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Hi guys, just kicked my back tire this morning with my boots and heard a rattle, turns out is coming from a slight side to side play on the rear brake rotor. The rim, abs ring and everything else is tight, is this supposed to be like this? Thanks for your response in advance.
 

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Hello Mechanic

Yes it is , it is a floating rotor brake system . When it worn out you can replace with an EBC rotor < $ but not so rust resistant as OE , not a functional problem just looks issue after rain or washing .

Bob G
 

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Thanks gbob, almost dirty my pants when I saw this play.
 

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This floating rotor can get loose enough to give you the famous "Cowbell" sound coming from the rear, and it quite embarrassing, but still quite functional. If you search under the "Cowbell" term you should get quite a few hits!

Welcome to our forum! :)

John
 

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Hi, I have a 2005 LT with 43,000 miles. My rotor made noise since 11,000 miles on the odometer. Two months ago I could no longer take people asking me what the cow bell sound was so I deceided to fix it. I went to the dealer and asked if it was a recall issue. They said no. They quoted me a price of $712.00 to replace it. I ended fixing it myself. I recalled reading that someone tried fixing it with silicone so I removed the rotor, cleaned it up really well. Set it on my shop table and aligned the rotor center on the hub and turned it clockwise so that the rotor was pressing against the rivits. This ensured that when the brake is applied the stopping force would be against the rivits. It is important that the rotor lays flat against the hub. You do not want any wobble (run out) when the rotor rotates or else it will rub against the brake pads. I then filled the gap around each rivit with a drop of GE Silicone. I let it set for 24 hrs. Reinstalled the rotor. 2500 miles later the rotor is still quiet and working great. I am very happy with the results. Harold
 

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Harold-NY said:
Hi, I have a 2005 LT with 43,000 miles. My rotor made noise since 11,000 miles on the odometer. Two months ago I could no longer take people asking me what the cow bell sound was so I deceided to fix it. I went to the dealer and asked if it was a recall issue. They said no. They quoted me a price of $712.00 to replace it. I ended fixing it myself. I recalled reading that someone tried fixing it with silicone so I removed the rotor, cleaned it up really well. Set it on my shop table and aligned the rotor center on the hub and turned it clockwise so that the rotor was pressing against the rivits. This ensured that when the brake is applied the stopping force would be against the rivits. It is important that the rotor lays flat against the hub. You do not want any wobble (run out) when the rotor rotates or else it will rub against the brake pads. I then filled the gap around each rivit with a drop of GE Silicone. I let it set for 24 hrs. Reinstalled the rotor. 2500 miles later the rotor is still quiet and working great. I am very happy with the results. Harold
Harold-NY;

Did you take pictures of how you did the work? My 2005 has 39,000 and started making the same noise about 3,000 miles ago.
Let me know, I might do the "fix" this week.

Regards,
Bowdon
 

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Sorry, no photo's. It was a pretty simple fix. If is does not work I just saw a EBC new rotor at Beemer boneyard on sale for $155.00. The 3 important things to remember are 1) Turning the rotor clockwise while you hold the hub tight. This sets the rotor against the correct side of the rivits, same side as when you apply the brakes. If you put it against the opposite side of the rivits then the silicone would be forced out when you appliy heavy braking pressure. 2) My rotor had play in 2 directions circular and vertical. When on the bench I measured from the center of the hub to the outside rotor circumfence at 6 differnt points to insure rotor was centered (vertical movement). 3) Make sure rotor to hub surface is clean as possible to insure it lays flat against the hub. This will make the rotor spin true ( as best as it can). Like I said, I had nothing to lose because I was about to buy a new rotor anyway. I am very happy with the results. Good luck with your fix. :wave
 

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mechanic said:
Hi guys, just kicked my back tire this morning with my boots and heard a rattle, turns out is coming from a slight side to side play on the rear brake rotor. The rim, abs ring and everything else is tight, is this supposed to be like this? Thanks for your response in advance.
The OEM rear disc is junk. Replace it with an EBC and forget about it.

I've done this on 2 k1200's and never regretted it. (And in fact loved the change)

Trying to make the OEM junk work is a waste of time. I just did my new K12LT with only 11000 miles. The OEM disc looks like new but is already getting loose.

Anyone stuck on the OEM disc, I'll sell them mine cheap. :bmw:
 

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How much for your rotor?
 
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