Opinion/knowledge of this...

[Roadracer350]

It does not matter if you turn them or not the cracked will still be in the underlying metal. Once they get hot again the metal will expand hence the cracks will open up and get bigger and eventually crack all the way thru and fail. Have you ever seen a rotor come apart? It looks like a grenade goes off in the wheel well. Let's do some simple physics.. You on the highway doing say 60. The rotor and the wheel are traveling at the same speed. Here is where it gets interesting... The edge of the rotor near the front of the car is doing 60 and slowing just like the tire, the bottom is doing 0, the rear edge closest to the cabin is doing 60 and accelerating and the top is at max velocity doing 120. I don't know about you but a hunk of steel doing 120 I want to be true and fatigue free... Just my opinion.

 

[SD_Stang]

^^^^That Answers that.

 

[back n a stang]

It does not matter if you turn them or not the cracked will still be in the underlying metal. Once they get hot again the metal will expand hence the cracks will open up and get bigger and eventually crack all the way thru and fail. Have you ever seen a rotor come apart? It looks like a grenade goes off in the wheel well. Let's do some simple physics.. You on the highway doing say 60. The rotor and the wheel are traveling at the same speed. Here is where it gets interesting... The edge of the rotor near the front of the car is doing 60 and slowing just like the tire, the bottom is doing 0, the rear edge closest to the cabin is doing 60 and accelerating and the top is at max velocity doing 120. I don't know about you but a hunk of steel doing 120 I want to be true and fatigue free... Just my opinion.

Thanks.....This is what I was thinking and feeling too. This is why I posted to ask you fellows opinions....Was hoping to hear otherwise but felt the reality was the cracks will come back to hault me. Metal is stressed and is trash...I will carry them next time with salvage

 

[hunterwiley]

I'll post my opinion FWIW.... that heat checking on the face of the rotors would not be concerning to me, especially if I can't catch a fingernail in the cracks. Certainly for a DD I'd be comfortable using them. An 65mph to panic stop isn't going to put nearly as much heat into a rotor as a track session, especially with street pads. Those rotors might last you years on a daily driver. If a crack extends to the outer edge of the rotor then it's trashed. But any rotor that goes through significant heat/cool down cycles is going to check like those pictured. I just put a brand new pair of stoptech rotors on the racecar, and after a single race weekend I have some checking. I expect to get a full 2014 season on them before the checking worsens enough to replace them. On my fox racecar I got 2 years out of a pair of Stoptech rotors... good cooling is key.

Now my rotor rings are nearly $300 each... for a daily driver where the rotors are cheap, sure, go ahead and replace them. Like changing your oil at 3k miles...

 

[NoTicket]

What rotors are you guys buying that spider web so easily? I have nothing like this happening on the standard motorcraft rotors while using Motul 600 and Raybestos ST-43 pads.

Is this from rapid cool down when using cooling ducts?

 

[kcbrown]

What rotors are you guys buying that spider web so easily? I have nothing like this happening on the standard motorcraft rotors while using Motul 600 and Raybestos ST-43 pads.

Is this from rapid cool down when using cooling ducts?

That's what I'm wondering as well. Is it really normal for these cars to go through a set of rotors per track day? So when you are at the track for a weekend, you wind up burning through at least two sets of rotors?

Replacing the rotors is not a completely trivial job, if I'm not mistaken. Aren't you looking at something like half an hour per corner for that? That's not the end of the world, but still, I somehow suspect that if there were that much involved, most people wouldn't bother taking their car to the track...

 

[NoTicket]

It is not normal for me. I have spent several track weekends on the same set of stock rotors and have yet to see any of these issues.

Sent from my XT907 using Tapatalk

 

[PLee]

I'll post my opinion FWIW.... that heat checking on the face of the rotors would not be concerning to me, especially if I can't catch a fingernail in the cracks. Certainly for a DD I'd be comfortable using them. An 65mph to panic stop isn't going to put nearly as much heat into a rotor as a track session, especially with street pads. Those rotors might last you years on a daily driver. If a crack extends to the outer edge of the rotor then it's trashed. But any rotor that goes through significant heat/cool down cycles is going to check like those pictured. I just put a brand new pair of stoptech rotors on the racecar, and after a single race weekend I have some checking. I expect to get a full 2014 season on them before the checking worsens enough to replace them. On my fox racecar I got 2 years out of a pair of Stoptech rotors... good cooling is key.

Now my rotor rings are nearly $300 each... for a daily driver where the rotors are cheap, sure, go ahead and replace them. Like changing your oil at 3k miles...

^^ I agree with this. I've raced on many a check'd rotor; it's what they do. Checking is fine as long as you monitor it and ditch them once any cracks hit the edge of the rotor. You can typically feel (in my experience) when a crack occurs in the rotor at the edge... it'll thump pretty good through your brake pedal.

It should be regular practice to give your car a walk-around after a session on the track (and/or just before going out on your next session), to check your tires, brake rotors, etc...

 

[Sky Render]

That's what I'm wondering as well. Is it really normal for these cars to go through a set of rotors per track day? So when you are at the track for a weekend, you wind up burning through at least two sets of rotors?

Depends on the ambient heat, how deep and hard you brake, how fast you drive, the pads you use, and a number of other things. Going through a set of rotors in one day is not unheard of, especially at competitive levels, and even more especially on big land yachts like the S197.

Replacing the rotors is not a completely trivial job, if I'm not mistaken. Aren't you looking at something like half an hour per corner for that? That's not the end of the world, but still, I somehow suspect that if there were that much involved, most people wouldn't bother taking their car to the track...

Seriously? You take the wheels off, remove the two bolts holding the caliper on, and pull the rotor off. If you think that isn't trivial, you shouldn't be working on cars.

 

[Bad06stang]

I would replace those dude. When I bought my Brembos the rotors looked like they had track time on them too so i went to have them turned at 3 different places and nobody would do it for me, they all said brembo rotors cannot be turned. (which I think is bullshit) but anyways rotors for this car are not badly priced man I would just scrap those and buy new ones if it was me. Look at rockauto.com, that is where i got my drilled and slotted powerstops for all four corners for $280 shipped. If you wanted to save the pads still couldn't you just scuff them with sand paper? I have never personally done this but I know people that have.

 

[kcbrown]

Depends on the ambient heat, how deep and hard you brake, how fast you drive, the pads you use, and a number of other things. Going through a set of rotors in one day is not unheard of, especially at competitive levels, and even more especially on big land yachts like the S197.

I guess that raises the question of how many spare sets of rotors you should have on you. Is it likely that someone who hasn't driven the track very much and who will be driving on street tires will burn through rotors like crazy?

Seriously? You take the wheels off, remove the two bolts holding the caliper on, and pull the rotor off. If you think that isn't trivial, you shouldn't be working on cars.

Oh, okay, that is trivial.

For some reason, I was recalling mention of dealing with the brakes taking an extra hour or something, but my memory is quite hazy in even the best circumstances. I may have been thinking of how long it would take to bleed the brakes with fresh fluid, rather than replacing the pads and rotors.

 

[JesseW.]

that is where i got my drilled and slotted powerstops for all four corners for $280 shipped.

made that mistake once. no more drilled/slotted rotors for me. cracked a set of front rotors in 4 autocross events..... the blank rotors have lasted me well over a year. street bling only.....