I purchased a wilwood 6 piston caliper + factory brembo kit rotors for my 2004 Infiniti G35x sedan from fastbrakes.com (http://fastbrakes.com/shop/product_i...oducts_id=1111) and had it installed - question: when the brakes are heated up after driving for a while, when I come to a stop and let off the brake pedal, I hear slow, then faster "whoot.... whoot.... whoot.. whoot.. whoot. whoot..." that goes away as I come up to speed again... It sounds worse when I'm coming off a stop and turning around a corner at the same time. I can feel it in the pedal too. It sounds like the new pads are dragging or warped rotors or something. Someone mentioned slotted/drilled rotors make a little noise but does this sound normal?

*L* I'm not sure my whoot-ing explanation helped much

 

Did you bed in the pads to the rotors?

 

yes, I bedded them in. I could do it again...

This is my closest guess on what's going on:

I had the new rotors, calipers & pads put on the front. At the same time, I also had new pads put on the rear (using the rear stock calipers and rotors). The noise I'm hearing sounds and feels like it's coming from the front... and since it started after I had the rotors, etc. put on the front, I assume the noise is coming from the front.

But... this morning, I drove it around the block with my parking brake engaged by 1-2 clicks. Since then, when I'm driving normally and stop, then go... the noise is much reduced. I'm thinking that the noise is really in the rear and that, when the new pads were put on the stock rear rotors, the new pads are hitting a high spot on the rotors. Maybe it's my old, stock rear rotors that are warped?

 

It's very possible it is your rear brakes like you said. I found that it is very difficult to get an even deposit on the rear rotors because they don't get as hot as the fronts do. You can try bedding them in again .. making sure you accelerate up to speed as fast as you can so the rotors don't get a chance cool down. Or, you can live with the squealing for a little while and see if it gets less or goes away.

I actually had to take the second approach on mine, but the noise has just about gone away (but then I have new rear rotors as well).

I doubt you rear rotors are warped, but you can always have them turned as a last resort.

 

thanks for the advice terrycs. I'll bed 'em again and see what's what!

 

Measure the lateral runout of MOUNTED and Torqued to spec rotors.
Procedure explained in the FSM.

 

thanks q45tech, I'll confirm the torque specs. as for lateral runout... sounds like something I will ask my dealership to look at (?)

 

I don't know if out of tolerance runout will cause brake squeal. If the runout is out, it usually causes pedal pulsation. The same thing if the two rotor faces are not paralled within spec.

I'm pretty sure high frequency brake squeal is usually caused by surface imperfections in the rotor and/or pads.

 

I'm going to record an audio file or something of the noise... it's not a squeel, it's like a vibration/rub noise. a "whoot whoot whoot" not a "squeeeeeeeee"...

fastbrakes.com says noise from xdrilled, slotted rotors is normal. I'm willing to believe that but, man, it's pretty loud and has quite a vibration with the noise. I just find it hard to believe they're supposed to make THIS much noise when they get warmed up (people turn around and look when I let off my brake because it's making the noise)

I'll see what I can do -- if all else, maybe I'll break down and get new rear rotors, etc. and see if that does it (don't tell my wife *L*)

 

Drilled and slotted always make whooooosh sound.

Squeeling comes from pad vibration against rotor or resonances within rotor.

 

I jsut changed to all slotted and hawk pads and noticed a wooooooooosh sound from the front, so they are supposed to do that?