MrAllGrain

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Dman302

farmington

MrAllGrain

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Dman302

WW7

I agree with the Huh? There's usually a spec for thickness of rotors before they need replacing, although most times now days rotors are not turned they are just replaced..

WW7

Here you go...This is minimum thickness
fronts.. 30.3 mm or 1.19 inches
​​​​​​​rears... 24.5 mm or .965 inches

MrAllGrain

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Lee Cromwell

Here's a hundred dollar question, can cross drilled rotors be turned? My routine is just replace them but if only to remove the glaze Can they be turned?🛃

BlindSpot

Yes is the technical answer.

Bruze is a Toolmaker. If he sees this thread he is best suited to validate or contradict my answer.

2008 Corvette

What doesn"t Bruze see ? He is always a big help.

HOXXOH

Rotors have the minimum thickness stamped on the outer edge. That's there so the guy who is turning them can be assured what the limit is, rather than trusting some printed or online source.
Yes, cross-drilled and slotted rotors can be turned. I wouldn't trust the Autozone or O'rielly's guy to do it without first asking him how many he has successfully done and is he willing to replace them with new if he ruins one. It requires different feed and speed than plain rotors, due to it being an interrupted cut. Bruze and any other machinist knows exactly what I mean. It's not something you want a rookie to do.

Bruze

I just build industrial tooling, no automotive machining -- it often requires different machine tools.

Hox is right about interrupted cuts being a potential problem.

FWIW: My mechanic buddy told me years ago that rotors don't get turned much any more. For the average vehicle out there it is cheaper to just buy new ones, as someone already mentioned above.

phileaglesfan

I would just replace the rotors when the pads are due to be replaced. My pads were replaced at about 45k but the used car dealer didn't turn the rotors. They warped a few k miles later with junk pads. I replaced each rotor for $75 ea (OEM) and the pads with some Carbotech pads. Yes, this won't be everyone's solution but it worked the best for me. Dealer tried to say they are not OEM even though they had the same part # and same dimensions but they wanted $150 each for rotors and $300 something for the stock pads.

BlindSpot

I was responding to the question "can they be turned" which technically they can. The fact that they're drilled, etc. does not preclude them from being resurfaced on a lathe.

Now that that is out of the way, turning down/resurfacing rotors is not economically feasible anymore and it is more economical to just replace them new. Besides, some of the "Monkeys" operating equipment like this...it's not worth the gamble. The last pair of rotors I had turned (back late in the last century), one of those monkeys mounted the rotor on a dirty faceplate and, yes, when he cleaned up the "WARP" (LOLLOLLOL) out of the rotor it was running .015" out of true on the car. That was my last rotor resurface.

WW7

I may try turning the front rotors on my car when they start to show wear, my 14" Wilwood rotors are $400.00 apiece......WW

TCW

Modern rotors are too thin to turn. Turning them makes them thinner and they will warp much quicker since they can't take the heat. Rotors are cheap. Replace them.

Tom

HOXXOH

J55 front rotors are 1.26" new. The discard is 1.19". I don't have my spec sheet right now, but I suspect .070 new to dead is the same for all C6 iron rotors. If the wear is even and can be cleaned up in.030 or less, you're pretty safe to go through a second set of pads. It's been a few years, but O'Reilly's turned some for me at $15 each. They had a retired machinist who worked there part time and he was the only one who did drilled/slotted rotors. Done correctly, for all but the track rats, they're as good as new.

BackInBlack05

Most likely not bedded properly and "contaminated" the rotor surface. Re-bedding CAN cure this.

Drilled stock Z51 rotors aren't $75 each. Closer to $200.

That said, my stock Z51 rotors and pads pretty much took each other out equally. Rotors were basically at the minimum limit (without turning), when the pads were due to be replaced. You get right close to 1mm per side (inside and outside) on C6 rotors. If the little ridge is approaching 1mm, plan on rotors.

BlindSpot

This will add another 20 posts easily - The comments about warped rotors (rotors warping) are inaccurate. Warped rotors are very rare to non-existent on a street car. Warpage is misdiagnosed constantly and the real cause is an uneven transfer of resin from the pads (often from cheaper pads). This uneven coating on the rotor surface gives the feel of a "grap-release" but very unlikely the rotor is running untrue. I've shown this several times by placing a dial indicator on the rotor when someone swore their rotors were warped and the runout was always within factory tolerances.

I don't do brake jobs for a living, but haven't seen a warped rotor in 25 years (as far back as I can remember). Although I haven't seen them, the only occurrence I've ever heard of is on a tracked car, but not on street cars. Even then, I didn't actually see a dial indicator reading.