IIRC, some 1970’s auto manufacturers offered-up special, slightly abrasive, disc-brake pads, used to true the rotors by just driving the car, to eliminate brake judder from warped discs w/o needing a shop skim. Just curious, has this technique been used to true out of round brake drums as well?
Never heard of it.
Said to be a Ford thing, in Europe.
Did it true up warped rotors?
Or did it smooth out any pad material buildup on the rotors?
If it was the former, I’d be curious how it worked.
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I’m not sure. The claim seemed to be it helped to address “brake judder” (disc brakes).
I think it did what @JoeMario alluded to
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EBC brakes sells disk brake pads with basically sandpaper on the surface of the pad.
They claim it cleans off the transfer layer from the old pads so that the EBC pad can lay down its own layer.
Doesn’t true disks, though.
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Yeah, all brake pads are somewhat abrasive, don’t think they would grind down high points on the disc. But abrasive ones could remove pad deposits.
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You’re going to pay shop to do this? Why not replace drums and be done?
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Depending on how those new drums were stored in the warehouse, There is a good chance they still need turned to be trued.
Drums stored on there edge will go out of round.
Must be Click-Bait. Think about it, any brake material that is so course, so tough, that it could grind down the high-spots on a rotor would have to have some really tough material. Can you imagine hitting your brakes and have the pad dig into the rotor to do its work, Well that is going to significantly affect stopping power.
It would be like running a stop light and hitting a pedestrian in the cross walk only to find out that it’s “Clark Kent” (aka Superman…)… That would flatten your rotors… L 
L . . .
If you have ever machined a drum or rotor on a brake laith, then you would understand better how a free floating sander (pad/shoe) is not going to knock off the high spots only, it is going to sand down the low spots also and it will never be completely true… That is why machine shops use laiths and milling machines to make precise parts… Wish I could explain it better… lol
Here is a video of a rotor being set up and machined, it is long and redundant to those of us that have done this many times before, so you can jump to around 10 minutes…
Sorry, unable to hear the video at this time, but it looked pretty correct…
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The sound worked fine both as shown on CarTalk and by clicking the direct link and view on YouTube…
Not to be insulting… DId you click and accidently turn off the sound or perhaps you volumn was turned off on your computer or even the speakers were turned off…
lol I said at this time, there are more than one reason why you can not do something… The wife is watching TV and I don’t feel like taking my computer to the another room to here what is being said… I don’t need to learn how to machine rotors or drums, have done it thousands of times over 30+ years… 
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