7
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Use less brakes.
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Old 08-12-2012, 08:42 AM   #8
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Lol.

Its the caliper flexing, there is no solution.

Dann
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Old 08-12-2012, 03:01 PM   #9
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Upgrade to big boy brakes.

Or replace pads at half life like I do because I'm too lazy to upgrade at the moment.
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Old 08-12-2012, 04:46 PM   #10
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BTDT. Run super-stiff metal race pads or upgrade to Wilwoods.

Eventually, if you plan to track the car with a turbo, the Wilwoods will be absolutely required.
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Old 08-12-2012, 07:12 PM   #11
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Do sport brakes suffer from the same problem?
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Old 08-13-2012, 05:27 AM   #12
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Seems silly, because I know a guy with a bone stock car that sees more track days than mine, and he has near perfect pad wear!!!
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Old 08-13-2012, 06:23 AM   #13
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Hes easier on them, he simply pushes them less hard.

Perhaps his pads have a higher coefficient of friction and require less pressure.

Perhaps he has more mechanical grip.

Perhaps he just corners faster.

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Old 08-13-2012, 02:23 PM   #14
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This notion that you can simply "corner faster" and not use the brakes as much is absolutely hilarious to me. If you are a good enough driver to corner faster, you're going to be going faster on the straightaways and using the brakes later, and you will always, always, always be HARDER on the brakes as a result.
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Old 08-13-2012, 02:26 PM   #15
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Quote:
Originally Posted by mitch_f1 View Post
Seems silly, because I know a guy with a bone stock car that sees more track days than mine, and he has near perfect pad wear!!!
He's probably slower than you.

Come to think of it, that's a perfectly valid solution - just drive more slowly. Kind of defeats the purpose, though.
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Old 08-13-2012, 07:41 PM   #16
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Quote:
Originally Posted by Savington View Post
This notion that you can simply "corner faster" and not use the brakes as much is absolutely hilarious to me. If you are a good enough driver to corner faster, you're going to be going faster on the straightaways and using the brakes later, and you will always, always, always be HARDER on the brakes as a result.
Not necessarily. That's true if you're really pushing the limits of the car, but in most HPDE situations I've found instructors will teach you to over brake rather than the alternative, and this stays with some drivers. At least that's my experience.

Either way, he's not solving his problem without different calipers and/or pads.
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Old 08-13-2012, 08:05 PM   #17
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Quote:
Originally Posted by Saml01 View Post
Do sport brakes suffer from the same problem?
Yes
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Old 08-14-2012, 05:41 AM   #18
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Quote:
Originally Posted by Savington View Post
He's probably slower than you.
He is, but only by just over 1second. He is the fastest in the stock class; no one has even come close to his best lap time. Be brutally abuses the brakes (with mechanical sympathy), but he is hammering the car to get around the track so fast. This is what makes me think that it could be a fixable problem.
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Old 08-14-2012, 06:26 AM   #19
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I've come into the pits on a trackday driving a MK1 with ABS equipped. The brakes were on fire they'd been abused that badly, pad wear on that car is 100% even all the time.
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Old 08-14-2012, 06:27 AM   #20
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Exactly what I mean. There must be something else at play here
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