OEM Disc Question

[510135]

Hello,
I know this may seem to be a 'how long is a piece of string question' but here it goes .
How many miles/kms are people getting out of OEM 135 Brake Disc's? This is non-track use just daily driving.

[Focusedintntions]

Well BMW says to replace them when you replace pads. How long that lasts is a question of driving habits and pad materials. My guess would be though 20-30k miles of average street driving through.

[510135]

Originally Posted by Focusedintntions

Well BMW says to replace them when you replace pads. How long that lasts is a question of driving habits and pad materials. My guess would be though 20-30k miles of average street driving through.

Don't they last more than 1 brake pad change. Can't they machine them ?

[Focusedintntions]

No sadly they cannot. BMW rotors are pretty thin for the 135. They don't recommend machining them at all...always replace. I know it's dumb, but I didn't come up with it.

[kb135]

On mine the "lip" seems to be quite pronounced at the edge, if I have correctly identified the "lip" that is. 55k kms and the rears squeal now when braking, but usually only at low speeds ~20km/h. if i go slow enough ~10km/h i can almost hear a faint intermittent squeak squeak squeak, so I think its also warped...
Are mine actually shot then?

[510135]

Originally Posted by kb135

On mine the "lip" seems to be quite pronounced at the edge, if I have correctly identified the "lip" that is. 55k kms and the rears squeal now when braking, but usually only at low speeds ~20km/h. if i go slow enough ~10km/h i can almost hear a faint intermittent squeak squeak squeak, so I think its also warped...
Are mine actually shot then?

Same kms .. Similar symptoms , no squeak squeak squeak though.

[Focusedintntions]

Rotors aren't warped....they're actually very very difficult to warp. More than likely you have pad deposits in the rotor if you're getting a vibration when hitting the brakes.

[kb135]

When I took mine in to the stealer they checked and said I had about 40% pad life left, but said nothing about the rotors. I even told them about the low-speed squeal, which occurs EVERYTIME i slow down, but oddly enough (or, more appropriately, surely enough) they were "unable to replicate it". Someone on bimmerforums said if the wear is ~1mm of depth from the lip, then it needs replacing - I am so unsure of what to do now - maybe will ask Mike at prestige&performance when I see him next. Might even just put a set of cross-drilled/slotted rotors on and some ceramic pads and be done with it

[My135]

I re-surfaced my rear rotors at 60,000 miles and the thickness is still within spec. I guess it all depend on your driving style and how many city miles. My 1 sees most highway miles.

[08LMB135i]

My car is predicting about 55000km total out of the brakes, I Auto X but no lapping days.

[DriveHard]

Originally Posted by Focusedintntions

Well BMW says to replace them when you replace pads. How long that lasts is a question of driving habits and pad materials. My guess would be though 20-30k miles of average street driving through.

focus.. this is not true, "BMW says to replace them when you replace pads." please allow me to clarify..

BMW has a printed minimum spec on the rotor hat.. if at pad change when the pads are less then 3mm, and the rotors are below that printed spec, then the rotors get changed.. IF the rotors are ABOVE the printed spec, then only a pad replacement is required and the rotors will last the life of those new pads

remember the printed spec is only looked at at replacement of pads.. not as a stand alone measurment..

BMW does recommend that new pads be replaced everytime rotors are replaced ( as if there is a pulsation issue all of a sudden )

NOTE: this spec is for USA warranty / Maint program !!!!!

other countries ????? your on your own LOL

Regards,

[Dackelone]

Thanks Alex for the info!


You guys know new (front)rotors and pads/sensor - can run upwards of $700 for just the parts alone!

[Pablito1702]

Originally Posted by DriveHard

.. IF the rotors are ABOVE the printed spec, then only a pad replacement is required and the rotors will last the life of those new pads

Huh? please clarify "rotors will last the life of those new pads" I just had front pads replaced at 40K miles under warranty, but rotors were barely above spec. I assume that when I take the car in for next service (45K miles) the rotors would be under spec and would be routinely replaced under warranty. What am I missing? Thanks in advance

[510135]

Originally Posted by DriveHard

focus.. this is not true, "BMW says to replace them when you replace pads." please allow me to clarify..

BMW has a printed minimum spec on the rotor hat.. if at pad change when the pads are less then 3mm, and the rotors are below that printed spec, then the rotors get changed.. IF the rotors are ABOVE the printed spec, then only a pad replacement is required and the rotors will last the life of those new pads

remember the printed spec is only looked at at replacement of pads.. not as a stand alone measurment..

BMW does recommend that new pads be replaced everytime rotors are replaced ( as if there is a pulsation issue all of a sudden )

NOTE: this spec is for USA warranty / Maint program !!!!!

other countries ????? your on your own LOL

Regards,

Thank-you for the reply, I thought this was the case!

[1speedbike]

My rotors pretty much lasted 58K miles. Went through 1 pad change, swapping out the rotors on the second. One autoX, the rest street driving. I was planning on selling them because I assumed they'd still have some life in them, but it looks like they're too thin.

And DriveHard is correct. Very well said.

[DriveHard]

Originally Posted by Pablito1702

Huh? please clarify "rotors will last the life of those new pads" I just had front pads replaced at 40K miles under warranty, but rotors were barely above spec. I assume that when I take the car in for next service (45K miles) the rotors would be under spec and would be routinely replaced under warranty. What am I missing? Thanks in advance

No Problem.. The minimum thickness is ONLY important when Pads are being replaced. What that means is that BMW already calculated that if the Minimum thickness isnt met at pad change the new set of pads will wear out before the rotor is "too thin" minimum thickness is not equal to too thin..

e.g.

minimum thicness is printed 25.5 mm
at pad change rotor is measured and its 27.2mm this equals no rotor change
if at pad change rotor measurment is 24.2 this equals rotor replacement

rotors inspected at any time that are under minimum thickness will only be replace IF pads are due...


so in your case you will not get rotors at your 45k service........unless you wore out your pads at the same time and rotors came in under spec.

Hope that helps..

[magha]

just got my front rotors, pads and sensors replaced at 42k kms the rotors were down to 20.8 fortunately the rears r still good just got new pads and sensors for those