Quote:
Originally Posted by Limegrntaln
If these brakes didn’t “just squeal” you wouldn’t bother reading multiple threads about it. You replied to this thread, and liked a comment on another brake squeal thread.
BMW has already had class action lawsuits on brake squeal from a number of years ago. Type Brembo brake squeal into a Google search, and you will see nearly every manufacturer that produces vehicles that come with Brembo brakes, from the factory, the brakes make noise.
Look at previous model years of Mustangs. Brake squeal. 2021 yours don’t squeal. Ok, so, Ford is tired of people complaining about it, so they develop their own pads for the car that give you 90% of the braking with no noise.
Straight from Porsches video on noisy brakes. “If you are experiencing brake noise, our professionals at Porsche are more than happy to determine whether it is a maintenance issue or A NATURAL OCCURENCE.” If bmw made a video on brake noise, it would likely say the same thing.
Take for example the overall size of a brake rotor. An 8” rotor has far less surface area and the outside edge of the rotor is closer to the inside center of the hub, as opposed to a 15 or 16” rotor. Now you have double the surface area between the outer edge and the inner, center point. Applying a clamping force to the outer edge of the 8 inch rotor is going to be far more controllable than a clamping force out at 16 inches.
Transfer this idea into linear feet. An Airbus A380 has a 261ft wingspan. During takeoff the wingtips can deflect up to 13 feet from center. Can you imagine seeing a wingtip deflect 13 feet? How much more wingtip control do you think the plane would have if the wings were only 20 feet long? You wouldn’t get 13 feet of wingtip deflection.
Apply the same concept back into brakes. The 16” outer edge of the rotor, is going to deflect more under braking, which in turn, can cause certain harmonics. This phenomenon is known as stick slip.
Engineering description
Stick–slip can be described as surfaces alternating between sticking to each other and sliding over each other, with a corresponding change in the force of friction. Typically, the static friction coefficient (a heuristic number) between two surfaces is larger than the kinetic friction coefficient. If an applied force is large enough to overcome the static friction, then the reduction of the friction to the kinetic friction can cause a sudden jump in the velocity of the movement.
A brake rotor and a pad friction surface, out at 16” vibrating thousands of times per second, causes a harmonic frequency. Alter the friction material, reducing or eliminating stick-slip, and the sound lessens or goes away.
I’ve never had an issue with the cars that I’ve owned that have Brembos. And I’m sure it has everything to do with my driving style. If you drive it like you’re wearing high heels, they’re probably going to make noise.
Here’s Porsches explanation. Which I know you saw in the other thread I posted in. But you have to watch it to understand.
And no I don’t work for BMW. Why would I have to?
https://youtube.com/watch?v=fUNHb9O52WQ&feature=shares |
Our Mustang GT has Brembos…still no squeal. I’ve driven/owned other vehicles from BMW that had Brembos, again, no squeal. The “all Brembos squeal” is a cop-out and even if it were a factual statement, still doesn’t mean it’s right for them to do so.
And all the people who do think that’s okay is likely the reason manufacturers don’t fix it.
I wondered about you being employed by BMW because you seem to be vehemently spreading their propaganda of “this is normal” on this issue.
If it was actually normal then all cars with Brembos would squeal and I know for a fact that not all do, so it can’t possibly be normal.
Also, let’s talk brake rotor size…larger rotor doesn’t stop better. Look it up. They make ridiculously large brake rotors then sell that they stop better so they can charge more money.