Brake Pads Grinding

[dcwang3]

Recently did an entire brake job on a 92 325i convertible that sat in the garage for 20 years. Rotors, pads, rebuilt the calipers (in really good condition), stainless steel lines, etc…One thing that I noticed when driving it around is that there is a humming noise. It is noticeable if you are looking for a noise. you can't hear it unless you are driving more than 30-40mph. I jacked the car up and spun the front tires, and it is definitely the pads grinding. I looked the pads out to verify it wasn't the wheel bearing and it wasn't.

The front tires rotate fairly freely when you get it a spin, but you can definitely hear the grinding. Is this normal to have some light grinding or should the pads reseat so that you don't hear it?

Not sure if it matter but I am using regular BREMBO rotors with HAWK HPS pads.

[superj]

did you seat them after you redid everything? I would imagine you will get a little sound for a while with all new parts but I wouldn't think it would last long or be really noticeable.

[John Adkins]

I'd run them awhile longer or change the pads.

[dcwang3]

what do you mean by seat them?

I have driven approximately about 60 miles or so with them. One thing that I noticed when I took it apart this weekend to see what was going on, the rotor had imprints of the pads. I wonder if the pad is heating up so much from the grinding that when I park, that may be causing the imprints. They are ceramic pads if it matters or not. It happened to all of the rotors.

[superj]

I was always taught that when you change pads and/or rotors, you take the car out and do some hard stops to "seat" the pads to the rotors. I guess it settles them in place and puts the tracks in them so they don't vibrate and make the high pitch squealing noise and lets the brake assembly adjust for the new wider parts?

[dcwang3]

yeah so I did something similar to what you mentioned. I actually read some notes last night about "bedding" new brakes. I didn't go that in-depth, but I did exercise them not too hard and then just drove normally. I'll probably still drive them around a little more to see what happens. If it doesn't go away, then I'm going to try a different brand of pads to see if it makes a difference.

[superj]

Sounds good. Let us know how it goes

[dcwang3]

so I did change the front pads with Akebono's. Compared to the Hawk HPS, they are not as thick, but I also made sure to grease the area on the calipers that the anti-rattle springs sits and slide on. Seemed to help. Definitely is not loud as it was before. After bedding them in, I jacked the front up and just spin the tires, there is a very very slight grinding but much more quiet than what was before. I's sure that the greasing helped solve most of the issue.

Rears are still somewhat loud. Haven't changed pads, but will take another look at it.

[superj]

that light sound will go away. that's normal

[ZeroDarkE30]

yeah pretty normal. Pads and rotors need to start mating and rub material off onto each other. the rear might need an adjustment to the star wheel for the drum brake shoes for the e-brake