Opinion/knowledge of this...

[back n a stang]

Seems I have leaned on you guys a lot with some road course related questions lately.
These Rotors came off a Boss that spent some time at VIR and I am wondering your opinion and/or what you would think/do with these?
No depth wear at all so just wanted to know would they be worth it for a DD or would they be warped. Turning average rotors is about a thing of the past but with this size is it worth it or just what would you fellows do with these?

The only thing that may be of concern and why I am asking is the crack like look in places in the fronts which I know comes from heat. The Hawk pads are not that warn but that's another story. The fracture look is my only reason asking and yes some I can lightly feel catches with my finger nail. I may could barely feel it in some of the places you see.
My rear rotors looked fine.

**NOTE** The first pic on the outer edge is duck type....just identifying all the rotor locations from car.

 

[marcspaz]

I have to say, it depends on a couple of things. One is, they are stock Boss rotors? I am not sure factory stock rotor are laminated like other high performance road race rotors.

If they are, then cutting them on the lathe is worth it. You can cut the surface flush and remove the layer(s) with the cracks.

If they are solid, then you can still cut them in most cases, but the pulsing and cracks resurface with much less stress than normal.

With that said... if if they are solid and you are using them on your own DD and willing to put up with the pulsing when it returns, they should be fine. Just remember to do a visual check every 5k with your tire rotation.

If you are thinking about selling them, I wouldn't bother. I notice that a lot people are whiny little girls who bitch and moan about things like road noise and suspension creek on these cars. They will end up coming back to you or the buyer may end up bitching on the interwebs in a few months about how they got screwed.

Me personally, if I want a smooth floating on clouds kinda ride, I'll go get my gandpa's 4 door land yacht formally known as a Cadillac Fleetwood Brougham. If I want to go 3 or 3 times the speed limit on highway off/on ramps... I'm getting a Mustang.

If they are laminated, cut em', make sure they pass state safety inspection for minimum thickness and use or them them.

 

[Department Of Boost]

Throw them in the trash.

 

[back n a stang]

Throw them in the trash.

LOL.....I have the feeling you are serious. The backs are worth keeping and using I know. Damn these fronts should be a salvage yard mans weight worth collecting with other junk.

 

[Roadracer350]

Trash

 

[stkjock]

Worth the risk to you if they fail at speed?

 

[07TGGT]

Scrap metal

 

[ddd4114]

My front rotors have looked like that since May, and I've put about 12 track hours one them since that plus driving to and from each track. One of them has just recently developed a crack that goes into the vanes, so I'll now have to replace them. Until that point, I didn't worry about them.

I'd just run them until you see something more significant than surface cracks. I would definitely keep an eye on them, but I don't think it's a big deal.

All of the rotors I've cracked occurred while the car was cooling down in the paddock. I think it's really unlikely that any will fail while you're driving. Even if it does crack, it's not like you'll suddenly lose braking. You'll just feel pulsation and wear through your pads quicker. The rotor has to fail pretty catastrophically to pose a real safety issue.

 

[07TGGT]

My front rotors have looked like that since May, and I've put about 12 track hours one them since that plus driving to and from each track. One of them has just recently developed a crack that goes into the vanes, so I'll now have to replace them. Until that point, I didn't worry about them.

I'd just run them until you see something more significant than surface cracks. I would definitely keep an eye on them, but I don't think it's a big deal.

All of the rotors I've cracked occurred while the car was cooling down in the paddock. I think it's really unlikely that any will fail while you're driving. Even if it does crack, it's not like you'll suddenly lose braking. You'll just feel pulsation and wear through your pads quicker. The rotor has to fail pretty catastrophically to pose a real safety issue.

This is the type of advice not to adhere to. Instead of buying a new set of rotors that cost significantly less than body repairs and hospital bills, you would rather risk it?

Just because yours didn't fail doesn't mean it's common for them not to. Please take your crap advice and go to another forum. Plain stupidity.

 

[ddd4114]

I know plenty of people who do the same thing as me - run them until they crack. Have you ever seen somebody lose control of their car from a cracked rotor? Have you ever driven on a cracked rotor? The pulsating pedal might be concerning, but it really doesn't compromise your braking power. Boiling your brake fluid or running your pads too low are much more dangerous.

I used to replace rotors that have surface cracks, but I realized it was a waste of money. If you don't track your car regularly, then $90 for a new rotor isn't a big deal, but if you do, those $90 investments add up fast. I guess thriftiness is stupid.

 

[SoundGuyDave]

ddd4114: I didn't in fact SEE it, but a fellow instructor lost his life when a rear rotor cracked, causing a crash. I've never driven on a cracked rotor, because I'm not STUPID enough to do so. Last month, a buddy and I were up at Road America, and he cracked a rear rotor on his last session of the season. Since mine is trailered, and he drove his, I pulled off one of mine rather than let him drive home on the street with it.

While the smaller "surface checking" in OP's photos is nothing to be overly concerned with, there are some that look like they would cast a shadow or snag a thumbnail being dragged across them. That means "that's all, folks" for that rotor. Do they have life left in them? Most likely. How much before they look like this:

Absolutely no way of telling. Could be one braking zone, could be more. As the rotor heats, the crack WILL expand, placing stress on the hub section that it simply wasn't designed to handle. If THAT happens, then THIS could very well happen:

So, you still want to drive on those?

Think about it: A "pulsating pedal" means that you're having spikes and sags in line pressure, and that's all from the pad deforming around the crack. It's also simultaneously ripping the pad material off...

Not to be a dick, but if you want to be thrifty, fine, do so with something that might prevent your car from starting, not something that might prevent it from stopping.

 

[ddd4114]

Sorry, I must be missing something. After installing new rotors, how long does it take for you guys before they look like the pictures the OP attached? For me, it's about 2 hours of track time. If I replaced my rotors as soon as I saw cracks like that, I'd need front rotors every weekend and rear rotors about twice per year. Maybe it's just a difference of looking at a picture instead of seeing it with my own eyes?

Also, to clarify - if a rotor does crack, I'm not saying that you should go flying around without care. I'm just saying that you would be able to maneuver your car off the track (or road) in a controlled manner. If you continued driving on it, then yes, it would inevitably fail much more significantly, and I'm not advocating that. I always bring a spare set of rotors to events in case that happens, so I guess I took that for granted when I first posted.

Dave, I'm very sorry to hear about the incident, and I mean no disrespect by posting this. I'm just trying to see things from both sides. If the rotor's thickness is not below the service limit and there are no excessively long cracks or cracks outside of the friction surface, I really don't see how the rotor can fail so suddenly and substantially that the car would be uncontrollable. Please believe me; I'm not trying to be difficult. Call it stupid if you'd like, but I still don't understand why it's so bad to wait until the rotor starts cracking beneath the surface.

 

[marcspaz]

ddd4114... in all honesty, going through a couple sets of rotors and pads in a single race day or race weekend is perfectly normal.

 

[ddd4114]

I know this is beating a dead horse, but this is what my rotors currently look like (sorry for the crappy picture):

I consider this in need of replacement. If it wasn't for the crack in the bottom of the picture, I'd still drive on them. Once I saw that crack form, I ended my weekend a session early, but I still drove home on it. However, the car has been sitting in my garage since it returned because, as Dave mentioned, it will continue to grow.

Please ignore the concentric groove on the outside of the friction surface. That isn't something I'd consider normal.

This is one from before my brake upgrade:

That one got replaced before leaving the paddock.

Am I still stupid? (not trying to be a wise-ass)

 

[JesseW.]

dddddddddddddd-holy shit, I would replace that immediately. ever seen what a clutch does when it comes apart? imagine that inside your wheel. lose wheel, tire, and brakes all at the same time

to the OP, one of the rotor pics (#1) looks ok but would check after every session (should do this anyway), the other (#2) i'd replace

 

[07TGGT]

Like I said, don't take his advice OP. That's asking for trouble.

Not only do you have to worry about your own safety, but the safety of other drivers as well. Running rotors like that is absolutely inconsiderate of others safety and shouldn't get past Tech IMO.

 

[back n a stang]

OK....I hear what every body is saying and everybody makes good points. Let me explain more on what I wanted to know and about them. These rotors probably have 500 miles total and only one day of tracking with the Boss. They are not on any car nor are the Hawk pads. Everything front and back is in that box.

My question was would they be something worth saving to use on a car for DD only?? No tracking at all while on the car. If so, should I have them turned?? I'm sure after cutting them smooth that cracks would/could return and could get worse like you guys are saying but I am just wondering if for DD use only. No hard breaking. Do the cracks resurface?? The rears look new and I feel certain they are very worth saving. Non of these rotors are used up thickness wise. Smooth as can be. That track event took its toll on those fronts and I expected so but just didn't know if worth keeping fronts for DD ok.


The numbers on the side of fronts are: Centric 1206 1089 min THK 30mm Y


The numbers on rear: 120.61087 min THK 17.4mm 157 10/31/11 0072 7697 M12
I don't think I even pictured the rear but I will look or can post them but they look fine.

If I throw out the front rotors for scrap I may as well shit can the hawk pads too, I guess and just buy all new stuff.

**note** If I was to track.... these fronts, I would not use again. Just throwing that in on the safety factor.

 

[Sky Render]

Those. Rotors. Are. Junk. Do not use them. Do not give them to someone else to use. Do not pass "GO" and collect $200.

 

[SD_Stang]

I think his question was if he resurfaces them would they be useable for a DD. I think you would need to inspect them after the resurface to see if they removed the surface cracks. He isn't talking about driving them as is. Now are you paying for the resurface or is someone doing them for you who has access t oa lathe? I think if there is cost involved that may be why they are saying junk them as the cost vs new would not be far off and the new you don't have have to worry about the cracks etc however they did not clarifiy that and just said "trash them".

Please clarify your answers to his question.

 

[Sky Render]

It doesn't matter if you resurface them. The metal is already clearly fatigued. The rotors are junk. I would not use them on my car, regardless of whether or not it is going on the track.