Squeeky Squeeky Squeeky....

[Matty K]

Hey all;

I have the FSVT brake upgrade up front, and stock sized rears, all cross-drilled and slotted. Anyway, lately I've been getting obnoxiously loud squeeking from, I'd say, all 4 wheels when I put the brakes on. If I clamp down all the way, it goes away. Same thing if I let off... no more sqeeking. So, searching around, it seems like the likely culprit is uneven wear on the rotors. Anything else I could be missing? There's only about 4k miles on everything, but the rotors are eBay CD/S...

If I do wind up replacing the rotors, I'm going back to blanks. Any recommendations on brands?

 

[Yawak]

it sounds like they might be warped but with only 4k miles? even the ones made in china aren't that bad. although those would only last as long as 1 set of pads.

tirerack has some nice brembo rotors for a great price.

 

[Big Jim]

Brake squeek is either from the friction compound or from lack of lubrication of the brake pad backing plates. It is also possible to be from not using any pad shims included with the pads. Sometimes it can be from inadequate chamfer or grooving in the brake pad. Depending on the type of noise, increasing the chamfer may help. Chamfer issues are not common on Contour or Focus brakes.

Proper lubrication is an often neglected part of a brake job and turns a so-so brake job into an excellent brake job.

It helps to apply some anti-seize compound between the hub and rotor. This makes it easier to remove the rotor next time and can help reduce noise.

The caliper slide pins must be cleaned and properly lubricated with brake caliper grease. This helps with noise as well as makes sure that the pads return to a proper "at-rest" position after braking.

And the part most usually missed. The brake pad backing plate needs to be lubricated with brake caliper grease at any point the backing plate contacts the caliper. On the edge, this again helps the pad return to the proper "at-rest" position. On the backside, it helps cut down on vibration (noise).

It may be worth your effort to redo the brake job and make sure all is properly lubricated.

 

[Matty K]

That would probably be the best place to start, Jim. Thanks!

I have noticed that the RR wheel has a constant squeek, and groans a bit when I roll and then dead-stop the car (i.e. doing a k-turn). The bearing has less than 10k on it, so I don't think it's that. However, that wheel only had 3 lugs for a while; I'm wondering if that wore the rotor in odd ways. And of course, can't get these stupid cd/s rotors turned...

 

[Big Jim]

They are machinable. Many are afraid of them. They can be turned with conventional equipment and methods as long as the technician doesn't try to drastically increase the speed and/or feed rates.

Try asking a few more machine shops.

I did them when I was a technician.

 

[Matty K]

Good to know!

I happened to be over at John's today, and he brought up a good point; if it was a lube problem, and the pads weren't retracting, wouldn't all the wheels squeak constantly, and not just when the pads are part way in?

He thought it might be glazing on the pads; to that end, I did a few medium-to-hard stops to try to clean them. It actually helped a bit, so that might be part of the problem. Even still, I think we're going to re-lube everything, and try some ant-squeak on the backside of the pads.

 

[Rara]

Ok, let me see if i can clarify some things here.

First off, Yawak, warped rotors? are you high? Even what most people call "warped rotors" aren't actually warped.

Big Jim is partly right in his description, but I'll see if i can throw a bit of background tech in to explain things.

Brake squeal is a result of vibration in the pad and or rotor. It happens when the natural frequencies of the rotor and pads line up and the pad vibrates with enough energy to create noise, much like a musical instrument.
OEM engineers (I used to be one) spend a ridiculous amount if time developing and testing brake parts so that the ensure these frequencies line up as little as possible on factory brakes. On aftermarket parts, there are so many hundreds of combinations possible, that there is NO way to guarantee that parts won't squeal, heck even after all the effort put in at the OEM level, some still squeal.
What you need to do, to get rid of the squeal, is to dampen the vibration at the pad. There are many ways to do this. One way is the brake grease on the back of the pads like Big Jim mentioned; the viscous nature of the grease dampens the vibrationa little bit, and is often all that is necessary. However, the grease can get washed out over time.
Other options are shims behind the pads. Sometimes just a thin piece of metal, sometimes they are rubber coated, sometimes they have a glue that bonds them to the back of the pad, sometimes they are sticky on both sides, and the pad is effectively glued to the caliper pistons. Pad slots and chamfers are another way OEMs change the frequencies as well, though i doubt any of you will be messing with those.

So, the bottom line is, if your pads came with shims, use them. Be sure to use brake grease / anti-squeak on any points where the pads may move against the caliper. And always be sure to grease any sliding points or bushings on the calipers.

And Matty, Jim wasn't referring to it being a lube problem on the sliding bushings (which would lead to pads not retracting properly) but to lube between the pad and caliper points. Though it really is more the grease's sticky properties than it is the lube properties that make it effective to decerase squeaks and squeals.

 

[Matty K]

Wow.


Thanks Rara! That actually clears up a TON. We should copy that into the FAQ, or something. So, seems like I have a plan of attack. Incidentally, I bought the calipers from Ford loaded, so I doubt they'd forget shims, but I might go see if they're available from Pep Boys or something. Same for the rear; otherwise, I'll grease up everything good, and use the anti-squeak stuff.

This seems to have all started when I got back from my honeymoon, so the car had been sitting for two weeks. Any way that could have affected it?

 

[Big Jim]

Yes. The car is unhappy that you have another love.

 

[Matty K]

This thing is finicky enough that that may be true...