Another question about my new Mazda 3. 2007 GX. The 4 wheel disc's are very sensitive when cold. By cold I mean the car has sat for several hours. When I first drive off, even just a feather touch on the pedal almost causes the anti-lock to engage. Almost nasty. once 2 or 3 normal city stops have passed by, they act 'normal' meaning I can do a gentle, brakes applied deceleration. At first I just thought it was because they were new and needed a bit of wearing in, but now at approaching 4000km they still act the same.

Any thoughts - anyone else notice this?

Mike

 

yeah, i have the same problem, but it goes away pretty quickly...
if i had to guess, it's just from the brake fluid being so cold

(ps... WOOHOO!! my 100th post!!)

 

Not sure about the brake fluid temp. After only a couple of gentle stops there is a marked improvement. I also found this exactly the same in the fall when I first got the car. Temp then were still plus 15C range. It almost feels like the pads or rotors are sticky, and it cleans off after a few dozen revolutions with the pads engaged.

 

On further close observation during the first couple of stops after several hours or more sitting - the brakes feel as if they are coated with a light surface corrosion. It feels very much light driving a car that has been stored for some time and the for the first few drives the pads are scraping light surface corrosion off the rotors. it also does occasionally squeal sounding like the front left, on that first or second stop if former braking is actually commanded.
Are the rotors Mazda uses more susceptible to fast surface corrosion build up, as little as during an overnight is damp/wet/cold weather?

 

wait, i just thought of something....
if the brakes get hot from use, adn its cold out and you park your car, could the hot brakes cause condensation, causing the rotars to freeze slightly over night??

 

Interesting thought. I may have to pull of a wheel to have a closer look after it has sat overnight.

If your thought is correct - why only on my Mazda. My GM's, Chrysler and Eagle Talon discs do not suffer from this. The Talon which normally is stored over the winter and goes for a drive on nice dry winter days to keeps everything lubed and loose, can suffer from a light corrosion build up on the rotors that causes the same feeling, but is accompanied by a distinct sound as the pads rub the corrosion off on the first few stops. The Mazda feels the same, but has no sound other than the occasional squeel that goes away after the brakes return to normal, after the first 2-3 stops.

 

i dunno.... the other cars you have (or had) are all domestics.
i doubt that'll have anything to do with it, but maybe.