What makes a brake pad squeal in stop & go traffic?

Joined
Jan 2, 2004
Messages
11,331
Location
California
Vehicle: 2005 Toyota Sienna, rear drum/front disc, no VSC(Toyota/Denso/Advics implementation of ESP).

I’ve noticed a squeal from the front brakes when the van is in stop & go traffic - this happened in the line waiting to get into Yosemite two weeks ago. Else, the van stops fine and the noise goes away and stays gone. Yesterday, my parents drove the van and the noise was back. My dad chalked it up as weird but normal braking behavior, my mom was panicking and called me in a tizzy while I was out on the river with friends for the day.

The brake pads installed are Toyota “warranty” pads, made by Advics with a FF friction level. I didn’t note the formulation number. 8mm left, so plenty of life. I took the front brakes apart, sanded the pads on a flat piece of marble with 150 grit sandpaper. Installed new aftermarket abutment clips, put a thin smear of Permatex moly silicone gray brake lube on the backs of the clips, as well as the “ears” of the calipers where they touch the outboard pad and on the piston. Noticed the passenger outboard shim sandwich fell off, so I bent the tangs to secure them back on, with a few dabs of lube between the shims and backing plate. Took the van out on a drive, brakes feel fine - I will note a local machine shop turned the rotors when the pads were replaced and there was a bit more runout than I would have liked.

Now, while Japanese cars use NAO “ceramic” friction that works on the cohesive friction principle, shouldn’t there be a microscopic(as in microns) layer of friction on the rotor at all times that’s constantly renewed when the brakes are applied? What else would cause this low-speed brake squeal?
 
It is possible that the rotors are glazed. Rotors can get glazed when they are cooled down rapidly, when very hot. For example, going through a car wash right after driving at highway speeds and/or hard braking. The only way to get rid of the squeal is to turn or replace the rotors.

Ask me how I know.
 
It is possible that the rotors are glazed. Rotors can get glazed when they are cooled down rapidly, when very hot. For example, going through a car wash right after driving at highway speeds and/or hard braking. The only way to get rid of the squeal is to turn or replace the rotors.

Ask me how I know.
Well, the Advics rotors I installed with a set of first generation of Toyota “service” pads were turned when I installed these pads. If there’s still squeal, I’m getting rotors.

My mom wanted me to parts cannon a set of pads on it. Meh.
 
Clean the hardware lube it up, and that probably will help

If your Sienna is anything like my GS350, this is the cause.
Yep, grabbed a Carlson disc brake hardware kit and installed that too. The pins are fine - brakes are wearing nice and evenly. Put some Permatex silicone lube on the underside of the abutment clips as a guard against rust jacking too.
 
Well, the Advics rotors I installed with a set of first generation of Toyota “service” pads were turned when I installed these pads. If there’s still squeal, I’m getting rotors.

My mom wanted me to parts cannon a set of pads on it. Meh.

Always replace the rotors along with the pads
 
Been replacing brakes a looooonnnngggg time. I stopped " turning" rotors eons ago. All good it does is give you a fresh starting surface, while taking away the " meat" of the rotor. Yeah, Yeah, I know, the rotors have those markings " Min thickness .08 or whatever ". Bologna. Less meat, they gonna squeak or warp. Get a different brand of rotors and match the pads to the rotor brand. My " new" go to is Bosch Quietcast pads and rotors. So far, so good. Not easy trying to find " middle of the road" pads and rotors that work / perform well.... It's either go dirt cheap or insanely expensive.
 
Provided all your brake components are in good working order, any squealing is the pad picking up a resonance from the rotor and vibrating like a reed. This is why OEM and good aftermarket pads have the rubber-like layer on the backs of the pads. To insulate it from vibs.
 
As superstitious as it sounds, I've cured light squealing on more than one occasion with a healthy dose of brake cleaner
 
So true JTK ! :) Thanks for the input. The Bosch Quietcast pads have that rubber layer in between the pad shims. Get the pads and rotors. Most importantly, make sure the pins are in good shape, pin boots, and lube them up. A sticky/ semi-seized brake pin will ruin any brake job. That's not superstitious D60, a nice bath of brake kleen does wonders. But, in nthach's case, the rotors were already " turned" after the new pads were installed. I'm shootin that he's runnin a bad set of rotors.
 
I'm confused. You're original thread said you installed Advics over " turned" ROTORS. Then you had a squeak. Rear drums don't squeak. They do warp, and get dusty, and get out of adjustment. So, where is the noise coming from ? The front or back of the vehicle. ? But, meanwhile, while you have the drums off, wash down everything with brakleen, wash out the drums, take some sandpaper and take off any glaze on the drum where the shoes hit, ( don't go crazy sanding..just a light hand sanding ). Pop off the rubber grommet in the drum, line the grommet hole up to a hole in the hub where you can see the " star" adjuster. Slide the drum on. Put the lug nuts on fairly tight to center drum. Spin it. If it spins freely, it's out of adjustment. Take a flashlight and a small bent flat screwdriver and slowly turn the star.( It will only move one way). Turn the star 2 clicks. Hit the sides with a rubber mallet to set the shoes, spin again Repeat. Stop tightening star when you sense the LEAST amount of resistance of the shoes rubbing against the drum. ( You can also hear it ). Drums are supposed to self adjust when you drive in reverse and stop, but it never works. Maybe 3-4 clicks on the star is all you may need. I'm not there to see or tell. Now back to the squeaking....the front or rear ???
 
By the way, I have 128, 698 miles on my ORIGINAL Toyota Solara brake drum shoes. They really don't do much stopping work. That's why most cars have 4 wheel disc brakes now. My Toyota is a 2003. Drum brakes are going bye bye.
 
AHHHHH !!!! The bologna of death !!!! DELISH :)......I grew up in The Bronx, NY...in the late 60's-70's. Lots of Italian butcher shops then, and deli's... No more...It all changed, for the worst. Don't remember much of the 80's....I was a bad boy...havin lots of FUN !!!!! :)
 
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