Vehicle: 1992 Honda Civic HB w/ B16a2
Brake and Suspension Mods: Lowered, Camber Correction, Brembo Slotted Rotors, Hawk Pads, Brake Master Cylinder Brace...

When cold the brakes sound fine, but after 15-20 minutes of city driving when I apply light to moderate brake pressure, they grind like a set of low pads on slightly warped rotor (inconsistent grinding noise). And are quite loud. Rotors mic out fine and precautiously were replaced, and pads have more than half life on them.

Whenever I do anything to the brakes to get rid of the noise its great until after 5-7 days, then the noise comes back, no matter what we try.

Have replaced rotors, have replaced pads, have replaced brake hardware, have replaced caliper stays, have replaced caliper, have replaced steering rack, have replaced tie rod ends, have even used a different kind of grease for the brakes, and bled the brake lines.... still cant get rid of the noise.

Thoughts? Similar scenarios?

 

have you installed the shims on the back of the pads? Did you apply anti squeal to the back of both pads? Are you running cheep rotors? I have seen cheep rotors squeal no matter what you do? what type of pads are you running? Cheap semi metalic pads tend to make a lot of noise esp after warming up. If you want quiet brakes buying the cheepest stuff out there is just asking for noise not that that is what you did. Just giving you somethings to think about. Did you run old pads on new rotors if so there is a big chance that is what it is

 

I tried to answer most of that in the post above... not cheap pads, not cheap rotors, etc...

Shims were installed and had the issue, tried removing the shims and still had the issue... new rotors, new pads...

What gets me is the part about no matter what we do, its prefect for 5-7 days, and then resorts back to the same noise as before, regardless of what has been done.

 

I have a question...did you ever clean the new rotors before installing it?

 

Everything gets degreased (aside from pads and caliper hardware) prior to the wheels going back on.

 

If you're already greasing your hardware, ignore the following - but for general discussion...

I think we can rule out worn parts...

I've owned/maintained a lot of different vehicles over the years, for family members - worked in a garage for a few years, yada, yada, yada. And, one of the 'tricks' I learned along the way is to make sure your brakes are greased!

LoL!

If that declaration comes as a surprise to you, that's likely the problem - a lack of "caliper grease"...

Sometimes videos are worth 1000 words!

Take a gander at this:
I agree with this guy 100%!

The only thing I would add is, I prefer Permatex Caliper Grease:

http://www.amazon.com/Permatex-24115.../dp/B000HBGKH4 (retailer picked at random)

And, check this out:
I differ with the 'author' here. I lube the perches, pins, and slides - regardless if they're exposed to the elements!

Sooo... that would be MY suggestion(s).

Lube your pins, slides and perches with a good quality "caliper grease" and see it that helps.

Works like a charm for me!

EDIT: BTW, I had a similar problem (as the OP) a few months ago and it was driving me crazy - but it only happened when I had my HX (alloy) rims mounted - no noise with the Si alloys...

Turned out to be a 'cocked' caliper body on the front passenger side. It *looked* fine, but when I tried to slide the caliper body (toward the outside of the car) it was stuck like a ****. I had to use a tire iron to break it loose from the perch - no kidding - popped so hard I thought I broke something.

Anyway, a little clean-up and caliper grease did the job (once again)!

 

Yes, I have greased it up thuroughly, and at one point even tried using anti-sieze grease to rule out that the grease wasnt simply deteriorating quickly. And you can guess that 5-7 days later, brake noise!

Also, another way I can describe the noise consistancy is imagine the pad was able to move linearly with the rotor (up and down across the face of the rotor). Heavy pressure would stop the noise, and no noise when off the brakes completely.

Im starting to wonder if its in the hydraulics, and as the fluid or calipers heat up, they are losing pressure against the pad. Doesnt seem like the right answer, but im out of ideas.

 

Ok, so here is my new theory. We are still thinking its hydraulic related now. Going to pull the master cylinder from the booster, and check the seal around the plunger. Im thinking fluid and pressure are being lost inside the booster. I wouldnt see any fluid leaking, and would explain a lot of whats going on.

Thoughts?

 

I would think that if that is the problem it would be doing it all the time not 5 to 7 days after the service. Also if it where fluid moving past a bad seal you should be able to pump the brakes several times to build enough pressure to stop the squeal. the one thing that you did not answer is did you add a materal called disc quiet to the back of the pads. Think of it as rubberized coating that absorbes harmonic freq and eliminates the squealling noise. Here is what I am talking about just a random sellers site
http://www.amazon.com/Permatex-82017.../dp/B000HBM8DY

 

Yes, used anti squeal.

And as far as 5-7 days, I figure its probably refilled the reservoir back up from the pistons being pushed back in, and the pressure takes about that long before it blows past the seal. Reason I am leaning on hydraulics now, is that I just refilled the reservoir yesterday, when it was just filled 2 weeks ago... and no visible signs of leaking on any lines, cylinders, booster, etc...

 

okay that makes more sence if you are looseing fluid. the problem is its going somewhere. I assume that you pulled the carpet back in the driver compartment and looked for a leak up by the pedal assy. Do you have rear drums? if so did you pull back the rubber seal and check for leakage there?

 

Correct, checked for leaks and the only thing I can figure is its leaking from the seal in the master cylinder in to the brake booster. Have seen the exact same thing happen to a Dodge truck once before.... thats where my train of thought brought me to on this. That and I noticed there has been a more noticable hissing sound around that area when you shut the vehicle off, until you completely let off the pedal... and the sound is gone if you go back to press it again (still while off).

 

wierd

 

just a thought....check the wheel bearings?

 

Wheel Bearings wouldnt explain the new found loss of fluid though.