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Discussion Starter #1
My front rotor thickness should be 30mm from new and I measure the wear, it has about 1.5mm wear from each side but there is no warning from the sensor.
By the book the disc min thickness should be 28.4 which should be way higher than what it has now. Should the discs be replaced asap?

The rear has about 1.2mm wear each side.

Thanks
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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!
 

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Discussion Starter #3
Sorry I don't quite get it.
The rotor thickness is now at 27mm but the min indicates 28.4mm. Should the rotor be replaced? The pad still looks good.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Why did you measure rotor thickness? Measure it at pad change, brake service.
 

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The sensor doesn't warn you if the disc is beyond the limit. It's a brake pad wear sensor.
Generally, every other pad change the discs need to be replaced.
 

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As for the rotor lasting two pad changes. I suppose that it depends on your driving. Bought my car with 30k miles on it. Pads and rotors appeared to be original. Changed both at 98k miles as I was experiencing a shudder when braking.
 

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2006 530xi 6 MT
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My 2 cents...

If someone measured the rotor thickness at the last pad change, and the rotors were not below the minimum thickness at that time, then no action is necessary on the rotors until the next pad change.
 

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Sorry I don't quite get it.
The rotor thickness is now at 27mm but the min indicates 28.4mm. Should the rotor be replaced? The pad still looks good.
If your rotors are below minimum requirement, it's VERY important that you change them. The rotor absorbs heat by breaking. 1.4 mm of steel all around the rotor is a lot of steel. If it's not there the excess heat will be absorbed by the steel that remains. In simple words, your brakes will overheat very quickly and that's not good.
 

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If you look at the BMW service instructions, they say:
"Important! New brake pads may only be fitted if the brake disc thickness is greater than the minimum brake disc thickness (MIN TH)."

https://www.newtis.info/tisv2/a/en/...ls/34-brakes/34-11-front-wheel-brakes/E9W1wvP

That statement means that I can have rotors greater than minimum thickness and install a new pad set. That would also indicate that BMW has taken into account the rotor wear beyond minimum thickness for that pad set.
 

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If you look at the BMW service instructions, they say:
"Important! New brake pads may only be fitted if the brake disc thickness is greater than the minimum brake disc thickness (MIN TH)."

https://www.newtis.info/tisv2/a/en/...ls/34-brakes/34-11-front-wheel-brakes/E9W1wvP

That statement means that I can have rotors greater than minimum thickness and install a new pad set. That would also indicate that BMW has taken into account the rotor wear beyond minimum thickness for that pad set.
+1 Good to know. Nominal size for non-perforated discs is -2.4 mm.
 
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