Just put new rotors & pads on and they already squeak

[LT_Z]

I just put new rotors & pads on my 89 240sx fast back. They are the mettalic autozone pads, and they are already squeaking. I put the old shims back on should i leave them off ? should i use that red silicone crap ? why would they be squeking already ?

[SmithSR]

Red silicone crap? Are you talking about the caliper slide lube? It'd be wise to not apply that to your friction material.

Disc brakes squeak. Combinations of heat, heat over time, compound, pad angle(which can cause chatter) and a few other variables can be or are all culprits. There are many factors which contribute to a squeak, and all these are heavily documented all over the internet, and at many local libraries and book stores. Google will probably give you over 5,000 references to read up on, depending on what criteria you enter.

[LT_Z]

Umm, i just put these on they have less than 3 miles on them. the rotors and the pads are brand new. I was wondering if anybody else ran into this.

[SmithSR]

Yes, I have run into this on hundreds and hundreds of vehicles from all sorts of makes and models over the years. Your problem is actually quite common, and is very often misdiagnosed, or is never properly explained as to what can/will cause a squeak. As I stated above, there are several likely culprits...and after a quick search on google, here are a few of the links...

http://www.gosstire.com/Brakes.htm"For example, Nissan has adopted semi-metallic brake linings that provide excellent brake performance. However, because of the metal-to-metal contact between semi-metallic pads and the brake rotor, these pads may sometimes produce more noise than pads with asbestos linings. As a result, some people may think that the noise they hear indicates a problem with the braking system. To further reduce noise, especially for disc brakes, manufacturers such as Nissan have begun introducing non-asbestos organic (NAO) pads. Nevertheless, a certain amount of noise from brake components is not unusual."

http://www.2carpros.com/topics/brakepads.htm

http://www.meineke.com/save/dashboards/2002-10.htm

http://ths.gardenweb.com/forum....html "Newer designed semi-metallic pads have a tendency to squeak like crazy. It seems that the better pads you use, the more they squeak."

http://www.canadiandriver.com/...9.htm"Stopping all brakes squeals is almost impossible, and most manufacturers state in their owner's manual that some brake squeak is normal."

This last link has some good info for trying to eliminate disc brake squeak. Perhaps the "red silicone crap" was packaged as an anti-sqeak material, designed to be applied to the backside of the pad.

"Some are like a silicone rubber that cushions the brake pad to the caliper so the pad does not vibrate. Other types of material are like lubricants, that allow the pad to vibrate without squeaking. Do not use ordinary grease to lubricate the back of the pad. The high temperature created by your brakes will quickly burn it off!"

[s14slide]

Here's something that I found was great and works like a champ. There is this "copper" spray anti-squeal compound. I found it at either Autozone or Pepboys, only a few bucks and will last you a while, I've had my can for 5 brake changes and still have plenty left. It sprays on like spraypaint, just apply to the BACKSIDE of the pad. I completely coat my shims also just to make sure. I never have a problem w/ this stuff. Hope that helps.

[Grant@tirerack]

Another cause may be the other caliper hardware. You should always replace any springs, shims, or pins when doing a brake job. These small metal parts will undergo a lot of heat stress and will not perform as they should keeping everything aligned after a while. Your brake system develops a lot of heat that can fatigue these smaller parts making them less effective. Semi metalic pad compounds are going to make a little more noise than an organic compound pad. That's the main trade off. Make sure you have broken them in correctly according to the enclosed instructions. If you do not get an even transfer film delveloped on the rotors it will cause pulsing and vibration as well. Most makers suggest 6-8 moderate stops from about 30 mph and then 4 or so from 40-50 mph and then park the car to let everything cool off for 12 hours or so. That will bed in the pads correctly and give you a nice even transfer film from the pad compound onto the rotor. Otherwise you get sections of the rotors that will grip better than others when force is applied. This 'grip-release-grip-release' will cause vibration and sometimes noise at lower speeds under moderate braking.