befast

A week ago or so I changed my pads all around. Yesterday I washed my car, and my rotors got the usual bit of rust on them. After driving, all the rust on the rotors is gone, except for a 5-8mm wide ring around the inner circumference of the disks. When I touched it, it just seems that the rotors are just not as deep there, as if it was etched out by something. All four discs have it, in pretty much the same fashion. Did I just keep my old pads in there too long? Are my rotors screwed?

I am going to try to get the pics on this asap...

Irksome

My rotors are also leaving a small lip on the outer edge. I don't think it is an issue, but if someone knows more than I I'd love to hear it!

I would expect that you would always have a lip on either the pads or the rotors, as getting the pad and rotor contact to be exactly the same size and shape and aligned exactly right would seem unlikely.

In my case, my lip is about 1-2 millimeters, on the rotor. 5-8 seems kind of big (much larger than mine, for sure), but I don't know what the tolerance is supposed to be.

I'm surprised how fast my rotors are being eaten up. I haven't hit 30k miles yet, but it looks like I'll be replacing the rotors in the next 10k at the current pace.

nmercier853

It is not a big issue. I only track my car and after a couple events I get them on all 4 sides with new rotors and pads. It has to do with the cross drilled holes and the build up on the pads that causes them to wear un-evenly. Change to slotted rotors if you do not want them, but it does nothing to the performance.

iii911ooo

It sounds like your rotors are normal. From your description, the relief is at the interface between the rotor surface and the rotor hub. This relief is used to provide clearance for the cutting tool when the rotors are manufactured. If the relief weren't there, the cutting tool would hit the outside of the rotor hub and cause accellerated tool wear.

befast

Since pictures are worth a 1000 words, I finally took some: below are left front and rear, but all four rotors have the nearly the same exact thing. Using a true bar, I can see that the pads wore in an non-even pattern as well. Running a finger over the rusty portion i can feel it dip slightly. What do you guys think given these pics?

medtech

Stupid question, but have u checked the brake fluid level? Seems that the inner piston isn't pushing evenly.

redridge

what pads are you using?

Ahmet

I would drive the car some more. You're probably fine, the new pads have not bedded on the rotors yet. This is less likely to happen if you replace rotors/pads at the same time.

And, I wish I had a set of rotors last me 30k, let alone anything more. I'm lucky to make it to 6k miles or so (lots of track use).

springgeyser

My rotors look much worse from <5000 miles of driving on PFC97 and new rotors. There are deep grooves.

Barn996

My look worse than yours...I wouldn't worry about it at all.

smackboy1

The inboard surfaces of both my front rotors were much much worse than yours. They looked like the rings of Saturn. I had changed my pads about 2000 miles ago. After talking to some folks with more experience than me and taking it to the dealer, the verdict was that there is no brake malfunction. The way it was explained to me is that the surface contours of the rotors wore to match the contours of the old pads. The new pad surfaces do not quite match up, hence the uneven wear. In my case I had autoX'ed the car several times so the combination of the heat and rotor holes caused some buildup, hence the uneven wear.

befast

Thanks everyone. I guess now I'll know when the bedding's done!

What causes for uneven wear to occur on pads in such a uniform matter? One would think flat on flat should stay that way.

Tippy

That is the point that the braking surface is the furthest from the OD of the rotor. Although not an Engineer, I am fairly cofident that it is the hottest point of the rotor, thus expanding outward with the heat build-up and then cooling causing a depression.

perryinva

Personally, I'd check rotor thickness with a gauge, and if close to min thickness, change out the rotors before the pads get too "shaped" by the old rotors. Crazy to kill the life on $300 worth of pads with old rotors. Rotors are not that bad, about $120 each IIRC. New pads & old rotors (if not flat) can cause hot spots and build up, shortening the usable life of all the parts. The lip on the outer edge of the rotor in the pic looks pretty pronounced.