what may be causing this ?

[apapada]

After my 1st track event in my NSX, I started hearing a weird sound as I descibed here .

This evening I removed the pads from the wheel the sound appeared to be coming from (rear driver side), and this is what they look like...


Any idea what may be causing this ? bad caliper ? I haven't look at the other wheels yet...

 

[apapada]

another shot. Anyone knows that brand ? (NISSIN)
The pads have supposedly 6-7K miled of street and 200 miles of track.

 

[ANYTIME]

Looks like a caliper piston is sticking, causing uneven wear. Time to either rebuild or replace your calipers.

 

[vincentvtec]

I think the piston of the caliper does not align at the right position. (Should be align with the pin on the pad)

 

[Vytas]

As mentioned, most likely the inner brake pad didn't seat right. I noticed the pad that was worn incorrectly has a pin on it (which wasn't seated correctly in one of the four slots in the piston). The front brake pads have pistons that you must push into the caliper to make room for new (thicker) pads. The rear caliper piston has a "+" or four slot design as seen below:

The piston should be turned clockwise so it can descend into the caliper and stopped so it appears as a "+" sign when looking at it straight. Notice the position of the caliper pistons in the rear calipers pictured below. The pin that sticks out on the rear brake pad will sit inside one of the slots and flush against the piston. If not poisitoned correctly, your pad will not be flush and sit at an angle and wear down the pad. Also, make sure the tops and bottoms of the caliper bracket (where the brake pads ride on) are clean as well.

 

[sjs]

Great job Vytas!

 

[NSX-Racer]

For the brand "Nissin": It's well known for brakes and "cup the noodle"...no joke, I guess it's the same company.

 

[apapada]

Thank you all for the very insightfull information. I removed the passenger rear side caliper and inspected the brake pads. These were evenly worn.

Seems that the driver's side rear pad was also the problem I was describing here as all these events started after triggering the ABS by hitting the brakes hard. That pad probably got unseated somehow and was causing the scratching sound. Then it got worn down to the metal thingy at the track.

I'll be replacing both rear pads tomorrow. The rotors are appearing ok.

thanks again. All u guys r gr8