Squeaky brakes

[mr_z4mc1m_oz]

Hi,

My z4mc has 36000kms and i've recently noticed that the brakes are starting to squeak just before you come to a complete stop under gentle braking. If I brake harder they don't seem to make a noise. My car still has the original brake pads which seem to still have a lot of pad left.

Has any one got any ideas what might be causing it?

Thanks

[Gallardo Rosso]

Most likely your pads/rotors are "glazed". These brakes have electronic sensors not the old school metal tab that squeaks when you reach the wear limit so it's probably not that...

First you should make sure everything in your brakes are truly perfect. Confirm all the pads (inner and outer) have the same thickness, are worn evenly, and aren't cracked or chipped. Then confirm the rotor meets the minimum thickness and isn't excessively wavy.

Typically, you could just have the rotors cut. These rotors don't cut well.

Replacing the rotors would likely rid you if the problem but its pricey. Swapping pads to a low dust ceramic might also stop the squeak. Once again, if the rotor is excessively wavy and/or thin the problem may occur again.

[ncnmra]

I have the EXACT same problem. I have 47000 km (29k miles). I don't think the pads need replacing. Will keep an eye on this thread to any additional advice.

PS: Sorry if this is a dumb question: what is the easiest way to check if the brake pads are still ok? I understand from Gallardo Rosso's reply that squeaking is NOT an indication of low brake pads, but I figured I'd check anyway.

[StickMon]

This may be a stupid answer, but the stock wheels make it pretty easy to see the thickness of the pads.
From my experience, if the pad material is at least 1/4" thick, you're fine.

[Gallardo Rosso]

You should be able to see pads thru wheel. Just confirm inner and outer pad are similar thickness as well as fore and aft on the pad. Unevenness would indicate a problem with the caliper.

A small "dental" mirror and a flashlight helps.

Taking the wheels off will give you a better view and removing the pads completely and laying all of them out on a table would be the most scientific. You would also be able to see if the pads are degraded. They would look dry and cracky. (Google Image cracked brake pads) If they are, most likely your rotors will need to be replaced along with pads because that friction interface is poor and over heating.

[ncnmra]

Thanks for the great reply guys! All that being said, from the sounds of it; the squeaky sound is likely not from pads being too thin unless they are damaged?

My car sits for long periods of time in a garage, maybe I should douse the rotors with some water, let them rust a bit to remove any of the surface glaze? Is that even remotely a good idea?

[Gallardo Rosso]

I think the glazed surface is deeper than that. It's basically a heat effected zone. Probably .030" thick. Admittedly I've scuffed rotors and pads (on much crappier cars) with a 2" 3m Roloc pad in a 90 degree grinder with small success. But the condition usually returns.

[The HACK]

Bed in the brake pads.

[Shipkiller]

I agree with HACK, re-bed the pads.

Also, the brake wear sensor is just an electrical wire with some rubber around it. When the pad gets worn enough to wear through the rubber the wire grounds to the rotor and lights the light. When that happens, you have to replace the 'sensor'.

[mr_z4mc1m_oz]

Thanks for all the replies. I'm still a little confused. Would a car with only 37,000 kilometers need the rotors replaced? Seems to be very over the top. Car has never been tracked. Its just my daily drive.

There appears to still be a lot of pad left when looking through the wheel openings.

The pads are the original OEM pads, so they are almost 7yrs old.

Not sure what i should do?

Thanks

[StickMon]

I bought my car with 39k on it, and some time later (<50k miles) noticed that the rotors had huge steps on the inner and outer edges where the pads don't reach. Both front and rear.
I don't know what the original owner got up to, but I don't think she tracked it.
Pads are fine, but not necessarily the originals. O.O. may have had them replaced.

So it is possible to wear the rotors down with seemingly low mileage.
I don't have ay squeaking, though. Brakes work fine, just never saw such deep wear on a rotor before.
Have new ones waiting for a convenient weekend to install.

[Shipkiller]

Originally Posted by StickMon

I bought my car with 39k on it, and some time later (<50k miles) noticed that the rotors had huge steps on the inner and outer edges where the pads don't reach. Both front and rear.
I don't know what the original owner got up to, but I don't think she tracked it.
Pads are fine, but not necessarily the originals. O.O. may have had them replaced.

So it is possible to wear the rotors down with seemingly low mileage.
I don't have ay squeaking, though. Brakes work fine, just never saw such deep wear on a rotor before.
Have new ones waiting for a convenient weekend to install.

What is your rotor thickness? Is it at the minimums?

[mr_z4mc1m_oz]

Have no idea. I'll have to investigate further I guess.

[StickMon]

I have no idea either. New rotors will be installed by the end of the year.
I'll mic them when I take them off, just for reference.

[Shipkiller]

Your micrometer needs to be larger than a 1". A 1" will not fit... You will need either a large jawed mic or a micrometer extension kit. I have both and both work well.

Personally, if the rotors are in spec I would leave them on the car until they go out of spec. Especially if you do not have any runout issues (vibration).

[udme86m]

Originally Posted by mr_130i_oz

Hi,

My z4mc has 36000kms and i've recently noticed that the brakes are starting to squeak just before you come to a complete stop under gentle braking. If I brake harder they don't seem to make a noise. My car still has the original brake pads which seem to still have a lot of pad left.

Has any one got any ideas what might be causing it?

Thanks

Did you get this resolved? Mine is doing the same thing - I tried bedding the brakes several times no luck. Rotors are within spec, pads plenty left. Really starting to get obnoxious most of my driving is stop and go with slight break pressure squeaking like hell. I have 25k on the car.

[mr_z4mc1m_oz]

Sorry for late reply. I gave the wheels a good clean with the mag wheel cleaning brush and issues gone. I think it was just some brake dust build up cause I'd be a bit slack over the past few months washing then due to work commitments. Planning on detailing her over the Xmas break.

[GP20]

I got brand new brake pads and rotors installed at the dealer a month ago under the extended maintenance warranty. They squeaked from day 1. Both the front corners squeaked so every time I came to a full stop, I got 2 separate loud horrid squeaks. I bedded the brakes 4 times following Zeckhausen's procedures but it didn't help.

Brought the car back to the dealer a couple days ago (700 miles after the initial install), they weren't gonna do anything at first and claimed that BMW doesn't cover brake squeaks after replacement. After a bit of discussion with the shop foreman, he agreed to deglaze the brakes and do a complete cleanse and make sure there would be sufficient anti-squeak gel. After 2 days of driving, the squeaks seem to be gone. I'm still crossing my fingers though.

[StickMon]

I put on ECS rotors and StopTech pads right after New Year's.
Didn't use any goo. Not a peep out of them.

Not sure it would be a good track set-up.
I think I set the front right on fire bedding them in.
3 fairly aggressive 60-20 decels in about 1/2 mile, then got stopped by a traffic light.
There was a lot of smoke, and you know what they say about where there's smoke.

Couple hundred miles since. It's all good.