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Discussion Starter · #1 ·
On my Evora, I have observed rather interesting wear pattern on all four brake rotors. The grooves all seem unusually uniform.

I'm not too concerned about it since the brakes perform excellent and there's plenty pad left. But definitely these need to get turned on my next brake change.

Have any of you seen rotors that have exhibited this same uniform wear pattern? Evora owners, perhaps it's particular to the Evora? <shrug>

(front rotors)


(rear rotors)


 

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I have the same wear pattern on my Evora. My rotors are all now cracked however from track use. New OEM on order as I could not find any aftermarket.
 

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those are the ruts caused by drilled rotors. The holes carve ruts into the brake pads, which wear the disk unevenly. Slotted rotors do not have this problem. Slotted rotors also dont squeeeeeel like drilled rotors.
 

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When I had drilled rotors, they looked exactly like that. I'd not even resurface these when you swap pads, they'll squeal for a few days after putting in new pads, then the two surfaces will mate to each other. Rotating rotors is a waste of precious rotor metal.
 

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Discussion Starter · #6 ·
Thank you for chiming in, guys. Glad it's TADTS :)

Given this, when I change mybrake pads, braking performance will be terrible until the two surfaces mate completely. Marcinr, how long did it take? I too am against turning the rotors for reasons stated already. But if it's going to take a long time to regain 100% braking performance, I'm inclined to use it as an opportunity to swap out the rotors with slotted ones when I install new pads. By anyone have any data on the specs for the Evora's rotors?
 

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Thank you for chiming in, guys. Glad it's TADTS :)

Given this, when I change mybrake pads, braking performance will be terrible until the two surfaces mate completely. Marcinr, how long did it take? I too am against turning the rotors for reasons stated already. But if it's going to take a long time to regain 100% braking performance, I'm inclined to use it as an opportunity to swap out the rotors with slotted ones when I install new pads. By anyone have any data on the specs for the Evora's rotors?
Braking performance is almost full right away, just squeaky. Braking force is basically force * surface area. When the pad doesn't fully touch the rotor, the full piston force is concentrated on the parts that do touch, they press far harder, and the mating doesn't take very long, a few days of a 4 mile commute did it for me. Just take it slow until you see how the brakes behave.

I have slotted rotors now, so I don't have this issue any more.
 

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so then when do you know when you're in need of new rotors? I have this same thing on my Elise happening and really only became noticeable after new pads a few months ago.

On previous cars if they wore unevenly I'd have them turned and when the disc fell short of tolerance thickness I replaced it. Just monitor the thickness of the rotor? What's in spec and not in spec?

edit: I've always been told that turning a drilled/slotted rotor was bad for the machine anyway as the tip will clip on each of those drilled holes and can damage the tip requiring replacement or even surface damage to the rotor
 

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so then when do you know when you're in need of new rotors? I have this same thing on my Elise happening and really only became noticeable after new pads a few months ago.

On previous cars if they wore unevenly I'd have them turned and when the disc fell short of tolerance thickness I replaced it. Just monitor the thickness of the rotor? What's in spec and not in spec?

edit: I've always been told that turning a drilled/slotted rotor was bad for the machine anyway as the tip will clip on each of those drilled holes and can damage the tip requiring replacement or even surface damage to the rotor
I believe you can lap them safely. This also leaves them smooth but not perfect. You should re-bed your brakes after this process as well (or just get new pads).
 

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Discussion Starter · #11 ·
one other question--

if I remove my calipers from the rotors, say, just for inspection purpose and put them back on, will they need to be bedded again? I don't want to remove the calipers if it requires the pads to be bedded again once the calipers are put back on the rotor. Because the way both surfaces are, it will take quite a bit of time to get the two surfaces to mate completely. I would hope that the grooves on the pad and rotor would line up exactly as before.
 

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Why dont you SOLVE the problem by buying slotted rotors. Then you dont need to worry about any of this. Think of my suggestion every time you come to a squeeeeeeeling embarrasing stop.
 

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Discussion Starter · #15 ·
Why dont you SOLVE the problem by buying slotted rotors. Then you dont need to worry about any of this. Think of my suggestion every time you come to a squeeeeeeeling embarrasing stop.

I don't have a problem with the grooves. I only asked if it was normal.

And my brakes don't squeal. They haven't squealed for the last 10K miles or so. In fact they perform flawlessly. Not sure how my question comes off as worrying but I guess you're just trying to be helpful ;)


Sent from my iPhone using Autoguide.com App
 

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Slotted rotors can still squeal, especially if fully floating like mine, and depending on what pad compound. If I stop too gently on my street pads, they'll squeal pretty bad. If I drive on the street on my race pads, They'll draw attention from about 4 miles away.
 

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Slotted rotors can still squeal, especially if fully floating like mine, and depending on what pad compound. If I stop too gently on my street pads, they'll squeal pretty bad. If I drive on the street on my race pads, They'll draw attention from about 4 miles away.
What is the advantage to "floating" rotors?
 

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Floating rotors use aluminum hats to minimize weight. A floating rotor is also able to "float" radially and or axially. You can have a fully floating rotor, or a radial only floater.

The idea is to minimize distortion of the rotor, with heat, by allowing the rotor to grow radially without trying to drag the cooler material at the center of the rotor hat along with it. The bolts that pin the rotor to the hat have oval slots (or the rotor has the oval slots) so the bolts slide as the rotor expands with heat. Then for axial float, the bolt hardware is a bit longer than the rotor+hat thickness, so the rotor is loose to the hat. This allows the rotor to float and find the center of the caliper and pads, so it isn't distorted by being pushed to one side. This also helps prevent pad knock-back.

Here you can see what happens if you have a rotor that is not allowed to float radially. The bolts have been stretched through the hat material.



Take a look at this Champ Car rotor and hat assembly. The bolts are in U-shaped grooves at the edge of the hat. The rotor is still radially fixed but free to expand a bit.



Here are the bolt hardware (also shown is a McLaren anti rattle spring). The spring is used sometimes on every other bolt, usually on road cars only. These floating rotors can squeak and make a lot of noise sometimes.

 
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