Smoking brake pads

[AlienBug]

Originally Posted by inquirer
Originally Posted by Char Baby
Originally Posted by inquirer
Originally Posted by Char Baby
I may have missed something in your post and others comments however, I am curious to know if you also installed new rotors and if so, did you clean off the machine oil that rotors are shipped with?


No the smoke wasn't from oil. It was from the pads. The rotors aren't new. I had installed them a year ago. They were painted, so they had no oil.
I had them turned before installing the pads.



Very good!



I'm not sure if the pads are good though. I don't mean damaged, but if they are up to the task as I have never experienced smoke from other pads in the past.


Could you help us out and just write the response you want? Everyone is saying your brakes are fine and you keep rejecting this information.

 

[inquirer]

I wrote that I think they are fine too. I don't feel they are currently damaged. But I'm not sure if they have a lower temp limit than the previous pads I have used, because it's the first time pads that I have used smoked.
If they are reaching their limit maybe it's wiser to upgrade. I don't know if it's a good thing to repeatedly smoke the pads, even if they won't immediately get damaged.

 

[CBR.worm]

My thought is that if they didn't smear pad material onto the rotor and disintegrate in that situation, they are probably fine. If you experienced little to no brake fade and the feel is similar to before, they are even more likely to be fine. It is not at all uncommon for brake pads and/or rotors to smoke in that situation, what is uncommon is to come to a full stop and sit there and observe the smoking hot pads and rotors. It is also not uncommon for brake rotors to turn blue or gold, particularly in the center of the swept area - though it usually takes reasonably high temp pads to discolor rotors. They should go back to silver after some regular use. It is more common to have pads overheat and no longer provide stopping power until they cool down. I don't believe Ferodo makes any bad pads, though certainly a pad with an appropriate heat range should be used. The trade off is usually a higher temp pad will have less initial bite and worse cold performance to go along with its higher thermal limits.

All of these things are harder on the caliper seals, brake fluid and wheel bearings than the pads themselves typically.

You can probably find the useable temperature range of these pads, but the fact that they continued to work while hot leads me to believe you were within range.

But, if you are not comfortable with them, swap them for something else.

As for the fluid, my process was always to bleed the fluid if the pedal got soft during repeated hard use, and to bleed them more frequently if I was doing track days or otherwise aggressive braking regularly. I never go more than two years on fluid. I don't know exactly what happens to brake fluid when it gets hot, but I do know that any water vapor in the fluid boils when they get hot, causing all kinds of unpleasantness, which it doesn't seem like you had any issues with.

 

[RayCJ]

When rotors (which are made of a type of cast iron) start turning an amber or light brown color, it means they have reached a temperature of about 500-600F. When they start turning light blue the temperatures are hitting 700-800F and dark blue means 800+ F.

If the discoloration in rotors is not uniform, it means the hardness of the metal is no longer uniform. Eventually, you might start seeing uneven wear in the pads.

The pads can handle these temperatures. It's all the other components that I'd be concerned about especially if this happened over a sustained period of time. Heat soaking (long term high heat) is a greater concern than one or two panic stops. In the OP's case, I would have no idea how hot the bearings got. Once hardened steel gets above approx 400F for sustained temperatures, it starts to anneal (soften). Is the grease in your bearings rated for high temperatures? Grease can cook just like engine oil. Did the brake fluid start to boil? What DOT rating is the fluid and what is it's temperature rating?

I see smoking pads and rotors on track cars all the time. No big deal. Track cars are usually slightly higher performance vehicles and track car owners are used to doing lots of brake maintenance. Folks doing laps on on the track are not out there for 2+ hours -that's for sure.

I think the OP is rightfully concerned about the condition of his brake system. I predict his pads will start wearing unevenly. If the heat was sustained, he just might have cooked some bearings depending on what kind of vehicle this was.

Ray

 

[inquirer]

Originally Posted by CBR.worm
My thought is that if they didn't smear pad material onto the rotor and disintegrate in that situation, they are probably fine. If you experienced little to no brake fade and the feel is similar to before, they are even more likely to be fine. It is not at all uncommon for brake pads and/or rotors to smoke in that situation, what is uncommon is to come to a full stop and sit there and observe the smoking hot pads and rotors.


It is a journey that I have driven countless times visiting a certain mountain resort. At the end of the steep downhill section I reach my destination and of course always come to a stop. I own the car for about a decade and have driven it fast and some times to the limit on the same journey both with Brembo standard pads and Ferodo Premier pads (the non-Eco compound) which are also Ferodo's standard version of brake pads. I have never experienced smoke in the past, although the pads I used are standard street pads and they are not recommended for that kind of driving. There was always a strong smell with the previous pads and you could feel the brakes radiating heat from a distance of lets say about 10 inches, but I have never seen smoke.

This was a first. The Ferodo Premier Eco-Friction are the only pads till now that smoked. Maybe the new compound which has less copper or maybe no cpper at all has a lower temp limit.

Anyway, I didn't experience any fade, certainly not any significant during the drive and the brakes still seem fine after cooling down, although I haven't pushed them that hard since, so I guess you are right and they are currently OK.

Originally Posted by CBR.worm
It is also not uncommon for brake rotors to turn blue or gold, particularly in the center of the swept area - though it usually takes reasonably high temp pads to discolor rotors. They should go back to silver after some regular use. It is more common to have pads overheat and no longer provide stopping power until they cool down. I don't believe Ferodo makes any bad pads, though certainly a pad with an appropriate heat range should be used. The trade off is usually a higher temp pad will have less initial bite and worse cold performance to go along with its higher thermal limits.

All of these things are harder on the caliper seals, brake fluid and wheel bearings than the pads themselves typically.


I use Motul's RBF600 brake fluid which is even intended for racing usage so I think it is almost impossible to boil it on a road with standard brakes. The pad fade temp will be reached before the fluid reaching its boiling point. I have never had any issues with wheel bearings and I have never changed them. The same goes for the calipers, no issues with them. I have only changed a brake line because it had developed a restriction, which I don't know if it is temperature related, but my guess is that it is.[/quote]

Originally Posted by CBR.worm
You can probably find the useable temperature range of these pads, but the fact that they continued to work while hot leads me to believe you were within range.

But, if you are not comfortable with them, swap them for something else.


The pads code is FDB1621. I am very curious to find their temp range. I don't think Ferodo provides that kind of information. At least I haven't been successful with finding it. If you can find it please share it.

I will progressively push the brakes harder and harder and if I see smoke again I think I will replace them. Probably smoke is a sign that they reach their limit and I don't want to risk brake fade and I don't know even if there is no pad fade, if there is a slow degradation of their capabilities if they repeatedly get smoked.

The problem is that the car is Lancer 1.5L and there are no many aftermarket options for spare parts. For example if you look at shock absorbers neither KYB nor Bilstein or Monroe offer an upgrade part, only their lowest range for the car.
The same goes for pads. I would have used Ferodo DS2500 if they were available for my car, but Ferodo does not produce them for it.

Originally Posted by CBR.worm
As for the fluid, my process was always to bleed the fluid if the pedal got soft during repeated hard use, and to bleed them more frequently if I was doing track days or otherwise aggressive braking regularly. I never go more than two years on fluid. I don't know exactly what happens to brake fluid when it gets hot, but I do know that any water vapor in the fluid boils when they get hot, causing all kinds of unpleasantness, which it doesn't seem like you had any issues with.


I too always change brake fluid every 2 years as Motul recommends.
I know that it is a standard practice to bleed it if you boil it. I don't if boiling it means that its boiling point gets lower, but it definitely means that you can reach its boiling point and the fade can happen again.

 

[inquirer]

Originally Posted by RayCJ

When rotors (which are made of a type of cast iron) start turning an amber or light brown color, it means they have reached a temperature of about 500-600F. When they start turning light blue the temperatures are hitting 700-800F and dark blue means 800+ F.

If the discoloration in rotors is not uniform, it means the hardness of the metal is no longer uniform. Eventually, you might start seeing uneven wear in the pads.

The pads can handle these temperatures. It's all the other components that I'd be concerned about especially if this happened over a sustained period of time. Heat soaking (long term high heat) is a greater concern than one or two panic stops. In the OP's case, I would have no idea how hot the bearings got. Once hardened steel gets above approx 400F for sustained temperatures, it starts to anneal (soften). Is the grease in your bearings rated for high temperatures? Grease can cook just like engine oil. Did the brake fluid start to boil? What DOT rating is the fluid and what is it's temperature rating?

I see smoking pads and rotors on track cars all the time. No big deal. Track cars are usually slightly higher performance vehicles and track car owners are used to doing lots of brake maintenance. Folks doing laps on on the track are not out there for 2+ hours -that's for sure.

I think the OP is rightfully concerned about the condition of his brake system. I predict his pads will start wearing unevenly. If the heat was sustained, he just might have cooked some bearings depending on what kind of vehicle this was.

Ray



I use Motul RBF600 brake fluid, which is a DOT 4 fluid with a very high boiling point. I think it's very difficult to boil it. It is used in racing too. I bleed it every 2 years as Motul recommends and I have never felt any fade, I have never felt the pedal getting softer.

The rotors looks like this:

They have turned darker and the color change covers their whole surface that has contact with the pads. What do you make out of it? Is it material from the pads or has the metal of the rotor changed color?

The car is a Mitsubishi Lancer 1.5L, the last model. I heat the brakes periodically. I could feel the heat from 6-10 inches away from the wheels, but I never had any bearing issues. I only have changed a brake hose because of a restriction that caused uneven pad wear. I don't know if that problem was temp related. I have never seen smoke with my previous pads by the way, despite driving the car in the same manner a few times.

By the way if the pads can handle the temp, what's the point of companies offering different compounds with different temp ranges? Is it only for performance reasons? Doesn't this have to do anything with pads' damage?

 

[Panos]

A little bit of smoking after heavy braking for a while before coming to a stop is normal and expected. It just tells that you have reached the upper acceptable temperature range and should be careful not to push harder next time. Simple as that. You should not worry.

 

[inquirer]

Originally Posted by Panos
A little bit of smoking after heavy braking for a while before coming to a stop is normal and expected. It just tells that you have reached the upper acceptable temperature range and should be careful not to push harder next time. Simple as that. You should not worry.


The pads were smoking for about 1 or 2 minutes. I don't know if that's considered a lot of smoke or not, but definitely I'm not going to push that hard immediately. I will gradually increase pressing their limits and if I experience smoke again I will think of an upgrade.

 

[SteveSRT8]

One thing for sure, rotors are NOT steel. They are iron.

I run 9000 pound service vans all over Central Florida. These vans really test brake components. Our rotors routinely turn blue during service, yet our pads last well beyond 100k miles when OEM.

Note: our factory pads do not seem prone to smoking in normal driving but we do experience very high rotor temps. No harm at all.


I believe the OP's issues were pad specific. Brake pads are like ice cream, over a million flavors...

 

[inquirer]

I'm sure the pads are the cause. I only have experienced smoke with this specific pads.
I'm not sure if this is a one time incident because they reached that temperature for the first time or if it is going to be an ongoing issue and I shall seek for other pads.

 

[RayCJ]

Originally Posted by inquirer
Originally Posted by RayCJ

When rotors (which are made of a type of cast iron) start turning an amber or light brown color, it means they have reached a temperature of about 500-600F. When they start turning light blue the temperatures are hitting 700-800F and dark blue means 800+ F.

If the discoloration in rotors is not uniform, it means the hardness of the metal is no longer uniform. Eventually, you might start seeing uneven wear in the pads.

The pads can handle these temperatures. It's all the other components that I'd be concerned about especially if this happened over a sustained period of time. Heat soaking (long term high heat) is a greater concern than one or two panic stops. In the OP's case, I would have no idea how hot the bearings got. Once hardened steel gets above approx 400F for sustained temperatures, it starts to anneal (soften). Is the grease in your bearings rated for high temperatures? Grease can cook just like engine oil. Did the brake fluid start to boil? What DOT rating is the fluid and what is it's temperature rating?

I see smoking pads and rotors on track cars all the time. No big deal. Track cars are usually slightly higher performance vehicles and track car owners are used to doing lots of brake maintenance. Folks doing laps on on the track are not out there for 2+ hours -that's for sure.

I think the OP is rightfully concerned about the condition of his brake system. I predict his pads will start wearing unevenly. If the heat was sustained, he just might have cooked some bearings depending on what kind of vehicle this was.

Ray



I use Motul RBF600 brake fluid, which is a DOT 4 fluid with a very high boiling point. I think it's very difficult to boil it. It is used in racing too. I bleed it every 2 years as Motul recommends and I have never felt any fade, I have never felt the pedal getting softer.

The rotors looks like this:

They have turned darker and the color change covers their whole surface that has contact with the pads. What do you make out of it? Is it material from the pads or has the metal of the rotor changed color?

The car is a Mitsubishi Lancer 1.5L, the last model. I heat the brakes periodically. I could feel the heat from 6-10 inches away from the wheels, but I never had any bearing issues. I only have changed a brake hose because of a restriction that caused uneven pad wear. I don't know if that problem was temp related. I have never seen smoke with my previous pads by the way, despite driving the car in the same manner a few times.

By the way if the pads can handle the temp, what's the point of companies offering different compounds with different temp ranges? Is it only for performance reasons? Doesn't this have to do anything with pads' damage?



The problem of brake fluid boiling-off is the vapor (gas) that liberates from any boiling fluid. This is effectively "air" in your system. If your brakes feel OK now and are not spongy, you're OK. Incidentally, the boiling does not happen until you let your foot off the brake and release pressure. Pressurized fluids have higher boiling point.

Someone here mentioned smearing of the pads on the rotors. This happens on rear brakes a lot when people at the track set the parking brake after a round of hot laps. The metal in the pad can fuse to the rotor. (Never set your parking brake on super-hot brakes).

Your rotors effectively got slightly "heat treated". Not real bad and I've seen them much more discolored than that. Rotors are made of black cast iron which is fairly low-grade but, high carbon material. The surface hardness of your rotors is now much higher than when new. Not a big deal really but, you might start seeing/feeling deeper grooves as time passes. You will not be able to resurface these rotors now because, to get an even finish, you'll need to cut deeply past the hardened surface and then they will be too thin. -Again, no big deal. (BTW, I use an industrial lathe to resurface my rotors and have ways around this problem).

Pads can handle incredible heat and be OK once they cool down. For passenger cars, some are designed to be quiet at the expense of durability. Some pads have greater resistance to fading. Even the lowliest pads can handle more heat than a typical set of iron rotors (depends on size of the rotor really). Beyond a certain point, you're trading longevity for other factors such as fade and loudness.

My biggest "concern" about your vehicle is that with 2 hours of super hot brakes, the rotors got completely heat-soaked. The grease in your bearings or hub-part of your transaxle could have been over heated. Bearings are usually made of a 6250-type of heat treated steel. They may have reached their annealing temperature. I can look it up specifically but, no point really as high-alloys like 6250 start to anneal right around 400F.

If it were my car, I'd sit back and watch the grooves start to show-up as the rotors wear (no big deal) and I'd also check one of the bearings and corresponding grease. If it looks cooked or if the bearings have a heat-discolored appearance, replace them.

You're probably OK because your rotors are a very light blue. Track cars look like this and much worse -but then again, the bearings and rotors are just considered normal wear items.

Ray

 

[inquirer]

Originally Posted by RayCJ
The problem of brake fluid boiling-off is the vapor (gas) that liberates from any boiling fluid. This is effectively "air" in your system. If your brakes feel OK now and are not spongy, you're OK. Incidentally, the boiling does not happen until you let your foot off the brake and release pressure. Pressurized fluids have higher boiling point.

Someone here mentioned smearing of the pads on the rotors. This happens on rear brakes a lot when people at the track set the parking brake after a round of hot laps. The metal in the pad can fuse to the rotor. (Never set your parking brake on super-hot brakes).

Your rotors effectively got slightly "heat treated". Not real bad and I've seen them much more discolored than that. Rotors are made of black cast iron which is fairly low-grade but, high carbon material. The surface hardness of your rotors is now much higher than when new. Not a big deal really but, you might start seeing/feeling deeper grooves as time passes. You will not be able to resurface these rotors now because, to get an even finish, you'll need to cut deeply past the hardened surface and then they will be too thin. -Again, no big deal. (BTW, I use an industrial lathe to resurface my rotors and have ways around this problem).

Pads can handle incredible heat and be OK once they cool down. For passenger cars, some are designed to be quiet at the expense of durability. Some pads have greater resistance to fading. Even the lowliest pads can handle more heat than a typical set of iron rotors (depends on size of the rotor really). Beyond a certain point, you're trading longevity for other factors such as fade and loudness.

My biggest "concern" about your vehicle is that with 2 hours of super hot brakes, the rotors got completely heat-soaked. The grease in your bearings or hub-part of your transaxle could have been over heated. Bearings are usually made of a 6250-type of heat treated steel. They may have reached their annealing temperature. I can look it up specifically but, no point really as high-alloys like 6250 start to anneal right around 400F.

If it were my car, I'd sit back and watch the grooves start to show-up as the rotors wear (no big deal) and I'd also check one of the bearings and corresponding grease. If it looks cooked or if the bearings have a heat-discolored appearance, replace them.

You're probably OK because your rotors are a very light blue. Track cars look like this and much worse -but then again, the bearings and rotors are just considered normal wear items.

Ray



I had my rotors turned in a shop with a lathe before installing the pads. The guy at the shop told me the rotors' metal was hardened around the dimples. I don't know if they can get resurfaced a second time anyway because of thickness.

I know about the thing with the parking brake. Fortunately my car has both rotors and drums in the rear for the parking brake, so I guess I'm safe even if I activate the parking brake when the brakes are hot.

Wouldn't a failing bearing produce noise? Isn't that a standard symptom?

 

[RayCJ]

Originally Posted by inquirer


Stuff snipped...

I had my rotors turned in a shop with a lathe before installing the pads. The guy at the shop told me the rotors' metal was hardened around the dimples. I don't know if they can get resurfaced a second time anyway because of thickness.

I know about the thing with the parking brake. Fortunately my car has both rotors and drums in the rear for the parking brake, so I guess I'm safe even if I activate the parking brake when the brakes are hot.

Wouldn't a failing bearing produce noise? Isn't that a standard symptom?


Two things going on there... If the shop is using a traditional brake lathe then, as the cutting bit passes over the dimple, it loses it's engagement at the cutting junction and cannot re-establish the cut fast enough when it re-engages. This leaves raised spots on one side of the dimple. Those raised spots will kill a set of pads real fast. The way to avoid this is to use a grinding technique (called Blanchard grinding) instead of traditional rotary machine carbide tip cutting. Also... When the rotors are hot the dimple causes the immediate area around them to cool faster. Heating metal does nothing to harden it... Heating it and rapidly cooling it (ie. temperature differentials) causes the martensetic structure of carbon to form -thus hardening it. All rotors with holes, slots or dimples will have hard spots around those features.

Yes... bearings make noise when they go bad. Often, you don't get much warning before metal starts grinding. Again, in your case, I think you're OK but, if you open that up and see burned grease, just change the bearings. Don't play games. When grease gets hot enough to cook and discolor, the bearings are (or will soon be) shot.

Ray

 

[inquirer]

Yeah, it's logical that the areas around holes, slots etc. cool down faster because of better ventilation, but the higher the temp the bigger the temp difference.

I have the car for about a decade and I heat up the breaks a few times every year. I don't know if this time I got them hotter or if the pad had a lower temp limit. Anyway, I have never replaced any wheel bearing all these years. I hope I won't have to do it now, but I'll have a look at them for discoloration.