[Ins_328]

So just got the car about 3 month ago from dealership and they did put new brakes in. Everything was fine first couple months but then I started noticing that it's kinda shaking when you apply brakes gently on any speed above 40mph. I'm thinking they just put cheapest brake pads available so now I'm thinking about upgrading brakes and wondering if there is even a 10% difference between stock rotors and slotted ones or I should just get akebono pads and be alright? Cause rotors in a good shape

[Fredo]

I had a similar problem on my 2009 335i. New front rotors fixed the issue. I asked for Akebono pads and was very happy with them.

I wonder if the dealership replaced your rotors.

[Pauloxxi]

try breaking firm and hard couple of times, I have this shaking or stick slip with akebono. Apparently the brake pads leave some deposits in the rotor which creates this condition. By breaking hard it cleans the rotor and minimize this shaking.

[ChuckThomas]

You need new rotors and new pads nothing less.

[Hydraulic]

The shaking is because rotors are worn unevenly. Rotors do not warp, but this is commonly called "warped rotors". What happens is, either due to paint dirt rust on wheel hub being uneven, or the wheel bearing axis being minutely out of alignment with brake caliper bolts axis, or a cheap rotor that was not true to begin with, a small amount of lateral runout was present at first when rotor was installed. This was imperceptable at first and caused no symptoms. But this maybe 3 thousandths of an inch runout or "high spot"(and an opposing high spot 180 degrees around rotor on opposite side) spin every time the wheel does, and tap the brake pad very lightly every turn of the wheel when the rest of the rotor does not. Over thousands of miles this wears two opposing spots 180 degrees apart on opposite sides of the rotor making your rotor potato chip like. You can replace the rotor, and the symptoms will disappear, but if runout is not measured and corrected it will come back. The best thing to do here, is to get an on car brake lathe done. A on car lathe uses the caliper bolts as its axis to true the rotor to. If the rotors do not have enough material left to do this, they must be replaced. And at first sign of the problem coming back, I would then on car lathe the new rotors. I spent hours and hours figuring this all out as I ate a few sets of rotors every 8-10k miles until I had a on car lathe done.

[Ins_328]

Originally Posted by Hydraulic

The shaking is because rotors are worn unevenly. Rotors do not warp, but this is commonly called "warped rotors". What happens is, either due to paint dirt rust on wheel hub being uneven, or the wheel bearing axis being minutely out of alignment with brake caliper bolts axis, or a cheap rotor that was not true to begin with, a small amount of lateral runout was present at first when rotor was installed. This was imperceptable at first and caused no symptoms. But this maybe 3 thousandths of an inch runout or "high spot"(and an opposing high spot 180 degrees around rotor on opposite side) spin every time the wheel does, and tap the brake pad very lightly every turn of the wheel when the rest of the rotor does not. Over thousands of miles this wears two opposing spots 180 degrees apart on opposite sides of the rotor making your rotor potato chip like. You can replace the rotor, and the symptoms will disappear, but if runout is not measured and corrected it will come back. The best thing to do here, is to get an on car brake lathe done. A on car lathe uses the caliper bolts as its axis to true the rotor to. If the rotors do not have enough material left to do this, they must be replaced. And at first sign of the problem coming back, I would then on car lathe the new rotors. I spent hours and hours figuring this all out as I ate a few sets of rotors every 8-10k miles until I had a on car lathe done.

Thanks for taking your time. I will be ordering new set from fcp soon to see if it's the problem.

[Pladi]

Just to add something here. Most of the time it is the rotors but front end shaking can also be caused by worn control arm bushings. Most likely rotors but there are other factors just FYI.