[pesarirany]

I have recently Purchased a 2017 BMW M3 with only 40K Miles. The previous owner had changes the rotors to ceramic rotors possibly rotor size is 500mm
I just picked up the car and as I was driving it I noticed at 60Mph when you push brake the whole vehicle shakes bad and pulls to the left.
I took it to my mechanic and we checked and made sure everything was tight on the rotors ( I had this issue once and we noticed it was just loose on another car)
my mechanic mentioned that the brakes has recently changed because the pad is like literally brand new.
I am trying to see if anyone here would know what could possibly be because I really like the car and I want to drive it a little before I sale it

[RockCrusher]

Originally Posted by pesarirany

I have recently Purchased a 2017 BMW M3 with only 40K Miles. The previous owner had changes the rotors to ceramic rotors possibly rotor size is 500mm
I just picked up the car and as I was driving it I noticed at 60Mph when you push brake the whole vehicle shakes bad and pulls to the left.
I took it to my mechanic and we checked and made sure everything was tight on the rotors ( I had this issue once and we noticed it was just loose on another car)
my mechanic mentioned that the brakes has recently changed because the pad is like literally brand new.
I am trying to see if anyone here would know what could possibly be because I really like the car and I want to drive it a little before I sale it

Did you ask your mechanic why the brakes were acting they way they were?

Shaking suggests a problem with the brake rotor surface. I don't want to say "warped" brake rotors but the rotor (both rotors) should be checked for in spec parallelism and runout.

My only experience with pulsing brakes came from uneven pad material deposition rising from an emergency stop from speed with rusty cast iron rotors. I didn't know this at the time so I checked the rotors for in spec parallelism and run out. Both were well within spec.

It could be possible for ceramic rotors to be at risk of uneven pad material deposition albeit though not from rust being present.

Pulling to the side suggests uneven braking action of at least the front brakes. Couple of explanations is a brake hydraulic line pinched or a stuck piston which results in the affected brake not producing the same braking force as the other side the good side.

With a 2017 I have to wonder when was its last brake fluid flush/bleed and one that includes proper cycling of the ABS pump?

While I have done the brakes -- replaced pads/rotors even did fluid flush/bleed services -- on a number of cars over the years the few times when the braking system manifested issues not related to normal brake wear I had the vehicle in to the service department. With 2 vehicles both were still under new vehicle warranty. In both cases the problem was brake fluid related and a proper flush/bleed was the cure. In the case of my JCW the fluid service was not over due. In the case of my Metris van the fluid service was sort of due. But the van sat outside some time on a dealer's storage lot before I bought van and this exposure resulted in accelerated degradation of the brake fluid.

The brakes are a safety critical system. So my advice is to have the vehicle in for this braking behavior.

[pbonsalb]

Best wishes to this brand new member who is here for help so he can flip the car. The help I can offer is that he should find a mechanic who is competent enough to know the rotors are not 500mm or 19.6 inches.

[M3SQRD]

Originally Posted by pbonsalb

Best wishes to this brand new member who is here for help so he can flip the car. The help I can offer is that he should find a mechanic who is competent enough to know the rotors are not 500mm or 19.6 inches.

There appears to be a lack of competence extending beyond just the mechanic. I bet the CCB rotors were abused on track, burned away more than the max allowed mass loss and ran the pads down to the backing plate (supposed to replace at 50% wear). All of this has probably damaged the rotor surface and smeared unequal pad material over the surface. A nice $8-12k cost for a set of used CCB rotors before flipping the car! I hope all potential buyers ask for a test drive and PPI before they consider buying this car. Hey, what’s wrong with a 500 mm diameter rotor? Lol

[pbonsalb]

If I had damaged CCBs, I would change to steel brakes.

[ShocknAwe]

Nothing wrong with steel/iron brakes.

[NSXR]

Originally Posted by pesarirany

I have recently Purchased a 2017 BMW M3 with only 40K Miles. The previous owner had changes the rotors to ceramic rotors possibly rotor size is 500mm.

It's not so easy, or cost effective to change iron rotors to carbon ceramic, so I'm highly doubting that's what has been done. Secondly, 500mm rotors will not fit.

We need pictures before we go any further with any sort of diagnosis.

This is what I need you to show me, front and rear.

Top shot is the standard blue brake caliper and iron rotor. Bottom shot is the carbon ceramic caliper with carbon ceramic rotor.

[pesarirany]

I recently took it to an alignment shop, and they diagnosed that both the front forward and front rearward lower control arms on the driver’s side are defective. I’m uncertain whether these issues could be contributing to the brake pulsation or shaking that I’m experiencing.

[Altamate]

Originally Posted by pesarirany

I recently took it to an alignment shop, and they diagnosed that both the front forward and front rearward lower control arms on the driver’s side are defective. I’m uncertain whether these issues could be contributing to the brake pulsation or shaking that I’m experiencing.

Maybe, but unlikely, however it could be contributing the pulling to the left,

[pbonsalb]

A bad control arm can cause pulsation or shimmy, in which case the problem might not be the brakes.

[pesarirany]

Problem solved.
Thank you guys