re: Brake Squeal, an enlightened approach.

[alex.fadeev@xxxxxxxxxxx]

"Steven Schlossman" <steven@domain.elided> wrote:
> jk writes:
> >Did you clean the cosmoline coating off the new rotors before 
> >installing them?
> >The rotors may look like fresh clean metal, but if you don't 
> >clean the cosmoline coating
> 
> Huh? We all know what cosmoline looks like on our engine.
> It can not be mistaken for something that is clear.
> I have bought BMW rotors that had a gray coating on it.
> Some people will sand it off, others don't. I did not the last
> time I changed my rotors. I have seen some BMW rotors with an 
> oily substance which is easily removed with a rag.

I have to agree with Steven. 
Most of the rotors I had purchased over time where covered in thin layer 
of light (engine?) oil. The last time I swapped rotors I did not bother 
cleaning it off and the oil easily burned off after the first few stops 
without any harm.

> The squeal is a high pitch vibration, not metal against metal 
> as I once thought in my pre-bimmer days.

One exception might be the brake pads on some Detroit cars. For those, 
some brake pad manufacturers embed metal into the pad to produce squeal 
when the pad needs to be replaced.
I've never seen or hear of such contraptions used on German engineered 
cars.

> With my little knowledge of cars, I do know changing brake pad 
> compounds can sometimes glaze a rotor, it is new. A few hard 
> stomps on the brakes take care of that.

There are also a few pad manufacturers that espouse brake pad material 
transfer onto the rotor. One side effect is that it takes them a few 
hundred miles to apply it evenly (interim brake application shimmy). The 
other is the if you swap to another pad (street vs. track, or just a new 
street set) it will take a while to wear it off (interim brake application 
shimmy).
Performance Friction is one such manufacturer. 

> Some ways I have got rid of squeal as Alex also mentioned.
>   o bezel the edges of the pad slightly
>   o use the shims supplied with some brake pads
> 
> And what always works for me
>   o turn the radio volume up

...or repeat after me: "brake squeal is normal, brake squeal is good. It's 
a God's way of telling you that your brakes are working!"
;-)

alex f

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