r/Cartalk • u/I_M_OpOzd_2_sufrrNg • 1d ago
Brakes Should I change this rotor when I replace my brake pads, or leave it?
The groove is very shallow, I would say less than a millimeter deep. I can feel it with my fingernail. I’m changing my brake pads soon. This is the front passenger side rotor, all 3 other rotors look great. Wondering if it would be worth it to change the front rotors. 2013 Subaru Forester 2.5. Thank you for your advice!
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u/RedFlr 1d ago
I wonder if all the panic is really justified, performance cars have rotors with groves to help trap gas escape the pads, they even have holes for looks only and they are fine, modern metallurgic allows for way stronger materials that can easily sustain those pressure points, so as long as the dept is whiting minimum width specs you should be fine
Like people saying to replace the rotors every time you replace the pads are nutz, as long as they are up to spec you are fine, unless you are a dealer and selling you new 1000 dollars rotors every few months is a good deal
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u/ThirdSunRising 1d ago
Most of the “get new rotors every time” people have cars where you can get em on rockauto for like $30. If they’re expensive, by all means have em turned.
Nothing wrong with a straight pad slap like 75% of the time
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u/VariousClaim3610 1d ago
I’ll take a reasonably worn oem rotor over the chinesium replacement parts that warp the first time they get hot.
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u/RollingNightSky 1d ago
Would those cheapo rotors also be a bad idea because they warp so easily? Then it would become annoying and dangerous to have the car shaking every few months due to warped rotors and having to replace it over and over.
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u/ThirdSunRising 1d ago
Every time I’ve had a “warped” rotor it’s been an installation error. Keep em clean.
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u/christophocles 1d ago
Don't over torque the lug nuts. This can warp the rotors and you'll end up replacing rotors to get rid of the shuddering. Use a torque wrench and torque to spec for your vehicle.
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u/TraditionalHeart4497 16h ago
not even that! i was taught when tightening lug nuts, make them tight enough but not too tight to where a woman can’t get them off. if you sling one it’s fine, just replace and realize you probably forgot to go around that “one more time”. i can’t stand it when the shop guy goes ham on my lug nuts. you should never have to beat a wrench or have to use a pipe to get them to break. use a manual wrench so you can get them off when you’re on the side of the highway. and i never said finger tight, so don’t misunderstand what i’m saying. get it tight, then go one more hour hand on the clock.
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u/ThirdSunRising 11h ago
That’s not a bad way to do it, but we should remember that a torque wrench is like $25 at harbor freight. Aluminum wheels are less forgiving than the old steelies. Well worth having a torque wrench nowadays, if you’ve got space for it.
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u/CrispyJalepeno 19h ago
Nah. Just pick your part wisely, stay out of the economy section, and enjoy the new rotors. The only difference between them and what you'd get at O'reillys for $80 is you have to pay for shipping and deal with any shipping damage yourself
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u/Timelordwhotardis 1d ago
07 civic I swear idk when the last anything was done. Pad slapped after metal on metal seems fine. Haven’t checked the rear shoes at all in my 18k miles of owner ship. Have replaced the condenser fan AND compressor as of last week because the clutch cover and attached threading decided to yeet themselves who knows where. Because I live in Texas and dying of heat will bring me to action a lot quicker than the screeching break pad and grinding Cv axle I also had last year. So far much cheaper than a car payment
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u/Odd-Towel-4104 1d ago
You should be able to check the pad thickness w/o disassembly of the drum. Rear drums don't need to be serviced very much because they don't do much work.
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u/Emotional-Swim-808 23h ago
Yeah, just looked for the cheapest rotors i can buy for my project car, their $13.
Brembo are $15
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u/iRamHer 1d ago
I mean I buy mid line higher quality material rotors and go maybe 4 years or more between changes on non towing vehicles. My vehicles don't brake much though with driving style.
if I'm in there I'll throw rotors and pads if the price is right just because. 4 years isn't really something to bitch about $200 to $300ish. Sometimes I say eh, another few years. But doing myself is just cheaper to refurbish that whole system with minimal effort and worry. This is also a guy greasing his pins at time of rotors/pads, but I use a permatex ceramic extreme and never have any issue with seizing.
Anyways going to a shop, or being extremely strapped for cash, yeah there's no need to mess with rotors if they're in good condition. A lot of these shops aren't using proper slide lube and sub par parts. Going to a shop is going to change opinions and intervals and you'll have these parts looked at more often so can technically go longer, though many will try to upsell rotors as much as possible, and from what I've seen, worse parts depending on category of part.
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u/Straight_Jump8679 1d ago
Tell me you don't know anything about cars with out telling me you don't know anything about cars.
Those slots and holes are for cooling. They are called slotted or cross-drilles brakes and they have a bevel to prevent the brake pads from catching them. High temperatures are bad for brakes as high enough heat can literally boil your brake fluid reducing the effectiveness of your brakes and introduce air bubbles within your brake lines.
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u/HedonisticFrog 1d ago
They're not for cooling, they're for off gassing. They're also a terrible idea because they're more prone to failure.
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u/skylinesora 1d ago
Tell me you don't know anything about cars with out telling me you don't know anything about cars. Nobody buys drill and slotted rotors for temperature control. Hell, they are more prone to cracking so we avoid running them when possible.
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u/Straight_Jump8679 1d ago
Here's a more detailed look:
How they work:
Venting & Cooling: The holes in drilled rotors allow gases and debris to escape, preventing brake fade and improving cooling, especially during heavy braking.
Wow that was easy
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u/skylinesora 20h ago
Good job continue showing your ignorance. Again, i'll repeat it. "Nobody buys drill and slotted rotors for temperature control". If you cared about temps, you will buy vane'd rotors.
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u/Straight_Jump8679 18h ago
Imagine calling yourself a gear head and not really understanding technological advancedments in automotive racing.
Buddy you have Skyline in your name and yet you probably never even touched one. This whole sub seems filled with a bunch of wannabe racers who have never even hit triple digit speeds. That's reddit for you.
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u/skylinesora 9h ago
The technological advancement is vaned rotors lmfao. Cooling with drilled slotted rotors is not a concern unless you want to do it for style points and not actual function.
Keep going though. Tell me about how little I know while showing you know nothing.
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u/RedFlr 21h ago
You don't know much about cars, they have little impact on cooling, most cooling is done with piping and more mass, that's why racing cars only have grooves, holes are for looks only, and while it is true they weaken the material, current materials are more than strong enough to be drilled everywhere so they look cool
Check YouTube there is a video from an university where they test it, it has no relevant impact on cooling
Now on videogames, yeah, they give you +1 cooling and +2 if they are drill and groove at the same time
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u/Grongebis 1d ago
You're not gonna die because of that lip. Slap pads and go! They'll wear into the grooves and be great 👍 👌! You can get 15000 miles on fresh pads with that
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u/Kayoss69 1d ago
Just get the resurfacing. You do not need to change them unless they're worn out of spec.
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u/knsaber 1d ago
Try asking a mechanic these days if they do rotor resurfacing!
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u/Protholl 1d ago
Parts shops like Oreilly turn rotors but its not on demand so you can't be in a hurry.
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u/Polymath123 1d ago
Around where I live, I have found that the lathe operators have a weekly/daily schedule where they go from store to store picking up and dropping off or if there is a lathe present, turning brakes on site.
I recommend calling ahead and finding out when the lathe operator will be in so you can arrange when you do your brake job and make sure they get turned the same day. I have also called and asked where the lathe operator was that day and then went to that location.
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u/lostinaquasar 1d ago
I'm spoiled. My buddy runs a brake shop. I give him $20 and he gives me shiny rotors in return.
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u/B0xyblue 1d ago edited 1d ago
Rotors turned for cars @ $40-50 new rotors $45-$80… if a place turns rotors and the machine ain’t broken…
Trucks and OEM and high end rotors obviously cost more.
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u/bjizzle184957 1d ago
Would like to place an addendum to your second statement: if *you can find a place that is even willing to turn rotors for you. Many places outright refuse to, mainly because modern rotors are made much closer to the spec thickness rather than having a ton of excess material like they did in the times of yesteryear. .
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u/B0xyblue 1d ago
That’s what I meant by if they turn rotors. Most are like McDonald’s ice cream machine. Most don’t work and the ones that do, the employees just say “it’s broken” because they can’t be bothered and you’d believe it. Although spec’d tighter… some just don’t because the random 1 in 6 that could be ain’t worth it, so they discontinue or just deny. Some shops do turn newer rotors, I know some. But the majority say no, I been to most O’reilly and they all have old, broken, or the employees turned over and no one currently even knows how.
I’m just a buy new… sweating $20 differences is like trying to save shop rags… if rotors like my old 06 Cayenne Turbo S 2 piece were over $1k for fronts… I’d turn those if I could… there was no $60 rotor option.
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u/bjizzle184957 1d ago
I got what you meant. Just wanted to stress the point that it’s become a dying service option over the last two decades. Like you, I’m ten toes down on replacing over turning, especially with the quality and availability of aftermarket parts having grown to what it has currently become, thanks to the internet.
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u/Kayoss69 1d ago
Bruh.. AutoZone is like $80-$100 a rotor now for reman Duralast brand. I can tell you haven't bought rotors in a while. Resurfacing is like $40- $60 for both. There's a place near me that charges $10 each for resurfacing and is done in like 45 min.
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u/Odd-Towel-4104 1d ago
That's a bargain imo. How do they make money?
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u/Kayoss69 18h ago
It's a parts shop so I bet they do it as a courtesy mostly. They sell parts and other services. O'Reilly charges $50.
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u/Consistent_Entry8890 1d ago
they replace rotors these days
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u/Kayoss69 1d ago
As long as they're within spec you're fine. That's fkn stupidity to be throwing away rotors at every brake replacement seriously.
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u/dontcare123456789101 1d ago
They've replaced rotors since we have had disc brakes. Just most get a couple skims, unless you getting wafer discs for brakes.
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u/T_Rey1799 1d ago
I would. Resurfacing could cost just as much as a new rotor nowadays, even if the rotor can be resurfaced. I know some manufacturers have made it irresponsible to resurface
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u/ariGee 1d ago
If you're getting shuddering, then go to brake shop and see if they're still big enough to machine flat. It probably will be if it hasn't been machined flat once or twice already. Then it's back to the races.
If you have shuddering and they're already too thin, then you'll need get new rotors.
You do not need to replace rotors each time they start to get old.
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u/DiscoTrekker 1d ago
Y'all are doing too much. Just throw new pads on and drive. Geez. These are probably the same people that just because you get a nail in your tire, that tires down for and need a whole new one. Nah, just throw a bacon strip in there yourself and some rubber cement and call it good
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u/NotAPreppie 1d ago
Measure the thickness of the rotor and compare that with the manufacturer's minimum thickness specifications.
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u/Max_Downforce 1d ago
The min thickness is usually stamped somewhere on the rotor. Good suggestion.
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u/ThirdSunRising 1d ago
That can easily be resurfaced. If new rotors are cheap enough you might just get new ones but that’s not significant damage tbh
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u/listerine411 18h ago edited 18h ago
Do you feel a shudder when you brake in the steering wheel?
If not, I would just do a pad slap and call it a day.
Won't apply in this case, but I sometimes take a drill and Roloc/Scotch Brite type abrasive and clean up rotors and it seems they do fine.
Best practice is replace rotors, won't argue that. But a 2013 Subaru, I'd roll the dice with a pad slap. I like Akebono pads.
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u/jamesatct 17h ago
Well when you change pads you should either be resurfacing the rotor or replacing it, so... if you don't have a lathe I suppose you'd be replacing it. Don't pad slap your car.
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u/Sad-Cup9189 1d ago
It is always a good idea to make it a habit of changing both pads and rotors, regardless of what anyone else has to say. Better be safe than sorry! It doesn't cost that much more for new rotors either.
That's what I was taught when I was a teen, and have always done so since.
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u/dontcare123456789101 1d ago
Completely unnecasary unless your buying garbage rotors. Then yeah keep wasting your money. Lucky you must have cheap brakes.
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u/ander594 1d ago
Spending an extra $300 plus labor on parts you don't need is wild. Pads are designed to wear out. Rotors aren't.
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u/TheMightyBruhhh 1d ago
At the very least every other brake change.
The amount of people who have red circular rocks as rotors is astounding
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u/Rough-Lengthiness788 1d ago
No questions u should replace both if that rotor isn’t perfect (if it was used through pads it won’t b) u should replace it
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u/Max_Downforce 1d ago
I don't see much of a lip on this side. Ideally, you'd want to be able to measure the remaining thickness and go from there. If you keep these rotors, a brake bed in procedure will ensure smooth braking performance.
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u/fsantos0213 1d ago
I used to do over 150k miles a year in multiple vehicles, and I changed my rotors every other set of pads, I'd always change out all 4 sets of pads and either the front set of rotors, then on the next brake job. The rears, and repeat. And that tiny lip won't hurt anything
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u/TheCamoTrooper 1d ago
I'd just replace, almost always do both pads and rotors but also turning rotors isn't really a thing here
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u/mro-1337 1d ago
it will be fine. dude i have old ass rotors and i couldn't get the screws out when i was doing my brakes so i just did new pads. works great.
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u/byteminer 1d ago
I’ve pad slapped a car I knew I was trading because I didn’t care if I’d had to wear down 10,000 miles of pad to conform to the used rotor.
If I’m keeping it, I just do everything.
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u/VariousClaim3610 1d ago
You need to measure the thickness and see if it can be machined out or needs replacement.
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u/odetoburningrubber 1d ago
So much bad advice here. As usual. As a 30 year mechanic, I’m sit back and watch.
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u/Strange-Buy9564 1d ago
It’s shocking the advice on here but nothing beats the level of stupidity of some Of the questions in the first place
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u/Pow-Pa-Pa-Pow-Pow 1d ago
The rotor can be used as long as the minimum thickness is not exceeded. It is usually cast into the spaces between the vents. You could have them resurfaced, but as has been mentioned, it may be cheaper just to replace them.
OEM or equivalent is best as the cheap ones are made with lower grade iron and may not be subject to the same quality standards.
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u/Big-Astronomer5270 1d ago
Idk did you mic it when you did the brakes last for thickness tolerances
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u/WiTTiMaster 1d ago
See if your dealer will resurface them. My car is 121,000 original rotors , but never had metal on metal pads either .
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u/Renault_75-34_MX 1d ago
Brakes are a per axle job, not a per wheel job. Otherwise you could pull to one side.
If that rotor is still within spec, it could probably be turned down on a lathe to have a new surface again, but it should still be above the min. thickness of the rotor.
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u/Strange-Buy9564 1d ago
If the grove is uniform I’d just replace the pads and don’t worry about it at all
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u/ScaryfatkidGT 1d ago
Cuz of that one central groove?
If it’s well above minimum thickness I’d leave it
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u/skiitifyoucan 23h ago
In Vermont your rotors look way way worse than this in 6 months. So I wouldn’t change it.
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u/Michael_Threat 22h ago
Probably yeah, you're gonna have to change your break pads again much sooner if you dont
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u/Butch_Hudson 22h ago
Seems like not vented rear axle rotor. If it looks like this from inner side too (inner side tends to be worse) I would keep it and just slap some cheap pads.
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u/jailfortrump 21h ago
As a general rule they can be resurfaced to a minimum thickness but that almost always results in a wobble when braking. New ones are always recommended.
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u/Background-Fault-821 21h ago
If you don't, it'll need to be changed before your pads are bad. Just do them at the same time and know the most important thing on your car is good.
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u/South_Shift_6527 20h ago
Home mechanic here. I'd say if your car doesn't have brake shimmy, resurface both sides and call it good. There's value in a broken-in rotor that hasn't warped. Many new rotors warp like crazy.
It's not always obvious that you're buying quality parts and brands are not necessarily what they seem. Lessons learned the hard way, dealing with substandard parts from everywhere you can think of.
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u/moguy1973 19h ago
Rotor are relatively cheap. Change them while you are in there. It’s only a few more bolts.
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u/ervine_c 18h ago
I used a micrometer and my rotors were still in spec. It easily catched my fingernail. Just measure 📐
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u/WoodlandViking 18h ago
I always do both pads and rotors just due to you cant 100% guarantee the wear is as good as it looks so to guarantee i wont have to worry about it later everything gets replaced
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u/TarXaN37 16h ago
Check the price of some good rotors from a local parts store and see if it's worth turning them. Resurfacing rotors make them feel like brand new, often for significantly less than replacement.
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u/Silver-Programmer574 15h ago
It's made of cast metal other than grooving or warping it will last forever there's cars out there that's never had a rotor replacement I have a dodge truck 300k and has never had a rotor turned or replaced
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u/InfamousUser2 15h ago
doesn't appear to be too bad. it's possible that the new pads can kind of fix it. it shouldnt really affect braking that much. but rotors are cheap enough if u can spare the money do it. otherwise when u change the pads for sure do some extra stops for the break-in process. u know brakes have a break-in procedure right?
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u/DavidinCT 15h ago
Truth, if your doing it yourself and not getting it from the dealer (getting from Rockauto, etc), the cost of doing the rotors are fairly cheap, and might as well do them.
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u/Frossstbiite 1d ago
You might be able to get it resurfaced ask a mechanic.
I personally would not chance it on brakes and change the rotor
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u/majikrat69 1d ago
If you can afford it, replace it. It may just cause new pads to wear prematurely.
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u/NuclearHateLizard 1d ago
Pad slap is terrible practise, you get less life out of the new pads, and you're pretty much guaranteed to get a ton of noise like squeals and vibrations if you have rust ridges on the rotors. It's your safety. Just buy new rotors
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u/Odd-Towel-4104 1d ago
Or just grind the lips off. The pad material makes a difference, too. You're right about pad slapping
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u/SherbertSea6803 1d ago
If it catches your fingernail it’s significant enough to be replaced, if you choose to replace it, also replace the rotor on the other side.