buffguy

My sister's c6 need new pads at 30k miles, the shop told her she need to change the rotors also.

My question is, when do you need to change the rotors and what are the indicators that the rotors need to be replaced?

Thanks.

Atomic Punk

first, we need to see pictures of your sister to give an accurate assessment...

Eritosthenes

Pads wear a wide groove into the front and rear surfaces of a rotor. That groove will have a tiny edge at the outside rim of the rotor. A rotor can be turned on a lathe to remove that rim edge and any irregularities that lead to a pulsing feel in the brake pedal caused by warping. The amount of iron removed by normal pad wear and by a lathe will take away from the metal mass that absorbs huge amounts of heat and slows the car. There's a machining limit you don't want to exceed. One resurfacing of a brake rotor is typically all you can do before you have to replace it with a new one.

How fast pads wear away the rotor depends on the driver's braking habits and the material the pads are made of. High performance semi-metallic pads are highly abrasive and can eat up a set of rotors after a surprisingly small number of track miles. Dust-free ceramic pads, on the other hand, are typically very gentle on rotors and could easily last 75K miles before they (the pads) have to be replaced. Pads themselves have a small contact finger that's designed to make a very audible screeching noise when the pad wears past a certain limit.

After 50K miles with GM ceramic pads I have about a 1/16" lip at the outer edges of my Z51 rotors. Because I plan to add an E-Force supercharger and enter a standing start mile event next year, I've decided to replace my rotors and pads earlier than I otherwise would.

AORoads

generally, rotors need to be replaced when they are heavily scored (grooved), or beneath minimum thickness measured by a micrometer. or, it could be the rotors need to be slightly turned and there's not enough thickness left to do that (it would go below the minimum). it could be that running the original pads too far down caused a situation with the current rotor(s).

it is not automatic that one needs new rotors at 30K miles, but it also isn't automatic that you don't need them, either. if you don't trust the shop, go for a second opinion.

cclive

Brake pad manufacturers are now saying to replace the rotor rather than machining it when needed. If the surface finish is OK and it is still thicker than the minimum thickness number that is stamped into the rotor, then replacement is not needed...new pads will be fine.

BEZ06

that unless the rotors have heavy scoring or gouging on them, put in new pads, bed them in, and drive!!!

The Service Manual says the minimum serviceable thickness for rotors is:

Fronts - 30.3 mm 1.19 inches

Rears - 24.5 mm .965 inches

Unless your sister has been doing a lot of track days running race pads with an aggressive compound, I'd be very skeptical that the rotors need to be replaced at 30,000 miles. And if she has been tracking the car a lot, the rotors will probably crack before they wear below minimum thickness.

Bob

1FASTVERT

If you have the stock rotors with no cross drilled or slots in the rotors then you can have them turned. I recommend that you switch to ceramic pads. They have little to no brake dust. Make the rims look much better without the black brake dust getting all over them. If you have crossdrilled/slotted rotors then you will have to replace them since you are not supposed to have them turned. I hope this helps. Go with the crossdrilled they add a asthetitics to the car.

FloydSummerOf68

Says who?

They can be machined just like any other rotor.

5 Liter Eater

I haven't measured with a mic but I'd say I have a ~.080" edge/lip on the inside and outside of my rotors. I have had Hawk HPS pads on for a few years and plan on moving to an even less-rotor-friendly pad, the HP Plus. I'll measure the rotrs to make sure they are within the minimum thickness but there appears to be plenty of rotor thickness left. These are drilled Z51 rotors BTW.

FloydSummerOf68

How have the HPS held up to track days (not drag racing)?

I've heard very mixed reviews and have a set that I was going to put on my Vette but heard they wore VERY quickly on the track, so I was just going to put them on my XLR-V instead (convenient to have two cars that use the same pads, lol). What has your experience been?

Sorry for the minor thread hijack.

5 Liter Eater

OK. They seem to have lost their bite in the last ~5k miles or so. Maybe they're glazed. They have been through two HPDEs (broke something at both so more like 1 1/2) and have been my daily driver pads for ~2 years. I like them. Notable difference over stock. Its likely I'll put the HP+'s on and they will not be as daily driver friendly as the HPS's.

Thrash

Pix first please ... and great advice will follow ...

jackhall99

No guys, great advice is freely given here without trying to demean the OP's sister.

simplegto

You would have to abuse the brakes to need rotors at 30K miles. New pads will seat if you don't drive crazy. You really need to have a shop that you can trust.

VET4LES

Only turn them if they are warped.

Dendk

I am at 35k on mine and the rotors will need replacing, have not tracked the vette more then a few times but I must have braked hard somewhere along the way...noticeable grooves all along the rotor surface, turning them did not look like an option...the shop for the OPs car probably saw something like this.

coryvte

Have you considers changing the points when you change the rotor?

keyplyr

5 ponies at least

Licit

I will call bs without even seeing the rotors. I'm sure the tech saw some "surface irregularities" on the rotors, anyone else would see rotors that don't need replaced much less turned. And speaking of turning rotors, what a waste of time unless they are warped. In any other case you'll just need new rotors sooner than you would have.

cclive

I would have to look at a better picture, but in this picture, I would not say the rotor definitely needs to be replaced. There will always be a wear pattern on the disc, replacement is either when the disc becomes too thin or when the grooves are deep...