mazda5 brake problem?

[BANANA2387]

has anyone else has vibrations when applying the brakes initially, but goes away after a while? Thanks.

 

[Dphillips]

I havent experienced this But it could be time for a brake job. Are you still using factory brakes that came with your car?

 

[BANANA2387]

Dphillips, thanks for the reply. Original brakes, only 14k miles and it's my wife's car - never driven hard because it's we have 2 small children. I read somewhere that other Mazdas had brake problems - anyone heard of that or of any TSB with the M5?

 

[Dphillips]

Hmm 14k huh? And just because its your wifes car doesnt mean anything to me. My GF is the definition of LATE braker(drive2)(attn)

 

[BANANA2387]

ha, ha! No - she drives like an old lady, speed limit, easy on the brakes, sometimes a bit too cautious - it's frustrating being in the car when she drives.

 

[mazdadude]

Although overheating can happen, the most common cause of the warped rotor is from improper tightening sequence, and or improper torque applied to the lug nuts.

Since the rotor is held onto the hub by the lug nuts and the wheel, I have also personally seen dirt getting in between the rotor and the hub when taking off the tire. What happens is when the wheel is off, the rotor will fall away from the hub a little bit and allow some dirt to fall into the gap between the hub and the rotor. If this happens, when the tire is reinstalled and torqued properly, it will still behave like a warped rotor. This is because of the trapped dirt offsetting the rotor on one side and causing a wobble in the rotors rotation.

Either way, a warpage also prevents effective braking because the action of the warped rotor keeps the pads further away from the biting point of the brake pad. It will make the first application of the brakes seem a bit mushy, and a second tap of the brakes during the same stop will be MUCH firmer.

In addition a warped rotor also will stress the suspension a bit more from the bad vibrations.

 

[BANANA2387]

Thanks MazdaDude! Great information. I know when I first got the car there was an issue with the tires and they ended up re-aligning and putting new tires on the car.

This forum is great - glad to get responses from all!

 

[zoooom]

I had that steering wheel vibration problem during braking few months back, especially during hard braking. To resolve it, I removed both front disc brake and send it to the machine shop for regrinding to remove the warpage. That pretty much resolve the problem.

Alternatively you can change the disc.

 

[KBrian]

Very interesting car list, zoooom. What part of the world do you hail from?

 

[monsta]

Thanks MazdaDude! Great information.

But there's more.


You see, rotors don't really warp in street use. It is very hard to get the metal to deform. It takes a tremendous amount of heat. That heat is typically only made in extreme events such as racing for hours.

"Warped" rotors due to dirt is also rare at best.

Improper torque certainly can cause the rotor to malform a bit but actually the most prevalent cause for "warping" is material transfer (aka cemetite deposits).

Notice how dirty your front wheel get with brake dust? That same brake dust can build up between the rotor and pad, that, along with gases and heat coupled with you holding the pads against the rotor at a stop cause uneven material transfer or high spots on the rotor. These cementite deposits cause the shimmy you experience.

Since it gets a little less noticeable after you brake harder then what is happening is the floating calipers (they all float) are able to move with the irregularities.

The best solution is to resurface the rotors or purchase new ones. And the best thing to do to prevent this from re-occuring is to use low-dust pads and break them in properly.

You could try a short term solution which is to brake very hard (ABS should activate on a dry surface) about 3 or 4 times. This could be enough to remove the deposits and to re apply a more linear amount of pad material to the rotor. Just don't come to a complete stop and hold the pads against the hot rotor! Allow cooling between runs. It's a long shot especially since you have stock pads.

An interesting read: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml