loco4rx8

Well, I guess it's all about perception. For all my life, I and most people have been brought up with "If the brakes are squealing, they're going bad." So, even though I know the brakes are fine on my car, it's just kind of embarrassing when they squeal like that because everyone else is thinking, "Oooh nice new car, bad brakes already?"

If the 8 didn't get so much attention, it wouldn't be a big deal. But when you're stylin' up to the light and people are looking at the car, it just is annoying to have this squealing going on.

I guess I need to get over what others are thinking.

takahashi

Start to squeal with my new brake pad - I think it is just the metal to metal vibration during braking as everyone says...

A little noise or dust is ok...

mikeb

mine have always made noise

I feel so stupid rolling up in a NICE BRAND NEW rx8 and having the brakes make noise like I don't know how to maintain my car

6speed8

I only hear the sqeal on very light braking too. If I really press on the brake pedal, it goes away. It is only during light braking because the rear pads are just starting to make contact, and it only happens after I have been driving in traffic for 30 minutes or so. This could explain why some people don't have it or hear it.

You see alot of brake dust on the front wheels, and very very little on the back wheels, this is because the fronts are doing most if not all the work, and hence the rear squeak.

There should be no squeaks or squeals, none of my other Mazdas did, other cars, nor did my Celica (which still had the original pads when I traded it in with 68k miles).

I am sure Mazda will figure it.

bfulmer

Take it from an engineer who has worked in brake industry for 15 years, squealing brakes are not necessarily bad brakes. I'm talking about noise DURING braking. Some noise during braking is someout normal but some brakes squeal more that others. High performance brakes with high friction brake pads will have a tendancy to squeal more. It is always a tradoff in brake designs between braking performance and brake squeal. Mazda my have pushed it little too much for some people and a different lining material may help. As for me, I'll take the squeal because I love the braking performance of the 8. BTW- Brake squeal noise while they are NOT applied means that the brakes are worn out thus allowing a thin metal "wear sensor" to contact the rotor causing a squeal noise. I think this fact it the reason why most people to associate squealing with bad brakes (plus some of the aftermarket pad suppliers falsy beat it into your head with misleading commercials so they can make a buck)

cash_money

I've taken my car in 3 times now for squealing brakes. Like a poster said above, there is nothing worse then rolling up to a stop light in a brand new, showy car and SQUUUUUUEEEEAK!

When I take it in for warranty work, they always tell me the brakes look brand new and can't find a problem with them.

However, I find this unacceptable. I plan to continually tell them everytime I take it in that the brakes squeal, please fix.

Anyway....

jinani4eva

I had that squealing breaks ever since I got the car I think...
Hope Mazda finds something that could lessen the noise a little if possible. I don't think it's pretty to have a showy car that makes squeek sound when u stop at where there's a lot of people.
As cash_money said, I can't take that sound.

DZeckhausen

The root cause of most squealing brake problems is rotors that have not been properly bedded. Try following the instructions on my web site to see if they fix your brake squealing problem: http://www.zeckhausen.com/bedding_in_brakes.htm

rx8cited

Typically how long does the bedding procedure's benefit last? IOW does beddding have to be repeated periodically?

TIA,
rx8cited

DZeckhausen

That depends on the type of pad being used and the driving conditions. It's dangerous to generalize but I'll do so anyway. Most normal street pads can be bedded once and you might never need to do it again. Drivers who only apply the brakes very lightly and are not agressive may find that the street pads don't heat up enough to get into adherent mode and slowly chew away the pad transfer layer from the rotor. After a few months, the squeaking may return and a quick bedding session will cure it.

This is one of those few occasions when driving hard and braking late is good for the car! Such agressive braking helps to maintain and refresh the transfer layer.

Track pads, when driven "cold" on the street, are very abrasive and will chew away the pad transfer layer from the rotors within a very short time. However, when used within thier normal operating range of temperature, they do not un-bed themselves.

A neat little trick when switching back and forth between track and street pads is to install the track pads a day before your event and then drive around with them normally. They will quickly chew away all the street pad's transfer layer, leaving the rotor clean and ready to be bedded. Then you bed the track pads at the track and enjoy your track event. After the event, leave the track pads on and drive home with them. They will cool off and then chew away their own transfer layer, leaving the rotors clean for your street pads. This avoids the vibration problems that frequently plague weekend track cars that are also driven on the street.

Rotary Nut

Mine is the same build and sale date and have had no issues except for this and mine squeal like a banshee! I hope to get it into the shop as soon as possible! It has been going on since about 3000 miles also!

DZeckhausen

Did you try the bedding procedure from my earlier post yet?

Rotary Nut

No!

And it was not mentioned during point of sale. My car now has over 8000 miles on it and I think it would be usless at this point.

DZeckhausen

Why would it be useless? If the rotors aren't bedded, they aren't bedded. Following that procedure, even five years after purchasing the car, should cure your squeaking problem.

Don't be hard on the dealer about failing to mention the technique. Most dealers and even most mechanics haven't got a clue about proper care and feeding of brakes.

Rotary Nut

I'll give it a whirl!

Thanks for the info!

red_rx8_red_int

That works for me also.

rx8cited

I'm wondering how close I'd get to the threshold of warping my rotors by following this procedure?

Why don't rotor / brake manufacturers or the auto manufacturers bed the brakes?

rx8cited

DZeckhausen

Rotors don't "warp" in the way most people think they do. As they heat up, they try to expand in all directions, but they are constrained because they are trapped between the wheel and the hub. As a result, under very high temperature conditions, they start to distort into a cone shape, facing outwards. The result is a soft pedal as the pads no longer fully contact the rotors. A noticeable top-to-bottom pad taper can also result. Mind you, this is under track conditions. As the rotors cool off, they return to their original shape.

The "warping" that you are worried about is characterized by rhythmic pulsation of the brake pedal under braking. Despite what most people think, this is NOT caused by distortion of the rotors. Instead, it is caused by uneven application of pad deposits on the rotors, resulting in a thickness variation that pushes the pads apart and also causes friction level to vary from one section of the rotor to the next.

The bedding process you should follow actually REDUCES the likelihood of this phenomenon. The purpose of bedding is to lay down an even transfer layer of pad material on the rotor surface. This transfer layer causes a second form of friction to become available. The first is called ABRASIVE friction and is simply the friction between pads and rotors, much like sandpaper against a block of wood. The second form of friction is called ADHERENT friction and is caused by molecular bonds forming between the pads and the pad material on the rotor surface. As the rotors continue to turn, the molecular bonds are torn apart and new ones are formed. The resistance of the bonds tearing apart is what gives you a higher friction level and is why bedding brakes is a good thing for improving brake performance.

How does all this relate to "warping" your rotors? If you fail to bed the brakes and then engage in a very hard stop from speed, it's possible that you will put down a partial transfer layer on the rotor. Now, you have greater friction levels on one section of the rotor due to the adherent friction. Under light braking, you may feel the difference in friction level as the brakes seem to grab and partially release under steady pedal pressure. At this point, there is no pedal feedback. Next time you do a hard stop, the section of rotor with transfer layer gets hotter and is more likely to accumulate MORE pad material until finally, at about four ten thousandths of an inch, you can feel it as a pulsation in the pedal. At this point, everyone blames the rotors for the "warping" when, in fact, the rotors are merely innocent bystanders and it is the pads and the driving conditions that have resulted in pad deposits.

The bedding process protects you from this happening. By following the process carefully, you REDUCE the likelihood of experiencing the "warped" rotor symptoms.

If the rotors really did warp in the way most people think they do, resulting in excessive runout (side to side wobbling) the floating calipers can adapt by sliding back and forth on the caliper slide pins. Up to a point, the float in the calipers would completely hide the effects of rotor runout. This point is about 6 thousands of an inch, at which point the inertia of the iron (or aluminum) caliper resists the side to side motion enough to allow the pad to be pushed back in the caliper, pushing the piston in and resulting in pressure waves being transmitted through the master cylinder and down to your foot on the brake pedal. Such runout is usually caused by a defective rotor, improper installation that traps a chunk of dirt or rust between rotor and hub, or a bad rotor turning by a teenager at Pep Boys that actually adds more runout than the rotors had to start with.

It only takes about 1/15 as much rotor thickness variation as runout to have the same symptoms occur, because the caliper can't move in any direction to compensate for a thick spot. The pads are simply pushed apart, resulting in the piston being forced back into the caliper body by the amount of the thickness variation.

Bottom line - don't worry about getting close to the "threshold of warping your rotors!" Just be sure to follow the instructions CAREFULLY. You don't want to come to a complete stop with very hot rotors or you may actually imprint an image of the pads onto the rotors and cause the very problem you are trying to avoid.

Nubo

How thick is this transfer layer if properly bedded? If I were to test for electrical continuity between two spots on the rotor surface would I be able to see a difference (open circuit or high resistance)?

Does this procedure have any affect on the amount of "brake dust" generated during normal driving?

dannobre

iTrader: (3)

OK...bedded the brakes yesterday as per the instructions.....have noticed that the random squeeling has been gone since. The brakes seem to grab better. Very subjective difference in normal driving. Hope this solves the squeeling

MEGAREDS

Is "squealing" something that might be characterized as "ringing?"

Ringing Brakes... What's Causing It?

DZeckhausen

I've heard squealing brakes characterized as all sorts of things! It all depends on the life experiences of the person reporting the problem. People tend to use terms and analogies relevent to their own experiences, which is why diagnosing car problems remotely can be incredibly frustrating at times.

Based on the description in the thread you referenced, as well as the dealer's reaction, I would guess that he/she is also experiencing the same issue and can cure it by following the bedding process.

rx8spiritR

i will not stop my car in the freeway from 60-45 and then gas back to 60 for like what eight or seven times and stop from 60-10 and then gas it back to 60 , people will think "is he nuts???" and probly cops will pull me over.

DZeckhausen

The transfer layer can vary in thickness depending on the type of pads and the bedding process, but it's measured in microns, not thousandths of an inch. And there is no electrical conductivity test you can perform to measure it accurately.

Bedding does reduce the amount of brake dust produced as well as increasing both pad and rotor life.

DZeckhausen

There's no requirement to do this on a crowded freeway. I have a road near me that is a couple miles long, very straight and smooth, and virtually empty of cars. That's enough room for me to do at least 5 slowdowns and, if necessary, pull a U-turn and do a few more on the way back.

If you try this in traffic, people will think you are crazy and they will start reacting in unpredictable ways. Do this early in the morning or late at night if there aren't any isolated road near you. It works and it's good for your brakes. If you're afraid of a traffic ticket, print out a copy of the technique and keep it on the passenger seat. If you get pulled over, hand the printout to the officer and blame me for your behavior!