Quick question: Bought a used car with a pulsing brake pedal when slowing. I assumed warped rotors. I have some front rotors on the way. Just the front , so I can figure out what which end is the problem. Any reason I should change the pads too? Thanks, Justin
yes. Pads are cheap. replace them with the rotors and bed them in properly.
Agreed. Always do rotors and pads together.
Done! Thanks
I'll be the dissenting cheapskate. If the pads are less than half worn, I will usually just scuff them on something coarse to break the glaze (un-polished concrete works nicely). Don't breathe the dust. Bed them right in on the new (or resurfaced) rotors and enjoy.
In my experience, on street cars, "warped" rotors are usually caused by:
In both cases, you can end up with a nasty pulsing pedal, but have pads that are nowhere near worn out, which I am too cheap to just throw away. As always YMMV, and if you don't know how much pad you have left, buying new ones is always a safe bet.
In reply to obsolete :
While this is generally true, there are cars that physically warp them because they're undersized.
Rotors probably have hard spots on them from hot pads baking more compound onto one part of the disc.
That said, for what they charge to turn rotors these days, its usually cheaper to replace them both.
And buy good parts. I went through a couple sets of "standard" quality brakes that warped and dusted repeatedly. Bought a set from power stop and they are great. Only $50 bucks more. Don't get the drilled/slotted stuff though.
Gearheadotaku (Forum Supporter) said:Don't get the drilled/slotted stuff though.
Why do you say not to get slotted and drilled? Not trying to start anything, just like to hear varying opinions.
In reply to drock25too :
Because every hole is a place where thermal mass was removed and a stress concentration point was added. Especially if the holes aren't chamfered.
They like to crack. Racecars don't care because they are replaced rapidly. Streetcars, not so much.
Some cars come stock with drilled. Why so?
preach (fs) said:Some cars come stock with drilled. Why so?
Fashion.
Streetwiseguy said:preach (fs) said:Some cars come stock with drilled. Why so?
Fashion.
Yup. The holes/slots are there to give escaping gasses a pathway to leave. On a race application where the brakes get glowing hot, there is a lot of oxidizing (burning) of pad material and it can make a barrier of gasses between the pad and rotor. A lot like an air hockey puck. On a street car or autocrosser, it's really not necessary, and it just A) removes mass that could be distributing heat and B) makes weak spots.
I find it hard to believe that the engineers at Porsche would make their brakes fashionable at the cost of stress cracking. Could be the case but...
EDIT: Not being argumentative at all since I am no system matter expert.
In my experience on track, slotted is okay, but drilled is not the best choice:
preach (fs) said:I find it hard to believe that the engineers at Porsche would make their brakes fashionable at the cost of stress cracking. Could be the case but...
EDIT: Not being argumentative at all since I am no system matter expert.
If you find it hard to believe that Porsche would sell something detrimental to longevity in the name of fashion.......
Not to be argumentative but that would make you naive.
My GT3 rotors have been replaced by non-drilled rotors merely to improve longevity as the drilled locations are prone to extreme cracking and early trash bins.
In reply to Olemiss540 :
Ok then.
I'll look iinto solid this Spring as mine need to be changed.
I think many auto manufacturers do things for fashion at the expense of longevity. Like GM's prolific use of cheaper non-coated ABS plastics that turn grey and swirly after 5 years, or Porsche stuffing a V8 in a Touareg and wondering why the Aisin automatic blows up at 100k...
... or anything built by Fiat.
WonkoTheSane (FS) said:In my experience on track, slotted is okay, but drilled is not the best choice:
I see your point. We use them on our dirt late model but they are vented as well. We usually get a whole season out of them sometimes more. The venting probably help as well.
Jah29 said:Quick question: Bought a used car with a pulsing brake pedal when slowing. I assumed warped rotors. I have some front rotors on the way. Just the front , so I can figure out what which end is the problem. Any reason I should change the pads too? Thanks, Justin
Sorry to have hijacked your thread and start the debate.
In reply to drock25too :
As soon as Gearhead said "drilled" I knew where the thread was going. I got my answer. Please continue:)
Don't feel bad. I was really, really tempted to get some for the FR-S, because I miraculously got over 46,000 on the original pads & rotors. Logic overruled heart. I've seen too many cracked rotors photos like Wonko's to risk money on a "what-if" especially on something as important as brakes.
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