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  #1  
Old 04-17-2003, 05:44 PM
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Why is the rotor hitting my brake pads?

Hi everyone

I was wondering if anyone could answer this. I had a seized caliper which I just changed, and I was hoping this would cure the problem I am having, but it did not cure it 100%

My problem is that on one of the wheels, it seems like the rotor is warped, but I just had it re-surfaced and it is straight and in good condition, however, in one spot on the radius of the turn, it tends to hit the brake pad on the caliper. With the seaized caliper this was so severe that it created a wha-wha-wha like sound while driving, with the new caliper, it is not so severe but it can still be heard.

Now the caliper is mounted on the on the wheel carrier, and so is the bearing, the bearings are fine, there is no play there.

Is there something else that could cause this? I'd love to get it fixed up for good, but I'm not sure where to turn now, replace the bearing? The wheel? races? Not sure what they do, but I hear they are quite important.

Thanx in advance.

xp
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  #2  
Old 04-17-2003, 06:13 PM
Ali Al-Chalabi's Avatar
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It is still possible for the pads to be in contact with the rotor under very light pressure when the brakes are released, as there are no return springs or anything in the assembly.

If the wheel spins relatively freely and the rotor does not get hot when the brakes are not being used, then I would say that everything is normal.
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  #3  
Old 04-17-2003, 08:14 PM
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you may have to have it cut while it's still on the wheel carrier. it may warp again in the long run since this is an indication that it is out of true. i've read the techs suggest a good cleaning of the wheel carrier before mounting the rotor to prevent any possibility that something will keep the rotor from mounting straight...
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  #4  
Old 04-17-2003, 08:22 PM
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This problem is killing me, the original caliper locked so tight that you had to use two hands to spin the wheel in Neutral past this certain point. Now the new caliper touches the rotor in the same spot too, but it does not lock the wheel like that anymore, however the noise is still there, and the intesity changes as you drive.

I am 90% sure that it is the rotor hitting the breake pad causing this noise because right after I mounted the new caliper and went for a drive, it was very hard to hear that noise, but now after an hour of driving it is almost back to the same point that it was with the old caliper.

HELP! what do I do about this? What can I do?

xp
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  #5  
Old 04-17-2003, 09:08 PM
jack baker
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I would first check the rotor after removing wheel while mounted on the hub, to make certain it is infact true while mounted, if the bearings are good, and the rotor is not true you may have a problem with hub or rotor even though it has been turned, check it with a stationary object and surely you will by elimination find the evil one...
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  #6  
Old 04-17-2003, 09:58 PM
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jack baker

are you sure that would be a valid check? after all on a w201, the rotor is mainly held down by the wheel slugs, once those are removed, it is only held in place by a small bolt which is only meant to hold it so it does not fall off, this is how I have been checking it so far.

What I was thinking of doing instead is take off the caliper and with the wheel still on, use a micrometer to see if there is any uneveness there, or just go for a ride with 3 calipers and see if the noise is still there, would have to block the last caliper so the breaks work and clip it to the spring so it does not drag behind the car.

xp
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  #7  
Old 04-17-2003, 10:19 PM
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you can check the trueness of the rotor with a dial indicator.It is a fairly simple do it yourself job to put on new rotors plus you get to check and repack wheel bearings at same time I change the rear grease seal also.Fastlane sells new rotors at a very reasonable price.I have heard that Mercedes dose not recomend having MB rotors turned.........
William Rogers.........
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  #8  
Old 04-17-2003, 11:19 PM
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you would have to put the lug bolts on with spacers to make sure the rotor is secured as if you had wheels on. the dial indicator would then tell you if it is out of true or not. sometimes an inanimate object such as a pencil point held securely on to the caliper will tell you the story.
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  #9  
Old 04-18-2003, 11:02 AM
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I'll be doing this next, thanx for all the tips, really have to solve this.

xp
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  #10  
Old 04-26-2003, 10:15 AM
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it's still there

Hey guys

I got some more updates on my problem, but at this point I'm not sure where this noise is coming from anymore.

I got new rotors for both rear wheels, they spin very nicely now and don't hit anything anymore. The calipers work fine and open up when you release the brake, everything has been cleaned multiple times, I even tried new wheels, but the noise is still there. It seems to go faint after I do something with the wheels but then it comes back.

I'm starting to think that this might be my differential, or maybe it's not even coming from the rear, but moreso rear then front that's for sure. This is an inside noise, you can only hear it in the car, I tried driving by walls to see if it echos off but nothing, or it's too faint outside to be heard like this.

This problem has me really worried and I'm not sure how to trouble shoot it either, or find out where it's coming from. I'm quite sure it is wheel related because the driveshaft spins at a different speed then the wheels do.

I will be doing more reaserch, maybe I can get the car on a lift and see if I can hear it as the wheels are spinning freely.

xp
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  #11  
Old 04-26-2003, 04:21 PM
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Wink

My car had a tyre that was making a fluttering sound. I was so loud that I thought it had to be a bearing or something mechanical. It dissapeared after a tyre change.
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  #12  
Old 04-28-2003, 06:40 AM
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Does it get worse when turning??
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  #13  
Old 04-30-2003, 08:27 AM
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it's the same at any time

Emilio it's the same all the time, it only varies with the speed of the car, turning or not.

It's also not the tires, I have two sets and I switched them around and nothing changed at all.

It could be related to my new flex discs, but they were changed a while ago, and the noise developed after that. I'm not sure what could cause it, but the guy doing the flex discs didn't install them correctly so I had to re-assemble the dirveshaft myself, but that didn't change anything either.

xp
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