Brakes squeak under light braking only.

[FoxS]

So I've had Wagner Thermoquiets on for a year and a half and 8k and for a while they have been squeaking under light braking. Noise is coming from the front disc brakes on a 2003 Sable.

Nothing happens with heavier braking.

Where should I start my investigation?

 

[mechtech2]

Brake anti squeal sauce on the back of the pads will fix it.

 

[demarpaint]

Originally Posted By: mechtech2
Brake anti squeal sauce on the back of the pads will fix it.


+1

I saw a spray at O'Reilly's that is silver, I was told you can spray it on the rotors, etc. w/o taking anything apart. I never tried it but it might be worth looking into. I think its called Squeal Medic made by Gunk. Maybe someone here has some experience with it. HTH

 

[spk2000]

This is considered a downfall of ceramic pads. They do often have a squeal under light loads. These pads should have a built in shim with the nitrile coating on it. Anti squeal or grease on back of pad will eat the dissolve the coating.

 

[Audios]

Try breaking them in again, sometimess squealing is caused by a too short break in procedure.

 

[Doog]

Originally Posted By: mechtech2
Brake anti squeal sauce on the back of the pads will fix it.


+2 I use permatex green

 

[ChrisW]

Originally Posted By: spk2000
This is considered a downfall of ceramic pads. They do often have a squeal under light loads. These pads should have a built in shim with the nitrile coating on it. Anti squeal or grease on back of pad will eat the dissolve the coating.


It has been my understanding that brake pad manufacturers who make pads with bonded or integrated shims [that are nitrile coated or not] do not expressly instruct utilizing brake grease on the shims. I can't remember exactly who doesn't recommend grease or where I read it on here but I believe that Akebono ProACT pads may be one of the ones I recall. I don't use grease on the back of pads that have bonded/integrated shims and have had minimal noise sans when there is brake dust buildup, after a car-wash or rain. I do make sure that the mating surfaces are clean [piston edges and caliper 'ears' that contact the pad]. If the shims are loose clip-on style, then I use grease in between the shims and the pad's backing plate [but usually none between the shim and caliper]; some OE designs use a two-layer shim system, however, I am noticing more and more OE/Aftermarket fitments that have bonded shims.

 

[JHZR2]

Originally Posted By: spk2000
This is considered a downfall of ceramic pads. They do often have a squeal under light loads. These pads should have a built in shim with the nitrile coating on it. Anti squeal or grease on back of pad will eat the dissolve the coating.


Im pretty sure that my 135i doesnt have ceramic pads, but I get this sometimes too...

 

[ChrisW]

To more directly address the OP's question, when you replaced the pads, did you replace the associated disc brake hardware? I often find that noise that you describe can be due to re-using the old clips/hardware which can produce less than optimal alignment of the pad, less than optimal alignment causes vibration, and the vibration becomes the noise you hear. However, I do see that Wagner lists the TQ pads as coming with new hardware, unless they're just meaning that tension spring on the top of the backing plate. O'Reilly's disc brake hardware kit 2003 Sable Not sure what hardware kit fits your vehicle as there appears to be two different clip styles, but the hardware kit is relatively inexpensive and is where I'd first start.

I know there are two style of ThermoQueits out there, the ones with the integrated shim into the backing plate and the ones with the bonded shims. I personally prefer the bonded shim design over the integrated one for TQ pads [or any pads for that matter]; if that TQ integrated shim design compresses over time due to wear, then it's not offering much noise suppression. I also recall it being discussed on here that the TQ pads with the integrated shims have thinner friction material to accommodate the thickness of the integrated shim, which is usually thicker than a bonded one. I am probably not using the best terminology here, but I hope you can understand what I mean, and someone please correct me if I'm wrong on any points. Thanks.

 

[FoxS]

Hi ChrisW,

My mechanic did the work but I do remember that the pads came with new tension springs.

I have the integrated shims and I can see the pistons are compressing the back of the pads.

I'm going to try some heavy braking and then apply anti squeal on the back of the pads.

I think it is the vibration between pad and puston as the sound doesn't always happen.

Thanks

 

[stephen9666]

Originally Posted By: spk2000
This is considered a downfall of ceramic pads. They do often have a squeal under light loads.


Considered a downfall by whom? My Bendix CT-3 ceramic pads don't seem to squeak under light load. They actually never really squeak, that I've noticed.

 

[The Critic]

Originally Posted By: spk2000
This is considered a downfall of ceramic pads. They do often have a squeal under light loads. These pads should have a built in shim with the nitrile coating on it. Anti squeal or grease on back of pad will eat the dissolve the coating.


The one-piece shims on these pads can be problematic. The piston will sometimes cut-thru the material after a period of time, resulting in brake noise. The Raybestos ad here, illustrates the problem:

http://www.raysbestbrakes.com/Images/uploads/Truthflyer_Friction_vsWagner.pdf