Question about drilled rotor wear (pic included)
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Junior Member
Joined: Mar 2008
Posts: 28
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From: Los Angeles, CA
2017 E300, 2017 GLC300
Question about drilled rotor wear (pic included)
I just picked up a 2006 C230, and have noticed a very light rumble in the front brakes. It's not bad, but noticeable. I wonder if this is a side effect of the drilled rotors, since I've never had them before.
But, I also noticed wear on the rotors that seems to be uneven - that is, there is a lip that is wearing slightly lower than the rest of the rotor on the outer edges of the front brakes.
Now, I thought this might have just been my car, but maybe this happens on all Mercedes of this model? I have attached a picture from a C230 on eBay - this one isn't my car, but it has exactly the same front rotor wear that I do. Note the silvery band around the outside of the rotor. Am I worrying about nothing here?
http://www.justcadillac.com/%7Echamp...23227-46sm.jpg
But, I also noticed wear on the rotors that seems to be uneven - that is, there is a lip that is wearing slightly lower than the rest of the rotor on the outer edges of the front brakes.
Now, I thought this might have just been my car, but maybe this happens on all Mercedes of this model? I have attached a picture from a C230 on eBay - this one isn't my car, but it has exactly the same front rotor wear that I do. Note the silvery band around the outside of the rotor. Am I worrying about nothing here?
http://www.justcadillac.com/%7Echamp...23227-46sm.jpg
Senior Member
Joined: Dec 2004
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From: Bay Area, CA
'04 Mars Red C230K Sport Coupe (not Coup-EH)
My brother's 2004 sport sedan has developed the same lip on the outer edge of the rotor. It doesn't seem to be causing any problems. However the rear brakes don't have this lip, though they are smaller and not cross-drilled.
If you're getting a rumble, it could just be from bad braking habits from the previous owner that warped the rotors slightly. Usually this happens with people that accelerate and brake repeatedly in stop-and-go traffic. More even braking should begin to smooth it out eventually, or you may look into replacing the rotors next time you replace the pads.
If you're getting a rumble, it could just be from bad braking habits from the previous owner that warped the rotors slightly. Usually this happens with people that accelerate and brake repeatedly in stop-and-go traffic. More even braking should begin to smooth it out eventually, or you may look into replacing the rotors next time you replace the pads.
Out Of Control!!
Joined: Nov 2005
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From: OC
a quarter mile at a time
do you actually feel pulsation when braking? I've seen this before on these brakes and it isn't a big deal. If you are experiencing pulsation, that is more of a reason for concern.
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From: Los Angeles, CA
2017 E300, 2017 GLC300
Thanks for both of your responses. I found a few more pics, and that wear seems to be normal. As for the rumbling, it is only evident when braking from high speeds, and it's not bad. I would guess (hope?) that jedcred is right about it smoothing out eventually. I haven't had it for more than a week, so maybe my more even braking will fix things.
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From: Orange County
2005 C Wagon (No snickering please!)
The shiney mark on the rotor could be due to some foreign material getting stuck between pad and rotor that "polished" the disc a bit. Nothing to worry about. All rotors will have a lip on the outer diameter that gets deeper as the rotor wears. This is because the pad does not touch the outer edge, so there is no wea on that part. No worries here either.
If you measure the rotor thickness at 8 points around the disc, and it is even within .02 mm you should be fine. You must also measure runout with the rotor mounted. If that measures .02 mm or less at a point 10mm in from the outer edge, you should not be able to feel and shuddering from the brakes.
Keep in mind that tires, bushings, shocks, and alignment can cause wobble to be felt if any of those parts are not up to snuff.
If you measure the rotor thickness at 8 points around the disc, and it is even within .02 mm you should be fine. You must also measure runout with the rotor mounted. If that measures .02 mm or less at a point 10mm in from the outer edge, you should not be able to feel and shuddering from the brakes.
Keep in mind that tires, bushings, shocks, and alignment can cause wobble to be felt if any of those parts are not up to snuff.
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Joined: Jul 2006
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From: Markham, Canada
C320 Coupe
donno if this will affect. if you were in the traffic and hard braked a few times, and immidiately you come to a complete stop and keep step down on your brake, what it does is that it because the brake pad is still hot, and the area of the brake disc melted due to this issue, which becomes braking rumble.
This is just my logic, and it might not be the real issue. just my 2 cents tho.
This is just my logic, and it might not be the real issue. just my 2 cents tho.
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Joined: Oct 2007
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From: Anchorage, Alaska
2005 MB C240
Are the rotors cracking around the drilled holes? I've heard of drilled rotors cracking due to incorrect drilling or just wear and tear.
Here is an example...
In this image, there is a ring of wear that formed due to a crack in the rotor. That would also explain the light rumbling feeling you have. If that is the case... I would change them out ASAP.
EDITED: Sorry about the last picture.
Here is an example...
In this image, there is a ring of wear that formed due to a crack in the rotor. That would also explain the light rumbling feeling you have. If that is the case... I would change them out ASAP.
EDITED: Sorry about the last picture.
Last edited by korean2nr; Mar 18, 2008 at 01:18 PM.
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'07 C230 SS
^^^ if what shown above is what you have then wouldnt that be some sort of manufacture defect with the creation of the rotors and then be covered by warranty.. although i doubt that type of problem would easy happen with good rotors it seems more likely to occur with ebay junk rotors then mercedes or brembo
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Joined: May 2007
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From: clearh²o, FL
2007 c230
when i first got my 07, it had buildup on the rotors (aka lot-rot) and i had a pulsation in the pedal when braking at speed.
its easy to re-bed them, if thats the situation you have
((i have had to do this more than once, driving in FL))
its easy to re-bed them, if thats the situation you have
((i have had to do this more than once, driving in FL))
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From: Orange County
2005 C Wagon (No snickering please!)
Let's talk about drilled rotors for a second. All rotors that are cross drilled will develop cracks around the holes. Cheap ones from Brazil, expensive ones from Italy (Brembo), and OEM from Mercedes will crack. If the cracks are like the one pictured by Korean2nr, the disc might fail and should be replaced without further driving. Mercedes says that hairline cracks upto 1 inch long (25mm) are normal, and they will not honor any warranty on such cracked rotors.
Rotors are cross drilled to allow air to circulate through the disc to help move the heat from braking away from the rotor. This is valuable on competition cars driven on the race track, where brake temperatures are significantly higher than on street cars. A daily driver does not benefit from cross drilled rotors, but it does look cool. A rotor modification that is helpful to a street car is slotted rotors. The slots act like a blanchard grinder to remove pad friction material to keep the surface flat. There is a minute amount of wear from this process, and the pads will not last as long. The payoff is brakes that are firm and stop as well as can be expected.
Rotors are cross drilled to allow air to circulate through the disc to help move the heat from braking away from the rotor. This is valuable on competition cars driven on the race track, where brake temperatures are significantly higher than on street cars. A daily driver does not benefit from cross drilled rotors, but it does look cool. A rotor modification that is helpful to a street car is slotted rotors. The slots act like a blanchard grinder to remove pad friction material to keep the surface flat. There is a minute amount of wear from this process, and the pads will not last as long. The payoff is brakes that are firm and stop as well as can be expected.
Newbie
Joined: Oct 2007
Posts: 20
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From: Anchorage, Alaska
2005 MB C240
Let's talk about drilled rotors for a second. All rotors that are cross drilled will develop cracks around the holes. Cheap ones from Brazil, expensive ones from Italy (Brembo), and OEM from Mercedes will crack. If the cracks are like the one pictured by Korean2nr, the disc might fail and should be replaced without further driving. Mercedes says that hairline cracks upto 1 inch long (25mm) are normal, and they will not honor any warranty on such cracked rotors.
Rotors are cross drilled to allow air to circulate through the disc to help move the heat from braking away from the rotor. This is valuable on competition cars driven on the race track, where brake temperatures are significantly higher than on street cars. A daily driver does not benefit from cross drilled rotors, but it does look cool. A rotor modification that is helpful to a street car is slotted rotors. The slots act like a blanchard grinder to remove pad friction material to keep the surface flat. There is a minute amount of wear from this process, and the pads will not last as long. The payoff is brakes that are firm and stop as well as can be expected.
Rotors are cross drilled to allow air to circulate through the disc to help move the heat from braking away from the rotor. This is valuable on competition cars driven on the race track, where brake temperatures are significantly higher than on street cars. A daily driver does not benefit from cross drilled rotors, but it does look cool. A rotor modification that is helpful to a street car is slotted rotors. The slots act like a blanchard grinder to remove pad friction material to keep the surface flat. There is a minute amount of wear from this process, and the pads will not last as long. The payoff is brakes that are firm and stop as well as can be expected.
