so i took my 8 in for the clicking while turning, the ac fix as well as complaining about the grinding and figured id throw the squeeking brakes in there again just so its nice and recorded. well they didnt do anything about the grinding gears, but they are going to get me new pads and machine my rotors. however, im not too keen on them machining them and if theyre bad enough to take action i think they should be replaced. i plan to track the car and know its not the best idea to machine rotors and use them on the track, but i guess it all depends on how much they have to take off. any opinions on this one?

 

Don't do it. Have the pads removed and reinstalled with the proper coating of anti-squeal lubricant ($0.99 at ANY auto parts store) between the shims (there are three shims on each side in the front), and you will never hear another sound.

I had to do it to mine at about the 3000 mile mark, and I replaced pads at 10000, and have NEVER heard another sound.

I did it myself in about 30 minutes, and I now have over 14000 miles, and 10-12 autocrosses without another sound.

My $0.02

 

The machining will eliminate the squealing for a time because it results in a non-polished surface on the rotor. It's not a permanent fix. If they are machining because the rotor is out of spec (depth of grooves or runout) then ok, but if their reason is for eliminating the squeal then I'd say it's not worth it. Your rotors come "machined" when brand new, but still developed a squeal.

 

Glad to hear this worked for you.

I put anti-squeal grease on my shims and pad backs - but still have squealing.

If the solution was so simple, I'd hope Mazda would be all over it by now.

rx8cited

 

Brake squeal is a very difficult problem to resolve, and often there is not a "quick fix". The "anti-squeal" grease that you can buy is such a sham. I'm surprised it worked for you tpryor--I think the new pads made the difference, not the lubricant.

My mechanical engineering professor back in grad school has projects on brake squeal funded by the automotive industry. It is NOT a simple problem, and there's no way auto companies would spend tens of thousands of dollars to fund research on this issue if there was a quick fix. Generally, squeal occurs when the properties of the friction material change such that a stick-slip type of excitation energizes the rotors during braking. The rotors then vibrate at one of their natural frequencies giving off a high-pitched squeal. The problem lies in how to effectively change the friction interface between the pads and rotors so that stick-slip excitation doesn't occur. Machining the rotors may help, as will changing the pads. The "anti-squeal" grease claims to reduce squeal by adding damping to the rotor, but the fact is that no thin layer of liquid will provide sufficient damping, and it will eventually just wear off anyway.

So you need to consider how much the squeal really bothers you. If it's not a big deal, I wouldn't have any work done on the rotors and would not have the pads replaced prematurely. Instead, you might want to try the technique some others have suggested: try hard braking from highway speed down to a slow roll several times to "clean" the rotor and pad surfaces. This might alleviate the squealing problem, at least temporarily. If it REALLY bothers you, consider changing the pads or machining the rotors. Unfortunately, I think brake squeal is a common problem on our '8s. It has to do with the aggressive friction material and vibratory characteristics (frequency response) of the rotors.

 

ive tried several of the 70-0 stops on many different occations and it did not solve the problem even temporarily.

im not too worried about the squeeling as i know its not a performance issue, but like i said just wanted the complaint in their records. im going to have them either replace the rotors or do nothing, but why do you recommend against new brake pads?

 

If you don't mind spending the money for pads to potentially solve the problem, then go for it! I was just saying that it would be a waste to replace the pads early if you could deal with the squealing.

 

oh, mazda is paying for it so i dont care!

 

I had my 25000 scheduled service done yesterday. I told them about my brakes squeaking during braking. My service manager told me that Mazda is working on a solution. He said they were trying a different material for the pads. He said when they figure it out and we get the new pads we will put them on for me. I was like sweet. I had the M flash done at my 20000 mile service but for some reason he thought I still had the L. He just came out and told me that they were checking to see if I had the latest flash and I didnt even have to ask them. My dealership has been AWESOME. Bob Moore in Edmond, OK.

 

Well, the first time I did it was putting the original (squealing) pads back on the car - I never heard another sound. LATER, I changed to the new pads, and again the (useless) anti-squeal lubricant, and I have never heard a sound from the new set at all.

So, I never changed the actual friction surface between the pads and rotors, yet I was able to stop the squeal entirely by using a useless (according to you) process?

Maybe there is a dynamic at work here that is not fully understood?

All I know is several race oriented shops recommended it (including Mazda Motorsports), I tried it, and it worked. I offered it as a suggestion only, but I really don't appreciate being implied that I am stupid (using a "sham" method that OBVIOUSLY doesn't work).

It seemed a better solution than machining the rotor down, which diminishes its heat dissapation capability (less metal, heats up faster, more prone to warp), and DOES NOT CHANGE THE MATERIAL INTERACTION AT ALL. It would still be the same pad material on the same rotor material - how does that solve anything?

I'll keep suggestions to myself from now on.....................

 

The sqeaking/Squealing is coming from the BACK brakes. The RX-8 has VENTED rotors in the rear (most cars have solid rotors), so HEAT is probably not the culprit since the back brakes do very little of the work. Because of the Rear vented rotors, I am inclined to believe it could be POSSIBLY(?) the pads get hot, but the rotor cools down quicker than the pads resulting in a temperature mismatch?

It will be interesting to see what (if any) fix Mazda comes up with.

 

tpryor: I'm surprised by your defensive reaction. I didn't mean to **** you off. I'm sure the grease worked for you--all I was saying was that it was surprising to me. I guess I really shouldn't say bad things about the grease since I have no personal experience using it. I was just stating the opinion of my professor back in grad school, who is brilliant when it comes to noise and vibration issues. So I apologize for making it seem like I was poking fun at your suggestion. There is no such thing as a bad suggestion.

Maching the rotors will change the friction interface because it creates a new clean surface--it's not all about the material properties. The old surface could have been wearing unevenly, causing varying braking force as the rotors spun against the pads. The other thing that maching does is to change the vibration characteristics of the rotor, i.e. different mass, inertia, geometry, effective stiffness, etc. Once again, I'm sorry for coming across too strong in my previous reply.

 

The backing grease can work in some cases. RX8 Buckeye rightfully attributes the vibration to stiction (stick-slip). With grease on the backing plate the pads can vibrate in that plane while the grease allows them to "slide" that small distance instead of transferring the vibration to the calipers. Elimination of stiction is also why machining will work temporarily. A used rotor is a highly polished surface. You've probably done the trick where you make a musical tone by rubbing a wet finger against the rim of a wine glass. Or you've squeaked a wet finger along a pane of glass or smooth bathtub. The sound here results from stick-slip as well. If you take a wet finger and rub it against something a little rougher, say a textured formica countertop, you may notice it is harder or impossible to get a squeak going because the "stick" portion of the stick-slip phenomenon has been modified. Homemade telescopes will often use bearing surfaces with one side of teflon and the other of slightly textured formica. This is to minimize stiction, which is an aggravation when the visual effect is magnified 200 times resulting in movement that appears jerky or inability to move small distances without overshooting.

After machining, the rotor surface is far less smooth than the "worn" but polished rotor. This may eliminate the squeal but it does not take long for the rotor to become polished once again.

 

I too took my car in for squeeling brakes. They told me that Mazda was looking into new brake pad material, and as soon as they found the right stuff, they would call me back in. Basically the same thing they told Jump120MPH. Hopefully its true, and we can get new pads out of the deal. Also got the M flash at 13000 miles, and it feels to have a lot more pep .

 

my rx7 always did this !!! I switched from Composit to Matalic pads.. I used the Lube.. nothing ever made it go away forever..

 

so after 2+ months they have finally fixed the problem. new rotors, new brake pads (per the tsb) and it seems to have gone away. granted, ive only had it for a few hours, but i just got back from breaking in my pads and 0 squeel on all 30 stops