“Finally”… a correction for Rear Brake Moan Noise

[cprcubed]

I haven't seen any reports back from anyone here that had 2308 done, so I think he's blowing smoke. Doesn't seem like the parts are readily available yet. Just my opinion, but I don't think the rear brake moan is a pad material issue. Cheers!

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[DirtyLuke]

Just had my "22 BSOB in for a PA state inspection. Talked to service writer about rear brake noise, having had them try various fixes over the past two years. I mentioned TSB 23-2308 and his reply was that it "doesn't work."

... He then said that installing ceramic disks would stop the noise but Ford won't authorize it to be done. So, if you want to fix the noise problem, you'll have to spend $200+ for ceramic brakes.

It's pretty well understood by now that the noise is a resonance mode in the rear brake system and not a mechanical grinding of any parts. With that said, I totally believe that changing the material of the rotors would solve the problem by changing the natural resonance frequencies of the rotor.

But, if the rotor material was the only reason we get a resonance, it would happen in the forward direction too. My hypothesis is that the pads (or the whole caliper bracket) shift when run in reverse into a position where they touch the rotor like a glass harp. The new TSB replaces the caliper spring. I'm hoping that changes or eliminates the pad/bracket shift, which alone could stop the resonance.

My BS is at the dealer as of yesterday for the TSB. Annoyingly, they have to do the formal diagnostic process in order for it to be under warranty, so I have to leave it there for several days. If the resonance doesn't go away completely after that, new rotors will be my last resort.

 

[Glamdring70]

"Use ceramic brakes" is not a cure-all phrase. There are many components to the brake system and many characteristics of those components. My Bronco has the adaptive cruise system. Do I want the system to operate via components that have different characteristics than Ford programmed/tested/built it for? NO!

 

[Mark S.]

"Use ceramic brakes" is not a cure-all phrase. There are many components to the brake system and many characteristics of those components. My Bronco has the adaptive cruise system. Do I want the system to operate via components that have different characteristics than Ford programmed/tested/built it for? NO!

Exactly. In addition, ceramic pads typically do not provide the same level of stopping power, and do not absorb heat like other pad material. That means the heat your brake pads would normally hold and dissipate is now going into other components in the system, like the calipers, fittings, and brake lines. There is no way short of testing to determine how those components will respond to the increased heat load.

Brakes are the most critical safety system on your car. You really ought to know what you're doing if you plan to modify them.

 

[Mwittke5857]

I've grown kinda fond of my whale noise. ?????

EBC Yellowstuff Street and Track Brake Pads $120

 

[Glamdring70]

Exactly. In addition, ceramic pads typically do not provide the same level of stopping power, and do not absorb heat like other pad material. That means the heat your brake pads would normally hold and dissipate is now going into other components in the system, like the calipers, fittings, and brake lines. There is no way short of testing to determine how those components will respond to the increased heat load.

Brakes are the most critical safety system on your car. You really ought to know what you're doing if you plan to modify them.

Yeah, I don't know how different the components are. On a vehicle from the last century, or even the last decade, I would be comfortable going into NAPA and picking up whatever mid-grade pads they stocked and a set of rotors and changing my hardware. As a driver I could get used to the different feel and function. I get nervous enough about the adaptive cruise stopping for stopped traffic without (un)intentionally altering the algorithm. And we all know if it crashes on ACC, that's the first thing they'll look at to determine fault.

I have a feeling that what is going on with the "whale noise" issue, is that the pads are wearing in for forward travel. This pushes the pad one direction and wears it accordingly. So when you reverse, the pressure between the pad and rotor "pulls" the pad opposite direction and it makes worse contact leading to the vibration/noise. New pads would absolutely fix that... until they also break in/ wear in the same way. I can live with how often mine does it (I park in a garage and back it in so no early AM whales for me) but when it's time for brakes, I may try to get the upgrade done then. I's not worth a few days of dealer diagnosis and possibly "speaking to the manager" about it.

 

[Meanderthal]

Exactly. In addition, ceramic pads typically do not provide the same level of stopping power, and do not absorb heat like other pad material. That means the heat your brake pads would normally hold and dissipate is now going into other components in the system, like the calipers, fittings, and brake lines. There is no way short of testing to determine how those components will respond to the increased heat load.

Brakes are the most critical safety system on your car. You really ought to know what you're doing if you plan to modify them.

I don’t know where you believe the heat from the brake pads dissipates to, but there isn’t enough free space for it to go much of anywhere other than the calipers and then the brake fluid and then the brake lines. If the ceramic is not dissipating the heat as quickly then the brake pad will just stay hotter than an organic pad. Which is the opposite of what you seem to be inferring.

I know that nobody is truly interested in a scientific discussion of heat transfer but “conduction” is the most efficient form (vs. radiation or convection).

This FUD about ceramic pads not braking as well as organic is just such a minor issue that some seem to latch onto. There is a difference in braking performance but it is small and really not worth talking about for the average person. Thousands (probably more) of cars are using ceramic brake pads and they aren’t constantly in rear in collisions or blowing through stop lights because of poor braking performance.

 

[Mark S.]

I don’t know where you believe the heat from the brake pads dissipates to, but there isn’t enough free space for it to go much of anywhere other than the calipers and then the brake fluid and then the brake lines. If the ceramic is not dissipating the heat as quickly then the brake pad will just stay hotter than an organic pad. Which is the opposite of what you seem to be inferring.

Slowing a mass using disc brakes converts mass momentum into heat. Different pad materials absorb and dissipate heat differently. Ceramic material does not absorb heat as readily as other materials, which is why it was one of the critical components of the Space Shuttle thermal protection system meant to prevent the Shuttle from burning on atmospheric reentry.

Ceramic pads do not absorb as much heat as other pad material, and that heat has to go somewhere.

https://www.advicsaftermarket.com/technical-resources/tech-tips/pros-and-cons-of-ceramic-brake-pads/

https://www.bridgestonetire.com/learn/maintenance/ceramic-vs-metallic-brake-pads/

https://www.minit-tune.com/blog/the-pros-and-cons-of-ceramic-organic-and-metallic-brake-pads

 

[Meanderthal]

Slowing a mass using disc brakes converts mass momentum into heat. Different pad materials absorb and dissipate heat differently. Ceramic material does not absorb heat as readily as other materials, which is why it was one of the critical components of the Space Shuttle thermal protection system meant to prevent the Shuttle from burning on atmospheric reentry.

Ceramic pads do not absorb as much heat as other pad material, and that heat has to go somewhere.

https://www.advicsaftermarket.com/technical-resources/tech-tips/pros-and-cons-of-ceramic-brake-pads/

https://www.bridgestonetire.com/learn/maintenance/ceramic-vs-metallic-brake-pads/

https://www.minit-tune.com/blog/the-pros-and-cons-of-ceramic-organic-and-metallic-brake-pads

So if the pads are not absorbing the heat, then the heat is going into the disc, where it has the most material volume and exposure to the air so that it can be dissipated.

From your sources about ceramic brake pads:

1. Efficient heat dissipation which yields a longer brake pad lifespan susceptibility to fading or warping.
2. Also, since both ceramic and copper can’t absorb as much heat as other types of materials, more of the heat generated by braking will pass through the brake pads and into the rest of the braking system.
3. In addition, ceramic doesn’t absorb as much heat as other materials. Consequently, more stress is distributed to the rest of the braking system.

One source claims they dissipate heat efficiently. The other two claim that they don’t absorb the heat so they pass it on to other components. From an engineering standpoint, this sounds like mumbo jumbo. If the pads aren’t absorbing as much heat, then the heat must be absorbed by the disk. The more heat the pads absorb, the more heat will get passed on into the caliper/fluid/lines.

All of the choices for brake pads are shades of gray. Some more heat here, some more noise there, some more wear, some more dust. Maybe the dust side is the one that is less gray than others. If you are operating the vehicle in extreme conditions (very cold, heavy towing, track racing) then things get less gray. For the average driving conditions, there isn’t enough difference between their performance to say that one is ”safer” or “performs better”.

 

[Mark S.]

The more heat the pads absorb, the more heat will get passed on into the caliper/fluid/lines.

Makes sense. This graphic is a good illustration:

Ceramic is a great insulator, which is why they used it on the Space Shuttle. You can see in the video below that the heat simply doesn't go through to the other side of the tile.



I think the primary danger is overheating the rotor, since heat that would have transferred to the calipers stays in the rotor.

There seems to be a lot of inconsistency out there regarding the pros and cons of different pad material. It likely has much to do with who is selling what!

All of the choices for brake pads are shades of gray. Some more heat here, some more noise there, some more wear, some more dust. Maybe the dust side is the one that is less gray than others. If you are operating the vehicle in extreme conditions (very cold, heavy towing, track racing) then things get less gray. For the average driving conditions, there isn’t enough difference between their performance to say that one is ”safer” or “performs better”.

Agreed! The manufacturer's recommendation is generally the best option for most.

 

[Escape2Bronco]

Mine was definitely much louder this morning after last week's snowstorms and cold weather. They finally started putting salt down yesterday and it clearly didn't like getting put away with all that crap on it. I'm guessing it go back to normal tomorrow which for me is just fine. As long as it stops, I'm not too concerned. I've been replacing my own brakes for 50 years and haven't had any failures and my pads or shoes have always just been Bendix or similar so I don't get too concerned about that either.

 

[Escape2Bronco]

I heard the Bronco Sport mating call answered yesterday by an Infinity QX50. That could make an interesting pair! It’s been really foggy this past few days. Must put the Sport “in the mood”.

 

[Mark S.]

I heard the Bronco Sport mating call answered yesterday by an Infinity QX50. That could make an interesting pair! It’s been really foggy this past few days. Must put the Sport “in the mood”.

Wait'll you hear the "whale call" from a stopping 18-wheeler.

 

[Escape2Bronco]

Wait'll you hear the "whale call" from a stopping 18-wheeler.

Not sure I want to be that close to that mating activity!

 

[Spartan007]

I appreciate everyone's opinion on these forums. Should I skip the dealer and just take it to a brake specialist for non-biased opinion? Just at the point I keep getting the run around from my dealer (telling me they hear nothing, or they need to keep it for a week which I cannot do without a vehicle that long). Feel like they dont want to bother with it as they wont make any money doing the TSB work. Also, keep hearing none of these "fixes" are actually eliminating the problem.

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