Why do my front rotors keep warping?

[hunnu]

2014 F32 435i with brembo upgrade brakes.

Put on new front pads and rotors at the same time. After around 100 miles i noticed a juddering under braking that could be felt through the pedal that gradually got worse. In the beginning i thought the pads and rotors just needed to bed in but it didn’t go away

So i went and got the rotors skimmed as it felt like they were warped. After rotors were skimmed they performed perfectly again for a couple hundred miles then the juddering started again.

Pads were still good so i went and bought a brand new set of rotors assuming there was some design flaw with the old set. New rotors bed in nicely and again performed great for 500-600 miles before the juddering started again and gradually got worse.

My next thought is sticking caliper possibly? But the piston pushes back in with ease.

Really confusing any help greatly appreciated!

[freakystyly]

Could it be a damaged flex line, not allowing the caliper to open?

[tracer bullet]

Look into the pad bed-in procedures. Rotors almost never actually warp, what happens is that the brake pad material deposits onto them unevenly. This makes them have spots that are sort of slick and grippy and that's what you feel in the steering wheel and car as they rotate while you brake.

Agree to look at the caliper and other possible issues that might cause this. And be sure you bed-in the pads and be careful about things like making a high speed stop then sitting at a streetlight a while right after (this can also be how the pad material gets onto the rotor unevenly).

[Weather Man]

When a rotor warps, they are junk, time for new.

[///MPhatic]

Originally Posted by hunnu

2014 F32 435i with brembo upgrade brakes.

Put on new front pads and rotors at the same time. After around 100 miles i noticed a juddering under braking that could be felt through the pedal that gradually got worse. In the beginning i thought the pads and rotors just needed to bed in but it didn’t go away

So i went and got the rotors skimmed as it felt like they were warped. After rotors were skimmed they performed perfectly again for a couple hundred miles then the juddering started again.

Pads were still good so i went and bought a brand new set of rotors assuming there was some design flaw with the old set. New rotors bed in nicely and again performed great for 500-600 miles before the juddering started again and gradually got worse.

My next thought is sticking caliper possibly? But the piston pushes back in with ease.

Really confusing any help greatly appreciated!

Your rotors aren't warping unless you're driving straight off of a racetrack into freezing lake water. It's uneven pad deposits caused by the terrible pads that BMW uses.

Bed-in is not the be-all, end-all it's made out to be, as it depends very much on the specific pad you're using, and how you drive the car.

You will not be rid of this problem until you replace the pad with either a less aggressive or more aggressive pad.

[Chappers 71]

I chased this issue on my old e92 35i for a while, it turned out to be a worn lower suspension arm causing vibration under braking, replaced them both & it was sorted.

Also as previously mentioned brake discs rarely warp & it’s usually brake pad deposits, if your cars an auto avoid holding it on the brakes especially when the brakes are hot

[tracer bullet]

Regarding bed-in, I didn't say it well, but suggest performing the process to see if that gets rid of the issue. I've fixed my own car once, a few friends have had success, and I once rented a car in Durango CO that had stupendous issues I managed to clear up after doing that procedure a couple times. Free to try and doesn't take long.

For new brakes it doesn't seem to be as much of an issue. I do it myself when I change pads and rotors but obviously 99% of people don't and things seem to be fine.

But I highly recommend trying it at times like this.

[s_ribs]

Originally Posted by ///MPhatic

Your rotors aren't warping unless you're driving straight off of a racetrack into freezing lake water. It's uneven pad deposits caused by the terrible pads that BMW uses.

Bed-in is not the be-all, end-all it's made out to be, as it depends very much on the specific pad you're using, and how you drive the car.

You will not be rid of this problem until you replace the pad with either a less aggressive or more aggressive pad.

This. On a street car it's crappy pads, and typically ceramic ones.

OP- you can prove/"fix" this by tossing some cheap semi-metallic pads on and drive around for a day or two. The pulsing feel will go away once the pad deposits are cleaned up.

[///MPhatic]

Originally Posted by tracer bullet

Regarding bed-in, I didn't say it well, but suggest performing the process to see if that gets rid of the issue. I've fixed my own car once, a few friends have had success, and I once rented a car in Durango CO that had stupendous issues I managed to clear up after doing that procedure a couple times. Free to try and doesn't take long.

For new brakes it doesn't seem to be as much of an issue. I do it myself when I change pads and rotors but obviously 99% of people don't and things seem to be fine.

But I highly recommend trying it at times like this.

Could make it worse.

When BMW replaces the rotors under warranty they don't bed the new pads, or advise the customer to do so. I take that to mean the stock pad is susceptible to glazing, which normally happens with pure street pads.

If it were my car I'd get a different set of pads for the street, throw some race pads on and hammer them several times to clear the deposits, then throw the street pads on with no bed-in, but I'm not sure if the OP drives street only, or how good they are with swapping pads.

[BMWCCA1]

Not enough information for this speculation.
What year/model of BMW?
What brand of rotors and pads?

That would be a better start.