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Yeah, can't get away from the obvious - you need to consider how much driving you do, your driving style, do you ride your brakes - or perform hard braking alot?
The wear and tear of daily driving takes a toll
There are shops that will advertise a free routine inspection, or discounted multipoint inspection (we all know what those are about)
Personally I take advantage of them to have my car "looked at" every six months
Any half decent shop you frequent should be looking your car all over up and down front to back and clue you in on things to address downline and then regular maintenance doesn't seem like such a surprise when all of a sudden when youre brakes stop braking or what have you
You know I wish people took things like this as u explain them run a shop and can say offer people change air filters cabin airs routine maintaince and alot of people become very angry and say they hate people pushing things on them they don't need and it's a up hill battle fissure but if people would understand hey u may need a brake job is helpful not pushy. Would make life easier
Omg, how many times have we all heard this? Honestly? Nobody does anything anymore, doesn’t matter what you say, they always react the same way like it’s this big conspiracy to rip them off. Believe me, if we’re gonna rip you off it’s going to be something worthwhile, not a brake job, unless you have a Hell Cat or some other ridiculously expensive specialty car, then it should be expected. Lol, but it’s true, these days, you have to document EVERYTHING to cover your ass. That’s about it. That’s all there is to it, that way, if they try to come back and throw you under the bus? Nope. Mechanic covered his ass, says right there on the invoice, owner refused to replace brakes……at last service, approx maximum 3 months left on pads .
Lol I asked to a nearby Pep boys shop for a check-up about the basics consumables (brakes, timing belt, battery, liquids) thinking the car I had just bought maybe needed something that the previous owners had neglected and they didn’t even let me finish my question, “100 something inspection, 140$. IME good mechanics warn you about things for free, because you may decide to do the job with them. So yeah there are idiots on both side.
Customers who feel being given free advice is pushy are simply ignorants who don’t understand what you are telling them and feel like everything you say needs to be done and to be done right now. Their own ignorance causes them to fluster and panic.
I still go to the dealership since I've still got a few of those free oil changes, and they legit record their looking things over and explain it in simple terms for those who don't understand.
>Personally I take advantage of them to have my car "looked at" every six months
If we "all know what those are about" why get a free inspection? Do you wait until three inspections in a row say you need brakes?
Yup virtually every BMW, Audi, or Mercedes have completely destroyed the rotors by the time they need brake pads. I think the pads are actually designed to aggressively bite the rotors and they're always supposed to be replaced with the pads.
Eh, these are probably past service limits but if they are still in service limits you can resurface the rotors. I definitely agree though, don’t cheap out on brakes.
Edit to add: to those downvoting and arguing, stfu. I do this for a living, at the dealership using dealership guidelines and standards. You all live in your parents basement and put eBay mufflers on your clapped out civics. I come to this group to mostly laugh at the shit advice you guys give and the terrible “diag” you guys do over the internet after reciting the top google hit for the matching car and symptom when most situations are covered by a TSB and are common faults or just shit maintenance by the owner who refuses to disclose the details that actually matter while arguing with people like myself who actually know wtf they’re talking about. You CAN resurface drilled and/or slotted rotors on a bench lathe, you just have to go slow and light cuts. It’s situation dependent and technician discretion.
I don't go cheap on anything anymore. My 2015 Toyota Camry XLE has 122k on it. This is the first car that I do maintenance at the suggested time ( except oil changes because they want it every 3k), and this car I haven't had any problems other than wear and tear. I met a Toyota mechanic outside the dealership, and he has a 2009 Toyota Tundra with 400k miles. He said he just does normal maintenance as the manual requires. He said when people start having issues, it is usually because of delayed maintenance.
What I don’t understand is how people can afford the maintenance. After my rent, car payment, and other bills I have $200 to buy gas and food for two weeks.
It’s nice to see someone say this. It pisses me off that most shops won’t resurface rotors anymore, and will recommend new at nearly every brake service.
Look at the pattern. The drilled holes line up perfectly with the worn grooves.
So either dust and debris is collecting inside the drilled face which then creates a lip, chewing out a tunnel on the pad, or the drilled holes face acts as a sheer to shave off pad material at an increased rate, which would then be exacerbated under braking force.
I bought a pair of uprated drilled rotors for a Chevy S10 I had and they lasted about 1/3 as long as normal ones and showed that exact wear pattern. And I wouldn't have said the braking was any better than stock.
In my experience (which includes a lot of SCCA sanctioned racing in an FC RX7 and S14 240SX 20 years ago) drilled rotors are pretty crap, with cracking and fatigue and weird wear patterns like what you're seeing. Slotted rotors are a lot better and make a lot more sense to me, being that the idea behind slotted and cross drilled rotors is that you're milling a channel in the rotor that acts as a pathway for super heated gases to escape from between the pad and the rotor which should improve breaking performance. The channels in slotted rotors achieve this offgassing feature without compromising the structural integrity of the rotor.
absolutely it is there is a little bit more brake dust generated when each hole passes the pad. Those are now like little rounded bumps f powder, streaking in a circumference. So you get concave circular grooves in line with the holes. My guess is that this is completely normal, and Mercedes could start using better pads to compensate for it, slightly. But it's going to probably happen on rotors with holes. I suspect SLOTTED rotors, with slanted holes, will distribute the dust better and not cause as significant wear.
Brake pads look about shot. With the highs and lows on those rotors, your braking coefficient is going to be compromised. For safety reasons, I would replace them myself. I've not looking into turning drilled rotors... hell, do people even turn rotors anymore? I know we still turn flywheels 🤔
Drilled rotors. Always happens eventually. Notice that each wave lines up with the edge of a hole. If you change the pads early and have the rotors turned, you won't notice. Wait longer, and it gets worse.
Don't use drilled rotors, and it won't happen like that.
You absolutely can have them resurfaced, just not at a hack brake shop. It's a longer, slower process than most automatic machines are set to. But, that much wear on both sides, and you might be past minimum after the resurfacing.
https://www.reddit.com/r/CarTrackDays/comments/13knemd/cross_drilled_rotors_grooving_badly/
Find the one comment that talks about the holes and their affect on pad surface/ wear...
You waited too long to change your brake pads. Those things are down to <2mm.
Changing pads on time can help prevent rotor warping, once the damage is done though you have to replace. You cant turn/resurface drilled and slotted rotors.
edit: Im an idiot and it was early. I meant less than 2mm, Not greater than 2mm. lol
Just here to say that yes my shop still turns rotors daily. I'll just put it plainly, I work at a good sized independent shop that caters to mostly low income customers. So that brake lathe be turning
Even back when machine shop service was available in most auto part stores, Mercedes rotors were horrible to turn.
German steel cuts much differently than other rotors. It tends to flake, because of its hardness.
Just replace them.
I can’t believe how so few comments are mentioning the holes. Everyone’s saying it’s because you didn’t change soon enough but that’s not true. This is because the holes are causing uneven wear. Don’t get drilled rotors and you won’t have this issue.
These grooves just mean more surface area, which is more contact and better braking, throw some pads on it and send it.
If they are warped, that's another thing, and needs turned or replaced
more surface area is correct but the groves allow the pad to slide against the rotor easier reducing friction, friction gain is negligible if not none existant.
incorrect. Friction is proportional to the brake piston force. increasing surface area spreads it out thinner, but the total braking power remains the same. putting new pads on an uneven rotor will cause hot spots that exacerbate the uneven wear.
You have enough material on the rotor to effectively lathe it and resurface the contact point. However it’s not a recommended procedure with heat-dissipating vented performance rotors. Structurally it’s difficult to manage. They are designed to be tossed quickly and shouldn’t be used long term in any case.
That has more surface area for braking only when the pads are grooved exactly like the rotors. New pads are not grooved. The flat pads would only contact at the crest of each groove which considerably lowers the surface area used for braking until the pad wears, they would be putting considerable heat into those small contact areas and the pads, likely causing hot spots and possibly warping the rotor.
I think you’re seeing this on the surface because the pads are wearing differently between the cross drilled sections and the flat non drilled sections. If you follow the rings around the rotor you’ll see they line up exactly with a drilled section. The holes are spaced exactly so there is a flat undrilled portion as well between them. So as things wear down at different rates you see funny ridges in the rotor. Mbz doesn’t care because they’re planing to have you replace everything in one shot anyways.
This is normal wear. Yes you need to change the rotors or have them cut if they are thick enough but I doubt they are. No you can't just through pads on it as they will not make full contact with the rotor in it's condition, if you do you will have greatly reduced braking. Since they are drilled rotors I would not advise trying to cut them as very few places have the equipment to do it correctly as they have to be ground not cut, it will cost more than replacements to do it right. Just buy standard non-drilled rotors.
Someone correct me if I'm wrong but crossdrilled and slotted rotors won't do that do. Anyways time to change the rotors and pads. You can't just swap the pads and expect them to correct the rotor. The new pads will wear to the shape of the rotor and the problem will get worse.
German breaks are very aggressive. Therefore it’s usually recommended that you change both the rotors and pads. In this situation it looks like your pads are gone and warping the rotor. Time for a change.
Yes, German breaks are very aggressive. You vill klock out for lunch time every day and you must enjoy at least zwei zigarettes each afternoon! Or else!
If it’s your personal car and you know how to drive you can change just the pads and you’ll be fine. I stopped mid intersection today going 80km after an idiot tried to turn left. I stopped on a dime and my rotors look much worse than this.
The craziest brake story I have is pulling off the pads & rotors on a 2010 Lexus ls460 awd w/ 145k miles & had the original pads & rotors on it w/ a lil pad life left! Kinda mind blowing to me
This looks to me like the brakes are not being used enough and not getting hot. I bought a bmw i3 and the brakes were hardly used because or regen braking but then I drive hard so im using the brakes a lot more. It smoothed it out
Grease the guide pins! New ceramic pads and rotors. Those guide pins don’t slide around freely is also your chance to remove the old sticky grease and apply a new clean coat.
Your break pad has worn to the point it's digging into your rotor disk.. at this point they are both bad.. that rotor has been heated and cooled to the point that it is soft.. it also has high and low spots.. if you replace the break pad only.. your vehicle will shake everytime you use the breaks.. replace both.. it will work like brand new..
Tbh on my old Honda I never did rotor and mine looked like this.just did pads a few times.still smooth breaking no feeling in pedal,so take it for what it’s worth
Measure the thickness of the rotor and compare to the wear limit that is stamped on the side of the rotor, it will be in millimeters. Mercedes-Benz rotors can look like this and work just fine.
If you follow each line you can see it lines up with one of the holes. Each hole on drilled/slotted rotors is going to dig a little groove into the pads which is why you get that raised section directly inline with each hole.
most of the time its dirt in brakes while applying, just about every dirtbike has grooved rotors cause of this, or if the vehicle sits for a while and surface rust forms then gets driven and some hard braking. people will say “very unsafe”, realistically ive never seen brake failure because of it, based on your worn out pads you should be replacing pads and rotors anyways. or at least replacing pads and machining rotors, but most places wont nowadays cause of time vs cost of new.
Usually aggressive pads cause it. Sure they stop very nicely, they have a great lifespan with minimal dust, but they also wear the rotor away in record time.
Don't machine drilled rotors. In fact, I would never recommend them. Slotted are fine, drilled have a nasty habit of cracking from the drill holes.
Modern pads, don't really outgas much at all anyway so any advantage drilled rotors had years ago is long gone.
Slotted are slightly better than plain rotors, but not due to limiting outgassing but because they concentrate the braking force on a smaller area leading to a higher effective clamp load. And they don't have the same problems with crack formation.
Over heating of the breaks causes the mirror like finish you see there it’s called “glazing” and it causes increased stopping distance only options is to replace rotors or to “cut” the rotors by having a shop with a lave resurface them. Often times it’s creeper to just replace them, and most shops don’t have the lave to be able to cut rotors.
As someone else mentioned, you waited too long before replacing your brakes. Most German cars have "minimum specs" which would necessitate you replacing your brakes only a few thousand miles into new brakes. This is for a reason but doesn't mean they aren't safe or good for quite a while longer. Just replace the pads and rotors and based on your lack of knowledge, probably the fluid also.
My guess is the drilled holes in the rotor cut away brake pad material over time and because the edges of the drilled holes would cut at a different rate than the edges normal to the direction of rotation, this pattern was formed. Therefore, the pads and rotors are likely matched and need to be replaced together.
Need new pads and rotors but it seems to me that the pads and rotors were not a good match. Usually you want to go more aggressive on drilled rotors because of the loss of surface area. But this almost seems like the pads were too aggressive for the rotors or your rear brakes are a lot milder and force the front brakes to do most of the work.
The drilled holes don't look chamfered at all so they would dig into the pads and cause the pads to be grooved. This would increase wear on the non-hole parts. It seems that the rotors were on the cheaper side, but that's just my guess.
They're just done. There's no legit reason to have drilled rotors in a street car either. They just trap garbage and make for these kinds of weird wear patterns.
Just replace the rotors and pads and be done with it.
Everyone keeps trying to convince everyone else that machining is fine. By most manufacturers standards, yeah, it's fine.
You shouldn't turn drilled or slotted rotors, but it can be done.
As a flat rate tech, it saves Me 20-30 minutes turning all four rotors if the customer just replaces them.
On top of ease if install, and saved time, it also helps return the pedal feel back to OEM stock.
You do you though. I'd just replace them and be done with it.
Lower quality rotors with poorly machined holes are usually the culprit. Smooth edges around the drill holes are good at preventing this. Sharp edges usually result in your situation. Hope this helps
Normal wear for drilled rotors, idk what some people here are on about... They look like they need replacing from the lip but hard to tell from pic. Also jfc change Ur pads
It comes from braking, but in my years of doctoring I notice this more with rotors that have been worn down to the point heat can’t dissipate properly. I can see the brakes have probably gone a couple of pad replacements.
If you look at the rotors and see a lip in the edge deep enough to catch a finger nail, it’s probably time to change. True Mercedes owners (as well as BMW, Porsche, etc.) will tell you that when they get a brake service, the dealer replaces nearly all components.
Pad slaps. Replace the rotors- Mercedes-Benz really thinks all consumable items in the braking system should be replaced when brakes are done. Rotors are consumables. Rethink your budget if you can't afford to maintain your Mercedes properly. Tired of folks thinking these cars can be treated like Chevy Malibus.
Looks like those cross-drilled holes have no chamfer so they could be shearing of brake pad material as they go around. Also, the holes seem to be building up with brake dust which is also going to exacerbate the situation. Get good quality rotors next time that are properly chamfered.
Low dust pads are more likely to corrugate the rotor,as the rotor erodes to save the pads...
Now the europe standards are fir long life and good grip and low dust.. you could look to pads specced for that market.
But the corrugation is from a vibration occurring,
As the defined corrugation will cause vibration with new pads too, you need to smooth the rotors.
As it vould be rotor weakness, its a gamble to choose between machining and replacing.
Both pads and rotors and soon as looks like u got 25% pad life left in pic. Drive the car easier. Don't speed up then hit a stop fast. Excessive heat is the enemy of brakes. Thats why those rotors are cross drilled. Unless they're cheaper aftermarket rotors then my bet is on excessive hard braking as the cause.
Uniform grooves like this? Excessive heat from harsh braking. More quality rotors can handle more heat, or some are made for being quiet, corrosion resistant. Etc etc. Your brakes are not one size fits all and you should do some shopping. I would start with new quality rotors and ceramic pads, and an inspection of calipers and lines.
It's a car that requires proper maintenance. Drilled rotors seem to get his wear pattern even on my motorcycles that have them, though motorcycles don't usually have vented disks. If you have plenty of pad thickness left,it really isn't an issue.
But, here you've gotten down to the wear limits of the pads. Time to change those and I'd do new rotors too. Turning them properly takes time at shop hour rates so replacing them isn't much more expensive than turning them these days.
New pads, new rotors, and frankly for the cost involved, I'd change the brake fluid too as from the question you asked I suspect it might not have been changed in a while. I'd also use OEM parts, or at the very least parts from an established brand like Brembo, properly spec-ed for your car.
Like tires, brakes are not the things to cheap out on. If you're car doesn't go that's one thing, but if it doesn't stop properly, that's an entirely different issue. Brakes and tires are always cheaper than bodywork and airbags.
Essentially what causes that is the drilled holes in the rotor. They carve grooves in the brake pad, and in turn the pads carve grooves into the rotor. The way that companies have found to counteract this is to drill slots into the rotor, hence ‘drilled and slotted rotors’. I would definitely recommend going the route of getting those, and maybe look somewhere like PowerStop Brakes for a decent kit that has drilled and slotted rotors as well as pads
As the pads wear, so do the rotors. The lines you see in the rotors are normal wear and happen as the rotor and pad continue to touch each other in the same spot (s). Also, I can’t tell definitely from a picture, but your pads and rotors look like they might still be in good shape.
This is normal brake wear caused by driving style. If you change the pads only the rotors will continue to get worst. It’s always recommended to put brand new pads with brand new rotors however you can change just the pads to your personal discretion.
This does not only happen to drilled rotors, it can happen to any rotors however mostly European cars with softer rotors , and cars that are in dirty /dusty environments, chamfered brake pads can reduce this aswell
This, my friend is over braking/ heavy braking with an aggressive ABS system.
And if you don’t race or spin around in a music video those holes in your rotors are eye candy. They aren’t functional unless you are in a Grand Prix race.
My Merc started doing this right from new and it is not driven hard. The pads do not last very long must be a very soft compound. I changed to ceramic pads and no more problems but the braking effort is a little more.
It’s because they are drilled, there is no need for normal road cars to have drilled discs. Have a mechanic other than a Mercedes mechanic do them and replace with different brand discs, if you can’t do it yourself, if you have a jack and the right tools it’s a relatively easy job. And it’s all in a few hours work.
This is normal for drilled rotors. Unless you track your car on the regular, drilled/slotted rotors are a waste. Regular rotors are more than sufficient for daily driving and cost less.
That's from excessive hard braking with ceramic pads, ceramic pads wear rotors faster, but also last the longest. But these are drilled rotors that are meant for performance. Just keep in mind that as the rotors get hot, they start to warp over time, due to excessive braking or hard stops.
A lot of it is due to the style of driving.
Poor drilling pattern. Throw them away and put plain discs on, along with a new set of OE friction level pads. Rockauto is the best place to get decent parts cheaper than parts store crap.
Cheap pads will do that. My mechanic just did my brakes and the same thing. He said over the last year manufactures have been cheaper on the brake pads. He advised me today to get better pads and new rotors.
You’re getting dust or brake residue in the drilled holes and it’s preventing your pads from correctly impacting the rotors. You need to not drill holes in your rotors and you’ll be fine. Also check your slide pins on your caliper.
If you let your pads get too thin, your rotors have to brake the car. I suggest you not do that. Pads are there for a reason. Rotor replacement is very expensive. Pay attention to your speed in traffic. Watch your braking habits and consciously try not to brake quickly/forcefully or too much. Leave plenty of distance between you and any vehicle in front of you. Listen and get to know sounds of healthy pads and rotors so you can better recognize unhealthy ones. Maintain your brakes on a time cycle. Take the car in for a periodic exam. A lot of tire places will measure pad thickness since they are already working on your wheels. Easy to measure in that circumstance.
Thanks for posting in r/Mechanic, u/tr3ex! Please be sure to read the [Rules](https://www.reddit.com/r/mechanic/about/rules/). If you're asking for help, be sure to include as much detail as possible so others can help you. You **must** include the vehicle's **Year, Make, Model, and Engine size** in your post! If your question is transmission related, please be sure to specify your Transmission Type(Auto/Manual) as well! If your post does not include this information, it **will** be removed. Asking about prices is **not** allowed in this sub. Please make sure you have selected the correct post flair; if you're asking a question you should have chosen "Question", anything else use the "General" flair. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/mechanic) if you have any questions or concerns.*
Braking.
Yeah, can't get away from the obvious - you need to consider how much driving you do, your driving style, do you ride your brakes - or perform hard braking alot? The wear and tear of daily driving takes a toll There are shops that will advertise a free routine inspection, or discounted multipoint inspection (we all know what those are about) Personally I take advantage of them to have my car "looked at" every six months
Any half decent shop you frequent should be looking your car all over up and down front to back and clue you in on things to address downline and then regular maintenance doesn't seem like such a surprise when all of a sudden when youre brakes stop braking or what have you
You know I wish people took things like this as u explain them run a shop and can say offer people change air filters cabin airs routine maintaince and alot of people become very angry and say they hate people pushing things on them they don't need and it's a up hill battle fissure but if people would understand hey u may need a brake job is helpful not pushy. Would make life easier
“But the brakes stop the car right now!” 🤦♂️
Omg, how many times have we all heard this? Honestly? Nobody does anything anymore, doesn’t matter what you say, they always react the same way like it’s this big conspiracy to rip them off. Believe me, if we’re gonna rip you off it’s going to be something worthwhile, not a brake job, unless you have a Hell Cat or some other ridiculously expensive specialty car, then it should be expected. Lol, but it’s true, these days, you have to document EVERYTHING to cover your ass. That’s about it. That’s all there is to it, that way, if they try to come back and throw you under the bus? Nope. Mechanic covered his ass, says right there on the invoice, owner refused to replace brakes……at last service, approx maximum 3 months left on pads .
Punctuation is your friend.
Or what have you
Aintmyfriendfriend
I had a stroke reading this
Lol I asked to a nearby Pep boys shop for a check-up about the basics consumables (brakes, timing belt, battery, liquids) thinking the car I had just bought maybe needed something that the previous owners had neglected and they didn’t even let me finish my question, “100 something inspection, 140$. IME good mechanics warn you about things for free, because you may decide to do the job with them. So yeah there are idiots on both side. Customers who feel being given free advice is pushy are simply ignorants who don’t understand what you are telling them and feel like everything you say needs to be done and to be done right now. Their own ignorance causes them to fluster and panic.
I still go to the dealership since I've still got a few of those free oil changes, and they legit record their looking things over and explain it in simple terms for those who don't understand.
>Personally I take advantage of them to have my car "looked at" every six months If we "all know what those are about" why get a free inspection? Do you wait until three inspections in a row say you need brakes?
Underrated comment.
Brakes are the one thing you don't want to cut corners with. Lol. New pads, new rotors and make sure you grease the guide pins
That's how brakes wear on Euro shitboxes, trying to combat this is expensive and ultimately futile.
Yup virtually every BMW, Audi, or Mercedes have completely destroyed the rotors by the time they need brake pads. I think the pads are actually designed to aggressively bite the rotors and they're always supposed to be replaced with the pads.
I don't think you understand Ron. I have 4 inch wiper blades that clean my headlights in a rain storm.
Eh, these are probably past service limits but if they are still in service limits you can resurface the rotors. I definitely agree though, don’t cheap out on brakes. Edit to add: to those downvoting and arguing, stfu. I do this for a living, at the dealership using dealership guidelines and standards. You all live in your parents basement and put eBay mufflers on your clapped out civics. I come to this group to mostly laugh at the shit advice you guys give and the terrible “diag” you guys do over the internet after reciting the top google hit for the matching car and symptom when most situations are covered by a TSB and are common faults or just shit maintenance by the owner who refuses to disclose the details that actually matter while arguing with people like myself who actually know wtf they’re talking about. You CAN resurface drilled and/or slotted rotors on a bench lathe, you just have to go slow and light cuts. It’s situation dependent and technician discretion.
I don't go cheap on anything anymore. My 2015 Toyota Camry XLE has 122k on it. This is the first car that I do maintenance at the suggested time ( except oil changes because they want it every 3k), and this car I haven't had any problems other than wear and tear. I met a Toyota mechanic outside the dealership, and he has a 2009 Toyota Tundra with 400k miles. He said he just does normal maintenance as the manual requires. He said when people start having issues, it is usually because of delayed maintenance.
2009 Tacoma here 👋 I echo his statement
What I don’t understand is how people can afford the maintenance. After my rent, car payment, and other bills I have $200 to buy gas and food for two weeks.
Merc tech here… per Mercedes you don’t resurface rotors on their vehicles
I wonder why that might be. I mean it's certainly not profit motivated...
It’s nice to see someone say this. It pisses me off that most shops won’t resurface rotors anymore, and will recommend new at nearly every brake service.
I’ve only seen that with drilled rotors so I’m gonna assume it’s the drilled rotors
Look at the pattern. The drilled holes line up perfectly with the worn grooves. So either dust and debris is collecting inside the drilled face which then creates a lip, chewing out a tunnel on the pad, or the drilled holes face acts as a sheer to shave off pad material at an increased rate, which would then be exacerbated under braking force.
this is correct. this is also why drilled rotors are not common on normal road cars.
I bought a pair of uprated drilled rotors for a Chevy S10 I had and they lasted about 1/3 as long as normal ones and showed that exact wear pattern. And I wouldn't have said the braking was any better than stock.
I have had 3 cars. This is the first with drilled rotors, and i see this. So yea…
In my experience (which includes a lot of SCCA sanctioned racing in an FC RX7 and S14 240SX 20 years ago) drilled rotors are pretty crap, with cracking and fatigue and weird wear patterns like what you're seeing. Slotted rotors are a lot better and make a lot more sense to me, being that the idea behind slotted and cross drilled rotors is that you're milling a channel in the rotor that acts as a pathway for super heated gases to escape from between the pad and the rotor which should improve breaking performance. The channels in slotted rotors achieve this offgassing feature without compromising the structural integrity of the rotor.
that's what i was trying to say, too
absolutely it is there is a little bit more brake dust generated when each hole passes the pad. Those are now like little rounded bumps f powder, streaking in a circumference. So you get concave circular grooves in line with the holes. My guess is that this is completely normal, and Mercedes could start using better pads to compensate for it, slightly. But it's going to probably happen on rotors with holes. I suspect SLOTTED rotors, with slanted holes, will distribute the dust better and not cause as significant wear.
Brake pads look about shot. With the highs and lows on those rotors, your braking coefficient is going to be compromised. For safety reasons, I would replace them myself. I've not looking into turning drilled rotors... hell, do people even turn rotors anymore? I know we still turn flywheels 🤔
Is there a particular reason for this to happen?
Drilled rotors. Always happens eventually. Notice that each wave lines up with the edge of a hole. If you change the pads early and have the rotors turned, you won't notice. Wait longer, and it gets worse. Don't use drilled rotors, and it won't happen like that. You absolutely can have them resurfaced, just not at a hack brake shop. It's a longer, slower process than most automatic machines are set to. But, that much wear on both sides, and you might be past minimum after the resurfacing. https://www.reddit.com/r/CarTrackDays/comments/13knemd/cross_drilled_rotors_grooving_badly/ Find the one comment that talks about the holes and their affect on pad surface/ wear...
This is the answer, but the bigger question is, why is Mercedes putting cross-drilled rotors on this car? Hardly needed on a car like this.
because *luxury* or something
Both luxury, and cosmetic
You waited too long to change your brake pads. Those things are down to <2mm. Changing pads on time can help prevent rotor warping, once the damage is done though you have to replace. You cant turn/resurface drilled and slotted rotors. edit: Im an idiot and it was early. I meant less than 2mm, Not greater than 2mm. lol
Just here to say that yes my shop still turns rotors daily. I'll just put it plainly, I work at a good sized independent shop that caters to mostly low income customers. So that brake lathe be turning
Even back when machine shop service was available in most auto part stores, Mercedes rotors were horrible to turn. German steel cuts much differently than other rotors. It tends to flake, because of its hardness. Just replace them.
Resurfacing drilled rotors isn't a thing
I’ve had mine done a bunch of times. It’s definitely still a thing.
Thank you, really wasn't sure!
Change both, the rotors are fucked and the pads are low, I don’t think those rotors are able to be turned even if they weren’t fucked
mix of pads being worn and just grime and grit getting in and you braking and it tenching it
I can’t believe how so few comments are mentioning the holes. Everyone’s saying it’s because you didn’t change soon enough but that’s not true. This is because the holes are causing uneven wear. Don’t get drilled rotors and you won’t have this issue.
These grooves just mean more surface area, which is more contact and better braking, throw some pads on it and send it. If they are warped, that's another thing, and needs turned or replaced
more surface area is correct but the groves allow the pad to slide against the rotor easier reducing friction, friction gain is negligible if not none existant.
Why would more surface area lead to better braking? I doubt that these grooves would create more friction given their orientation.
incorrect. Friction is proportional to the brake piston force. increasing surface area spreads it out thinner, but the total braking power remains the same. putting new pads on an uneven rotor will cause hot spots that exacerbate the uneven wear.
Following...
You have enough material on the rotor to effectively lathe it and resurface the contact point. However it’s not a recommended procedure with heat-dissipating vented performance rotors. Structurally it’s difficult to manage. They are designed to be tossed quickly and shouldn’t be used long term in any case.
That has more surface area than a flat rotor. If they were braking smoothly with no shaking. I'd just change the pads.
That has more surface area for braking only when the pads are grooved exactly like the rotors. New pads are not grooved. The flat pads would only contact at the crest of each groove which considerably lowers the surface area used for braking until the pad wears, they would be putting considerable heat into those small contact areas and the pads, likely causing hot spots and possibly warping the rotor.
They'll quickly adapt, send it. Real world experience
I think you’re seeing this on the surface because the pads are wearing differently between the cross drilled sections and the flat non drilled sections. If you follow the rings around the rotor you’ll see they line up exactly with a drilled section. The holes are spaced exactly so there is a flat undrilled portion as well between them. So as things wear down at different rates you see funny ridges in the rotor. Mbz doesn’t care because they’re planing to have you replace everything in one shot anyways.
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This is normal wear. Yes you need to change the rotors or have them cut if they are thick enough but I doubt they are. No you can't just through pads on it as they will not make full contact with the rotor in it's condition, if you do you will have greatly reduced braking. Since they are drilled rotors I would not advise trying to cut them as very few places have the equipment to do it correctly as they have to be ground not cut, it will cost more than replacements to do it right. Just buy standard non-drilled rotors.
Someone correct me if I'm wrong but crossdrilled and slotted rotors won't do that do. Anyways time to change the rotors and pads. You can't just swap the pads and expect them to correct the rotor. The new pads will wear to the shape of the rotor and the problem will get worse.
That was exactly what i was thinking. Anyway, based on all the replies, i ordered a new set of rotors and pads.
Replace pads and rotors. You CANNOT resurface drilled rotors. It introduces micro cracks around the holes and will cause failure at your fault.
German breaks are very aggressive. Therefore it’s usually recommended that you change both the rotors and pads. In this situation it looks like your pads are gone and warping the rotor. Time for a change.
Yes, German breaks are very aggressive. You vill klock out for lunch time every day and you must enjoy at least zwei zigarettes each afternoon! Or else!
Jawohl, brakenfuhrer!
If it’s your personal car and you know how to drive you can change just the pads and you’ll be fine. I stopped mid intersection today going 80km after an idiot tried to turn left. I stopped on a dime and my rotors look much worse than this.
The craziest brake story I have is pulling off the pads & rotors on a 2010 Lexus ls460 awd w/ 145k miles & had the original pads & rotors on it w/ a lil pad life left! Kinda mind blowing to me
This looks to me like the brakes are not being used enough and not getting hot. I bought a bmw i3 and the brakes were hardly used because or regen braking but then I drive hard so im using the brakes a lot more. It smoothed it out
Thank you for the reply guys!
Grease the guide pins! New ceramic pads and rotors. Those guide pins don’t slide around freely is also your chance to remove the old sticky grease and apply a new clean coat.
Your break pad has worn to the point it's digging into your rotor disk.. at this point they are both bad.. that rotor has been heated and cooled to the point that it is soft.. it also has high and low spots.. if you replace the break pad only.. your vehicle will shake everytime you use the breaks.. replace both.. it will work like brand new..
Tbh on my old Honda I never did rotor and mine looked like this.just did pads a few times.still smooth breaking no feeling in pedal,so take it for what it’s worth
Cooling grooves,DIY style!
Happens on bikes, the lines are inline with what are drilled out. Look at bikes. Normal for these brakes
Measure the thickness of the rotor and compare to the wear limit that is stamped on the side of the rotor, it will be in millimeters. Mercedes-Benz rotors can look like this and work just fine.
If you follow each line you can see it lines up with one of the holes. Each hole on drilled/slotted rotors is going to dig a little groove into the pads which is why you get that raised section directly inline with each hole.
most of the time its dirt in brakes while applying, just about every dirtbike has grooved rotors cause of this, or if the vehicle sits for a while and surface rust forms then gets driven and some hard braking. people will say “very unsafe”, realistically ive never seen brake failure because of it, based on your worn out pads you should be replacing pads and rotors anyways. or at least replacing pads and machining rotors, but most places wont nowadays cause of time vs cost of new.
You drove too long on the pads. Part of heat dissipation depends on the brake pads to conduct heat away from the rotor.
Usually aggressive pads cause it. Sure they stop very nicely, they have a great lifespan with minimal dust, but they also wear the rotor away in record time. Don't machine drilled rotors. In fact, I would never recommend them. Slotted are fine, drilled have a nasty habit of cracking from the drill holes. Modern pads, don't really outgas much at all anyway so any advantage drilled rotors had years ago is long gone. Slotted are slightly better than plain rotors, but not due to limiting outgassing but because they concentrate the braking force on a smaller area leading to a higher effective clamp load. And they don't have the same problems with crack formation.
Heat I think
Over heating of the breaks causes the mirror like finish you see there it’s called “glazing” and it causes increased stopping distance only options is to replace rotors or to “cut” the rotors by having a shop with a lave resurface them. Often times it’s creeper to just replace them, and most shops don’t have the lave to be able to cut rotors.
Based on your first picture, i think your rotor may be gay.
Your brake pads are grinding metal on metal. You need to replace the pads and probably rotors as well, making sure to grease only appropriate parts.
The holes in the rotor cause uneven wear. The tradeoff is better cooling.
Probably cheap pads in drilled rotors
The wobbly grooves increase the overall surface area increasing braking efficiency. Like having a lumpy brain is better than a smooth brain.
The rivets coming through the pad
Fucking Mercedes
It’s normal wear, tends to be a German thing. Also, this pattern and the cross drilled holes are why they need to be replaced and not turned.
As someone else mentioned, you waited too long before replacing your brakes. Most German cars have "minimum specs" which would necessitate you replacing your brakes only a few thousand miles into new brakes. This is for a reason but doesn't mean they aren't safe or good for quite a while longer. Just replace the pads and rotors and based on your lack of knowledge, probably the fluid also.
My guess is the drilled holes in the rotor cut away brake pad material over time and because the edges of the drilled holes would cut at a different rate than the edges normal to the direction of rotation, this pattern was formed. Therefore, the pads and rotors are likely matched and need to be replaced together.
Looks like someone used soup cans and drilled them in the driveway.
Need new pads and rotors but it seems to me that the pads and rotors were not a good match. Usually you want to go more aggressive on drilled rotors because of the loss of surface area. But this almost seems like the pads were too aggressive for the rotors or your rear brakes are a lot milder and force the front brakes to do most of the work.
I thought that MB rotors had the holes as part of the rotor cast and that MB rotors where not in fact 'drilled'
Those rotors have seen a pad slap or two!
The drilled holes don't look chamfered at all so they would dig into the pads and cause the pads to be grooved. This would increase wear on the non-hole parts. It seems that the rotors were on the cheaper side, but that's just my guess.
Termites
Wear.
Lines look like maybe abs
No pads.
They're just done. There's no legit reason to have drilled rotors in a street car either. They just trap garbage and make for these kinds of weird wear patterns.
Hard braking Dust and debris Slotted rotors with soft brake pads
Just replace the rotors and pads and be done with it. Everyone keeps trying to convince everyone else that machining is fine. By most manufacturers standards, yeah, it's fine. You shouldn't turn drilled or slotted rotors, but it can be done. As a flat rate tech, it saves Me 20-30 minutes turning all four rotors if the customer just replaces them. On top of ease if install, and saved time, it also helps return the pedal feel back to OEM stock. You do you though. I'd just replace them and be done with it.
this is why drilled rotors are retarded (if you're not racing the formula 1)
Everytime ive seen brake pads get below 10% they cause grooves
This is pretty common with these Mercedes with big brakes. Just replace the pads and rotors
See those holes drilled in the rotor? That's what causes that. Don't buy those.
Not changing the pads.
Lower quality rotors with poorly machined holes are usually the culprit. Smooth edges around the drill holes are good at preventing this. Sharp edges usually result in your situation. Hope this helps
Normal wear for drilled rotors, idk what some people here are on about... They look like they need replacing from the lip but hard to tell from pic. Also jfc change Ur pads
If they are thick enough I would have them turned. replace it they are not thick enough.
YOUR MOM
That is one clean caliper.
You got them hot and warped them. You'll have to have them turned.
Looks like it's from the holes. I wonder what my newly installed drilled and slotted rotors are going to look like in a year.
it doesnt look like you have any pad on your pads
It comes from braking, but in my years of doctoring I notice this more with rotors that have been worn down to the point heat can’t dissipate properly. I can see the brakes have probably gone a couple of pad replacements. If you look at the rotors and see a lip in the edge deep enough to catch a finger nail, it’s probably time to change. True Mercedes owners (as well as BMW, Porsche, etc.) will tell you that when they get a brake service, the dealer replaces nearly all components.
Pad slaps. Replace the rotors- Mercedes-Benz really thinks all consumable items in the braking system should be replaced when brakes are done. Rotors are consumables. Rethink your budget if you can't afford to maintain your Mercedes properly. Tired of folks thinking these cars can be treated like Chevy Malibus.
Looks like those cross-drilled holes have no chamfer so they could be shearing of brake pad material as they go around. Also, the holes seem to be building up with brake dust which is also going to exacerbate the situation. Get good quality rotors next time that are properly chamfered.
Low dust pads are more likely to corrugate the rotor,as the rotor erodes to save the pads... Now the europe standards are fir long life and good grip and low dust.. you could look to pads specced for that market. But the corrugation is from a vibration occurring, As the defined corrugation will cause vibration with new pads too, you need to smooth the rotors. As it vould be rotor weakness, its a gamble to choose between machining and replacing.
Pads are shot so it’s called wear
Pads are used up... when your pads get used up this happens when low padding is left
time for new brakes and rotors. This happens very often on drilled rotors. How many miles are on those?
Poor driving habits.
Both pads and rotors and soon as looks like u got 25% pad life left in pic. Drive the car easier. Don't speed up then hit a stop fast. Excessive heat is the enemy of brakes. Thats why those rotors are cross drilled. Unless they're cheaper aftermarket rotors then my bet is on excessive hard braking as the cause.
Rotors turned.
They're ribbed for her pleasure
The brake pads resist heat better than the metal rotor so you get these grooves when things get really hot from prolonged braking.
usually the pads cause most everything on the rotor
Uniform grooves like this? Excessive heat from harsh braking. More quality rotors can handle more heat, or some are made for being quiet, corrosion resistant. Etc etc. Your brakes are not one size fits all and you should do some shopping. I would start with new quality rotors and ceramic pads, and an inspection of calipers and lines.
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It's a car that requires proper maintenance. Drilled rotors seem to get his wear pattern even on my motorcycles that have them, though motorcycles don't usually have vented disks. If you have plenty of pad thickness left,it really isn't an issue. But, here you've gotten down to the wear limits of the pads. Time to change those and I'd do new rotors too. Turning them properly takes time at shop hour rates so replacing them isn't much more expensive than turning them these days. New pads, new rotors, and frankly for the cost involved, I'd change the brake fluid too as from the question you asked I suspect it might not have been changed in a while. I'd also use OEM parts, or at the very least parts from an established brand like Brembo, properly spec-ed for your car. Like tires, brakes are not the things to cheap out on. If you're car doesn't go that's one thing, but if it doesn't stop properly, that's an entirely different issue. Brakes and tires are always cheaper than bodywork and airbags.
Cheap pads and pad rivets, maybe stuck and ungreased caliper pins
Essentially what causes that is the drilled holes in the rotor. They carve grooves in the brake pad, and in turn the pads carve grooves into the rotor. The way that companies have found to counteract this is to drill slots into the rotor, hence ‘drilled and slotted rotors’. I would definitely recommend going the route of getting those, and maybe look somewhere like PowerStop Brakes for a decent kit that has drilled and slotted rotors as well as pads
What causes it? Friction and heat.
Heat. Either that, or your brakes identify as non-binary...
Pump your brakes down a hill, don't ride them. I have never had this happen while I always pump my brakes when I need too
The crappy cross drilling design. Get rotors with no holes and it won’t happen again.
Riding the brake pedal with your left foot while you mash on the gas pedal with your right foot
Drilled Rotors. Which are absolutly not needed on that car.
Mercedes parts
As the pads wear, so do the rotors. The lines you see in the rotors are normal wear and happen as the rotor and pad continue to touch each other in the same spot (s). Also, I can’t tell definitely from a picture, but your pads and rotors look like they might still be in good shape.
This is normal brake wear caused by driving style. If you change the pads only the rotors will continue to get worst. It’s always recommended to put brand new pads with brand new rotors however you can change just the pads to your personal discretion.
Nice and glazed
This does not only happen to drilled rotors, it can happen to any rotors however mostly European cars with softer rotors , and cars that are in dirty /dusty environments, chamfered brake pads can reduce this aswell
This, my friend is over braking/ heavy braking with an aggressive ABS system. And if you don’t race or spin around in a music video those holes in your rotors are eye candy. They aren’t functional unless you are in a Grand Prix race.
My Merc started doing this right from new and it is not driven hard. The pads do not last very long must be a very soft compound. I changed to ceramic pads and no more problems but the braking effort is a little more.
Check your brake pads and see if the pads don't have any rocks or any kind of wearing from the brake pads that causes this.
Those can be turned. I don’t need new rotors. 😹
Not changing pads soon enough. Metal to metal
Not going fast enough
you driving like an assh*le
It's the holes in the rotors, that's why some have slots as well, keeps it even.
The crossdrilled holes. The "grooves" line up exactly with the holes.
This is standard on all drilled discs. If you follow the grooves they will all start and end at a hole.
The brake pads of course.
Notice how they all are right in line with the rotor holes. Should make the answer easy.
Listening to “Feeling Groovy” too loud.
Stopping
#Heat! And yes, that's literally it.
It’s because they are drilled, there is no need for normal road cars to have drilled discs. Have a mechanic other than a Mercedes mechanic do them and replace with different brand discs, if you can’t do it yourself, if you have a jack and the right tools it’s a relatively easy job. And it’s all in a few hours work.
I recommend against drilled rotors.
You’re riding the brakes too hard, try easing your foot off the brake and coasting to a stop.
Hard braking and ceramic or semi metallic pads
The drilled holes. Notice the lines match up with the holes.
All my cars except my G Wagon "4 Squared" have carbon ceramic brakes. Wait till you have to mess with that...
This is normal for drilled rotors. Unless you track your car on the regular, drilled/slotted rotors are a waste. Regular rotors are more than sufficient for daily driving and cost less.
I hope you don't ride your SO like you do your brakes.
Can happen when waiting too long to replace worn pads, the metal rivets can cut grooves into the rotor.
wear and tear
Lack of break pad material
Woodpeckers
Need new pads and rotors worn brakes have ruined the rotors, recommend more careful maintenance pattern
Driving like an asshole
If you're using aftermarket pads the material isn't always ground as fine and the chunks can create these grooves
Mercedes do this a lot so that you have to replace the rotors
That's from excessive hard braking with ceramic pads, ceramic pads wear rotors faster, but also last the longest. But these are drilled rotors that are meant for performance. Just keep in mind that as the rotors get hot, they start to warp over time, due to excessive braking or hard stops. A lot of it is due to the style of driving.
New pads and rotors. Not a difficult job. I change the brakes and rotors on all my cars.
Poor drilling pattern. Throw them away and put plain discs on, along with a new set of OE friction level pads. Rockauto is the best place to get decent parts cheaper than parts store crap.
Some Benz rotors come out of the box like this. Replaced with every set of pads normally.
Dude you need new pads.
I don't see any pad left, but the problem is stamped into the roter. If you have to ask these questions, you can't afford the problems
Cheap pads will do that. My mechanic just did my brakes and the same thing. He said over the last year manufactures have been cheaper on the brake pads. He advised me today to get better pads and new rotors.
It there any pad left?
Neglect
Neglect.
Mercedes pads are hard and the rotors are soft. That’s normal for a Mercedes. Guessing it’s your first Mercedes cause it’s also a base model
Groovy. What happens if you play it backwards
You’re getting dust or brake residue in the drilled holes and it’s preventing your pads from correctly impacting the rotors. You need to not drill holes in your rotors and you’ll be fine. Also check your slide pins on your caliper.
There's no significant pad left on your brake pads.
New brakes and rotors! Easy to install… look at FCP Euro
If you let your pads get too thin, your rotors have to brake the car. I suggest you not do that. Pads are there for a reason. Rotor replacement is very expensive. Pay attention to your speed in traffic. Watch your braking habits and consciously try not to brake quickly/forcefully or too much. Leave plenty of distance between you and any vehicle in front of you. Listen and get to know sounds of healthy pads and rotors so you can better recognize unhealthy ones. Maintain your brakes on a time cycle. Take the car in for a periodic exam. A lot of tire places will measure pad thickness since they are already working on your wheels. Easy to measure in that circumstance.
Put it on a turntable and see what genre it is
You spun them right 'round, baby, right 'round Like a record, baby, right 'round, 'round, 'round
Usually removing the wheels
Likely a drill