I've got an interesting situation with poorly bedded front rotors causing pulsation and I'm not sure if there's a worthwhile fix other than new rotors. These are nearly new and barely even worn Bosch Quietcast coated rotors and Quietcast pads in otherwise perfect condition. On inspection just now, there is a thinner area of the rotors, the size and shape of a brake pad, on both sides of the rotors -you can feel the edge with your finger. It's clearly an area where the pad friction material hasn't fully coated.

More specifically, it's an area of the original bedding that was soft under high heat and at a prolonged full stop during the high speed bedding process some of it cooled back onto the pad. I know where this likely happened, a long traffic light I was forced to stop at the bottom of a steep mountain highway where I'd been doing the heavy braking bedding from highway speed and it didn't have a chance to cool and set with the brakes off, but rather cooled at the traffic light with the brakes applied. Now in city braking conditions, I didn't notice any brake pulsation at the time so never realized this had happened.

Over time (say 2000 km of highway driving), it's gotten worse to the point there is now horrid pulsation when the rotors are hot and expanded. What's happened is that as the high area of the rotor (90% of the face) goes under the pad, at high heat it keeps picking up friction material, whereas the low area picks up nothing, accentuating the difference. I just measured it and the difference is now .0007" thickness variation in that pad-sized area. Runout is still well within spec and also thickness variation. Because it's such a small and distinct indented area plus the brake friction is different in that poorly coated area, it's felt as pulsation and as I said it's magnified when the rotor is hot.

So my question is, is it worth trying to resurface the rotors and re-bed them properly? New rotors aren't that expensive, but it seems a shame to waste two barely used rotors that are otherwise in perfect shape. There are a few options and my online research indicates mixed results. Lots of theories and advice on possibly cutting corners, but little in the way of follow-up reporting.

a) Having the rotors turned is a definite option as there's lots of material, but you're soon at half the cost of mid-priced new rotors and turned rotors are never as good as new rotors. Years back I had badly scored rotors turned that their machine didn't do to spec, possibly not centering the mounting hub properly.

b) Try to resurface them manually to remove the friction material and restore uniform width around the rotor then re-bed them. It can't be done chemically, so abrasives are needed. A tufted wire wheel likely isn't good enough for this job, but it would at least be a start. Grinding would be too severe. Sanding would seem the best option. Hand sanding might take forever. I was thinking a pad sander, or better still a belt sander with a 220 grit aluminum oxide belt.

c) Simply try re-bedding it. Some have tried this with limited success. This might take three to ten times the usual number of high speed stops to get the brakes good and hot to fully soften and redistribute the embedded pad friction material. I'm tempted to try this, but it means a bit of travel to get to a suitable stretch of highway and doing it in the middle of the night.

d) Bite the bullet, open the wallet wide and get new rotors, this time going up a step in quality to Zimmermanns with Pagid pads. Now knowing better, I will go out of my way to ensure they are properly bedded by doing it in the middle of the night where I can crawl through a red light if needed in order to ensure a proper cool down. The old pads can be kept as spares when the Zimmermanns get closer to end of life. The good and lightly used rotors either go to metal recycling or take up space in my workshop for the next x years figuring I might someday have them turned.

Thoughts? Anyone have this kind of experience?

As additional discussion, I'll mention that many people (and shops) don't bother to bed in the brakes with the newer technology pads and rotor metals and simply let nature take its course. There's nothing really wrong with that approach as long as you don't make the kind of mistake I did. Over time the friction material will build up on the rotor. With extended city driving and moderate highway braking the build up will be reasonably uniform. The problem is for people like me who might do mountain highway driving before the rotors are fully bedded. If you come to a full stop with the brakes hot and keep your foot on the brake (such as at a very long light), if the brakes get a chance to cool there may be uneven bedding until the pads and rotors have reached a state of equilibrium and no longer transferring significant friction material. Until now, I've been more middle of the road on bedding new rotors, usually only the initial step of bedding doing numerous hard stops from city speeds to low speed to mate the friction surfaces under heat followed by a bit of cool down driving.