Morning folks, bit of a dumb question here perhaps...but I know when the pads are gone , it breaks the sensor and you get the light...i had the front pads and sensor replaced by a great shop in town, reset the light..mechanic mentioned rotors were still good, didn't even have to turn them...

my question is...how would I know when i do need to replace the rotors? will I get a warning light as well? i know the most obvious solution would be to periodically take a look at them, but that's just not an option for me, since i recently relocated and i dont have any tools or means to check them, plus it's freezing cold up here to mess around outside under the car lol.


thank you.

 

It's purely a measurement.
There's a minimum thickness required on each rotors.
Using the OEM specifications and a pair of measuring calipers, you simply check the thickness of the overall profile.
If the thickness is greater than the require thickness, they're good to go.
If not, then they are replaced.

Rotors are rarely turned-down anymore due to case-hardening (rip apart tooling) and are more cost effective to replace than to machine.

- Erik

 

The spec is in the Bentley manual, and probably stamped into the rotor itself somewhere. I don't have a brake measuring caliper, regular machinist Verniers wont get around the lip on the edge, so I just use a micrometer.

 

thank you...so therefore no light will go off or anything? will i be able to tell by the way it may brake or nay? perhaps will i hear a sound? now i'm kinda concern, because it probably wont be a while until im able to have them check, and i just dont know how long will they last...i have about 29k on the car, and just replaced the front pads yesterday...

 

Correct, no light.

Not typically.

Only 29K miles? Unless you've done countless track days, and been hanging on the brakes for hours at a time, I can almost guarantee you're a-ok!

Correct.

Front Rotor Thickness
New: 22.0mm (0.866 in)
Wear Limit: 20.4mm (0.803 in)

Rear Rotor Thickness
New: 10.0mm (0.394 in)
Wear Limit: 8.4mm (0.331 in)

- Erik

 

29K is a bit on the early side but not too bad depending on how aggressive you are. That said, my feeling is that it's a good idea to replace the rotors when you do the pads. The rotors are simply not expensive enough not to replace everything while you are in there.

I also change the brake fluid each spring and change the oil with 0-40 M1 every 5000 miles.

Rich

 

Not sure about the owners manual but Bentley manual says replace rotors when pads are replaced.

 

Yeah, MINI rotors are soft and mine had a lip worn into them by the pads that was probably .050-.080" deep on each side. From the specs, you have about .030" per side to play with for machining. Unless you have a very minimal lip, you generally have to replace the rotors with the pads.