Back info: I replaced my front rotors and brake pads at the same time on my s4 GXL (4 piston front brakes). I used Hawk HPS pads which I know aren't supposed to squeak anymore than stock pads. I used brake quiet goop on the backs of the brake pads, on the front and back of each shim plate, and on the two guide pins that hold the pads in place.

Symptoms: Whenever I am going less than about 15mph either accelerating, decelerating, or maintaining constant speed, I get a constant squeak emanating from my driver side front wheel and its been happening ever since I did the brake job. I actually redid the job 4 times over and re-gooped everything and it still does it. When I press the brakes to come to a stop, sometimes it gets louder. The squeal is never earsplitting, but it can be heard even with the window up and the radio on at a moderate level.

I've done lots of searching and come up with several ideas but none of them seem to fit me exactly. I've heard these causes:

1) The pistons in the caliper are exerting an uneven load on the brake pad, causing it to squeal. I do not believe this is the cause because it starting squeaking exactly when I did my brake job.

2) My hub is loose. This is actually something I know is loose, although I've been told it is still within spec. I do not believe this is the cause because it starting squeaking exactly when I did my brake job.

3) I didn't apply the grease to all of the correct places. Again, I did the back of the brake pads, the front and back of the shims / plates, and the guide pins. I do not believe this is the cause because the passenger side wheel isn't making any noise whatsoever.

Thanks for helping me out guys!

 

The guide pins aren't supposed to have the "GOOP". The guide pins are there to allow the brake pads to SLIDE. Applying "goop" to the guide pins will cause the brake pads NOT TO SLIDE. Use grease.

The same applies to the brake pad shims that go on the top and bottom of the caliper. You need the brake pad to SLIDE not "gooping" it up with that stuff. I used to use the "goop", pointless in my opinion since it really serves no purpose but to allow the brake pads to "return" better after releasing the brakes when applied properly. Just grease the PROPER points slide points.

End of story.

 

Just want to point out:

THIS:
is not grease. It is tacky stuff that when applied wrong (as in your case) defeats the purpose of slide pins/points.

 

That is the exact product I applied. So what exactly are the "proper points" to grease then, and what sort of grease should I use?

Thanks so much for your help!

 

Use any high-temp grease. I prefer the valvoline synthetic grease that comes in the small can.

Proper points are already posted above. Please read my first post. I'll post them here again if they aren't too clear.

Grease points:

Slide pins on caliper
Top and Bottom Guide Shims on the calipers (brake pad slide on this)

Basically look at the components and ask yourself: "does this need to slide or move?" if it does, grease it (besides the caliper piston, that already is lubricated internally).

 

I apologize for my confusion, I just wanted to make sure that those points were the only places that needed to be greased. Ok, thanks for your help - I'm off to the hardware store to get that Valvoline synthetic grease. I'll report in this thread later on the outcome of the noise.

 

Ok I just finished the job. You were right - that "Disc Brake Quiet" orange goop dried into almost a glue. There definitely was no lubrication there. I had to use a metal brush bit on the end of an electric drill to get all of it off since it wouldn't even wipe off with brake cleaner and a towel.

I used the Valvoline Synthetic Grease in the can as you recommended on the back side of the brake pad, and both sides of the two shims behind each pad. The squeak is definitely gone, but now there is a noise I would best describe as a sprinkler which varies the time between each noise with the speed of the car. Again, this is on the driver's side wheel only it seems. Any ideas as to what may be happening?

 

Something is rubbing against the rotor I would say. Maybe a small pebble, the splash shield or could be an issue with the wheel bearings. Pull the pads out and check for debris on the friction surface. You should be able to duplicate the noise if you lift the front and rotate the tire.

I didn't see it in your post, but hopefully you also remembered to lubricate the pins that go through the brake pads. The back of the brake pads themselves do not require lubrication, but it doesn't hurt. It is the top and bottom shims on the caliper itself that also need lubrication

 

no teflon shims?

 

HPS pads need to be bedded in to be quiet, especially with new rotors. 4-5 hard stops from 60-20mph then let the brakes cool all the way down. All hawk compounds are noisy if not bedded in. Even the blue's quiet down considerably after proper bedding.

Also as mentioned the pins get grease. DONT USE GREASE ANYWHERE ELSE. Whoever told you to put grease on the back side of your pads or inbetween the shims is wrong. They were probably thinking of either the rear brakes with the floating caliper (there are shims for the ENDS of the pads that can be greased but dont have to be).

Ive never used any of that disc brake quiet crap. I don't think it works worth a damn. As long as you have all 4 (2 per pad) stock shims properly installed and the pins are greased on the front 4-piston aluminum calipers they are usually VERY quiet. Much more so than any front single piston setup...

This has nothing to do with your hub.....

 

I would bet the vent shield is rubbing your caliper.

 

Thanks for all the replies guys. I did lubricate the guide pins as well as the backs of the brake pads. I'll get the car back up in the air tonight and turn the wheel manually to see if I can replicate the noise and will check for debris and to see if the vent shield is rubbing the caliper (which would be an embarrassing).

After all that, I'll give it some hard stops and hope for the best.

 

I just took the wheel off of the offending side and sprayed brake cleaner all over the rotor and contact patch of the brake pads. I didn't find any dirt, but I assume there must have been some since the dust shield wasn't in contact with anything.

Thanks for your help guys, problem solved!