Can not get brakes to stop squealing

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2,414
Location
Seattle-ish, WA
I have rear brakes that squeal, and I'm stumped. 1998 Acura SLX. Generally excellent condition and well-maintained. This fall I noticed the rear brakes squealing on stopping. I checked the pads a few thousand before and they had plenty of friction material. I ordered some Raybestos Premium Ceramic pads "Quiet Stop". I installed them and I found one set of pads wearing unevenly fore-aft, and a very stuck caliper bolt. Rotors look fine. Calipers seemed fine. The Raybestos pad had a metal backing plate on them that precluded fitting the stamped steel shims back along with them, so I just added a generous amount of Disc Brake Quiet (the orange goo) to the piston and the pad, let it set up, and re-assembled. I cleaned and lubed the caliper pins and used anti-seize. Wheels spun ok after assembly w/o dragging/sticking. Braking performance is great; one of the pad sets was clearly sticking and dragging, also robbing some mpg I think. Drag is gone. I followed a standard break-in/bed-in procedure with the pads per instructions (rolling slow downs multiple times before full stops). I still get a squeal on stopping, though much less than before. I jacked up the rear and spun the wheels - no drag on either side (front either for that matter). I flushed and bled the brakes, too - performance gain but no change in squeal. Squeal maybe worse after bleeding. I'm baffled as to why. Should I: a) open them back up and try to get the shims in now that the pads have worn a bit? b) something else...? 2nd question - I noticed on the back of the pads, while all were identical, two of them had a clip riveted in one corner, sort of to pull them with? Not all four did, only two. Are those supposed to be inboard, outboard, or...? Like the little clips on the two of the four pads in this picture: http://www.autotrucktoys.com/ram/Mopar-Dodge-Ram-OE-Replacement-Brake-Pads-PRD35698.aspx Haven't encountered that before on a vehicle. Are they supposed to go in a certain position? The instructions from Raybestos did not illustrate them or mention them; I checked.
 
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Messages
17,501
Location
Clovis, CA
Originally Posted By: Oro_O
2nd question - I noticed on the back of the pads, while all were identical, two of them had a clip riveted in one corner, sort of to pull them with? Not all four did, only two. Are those supposed to be inboard, outboard, or...?
The pads with the clips (actually wear indicators) go on the inboard side. When your pads wear down far enough for the wear indicators to make contact with the rotor, you'll hear a shisk shisk noise. If you've ever been to a Walmart parking lot, that noise is prevalent there.
 
Messages
13,389
Location
ROCHESTER, NY
The SLX is an Isuzu Trooper for those who didn't know. A good vehicle as I remember! smile 1st...Did you also install new rotors? If not, there may be some rust build up on existing rotores if you did not replace them. This could contribute to the noise/squeal that you're hearing. But, it's not detrimental! 2nd...I know lots of people that use anti-seize/never-seeze on brake parts. I don't use anti-seize on the slider pins or any brake parts. The anti-seize is OK at the start but, it just doesn't last. Use brake assembly lube products. I have my favorite!(Permatex or Sil Glyde) 3rd...also use the brake assembly lube on the backing plates of the pads(not that spray on stuff or the stuff that dries/in colors). And use the lube on the ears of the pad where they slide into their grooves/anti-rattle clips. And the clips too! 4th...those riveted clips are a noise sensor that allows you to hear when the pads are getting low. Put one pad w/clip on each wheel(where it fits best, inside/outside)! Some brake designs are such that, the sensor only fit in one spot on the caliper hold down bracket. And others vehicles may not be specifically fussy! 5th...and this could be only a slight chance, that the parking brakes(under the rotor hats) are squealing upon braking though, this is a small chance that it is!
 
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Messages
6,520
Location
Scruffy City
Originally Posted By: Char Baby
The SLX is an Isuzu Trooper for those who didn't know. A good vehicle as I remember! smile
Yep, just make sure it doesn't run low on oil, the DOHC motors are notorious for burning oil and blowing up when they get low. IIRC. Pain to get out if locked up.
Originally Posted By: Char Baby
1st...Did you also install new rotors? If not, there may be some rust build up on existing rotores if you did not replace them. This could contribute to the noise/squeal that you're hearing. But, it's not detrimental!
Or turn them? Remove and clean the mounting surfaces?
Originally Posted By: Char Baby
2nd...I know lots of people that use anti-seize/never-seeze on brake parts. I don't use anti-seize on the slider pins or any brake parts. The anti-seize is OK at the start but, it just doesn't last. Use brake assembly lube products. I have my favorite!(Permatex or Sil Glyde)
I use what the factory repair manual says, where it says to use it.
Originally Posted By: Char Baby
3rd...also use the brake assembly lube on the backing plates of the pads(not that spray on stuff or the stuff that dries/in colors). And use the lube on the ears of the pad where they slide into their grooves/anti-rattle clips. And the clips too!
See 2. That orange (and blue and red) stuff is the devil. It does more harm than good. If the pads will not use the OEM shim pack, I will not use them. The OEM's design these shim packs to minimize noise. You can bet that if they did not work some bean counter would have eliminated them. I'm not sure what you might get with an SLX since it is an Isuzu designed product, but OEM Honda/Acura pads have always worked for me, and they always come with new shim stacks and usually a small tube of silicone paste. They are usually reasonably priced - although the ones for this vehicle seem higher, not sure what aftermarket run for it.
Originally Posted By: Char Baby
4th...those riveted clips are a noise sensor that allows you to hear when the pads are getting low. Put one pad w/clip on each wheel(where it fits best, inside/outside)! Some brake designs are such that, the sensor only fit in one spot on the caliper hold down bracket. And others vehicles may not be specifically fussy!
From the parts diagram on Delray Acura it looks like they go inboard and down. The factory repair manual should also illustrate the orientation.
Originally Posted By: Char Baby
5th...and this could be only a slight chance, that the parking brakes (under the rotor hats) are squealing upon braking though, this is a small chance that it is!
Yep, parking brakes are oft neglected, you can find all sorts of disaster in there sometimes, worth a look.
 

Oro_O

Thread starter
Messages
2,414
Location
Seattle-ish, WA
Thanks for the replies. It all helps me visualize what I can go back and do to sort this out. An yes, I meant up top to say Acura SLX is a re-branded Trooper, the SLX is less recognizable and usually I identify it that way. Slightly dressier last-generation one. Very, very good vehicle I may keep around a while longer. 1) Thanks for explanation of the noise sensors. 2) Anti-seize was on threads only, not the whole caliper pin, and a generous coating of axle grease on caliper pin bodies (forgot to mention). 3) Rotors were smooth, not glazed, replaced 25k ago and look in great shape. Were de-greased and cleaned after work done. 4) Ant-squeal/lube: OK, I see an error. I thought the lube pack in the kit was for the caliper pins and I used other lube I had. I'll take them out, clean off the orange goo, fit the shims, and lube with that. That was likely my mistake. I have done a few brake jobs over the years and never had this problem - only issue this time was the shims not wanting to fit. DuckRyder, you are correct as to oil burning, though it was limited to the 98/99 model years and from a bad oil ring design. I researched what others tried and instead of re-ringing it, I cured mine of it through soaking pistons and HDEO use. Now I've got it fixed and I switched to synthetic oil to minimize it going forward as well as extended HDEO use and potential cat issues. Made a post about it a few months ago: http://www.bobistheoilguy.com/forums/ubb...ont#Post3517502
 
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Messages
5,024
Location
Southeast
I have had this happen before---- one thing that has helped/fixed this for me in the past is to scuff up the rotors with sand paper. I actually just let the rotor spin while holding a belt sander to each side and let it go for 20 seconds or so. both sides. this has done what many re-lubes and re-do's and anti-squeal goos have not. Now I do it whenever brakes are done.
 
Messages
4,257
Location
Central Maryland
Originally Posted By: Oro_O
2) Anti-seize was on threads only, not the whole caliper pin, and a generous coating of axle grease on caliper pin bodies (forgot to mention).
Better than nothing, and I used to do this, but I've given up on axle grease and moved on to Sil-Glyde. The reason is axle grease can't take the heat, it was made for bearings not brakes. There are other good choices such as Permatex Ceramic Extreme.
Originally Posted By: Oro_O
4) Ant-squeal/lube: OK, I see an error. I thought the lube pack in the kit was for the caliper pins and I used other lube I had. I'll take them out, clean off the orange goo, fit the shims, and lube with that. That was likely my mistake. I have done a few brake jobs over the years and never had this problem - only issue this time was the shims not wanting to fit.
Lubrication points vary by design, but in general include any part of the brake pad metal backplate that contacts anything else. Besides the caliper pins, your brake may (or may not) have some surface that the brake pad rides along. If so, check it for flatness, replace or dress lightly with a file if necessary, and lightly lube it. As for shims and abutment clips, their design and requirements also vary widely. Many aftermarket pads say they eliminate the need for factory clips and shims, further confusing the issue. In some designs, the abutment clips act as shims that limit the rocking or forward/back movement of the pad. The more the pad is limited the less it can vibrate, but they still require some clearance to let the brake operate properly. Sorry to speak in vague generalities but I'm not familiar with your particular brakes.
 

Oro_O

Thread starter
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2,414
Location
Seattle-ish, WA
Thanks to all, it's gone now. I took the calipers off, wire-brushed the CRC orange stuff off the back of the pads and the old shims. The CRC stuff had basically already hardened and been forced out from between the pads and caliper contact points. It was not doing anything. I put it back together with generous amounts of silicone grease and the original shims, and wiped the pins clear of axle grease and put silicone grease there, degreased rotors before installing wheels. It squeaked once as I was backing out of the garage and had to use the brakes. But after that I did another 'bed-in' run (10 slow downs of increasing pressure before a full stop). I drove a few miles around normally, stops, etc. and no noise. Next time I am by Napa I will get a tube of Syl-Glide and that will be the new method. I will also scuff the rotors with a sander; I've heard of that and it can't be a bad idea. That was my next step if this didn't work (or will be if it comes back). Again, thanks for the help.
 
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1,581
Location
UT
Turn or replace the rotors. Many years ago, I made the mistake of washing my car while I was on a cross country drive, when the brake discs were hot. It cooled the rotors down too fast, and they got a surface glaze. The brakes squealed from that day forward, until I replaced the rotors.
 

Oro_O

Thread starter
Messages
2,414
Location
Seattle-ish, WA
Originally Posted By: BHopkins
Turn or replace the rotors. Many years ago, I made the mistake of washing my car while I was on a cross country drive, when the brake discs were hot. It cooled the rotors down too fast, and they got a surface glaze. The brakes squealed from that day forward, until I replaced the rotors.
Yes, cryo-hardening rotors is a real thing. I've been a life-long motorcyclists and that is the source of my brake performance fetish. And I learned with them long ago to be cautious about water when they are hot. I am good now, but in the future I will follow the advice to scuff/sand them when new pads go in. I've heard that before and in the past have done it on some motorcycle rotors, but never found it necessary on a car. But now I'll start doing it anyway.
 
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18,204
Location
NH
I started getting into the habit of pulling the brakes apart every 5k and lubing the sliding areas of the pad ears--after 10k and certainly by 20k I'm finding heavy corrosion on my fleet. I've been using Sta-Lube and I'm not impressed with it--it's all gone by the end of 5k. Anyhow, a couple of times I wiped it onto the back of the disc pad, where the piston of the caliper hits it. Ever since I seem to have squealing brakes. Coincidence? Not sure. I put the pads back into the same place, but will only lube the ears from now on.
 
Messages
4,257
Location
Central Maryland
Glad you got a handle on it. Virtually all brakes squeak the first time you use them on a drive, especially if you are backing-out. Partly due to rotor surface rust that forms overnight, partly due to the pad settling into the backwards-braking position. I find it squeaks the loudest after a rainy drive and overnight park- more rust.
 
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