Philostang
Chrome Hater
So long as we're in a "freak out" mood...and I'm feeling chatty...
Welcome to the track baby! Take your bling and WALK.
Background notes:
First, this isn't my rotor, nor is it a Mustang rotor (Civic, as I recall). This was the rotor of a pretty aggressive track rat (if you don't respect Civics yet, you will when Joe passes by you).
Second, the above occurred largely due to "pushing it" in two ways. A.) He drives fast, requiring hard braking, which he likes to do late. B.) I'm pretty sure he knew he should have replaced that rotor earlier, but he thought "just one more..."
Third, this is a solid rotor. Had it been drilled it would have come to this much sooner.
If you're checking your rotors as you should, you'll start to notice spider cracks developing (heat cracks, stress cracks, etc.). No biggie, at least until they start to get big. For me, this means either they get larger than about 1-1/4" long or I can feel my finger nail catch on them when dragged across the surface. After that, they're getting into a danger zone: what exactly they'll do the next time they're put to service isn't predictable. Usually I've seen them just "open up" (they get only a bit longer, but suddenly develop a gap in them, no longer looking like a spider's thread). Sometimes they open the hell up! (see above pic), make horrendous noise and chew up your pads to nothing. Seen this happen a few times to folks. And sometimes I've heard they just give up the farm entirely (i.e. fragment while spinning).
Alrighty then, now think about the process a bit. Spider cracks develop and grow lengthwise before opening up. In a solid rotor they grow a bit over an inch before they become dangerous. At an inch, what's surrounds them? A: lots more metal that helps sustain the structure. In a drilled rotor, at 3/4" of length what surrounds them? A: nothing, they've already met a drilled hole which does little to support the growing stress as it's put into service again. They become dangerous much sooner.
And of course, what started the stress crack in the first place? A: heat, which is largely managed by mass (and of course quality metallurgy), which has just been reduced in a drilled rotor. The factors contributing to an early demise are capitalizing on one another. Less mass means quicker growth of stress, and then there's very little room for that stress to get help.
History: there was a time when drilled rotors were used in racing, but that was a long time ago and for a purpose. The benefit lie in dealing with the gassing of pads (offering an avenue for the gas to escape before it buffered the contact surface), which was a real concern with the pad compounds used years ago. These days race pad compounds don't gas nearly as much as they once did. So if you look at all the high end race teams you'll see they don't use drilled rotors (and most are now on to carbon ceramic, but that's another story). Why would they? Drilling was considered a necessary evil with only one lingering benefit - BLING! So on some factory sports cars destined for consumers who are not real drivers, just all-show pocketbooks (*cough*Porsche*cough*), you'll still find drilled rotors. Attractive to the Viagra-triangle crowd? Yes. Useful? No.
Best,
-j
Welcome to the track baby! Take your bling and WALK.
Background notes:
First, this isn't my rotor, nor is it a Mustang rotor (Civic, as I recall). This was the rotor of a pretty aggressive track rat (if you don't respect Civics yet, you will when Joe passes by you).
Second, the above occurred largely due to "pushing it" in two ways. A.) He drives fast, requiring hard braking, which he likes to do late. B.) I'm pretty sure he knew he should have replaced that rotor earlier, but he thought "just one more..."
Third, this is a solid rotor. Had it been drilled it would have come to this much sooner.
If you're checking your rotors as you should, you'll start to notice spider cracks developing (heat cracks, stress cracks, etc.). No biggie, at least until they start to get big. For me, this means either they get larger than about 1-1/4" long or I can feel my finger nail catch on them when dragged across the surface. After that, they're getting into a danger zone: what exactly they'll do the next time they're put to service isn't predictable. Usually I've seen them just "open up" (they get only a bit longer, but suddenly develop a gap in them, no longer looking like a spider's thread). Sometimes they open the hell up! (see above pic), make horrendous noise and chew up your pads to nothing. Seen this happen a few times to folks. And sometimes I've heard they just give up the farm entirely (i.e. fragment while spinning).
Alrighty then, now think about the process a bit. Spider cracks develop and grow lengthwise before opening up. In a solid rotor they grow a bit over an inch before they become dangerous. At an inch, what's surrounds them? A: lots more metal that helps sustain the structure. In a drilled rotor, at 3/4" of length what surrounds them? A: nothing, they've already met a drilled hole which does little to support the growing stress as it's put into service again. They become dangerous much sooner.
And of course, what started the stress crack in the first place? A: heat, which is largely managed by mass (and of course quality metallurgy), which has just been reduced in a drilled rotor. The factors contributing to an early demise are capitalizing on one another. Less mass means quicker growth of stress, and then there's very little room for that stress to get help.
History: there was a time when drilled rotors were used in racing, but that was a long time ago and for a purpose. The benefit lie in dealing with the gassing of pads (offering an avenue for the gas to escape before it buffered the contact surface), which was a real concern with the pad compounds used years ago. These days race pad compounds don't gas nearly as much as they once did. So if you look at all the high end race teams you'll see they don't use drilled rotors (and most are now on to carbon ceramic, but that's another story). Why would they? Drilling was considered a necessary evil with only one lingering benefit - BLING! So on some factory sports cars destined for consumers who are not real drivers, just all-show pocketbooks (*cough*Porsche*cough*), you'll still find drilled rotors. Attractive to the Viagra-triangle crowd? Yes. Useful? No.
Best,
-j
