squealing noise with good pads and rotor

[drivingj30]

Hi Everyone,

I post my question about squealing noise from front wheel weeks ago. And asked about the fair price to fix it.

My mechanic just came back and had my pad and rotor checked. He said the pad are good enough for another year. But even when he roll the wheel in the mechanic shop, there was noise coming out from the wheel. But the pad and rotor are ok.

What is the problem?

Thank you.

[driverdriver]

If the rotors aren't Nissan OEM and the pads aren't OEM or a high quality ceramic you'll get squealing.

[drivingj30]

Yes, my mechanic did mention the bad quality of the pads. But what I don't quite understand is even i don't step the brake and just hang up the car in the shop and roll the wheel with hand, I can hear the noise? I asume that the pad and the rotor are not supposed to contact with each other in this situation. How come the noise?

[Defiant]

Well, inganeers call it "stiction", or slip/stick friction. Some people can do it with the side of their hand across a slick desktop, making a judder as they slide it along. Chalkboard squeak is the same phenomenon. On brake pads, it can be ameleorated with the use of brake-squeal silencing concoctions, with such names as "Brake Quiet". It's a kind of gluey goo that absorbs the vibrations enough that they don't make sounds you can hear, when it works. Also, all the cheezy little bits of tin on, around, behind and next to the pads have to be put back in place (replaced, when supplied) when doing a brake job. They're primarily there to keep brake noise from starting.

[DominickJ30]

If the rotors aren't Nissan OEM and the pads aren't OEM or a high quality ceramic you'll get squealing.

You honestly believe that???

That is a completely false statement.

The reason brake parts squeak is because of metal touching metal at high frequency. A good quality brake lube will eliminate any and all squeaking if applied to the proper contact point.

I have a set of ebay cross drilled rotos and raybestos ceramic pads, no squeaking here.

[rdorman]

I have NAPA pads and rotors and they work just great. But, I did need to get the anti-squel (forget the exact name) from the dealer to keep them silent.

[Nissansbitch]

I am employed as a technician, and am required to be ASE certified. An ASE study book will tell you calipers always keep a very light contact with the rotor. This is unlike drums, that when adjusted properly and have working return springs, pull the shoe back away from the drum. That's why if you have disc in the front, and drums in the rear, you have a combination valve with a metering valve to adjust for the brake contact time difference. But as long as a wheel bearing is ruled out, the brake rotors should be re-surfaced on a table lathe--I do not believe in on-car lathes!--with a multi-directional finish added at the end, the pads beveled, and all contact/sliding surfaces lubed with a high-quality grease. And I'm sure you may as well replace the pads for little extra cost now, before you have to do this again, or deal with the sound until they are in need of replacement. And to make extra sure, replace the rotors. But sometimes pads come from the parts house with paint on the sides. This causes noise later, and should be removed. A good tech will do this. Rotors should be refinished every brake job, and a good tech/shop will re-surface them brand-new-out-of-the-box, even. They do come out of the box warped occasionally. No on-car lathes. The rotors "chatter" on the machine, no matter how "good" the tech says they can do it. Translating to vibration and noise when under application. They also only make one pass. A table-lathe has a fast, course cut first, to turn out the warpage. Once the rotor is flat again, it takes a slow, fine second cut.