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Last year I have complained that my brakes were "pulsating" at low speeds, say when I was slowing down at the traffic lights. My dealership changed the discs and told me they were worped. It fixed the issue.
But this feeling of pulsating brakes (different from vibration), as if the brakes were periodically letting go a little bit, came back to some extend. It is not consistent and it doesn't feel as they are failing, since when pushed hard they behave normally.
What could be the cause of it? It is hard to believe that new discs are worped again.
I had the same issue on my 2015 B250.
I did again the bedding-in procedure and the brakes are perfect now.
Did you bed-in your brakes after the rotors were replaced?
I had the same issue on my 2015 B250.
I did again the bedding-in procedure and the brakes are perfect now.
Did you bed-in your brakes after the rotors were replaced?
No, I didn't do it, at least not to a specific protcol. I assume they changed rotors and didn't realized bedding-in should be done. Did they change pads or rotors in your case?
Last year I have complained that my brakes were "pulsating" at low speeds, say when I was slowing down at the traffic lights. My dealership changed the discs and told me they were worped. It fixed the issue.
But this feeling of pulsating brakes (different from vibration), as if the brakes were periodically letting go a little bit, came back to some extend. It is not consistent and it doesn't feel as they are failing, since when pushed hard they behave normally.
What could be the cause of it? It is hard to believe that new discs are worped again.
one of the causes that most people overlook including mechanics, is taking into consideration when owners wash the car. Do you run errands before washing the car? Do you cross over deep enough puddles? Its best to wash the car when its cool, but if you've already ran a few miles and you go to a carwash or wash the car yourself, mind the disc brakes. Specially, the fronts, as they tend to be hotter. once water is sprayed and If steam comes up, that means the discs are hot enough where they could warp.
Thats why its possible for brand new discs to get warped right away, if the practice isnt avoided or changed.
I always wash my car and make sure the discs are cold enough to touch. If i really have to go to a carwash i do it before running errands and i always drive slow on my way to the carwash.
Hope this helps.
one of the causes that most people overlook including mechanics, is taking into consideration when owners wash the car. Do you run errands before washing the car? Do you cross over deep enough puddles? Its best to wash the car when its cool, but if you've already ran a few miles and you go to a carwash or wash the car yourself, mind the disc brakes. Specially, the fronts, as they tend to be hotter. once water is sprayed and If steam comes up, that means the discs are hot enough where they could warp.
Thats why its possible for brand new discs to get warped right away, if the practice isnt avoided or changed.
I always wash my car and make sure the discs are cold enough to touch. If i really have to go to a carwash i do it before running errands and i always drive slow on my way to the carwash.
Hope this helps.
I don't usually wash my car after driving. My impression is that the first time the discs were warped from the begining, if that was the problem.
What is strange now, is that it is not consistent, meaning that sometimes I feel it strongly (eg recently after a 4 hours trip) and sometimes very little. Also, at higher speeds the brakes are smooth.
one of the causes that most people overlook including mechanics, is taking into consideration when owners wash the car. Do you run errands before washing the car? Do you cross over deep enough puddles? Its best to wash the car when its cool, but if you've already ran a few miles and you go to a carwash or wash the car yourself, mind the disc brakes. Specially, the fronts, as they tend to be hotter. once water is sprayed and If steam comes up, that means the discs are hot enough where they could warp.
Thats why its possible for brand new discs to get warped right away, if the practice isnt avoided or changed.
I always wash my car and make sure the discs are cold enough to touch. If i really have to go to a carwash i do it before running errands and i always drive slow on my way to the carwash.
Hope this helps.
I'd only believe this if you are dropping in on the Daytona 500 on your way to work.
I have the exact same problem on my side. Since 12 months, the dealer changed the front rotors 4 times. Every 3 months/5000km...the pulsating pedal start again and each time, they tell me it's probably the car wash or my driving habit. Strangely enough...even the brake booster broke in November. I'm in eco-mode 95% of the time and I do highway runs without touching the brake pedal...I drive the car and maintain it to last..but I'm very mad about this problem. I even called Mercedes Canada to tell them about the repeating issue and they constantly send me back to the dealer manager
Have been able to create and eliminate this characteristic,
Iron fallout or iron removing wheel cleaner products IF used can clear the ferrous iron layer on one side of the outer face of the rotor but of course leave the area behind the calliper....
This can cause pulsing breaks which is not remedied by the "breaking in new pads' style method.
To correct I ended up using the same cleaning product and scrubbing the whole disc face (either raising the car or rolling it forward half a wheel dia etc.)
Either way it cured the issue, and was able to recreate the issue and the fix subsequently...
Warping discs is actually pretty hard to do, so shouldn't be assumed to be the first possible cause.
Follow the described procedure and see if you still have the problem.
I have tried this procedure today, but I don't think it helped much, if at all. I've seen it quoted in various places for new pads, so maybe if the problem already exists it does'nt work.
Anyway, the problem is not very serious, so it's not a big deal. I will ask my dealership to look at it again. What is puzzling, is that in many cars I owned including Mercedes, I have never seen anything like that. So, it seems that it is specific to 205 only.
I have tried this procedure today, but I don't think it helped much, if at all. I've seen it quoted in various places for new pads, so maybe if the problem already exists it does'nt work.
Anyway, the problem is not very serious, so it's not a big deal. I will ask my dealership to look at it again. What is puzzling, is that in many cars I owned including Mercedes, I have never seen anything like that. So, it seems that it is specific to 205 only.
its actually pretty common with a lot of different cars. Most people just don't notice or care because the car still stops. Its happened to a friend of mine with a 203 and my cousin's nissan minivan... there's almost no rhyme or reason to which car it happen to...
its actually pretty common with a lot of different cars. Most people just don't notice or care because the car still stops. Its happened to a friend of mine with a 203 and my cousin's nissan minivan... there's almost no rhyme or reason to which car it happen to...
The whole "Warped rotors" concept is a myth. Rotors are designed to withstand temperatures over 1400 degrees F. Your stock DOT 3 brake fluid will boil over at around 600 degrees F.
Anytime someone thinks they have a warped rotor, what they really are experiencing is uneven pad deposits on the rotor as described in the link by Webmoto and this one by Stoptech.
Please do yourself a favor and read these technical articles by two of the top brake manufacturers and parts suppliers.
For the OP, I'm guessing that there's a high probability that your braking style is contributing to the issue. Do you do ride the brakes? Do you do abrupt stops from higher speeds? Do you manually downshift when going down long hills or mountains, or do you use the brakes?
The whole "Warped rotors" concept is a myth. Rotors are designed to withstand temperatures over 1400 degrees F. Your stock DOT 3 brake fluid will boil over at around 600 degrees F.
Anytime someone thinks they have a warped rotor, what they really are experiencing is uneven pad deposits on the rotor as described in the link by Webmoto and this one by Stoptech.
Please do yourself a favor and read these technical articles by two of the top brake manufacturers and parts suppliers.
For the OP, I'm guessing that there's a high probability that your braking style is contributing to the issue. Do you do ride the brakes? Do you do abrupt stops from higher speeds? Do you manually downshift when going down long hills or mountains, or do you use the brakes?
I undertand that the warped rotors is not a common problem, but that is what the dealership service told me. I also don't think that my driving style has anything to do with the problem. I am driving more than 40 years and never had this problem before. That is why I think it is specific to this car.
By the way, whether it is due to the pad deposit or not, the driving and stoping procedure, suggested in one of the articles you have pointed out to, didn't work.
I'd only believe this if you are dropping in on the Daytona 500 on your way to work.
that actually sounds fun. But believe it or not, you probably hit the brakes more often driving around town than doing a lap in Daytona.
Originally Posted by Hapa88
The whole "Warped rotors" concept is a myth. Rotors are designed to withstand temperatures over 1400 degrees F. Your stock DOT 3 brake fluid will boil over at around 600 degrees F.
Anytime someone thinks they have a warped rotor, what they really are experiencing is uneven pad deposits on the rotor as described in the link by Webmoto and this one by Stoptech.
Please do yourself a favor and read these technical articles by two of the top brake manufacturers and parts suppliers.
For the OP, I'm guessing that there's a high probability that your braking style is contributing to the issue. Do you do ride the brakes? Do you do abrupt stops from higher speeds? Do you manually downshift when going down long hills or mountains, or do you use the brakes?
So, i did myself a favor as you said, and read both links. I just realized i've read this before. The problem is, they only talk about how high temps can get during braking and how deposits can affect the discs and different materials, bllah, blah, blah. They never mentioned anything about washing the cars right after the tests.
Since you don't believe that hot metals and water don't mix well. Try doing me a favor and take a drive with your car for a good 30-45 mins. With a nice amount of stop and goes and waiting on a stop light. Then go straight back home and before you grab a sandwich and a soda, get a garden hose, and go straight for the front disc brakes, just like how they do it when you get a carwash from your neighborhood hand wash place. If you hear the discs sizzle and steam starts coming up out of the wheels and the fenders (sounds and looks cool, btw) thats your hot discs trying to break apart. That immediate cool down, can cause warpage even if your discs aren't glowing orange at 1400*F. Of course, i release myself from any and all liabilities with this experiment you'll be conducting so you can report back to us. Although you may be able to get away with it once or twice, but done frequently enough, you most likely will have to replace something, i'm just not sure what. But I'm sure the dealer can definitely help you out with parts and labor.
that actually sounds fun. But believe it or not, you probably hit the brakes more often driving around town than doing a lap in Daytona.
So, i did myself a favor as you said, and read both links. I just realized i've read this before. The problem is, they only talk about how high temps can get during braking and how deposits can affect the discs and different materials, bllah, blah, blah. They never mentioned anything about washing the cars right after the tests.
Since you don't believe that hot metals and water don't mix well. Try doing me a favor and take a drive with your car for a good 30-45 mins. With a nice amount of stop and goes and waiting on a stop light. Then go straight back home and before you grab a sandwich and a soda, get a garden hose, and go straight for the front disc brakes, just like how they do it when you get a carwash from your neighborhood hand wash place. If you hear the discs sizzle and steam starts coming up out of the wheels and the fenders (sounds and looks cool, btw) thats your hot discs trying to break apart. That immediate cool down, can cause warpage even if your discs aren't glowing orange at 1400*F. Of course, i release myself from any and all liabilities with this experiment you'll be conducting so you can report back to us. Although you may be able to get away with it once or twice, but done frequently enough, you most likely will have to replace something, i'm just not sure what. But I'm sure the dealer can definitely help you out with parts and labor.
So basically your saying anytime you are out driving around and run into a rain storm you are screwed?
So basically your saying anytime you are out driving around and run into a rain storm you are screwed?
Not buying it.
During a rain, water won't sit long enough while moving and high pressure, high quantity of water isn't sprayed against the brakes. So, unless you park in a 3 foot puddle, it's not the same....
that actually sounds fun. But believe it or not, you probably hit the brakes more often driving around town than doing a lap in Daytona.
So, i did myself a favor as you said, and read both links. I just realized i've read this before. The problem is, they only talk about how high temps can get during braking and how deposits can affect the discs and different materials, bllah, blah, blah. They never mentioned anything about washing the cars right after the tests.
Since you don't believe that hot metals and water don't mix well. Try doing me a favor and take a drive with your car for a good 30-45 mins. With a nice amount of stop and goes and waiting on a stop light. Then go straight back home and before you grab a sandwich and a soda, get a garden hose, and go straight for the front disc brakes, just like how they do it when you get a carwash from your neighborhood hand wash place. If you hear the discs sizzle and steam starts coming up out of the wheels and the fenders (sounds and looks cool, btw) thats your hot discs trying to break apart. That immediate cool down, can cause warpage even if your discs aren't glowing orange at 1400*F. Of course, i release myself from any and all liabilities with this experiment you'll be conducting so you can report back to us. Although you may be able to get away with it once or twice, but done frequently enough, you most likely will have to replace something, i'm just not sure what. But I'm sure the dealer can definitely help you out with parts and labor.
Yea, Daytona was a poor example, I should have used a road course from formula 1. Steaming brakes in a car wash is still a farce.
Right before I traded in my 2015 C300 4Matic Sport with about 10,000 miles on it, I too started to notice a slight vibration only when applying the brakes, but that was at highway speeds...felt like a warped rotor to me.
Yea, Daytona was a poor example, I should have used a road course from formula 1. Steaming brakes in a car wash is still a farce.
Formula 1 is a very good example as well. But, i've never seen any of the pit crew spraying water on the brakes to cool them down. I've seen use their highly modified leaf blowers to fan the brakes, but never a garden hose.
Farce or not, i'll stick to my practice. And since i've driven cars almost all my life and never had to replace discs and pads before 30k mi. I guess something is working for me.
That immediate cool down, can cause warpage even if your discs aren't glowing orange at 1400*F. Of course, i release myself from any and all liabilities with this experiment you'll be conducting so you can report back to us. Although you may be able to get away with it once or twice, but done frequently enough, you most likely will have to replace something, i'm just not sure what. But I'm sure the dealer can definitely help you out with parts and labor.
If you read them you obviously didn't really get what you were reading. Here's what's happening in your car washing example: Your pad & rotor get hot from repeated braking from driving. You go and park your car in the driveway and now the hot rotor and pad are now stopped and fixed in one position on the rotor. At this point the pad is essentially melting onto the rotor while you're stopped. As it cools (with the cooling process sped up by the water), it essentially melts onto the rotor leaving a deposit (in the shape of a brake pad) and also creates a sort of binding to your rotor.
The next time you drive the car and hit the brakes as the rotor is spinning, you feel a pulsation every time the brake pad rolls over that part of the rotor with the pad deposit on it. The pulsation is NOT because of the rotors warping, its because of the brake pad deposit.
There are 3 basic ways to solve the problem: 1) get all new rotors, since new rotors have a uniform thickness 2) have your rotors "turned" which is basically a machining process that sands the entire rotor down to a uniform thickness (this removes that little bit of pad deposit in that one area). 3) Somehow get the pad to evenly deposit around the entire surface of the rotor.. This is a process that is similar to "bedding" the brake pads.
Here's what a pad imprint looks like.
Lastly, the sizzling action and steam is because the rotors are hotter than 100C (the boiling point of water) when you spray them. As soon as the water hits the hot rotor it turns into steam, and at the same time the metal contracts. Its the same thing that happens when you cook on a pan and run the pan under water immediately after.
If you read them you obviously didn't really get what you were reading. Here's what's happening in your car washing example: Your pad & rotor get hot from repeated braking from driving. You go and park your car in the driveway and now the hot rotor and pad are now stopped and fixed in one position on the rotor. At this point the pad is essentially melting onto the rotor while you're stopped. As it cools (with the cooling process sped up by the water), it essentially melts onto the rotor leaving a deposit (in the shape of a brake pad) and also creates a sort of binding to your rotor.
The next time you drive the car and hit the brakes as the rotor is spinning, you feel a pulsation every time the brake pad rolls over that part of the rotor with the pad deposit on it. The pulsation is NOT because of the rotors warping, its because of the brake pad deposit.
There are 3 basic ways to solve the problem: 1) get all new rotors, since new rotors have a uniform thickness 2) have your rotors "turned" which is basically a machining process that sands the entire rotor down to a uniform thickness (this removes that little bit of pad deposit in that one area). 3) Somehow get the pad to evenly deposit around the entire surface of the rotor.. This is a process that is similar to "bedding" the brake pads.
Here's what a pad imprint looks like.
Lastly, the sizzling action and steam is because the rotors are hotter than 100C (the boiling point of water) when you spray them. As soon as the water hits the hot rotor it turns into steam, and at the same time the metal contracts. Its the same thing that happens when you cook on a pan and run the pan under water immediately after.
Alright, so lets try this one more time. When you drive, whether its around town, to work or home, once you've stopped and put the car in park, the pads are essentially melting onto the discs. Damn, that means everyone on the road then.
So, why isn't everyone experiencing pulsating brakes?
I doubt if people bed their brakes everyday to get rid of the material deposit from the day before.
You also mentioned that as it cools (SPED up by WATER) it leaves a deposit in the shape of the brake pad (thanks for the pic, btw). Does that mean its bad to wash your car when you've already driven it for some time? I think thats what i was telling everyone to avoid doing.
From what i remember, warped is anything thats out of its original shape. Whether its caused by force or DEPOSITS that take it out of its original form, thats warped.
In other words, you basically want us to say we have UNEVEN FRICTION MATERIAL DEPOSITS ON DISC BRAKES instead of warped discs? Cool! I can live with that.
But, do you also want us to say, i had a CATASTROPHIC MASSIVE AIR DEFLATION ON MY TIRE, instead of flat?
Alright, so lets try this one more time. When you drive, whether its around town, to work or home, once you've stopped and put the car in park, the pads are essentially melting onto the discs. Damn, that means everyone on the road then.
So, why isn't everyone experiencing pulsating brakes?
No, only in the extreme case you described. That is, the case when the brake rotors and pad become excessively hot and then are rapidly cooled. Most people don't drive or brake in a way that makes this a problem, but some do.
After doing track events for a number of years, I know how to prevent it from happening. If the brakes are excessively hot, let the brakes cool naturally, go easy on them before parking the car (don't do abrupt stops or hard stops from higher speeds). When doing high speed stops, its best to do rolling stops as it prevents the pad from imprinting on the one spot on the rotor. Don't set the parking brake immediately after hard stops. After a track session, we roll into the pit area and park the car in neutral, using chocks to hold the car in place until the brakes cool to ambient temperatures. You shouldn't need to do that on a street driven car, but then again I don't know how everyone brakes. Some people do 100 on the freeway, some people drive like they're driving Ms Daisy.
Originally Posted by mo11
I doubt if people bed their brakes everyday to get rid of the material deposit from the day before.
You kind of do, just the process of regular braking helps even out material deposits. Only in the extreme case I described before do you run into problems.
Originally Posted by mo11
You also mentioned that as it cools (SPED up by WATER) it leaves a deposit in the shape of the brake pad (thanks for the pic, btw). Does that mean its bad to wash your car when you've already driven it for some time? I think thats what i was telling everyone to avoid doing.
Agreed, but I disagreed with the reason you gave.
Originally Posted by mo11
From what i remember, warped is anything thats out of its original shape.
I agree with this.
Originally Posted by mo11
Whether its caused by force or DEPOSITS that take it out of its original form, thats warped.
I would have to disagree. Warped is the original rotor out of original shape. Pad deposits are are foreign object and not a part of the original rotor material. Therefore I would suspect that it is incorrect to claim the rotor is warped in this case.
This is what I see as "warped":
Originally Posted by mo11
In other words, you basically want us to say we have UNEVEN FRICTION MATERIAL DEPOSITS ON DISC BRAKES instead of warped discs? Cool! I can live with that.
Yes, that's correct and the articles and brake manufacturers I posted back that up.
Originally Posted by mo11
But, do you also want us to say, i had a CATASTROPHIC MASSIVE AIR DEFLATION ON MY TIRE, instead of flat?
You can say either, because they're pretty much the same in my book.
No, only in the extreme case you described. That is, the case when the brake rotors and pad become excessively hot and then are rapidly cooled. Most people don't drive or brake in a way that makes this a problem, but some do.
After doing track events for a number of years, I know how to prevent it from happening. If the brakes are excessively hot, let the brakes cool naturally, go easy on them before parking the car (don't do abrupt stops or hard stops from higher speeds). When doing high speed stops, its best to do rolling stops as it prevents the pad from imprinting on the one spot on the rotor. Don't set the parking brake immediately after hard stops. After a track session, we roll into the pit area and park the car in neutral, using chocks to hold the car in place until the brakes cool to ambient temperatures. You shouldn't need to do that on a street driven car, but then again I don't know how everyone brakes. Some people do 100 on the freeway, some people drive like they're driving Ms Daisy.
You kind of do, just the process of regular braking helps even out material deposits. Only in the extreme case I described before do you run into problems.
Agreed, but I disagreed with the reason you gave.
I agree with this.
I would have to disagree. Warped is the original rotor out of original shape. Pad deposits are are foreign object and not a part of the original rotor material. Therefore I would suspect that it is incorrect to claim the rotor is warped in this case.
This is what I see as "warped":
Yes, that's correct and the articles and brake manufacturers I posted back that up.
You can say either, because they're pretty much the same in my book.
Hahaha! I can just see it now... me and my service advisor.
Me: hello, i'd like to make an appointment.
SA: sure, what are you coming in for?
Me: i have excessive uneven friction material on my disc brakes.
SA: what?
Me: i have excessive uneven friction material on my disc brakes!
SA: What? What do you mean?
Me: you know, excessive uneven friction material on my disc brakes!!! My brakes are pulsating!
SA: oh, WARPED... bring it in tomorrow, we'll take a look at it...
Now, me and roadside assistance
Me: hello, i have a flat.
RA: oh, i'm sorry about that we'll be there in 30mins...
Hahaha! I can just see it now... me and my service advisor.
Me: hello, i'd like to make an appointment.
SA: sure, what are you coming in for?
Me: i have excessive uneven friction material on my disc brakes.
SA: what?
Me: i have excessive uneven friction material on my disc brakes!
SA: What? What do you mean?
Me: you know, excessive uneven friction material on my disc brakes!!! My brakes are pulsating!
SA: oh, WARPED... bring it in tomorrow, we'll take a look at it...
That's true. Service advisors are usually high school educated and know very little about cars. In most cases they come on with no experience at all. The ability to communicate and a valid driver's license is usually the minimum. Then it's an on-the-job training from there on out.
Remember their job is to make money for the service department (and the dealership) by pushing services and replacement parts that aren't always required. A service department will make much more money replacing your "warped" rotors than they will if they just "turn" or resurface your existing ones.
SA: "Sure, you still have a little life left in this part, but you're already here and it's already taken apart. You can save money now in labor if we just replace it now."
SA: "You can, not do anything now, but it's definitely a safety issue in my opinion.. You wouldn't want your family to be hurt if it should fail, would you?"
That's true. Service advisors are usually high school educated and know very little about cars. In most cases they come on with no experience at all. The ability to communicate and a valid driver's license is usually the minimum.
04-17-2017, 05:27 PM
