2006 300 Front Brake Squeak

Hello,

My friend has a 2006 300 with 26k miles. He has developed a
squeaking noise when the front brakes are applied. I was going to
apply some brake quiet to the back of the shims but found out that
they are riveted to the pads.

I think from what I remember the noise began when we had to replace
the front rotors as they were warped. Could it be the brake material
is reacting with the rotors causing this issue? He does a lot of heavy
braking so if he needs to get higher quality rotors, what should he
get?

Thanks in advance,
Nick

 

Depending on how the vehicle was driven, what your friend may be hearing
could simply be the front disc wear indicators signaling that you have
reached the end of the brake pad friction material. If so, they will need
to be replaced. If you wait too long, the rotors will need replacement too.

An inspection should reveal the cause. Good luck.

Bob

 

I checked the pad thickness today and they were only about 1/4 used
from what the new pads look like. He bought another set thinking that
they were low too and when I was about to swap them out for him
noticed that there was a lot left on the original ones.

 

There are a bunch of different chemicals to quiet different sources of
squeaks in brakes. You might want to try CRC De-Sqeak. Also, of
course, remember that disc brakes just plain squeak when they get
dirty, and then stop again on their own...

 

Make sure the rotor shield (sheet metal behind the rotor) is not bent
and rubbing against the rotor - that will make an intermittent squealing
noise. I know this can happen on the LH cars - not sure about the 300.
Usually it make the noise not just when the brakes are applied, but
thought I'd mention it anyway - just in case...

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

The wear indicators will usually make noise when brakes are off and not
make noise when they are applied, Bob. But - yes - that should be checked.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Put a coat of brake grease or anti seize between the shims and the
caliper on the outside and the shim and piston(s) on the inside.
A light coat is sufficient.

Brembo makes very good stock replacement rotors, price is in line with
NAPA (and other) premium brands.

The new rotors need to be cleaned very carefully, after they are
degreased, you need to wash them with hot soapy water and wipe dry with
paper towel until the towel doesn't pick up any more metal dust.
This last part is very important.

Once reassembled, bed in the new brakes as recommended by the brake pad
manufacturer.

 

That hasn't been my experience on any vehicle I've ever owned...

 

OK, Joe. Maybe one of us is wrong, or maybe it varies with vehicle?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Those are the two (or three, depending on how you count) options.

 

In the old days (when you found disc brakes almost only on foreign sports
cars) there was a lot more brake squeal. (We never did cure it on my
friend's Fiat 124.) The back yard fix was to lightly sand the surface of the
pads, just enough to remove any glazing they might have acquired. Then the
leading edge of each pad was sanded to slightly bevel it, just enough to
remove the sharp corner. It usually worked, at least for a while, and the
best part was that the fix was free.

 

I know the pads for the LH cars have the trailing and leading edges
totally chamfered (perhaps a lot of other cars too) - something on the
order of, oh, 25 or 30° from parallel to the friction surface - maybe
for that reason? Perhaps it helps shed water? Coincidentally that also
has the effect of increasing friction surface area as the pad wears -
maybe by 30% or more at end of life.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

I don't know if that could be the issue. I think it could be the rotor
with the materials of the brake pads, since this started after we
changed the rotors from stock to aftermarket ones. I may try putting
back his old rotors and seeing if the squeak goes away. I know that
you should put new pads in when swapping rotors but this is a trial
for now.

 

Well - you have to *LOOK*.

The problem usually occurs after work of that type is done - the person
doing the work inadvertently bends the shield - that's when the noise
starts.

Well - it would certainly be worth *LOOKING* at the rotor shield as a
preliminary to doing your experiment. If it is bent and rubbing the
rotor, you could stop then rather than continuing with a possibly
unnecessary experiment. If your engine doesn't start and you discover
you're out of gas, do you pop the hood and start troubleshooting the
ignition?

 

Yes I will have a look but again if you had a bent shield wouldn't it
make a squeal when you are driving as well and not just braking?

 

Not necessarily. When the bent rotor rubbing squeal problem occurs, it
is almost always intermittent. Often it can be turned on and off by
turning the steering wheel to one side or the other while rolling, and -
yes - by applying or not applying brakes. Here's why: The squeal will
happen when the right amount of pressure is on the shield against the
rotor - too much pressure - no squeal; too little pressure - no squeal.
Just the right amount of pressure - squeal.

The difference between the right amount of pressure and the wrong amount
of pressure (to create the noise) is probably only a couple of
thousandths of an inch of relative motion between the shield (mounted on
the steering knuckle) and the rotor. The relative motion created by the
stresses of turning and braking (as well as temperature changes) is more
than enough to make the noise come and go.

Also - generally the noise occurs at lower speeds and not higher speeds.
That is because the rubbing has to excite the resonant frequency of
the shield.

My disclaimer is that I'm not saying for sure that this is your problem.
I'm only saying that it should definitely be on the short list of
things to consider and actually check.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Sigh. I've been having that brake shield squeal with the right front wheel
recently again. I've tried to work the junk (that builds up between shield
and disk) loose without removing the wheel, but have not been successful. I
was going to do it when I rotate my overdue tires, but at 60,000 miles and
ten years of age, I think I will just buy new tires instead, although there
is still some decent tread left.

Any suggestions for tires for my Intrepid? I'm partial to Michelin / BF
Goodrich, mainly because Costco and BJ's have regular sales with them and
they have an excellent reputation. The stock Goodyear Eagles have shown
longevity though.

 

What size are your wheels, Greg?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Oh - and what year (mainly is it 1st gen or 2nd gen)?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Hi Bill,

I have a 99 Intrepid ES, with 16" wheels. Thanks!