[crazed792]

I purchased Akebono ceramic f/r pads for my 328i, and slotted rotors from brakeperformance.com. There was a slight squeak for the first 500 miles or so and I was hoping it would go away, but now I'm over 1000 and it has gotten far worse. People stare at me every time I come to a stop.

Is there some way to tell what is causing the problem, or anything to stop the squeal? I tried a bed in procedure after it really started getting bad, and had no noticeable difference. Tried using the "reversing" method of bed-in, too.

[E92Fan]

Originally Posted by crazed792

I purchased Akebono ceramic f/r pads for my 328i, and slotted rotors from brakeperformance.com. There was a slight squeak for the first 500 miles or so and I was hoping it would go away, but now I'm over 1000 and it has gotten far worse. People stare at me every time I come to a stop.

Is there some way to tell what is causing the problem, or anything to stop the squeal? I tried a bed in procedure after it really started getting bad, and had no noticeable difference. Tried using the "reversing" method of bed-in, too.

You will probably have a build-up of brake dust in the grooves of the discs as the pads were new when the whole setup was installed. Try taking the wheels off and cleaning out the grooves on the discs on both sides

[ECSTuning]

We have a selection of anti-squeel compounds available:

http://www.ecstuning.com/BMW-E90-328...aign=postreply

[crazed792]

Originally Posted by E92Fan

You will probably have a build-up of brake dust in the grooves of the discs as the pads were new when the whole setup was installed. Try taking the wheels off and cleaning out the grooves on the discs on both sides

Originally Posted by ECS Tuning

We have a selection of anti-squeel compounds available:

http://www.ecstuning.com/BMW-E90-328...aign=postreply

Thanks guys! I'll try cleaning out the disks and if that doesn't work I'll look into compunds and other ideas. Is it true that the slots on a disk should be facing a certain way? I don't want it to continue to be a problem because if improper installation...

[crazed792]

Originally Posted by DV

If you still have your OE rotors I would try putting those back on and see if the noise goes away. I have the Akebono pads on my car with stock rotors and they are silent. Those pads are not designed to be used with a slotted rotor and may be noisy as a result. Did you apply the supplied grease to the inside of the caliper fingers and the face of the piston?

This picture shows a correctly installed slotted rotor:

Ok, yeah the picture looks like a match. Unfortunately, I don't have the OEM rotors. They had some grooving I could feel and I didn't care to have them resurfaced. The dealer still thought they were fine, so when I had them replaced I didn't care to hold onto the old ones. The people that installed my brakes stated that they did use the grease. I'm really hoping that these pads will work with the rotors. I had no idea you shouldn't use slotted rotors with the Akebono.

[The HACK]

Originally Posted by DV

This picture shows a correctly installed slotted rotor:

The direction of the slots are irrelevant, it's the direction of the internal cooling vanes that matters on which way the rotors are installed. It doesn't matter if the slots sweep forward or backward.

[crazed792]

Originally Posted by The HACK

The direction of the slots are irrelevant, it's the direction of the internal cooling vanes that matters on which way the rotors are installed. It doesn't matter if the slots sweep forward or backward.

Ok, I'm attaching a few pics of my rear drivers side rotor without wheel on. 2 more or less front on, and one with as good a look at the inside as I can manage. I've never taken a rotor/pad off of a car before, and had the install done by someone else. Apparently even cleaning the back side could be an issue because of some sort of shield. Can anyone tell me if they see a problem with install/product?

EDIT: Oh, and what product would you guys suggest for cleaning any brake residue off? Or just use a cloth and water and go to town on the slots?

[The HACK]

IMHO, your problem does NOT stem from the grooves filling with brake dust, but from the simple fact that squeal comes from vibration of the pad against the pad carrier/caliper housing, and that the slots on the rotor as the car slows down causes the pads to bounce on the slots and therefore vibrate against the pad carrier/caliper housing. No amount of "cleaning" is going to do squat to help. The only thing that will help, is if you take the pads out and apply "anti-squeal" compound, a glue like substance that prevents it from vibrating in the housing as suggested by "ECS Tuning" in post 3.

It's the nature of the beast. I used to have a buddy who works at Brembo and he said the biggest issue he has selling slotted or drilled rotor is that they're really meant for track use but typically, people who put them on, do it strictly for "looks" purposes and once they find out that drilled or slotted rotors possibly and typically make more noise than blanks they freak out.

There are, of course, a couple of other things you might try. Different brake pad compound will have different bit characteristics that may minimize this vibration effect, typically the higher the organic compound the more "forgiving" it is when it comes to vibration against the caliper housing. I've had good experience using Axxis Ultimates for street use against slotted and drilled rotors, although they s*ck donkey balls on the track.

As for the direction of the rotors, I still can't quite tell if the vanes are rotating in the right direction. The only logical thing I can tell you, is that the vanes should sweep BACKWARDS, meaning if you follow their direction from the center of the rotor to the outside of the rotor, the top vanes would appear to move backwards while the bottom vanes would move forward, so when the car's moving forward the air would be evacuated from the center of the disc, not get scooped up and shoved into the center of the disc. Judging from the pictures, it appears the vanes are running in the correct direction and that if you were to install your rotors based on the direction of the slots as suggested by DV in post 5, your rotors would in fact be installed BACKWARDS.

As for the slots, I've heard argument that having the slots point in the direction of post #5 by DV would give the pad more initial bite, but I've heard from some very experienced track guys explain that having those slots run in either direction makes absolutely no difference in bite characteristics. And these are the guys that would care most about the last 1/10th of a second of difference.

[crazed792]

Thanks for the info The HACK. I'll probably give the compounds solution a try sooner than later. I don't mind a little bit of squeal too much, but my braking from 30-0 is so loud that when I say people stare, I'm not overstating it. I grit my teeth every time I stop and hope that I can apply the perfect amount of pressure (which seems to adjust as the pads/rotors heat up with use) to minimize the sound. Even with all of my windows up and my stereo on loud, the noise is overpowering in the cabin. If I drove down a street too late and a cop was looking for an excuse to give a ticket, I'd get a noise violation/fix it ticket, as it's a hell of a lot louder than a cat-less exhaust.

The only thing that made me think that it might be buildup is that it has steadily gotten worse over the last 1k miles or so. If it gets much worse or if I can't find a way to get rid of the sound I'm going to be buying another set of freaking rotors, as this is just embarrassing.

[NotMe]

it has nothing to do with a particular rotor, although the slot running out to end of that rotor looks less than optimal for durability and noise.

here is what you need to take care of the sound

http://www.zeckhausen.com/bedding_in_brakes.htm

if you did not do this initially that could be the issue.

hit those things hard and you should be good

[crazed792]

Originally Posted by NotMe

it has nothing to do with a particular rotor, although the slot running out to end of that rotor looks less than optimal for durability and noise.

here is what you need to take care of the sound

http://www.zeckhausen.com/bedding_in_brakes.htm

if you did not do this initially that could be the issue.

hit those things hard and you should be good

Thanks, but as I said in my first post, I have tried the bed in procedure (the one listed, actually), and then a reverse procedure somewhat similar, but with the car in reverse, as per some other threads. No good.

[crazed792]

Originally Posted by DV

The HACK is correct. The vane orientation is definitely what to go by. All of the slotted rotors I have been exposed to at Roush and Akebono have had slots that swept counterclockwise when installed correctly. Look at any non-cross-drilled BBK. I thought that it would be easier to show you that than a vane diagram.
As I stated before: If the pads were properly greased, I would say you can have Akebono pads and you can have slotted rotors, but not both.
Hope this helps.

Ok, thanks guys for all of your help. So here is my plan for later today. I'm going to run to an auto parts store and pick up some anti squeal and brake cleaner. Pull my pads/rotors, clean my rotors. Apply antisqueal to the pad backs. If the sound either remains or goes away and comes back with a vengeance (as is what happened this time), I'll live with the noise until I get annoyed enough to spend a couple hundred on non-slotted rotors. I'm not switching pad brand/type. These pads do a great job stopping me like an OEM pad, while still being very low dust (and usually noise). I haven't used another manufacturer that has given me that combo before. They also take quite a while to fade, unlike most ceramics.

Btw, I know it may not matter, but my rotors do appear to be a match to DVs as far as the slots go. From any rotor a slot on the top half of the rotor is pointing toward the front of my car on the outside edge. So on the passenger side it would look like his pic, and the opposite goes for the drivers side. Makes me wonder if they installed half of them backward. Later when I take off wheels again to look, I'll try to check out the vane orientation, although from what I could see, they seemed rather flat...

On another note, knowing what I'm going to do today, and after spending the morning reading up on the process of changing pads/rotors, I wish I had just done it myself the first time.

[DV]

Originally Posted by crazed792

Ok, thanks guys for all of your help. So here is my plan for later today. I'm going to run to an auto parts store and pick up some anti squeal and brake cleaner. Pull my pads/rotors, clean my rotors. Apply antisqueal to the pad backs. If the sound either remains or goes away and comes back with a vengeance (as is what happened this time), I'll live with the noise until I get annoyed enough to spend a couple hundred on non-slotted rotors. I'm not switching pad brand/type. These pads do a great job stopping me like an OEM pad, while still being very low dust (and usually noise). I haven't used another manufacturer that has given me that combo before. They also take quite a while to fade, unlike most ceramics.

Btw, I know it may not matter, but my rotors do appear to be a match to DVs as far as the slots go. From any rotor a slot on the top half of the rotor is pointing toward the front of my car on the outside edge. So on the passenger side it would look like his pic, and the opposite goes for the drivers side. Makes me wonder if they installed half of them backward. Later when I take off wheels again to look, I'll try to check out the vane orientation, although from what I could see, they seemed rather flat...

Stick a long, thin screwdriver into one of the vanes and see which way it points. I can't tell from the picture. I have seen rotors with straight vanes before, but I would imagine that yours would be directional.
You might be able to find someone with lightly used rotors in the market for some slots and do a trade + cash. Just make sure to have used rotors resurfaced first, as the Akebono pads need a clean surface to lay down a transfer layer. This is very important.
And a "good man" for sticking with the Akebono pads. You won't regret it.

[crazed792]

Originally Posted by DV

Stick a long, thin screwdriver into one of the vanes and see which way it points. I can't tell from the picture. I have seen rotors with straight vanes before, but I would imagine that yours would be directional.
You might be able to find someone with lightly used rotors in the market for some slots and do a trade + cash. Just make sure to have used rotors resurfaced first, as the Akebono pads need a clean surface to lay down a transfer layer. This is very important.
And a "good man" to sticking with the Akebono pads. You won't regret it.

Thanks, I love Akebono pads in general, and was surprised when I heard the squeak, but that doesn't make me want the Akebono pads less. More the rotors... I see what you mean on the vanes with the screwdriver trick, however they still seem to each be straight and they go directly to the center of the rotors, rather than having any angle to them. Is that bad?

I took off a caliper using the 18mm bolts, and it took the pads with it. I realized after a moment that I probably need to take the caps off of the other bolts back there and remove those instead. I don't have a tool to remove the bolts once I took off the covers. They look like a hex tool would get 'em, but I only have 6mm and smaller(and a huge set, which are way too large). I'm guessing they're 7 mm? I have my freaking wheel off yet again, and now I think I have to put it back on and go to the store again. Assuming anybody knows what size that is, please let me know. Otherwise I'm planning on picking this up tomorrow.

[crazed792]

Never mind on the sizing. I got to where I felt like trying again, so I ran to the store and bought a better allen set. It is 7 mm. Both of my front brakes have had the compound applied and the rotors cleaned. It sounded like it was coming from the front, so I'm holding off on the rear until I see if this makes a difference. Btw, that shit is tacky and gets EVERYWHERE if you aren't careful. I bet most of you already know that though. I'll update this post in a bit with whether or not it made a difference. Wish me luck.

Update: I exited my driveway, and the dip that usually causes the first squeal of the trip didn't cause a sound to be made. Unfortunately, that was the only difference. After a couple of braking applications, it was back to how it was before. Either it wasn't the front brakes overall or this didn't do anything but make the visible part of the rear of my brake pads currently hot pink. It still sounded like it was coming from the front, but I've gone too far to stop now. I'll give the rear a shot tomorrow if I have the time. My guess is rotor replacement isn't too far off though, probably spring at the latest. This time I won't be paying someone my money though, so some good did come of this.

[AP Racing - Chris_B]

It is a bit difficult to offer help remotely, but this may be one set of rogue pads. I'm usually the last to blame squeal on the pads, as they get all of the blame even when the system design is usually the culprit for NVH issues. The pads are just the easiest things to change.

However, semi-metallic pads have bits of iron and steel in them, which, when oxidized, form ferrous oxide on their surfaces. There are very few things in the world that will cause brake squeal more than ferrous oxide. Most "ceramic" pads (a HUGE misnomer) also have metallic bits in them, but their ceramic content is higher.

This can happen during compound powder production when the iron and/or steel is chopped up or shredded and allowed to sit too long before being compounded. Imaging preparing the metals on a Friday and then compounding them on Monday. Not good. Most pad manufacturers know this and avoid it like the plague. However people are human and production quotas need to be met, so stuff can happen.

You might go back to whoever you got the pads from and ask for a replacement set from a different batch. Before putting these on, scrub the pad transfer layer off of the rotor faces with a Flex-Hone and an air tool or Scotch-Brite and elbow grease. The goal is to not remove iron. Then bed the new ones from scratch.

One more comment: From the picture you have shown, the pad transfer layer is a bit weak near the rotor OD. This could indicate that the caliper slider pin bushings are worn or becoming soft. Worn bushings allow for additional caliper movement, which can contribute to brake noise. I would have these looked at and possibly replaced. This is the main reason I prefer fixed calipers instead of sliders as the only moving parts in a fixed caliper are the pistons. There are companies who make brass bushings to replace the rubber bits, but I don't have direct experience with them. Maybe someone else can chime in?

Chris