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Suspension & Braking
Have some questions about suspension or brake setups for your E46 BMW? Get all your answers here! |
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#1 |
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Registered User
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Outer brake pad non-continuous rubbing
So, I have about 146,000 miles on this car. Few weeks back noticed a faint non-continuous rubbing sound. took the wheel off and found the outer pad (rear passenger side) rubbing on the rotor...as if though the rotor was warped. Took the brake apart and cleaned it. That didn't help. Had the rotor resurfaced. Resurfaced rotor had the same problem from the get go. I could see the pad rubbing as i put the caliper back on. This really puzzled me. Why would the newly resurfaced rotor have the same problem?
Replaced the guide pins as well, but no fix. I've searched the forums but haven't seen anything like this problem. And By the way, over the past few weeks that I've been driving with resurfaced rotor and new guide pins, the rubbing seems to be getting worst. Any ideas of what this might be? Thanks. |
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#2 |
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Wears carbon fiber boxers
Join Date: Jun 2009
Location: In a van down by the river
Posts: 3,697
My Ride: 330Ci ZHP 6sp
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Got a similar problem on one of my rotors as well. In for ideas
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E46Fanatic's resident mathemagician
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#3 |
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E46 is strong with this one
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Same. Sounds like could be E-Brake shoes rubbing too.
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#4 |
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Registered User
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I guess I can swap the passenger and driver side rotors today to see if the problems moves with the rotor. My gut feeling is that it will stay on the passenger side since the resurfaced rotor had the same problem.
At the same time, I can't think of other possibilities as the source for the problem. |
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#5 |
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Registered User
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You need to make sure the hub flange is clean and free of rust. That will cause the rotor to not sit properly.
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#6 |
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Registered User
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^Agreed. I did scrub and clean it thoroughly when i replaced the rotor. That didn't fix it either.
By the way, a dirty hub flange should cause this sort of issue on both inner and outer pad. Having said that, I did scrub it as I was grasping at straws at that point. |
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#7 | |
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Registered User
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Quote:
Last edited by RayPooley; 01-20-2013 at 09:20 AM. |
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#8 |
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Stay stock my friends!
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Did you clean and grease the caliper carrier where the pads slide on it? Did you inspect the seal on caliper piston to see it's not broken? If that seal is broken, you'll have some rust on piston which will hold the pad against the rotor...and the pad might not be squarely seated either. I've seen posts here where the pad actually tilts into the rotor from the top because of the notches being worn/bad.
...and for my final random guess...could be the dust shield...very common...particularly after a wheel comes off and it gets bent a tad. Pull out on dust shield all around...pretty firmly and evenly...it sits very close to rotor and doesn't take much at all to bend it so rotor is hitting it once a rotation. GL...hope one guess of mine helps!
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#9 |
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Registered User
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Can also be a failed soft brake line, which holds pressure and doesn't release it.
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#10 |
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Registered User
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Thanks for all the input thus far.
Since the problem is on the outer pad, I dismissed piston sticking. I've never lubed the caliper guide pins dice they are supposed to be dry fit. I did buy and replaced with new bushings and pins to rule that out as well. I've also verified that the problem is not the shield. |
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#11 | |
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Stay stock my friends!
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Quote:
I actually meant, though, where the bottom of the pad slides on the caliper carrier...those two rails. Clean well with whatever and put grease where the metal backing of the pad slides on the rail...I've heard of them hanging up. Also, did you remove the inner pad from piston? I had an issue where part of the backing plate was loose (little sliver under the clip in back) and thus the clips didn't hold so well and the pad slid up slightly to rub the lip on rotor...just because it changed position slightly. I removed the loose piece, reinstalled pad...all good. Also, sometimes those clips need to be pulled out a bit to hold more firmly in piston. HTH
__________________
![]() This huge woman, like 400 pounds comes up to me and says, "Doug, I would rock your world." I replied, "but I need to breathe." The girl in my sig:http://forum.e46fanatics.com/showthr...highlight=dmax |
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#12 |
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Wears carbon fiber boxers
Join Date: Jun 2009
Location: In a van down by the river
Posts: 3,697
My Ride: 330Ci ZHP 6sp
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If you do grease the pins, use synthetic, silicone brake grease. I think the reason why the TIS advises against it is because the bushings are rubber.
IMHO I hate dealing with the messiness of greasing the pins and would rather just clean them very well using brake cleaner. Plus, the grease will attract dust.
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E46Fanatic's resident mathemagician
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#13 |
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Registered User
Join Date: Apr 2010
Location: Murrieta, CA
Posts: 4,973
My Ride: '94 325iC & '00 323i
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Brake pads ALWAYS rub. That's how disc brakes are designed. They NEVER don't rub.
You apply the pedal, and the pads come under pressure and press against the rotors. You release the pedal and the pressure stops and the pads relax, but they NEVER stop rubbing. |
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#14 |
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Registered User
Join Date: Apr 2010
Location: Murrieta, CA
Posts: 4,973
My Ride: '94 325iC & '00 323i
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You are not supposed to grease the guide pins. They should be clean and dry.
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#15 |
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Registered User
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^Agreed. I've never greased them in the past and all other wheels are fine.
^^this rubbing is not "normal" |
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#16 | |
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Registered User
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Quote:
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#17 |
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Stay stock my friends!
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I've read that the pad sits about 5/1000" off the rotor...there's very little tolerance for them, but they should pull off the rotor when you're off the brakes.
The little square "o-ring" in the caliper rolls out with the piston, and after pressure is released, it pulls the pads off. JD might have a pad slipping and hitting the lip, or he may need a new caliper and/or rebuild it. Real test is to drive on highway for 10 mins or so and pull off without using the brakes. If one rotor is hot, then it's seized somehow...maybe can be rebuilt, but if you need new pistons, you might as well get remanned. OP...don't think this is your issue.
__________________
![]() This huge woman, like 400 pounds comes up to me and says, "Doug, I would rock your world." I replied, "but I need to breathe." The girl in my sig:http://forum.e46fanatics.com/showthr...highlight=dmax |
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#18 |
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Registered User
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Ok, dope slap me. Found the problems. I had two issues.
With the car on stands and wheels off, Swapped the passenger and driver side rotors. The problem moved with the rotor, but to a smaller degree. However, now I noticed passenger side grabbing the rotor to an extent that with car in D, only one side was spinning. Took the caliper off and found some junk buildup on the slider. Cleaned it with brass brush and all is good. It gets better...while doing the troubleshooting for brakes, saw too much play on the differential. Got cracked diff bushing! Wonderful. New post! |
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