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I searched this but no luck finding an answer.

I recently did a disk brake rotor and pad replacement on a friends car. One of the pads would not fit in the allocated space in the caliper frame. The mounting hardware was seated properly (removed the rust that had formed), there was nothing else in the way, but the pad was just too long for the space in the caliper mounting frame. So, I ground off what was probably one thousandth of an inch, maybe two thousanths, bottom line, very, very little material came off. Just enough to take a tiny bit off, try the fit, repeat till it seated in the frame.

Couple of questions:

  1. Is this the correct procedure when this happens?
  2. If it is, should I have painted the now bare metal "ear" to prevent it from rusting? (I did use a high temperature silicone lubricant to keep it moving against the new stainless mounting hardware)
  3. Is there anything else I should have done to the ground down "ear" to insure a long serivce life?

Note: The car was a 2004 Kia Optima, with 160k miles. Since the replacement the brakes are much improved. They are a floating caliper design, and the caliper guide pins were cleaned and lubricated.

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    A few thousandths? no problem. Its certainly possible within the realm of manufacturing variance. No paint, that's not a problem either. You should be fine. Nice work. Drive on, drive safe! And as for the question of "Correct Procedure" .. a few thousandths is okay for you for now, but it may not be okay to take off 1/4" of steel for the next guy who reads this note; and who may be using wrong parts, or doesn't have retention springs in correct place. That could be dangerous. I will say for most of us, bring the parts back to where you bought 'em, get new ones. Feedback to mfgr!
    – zipzit
    Commented Jun 6, 2016 at 17:42

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This is acceptable practice. Low quality brake pad backing plate edges can be very rough and the dimensions are often off spec. Higher quality pads usually have a better formed edge that fits correctly. As long as there are not rust flakes causing "rust jacking" under the pad end shims and the end shims are in good shape it is OK to file off the high spots on the pad tabs.

The pads must move freely in the channels but not have enough end play that they create a click sound on braking.

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  • No clicking here.. That's why I wanted the fit to be only just enough to get it into the pad frame and no more. The fit is snug, but not so snug that they don't move. Taking that tiny bit of merterial seemed to get them the way they should be. Snug fit so they can be inserted by hand (not persuaded into place with a rubber mallet) but loose enough that they still move with the caliper. Good info, thanks!
    – cdunn
    Commented Jun 6, 2016 at 18:06
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I had to hammer out the rear pads on a Kia Rio. And the replacements were very tight going in. Wagner TQ, not cheap stuff. The caliper was cleaned & new clips were used. I ground down the ears on the new pads to make them fit. No wonder I barely got 60K miles on rear brakes. And a very lightweight car that is driven a lot on the highway.

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