diagnose brake pulsation
03-14-2016, 07:51 AM
#1
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diagnose brake pulsation
I had the front wheels off on my 95 Accord yesterday working on the suspension. My wife said that there was a pulsation in the brakes that I hadn't noticed. I took a quick look at them but didn't see anything with the naked eye. The brake pads were changed when I bought the car. I noticed that the rotors were turned and not replaced, and the brake pads don't look normal, I'm guessing that they are ceramic. I have heard about them warping rotors, but before I condemn them I want to make sure there isn't another problem causing a warping. What kind of tests can I do to make sure there isn't another issue. The problem is definitely in the front, but only felt when braking hard.
03-14-2016, 08:05 AM
#2
Honda-Tech Member
Re: diagnose brake pulsation
I had the front wheels off on my 95 Accord yesterday working on the suspension. My wife said that there was a pulsation in the brakes that I hadn't noticed. I took a quick look at them but didn't see anything with the naked eye. The brake pads were changed when I bought the car. I noticed that the rotors were turned and not replaced, and the brake pads don't look normal, I'm guessing that they are ceramic. I have heard about them warping rotors, but before I condemn them I want to make sure there isn't another problem causing a warping. What kind of tests can I do to make sure there isn't another issue. The problem is definitely in the front, but only felt when braking hard.
The issue sounds like thickness variation. This can be corrected by resurfacing(if applicable) or replacing the front rotors. The runout can be checked with a dial indicator,in order to verify if the rotors are indeed the culprit.
DTV(disc thickness variation) typically occurs when the pads are not bedded in properly and usually results in what many DIY'ers and uninformed "professional" mechanics refer to as warped rotors. Cheap pads can also cause this phenomena if the pads wont bed properly and instead "chunk".
None of this can be seen with the naked eye.
03-14-2016, 08:13 AM
#3
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Re: diagnose brake pulsation
You cant warp brake rotors. The brake pads would catch on fire long before you could generate enough heat to warp the rotors.
The issue sounds like thickness variation. This can be corrected by resurfacing(if applicable) or replacing the front rotors. The runout can be checked with a dial indicator,in order to verify if the rotors are indeed the culprit.
DTV(disc thickness variation) typically occurs when the pads are not bedded in properly and usually results in what many DIY'ers and uninformed "professional" mechanics refer to as warped rotors. Cheap pads can also cause this phenomena if the pads wont bed properly and instead "chunk".
None of this can be seen with the naked eye.
The issue sounds like thickness variation. This can be corrected by resurfacing(if applicable) or replacing the front rotors. The runout can be checked with a dial indicator,in order to verify if the rotors are indeed the culprit.
DTV(disc thickness variation) typically occurs when the pads are not bedded in properly and usually results in what many DIY'ers and uninformed "professional" mechanics refer to as warped rotors. Cheap pads can also cause this phenomena if the pads wont bed properly and instead "chunk".
None of this can be seen with the naked eye.
I don't want to just change things when a problem exists, it will happen again.
03-14-2016, 09:57 AM
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Re: diagnose brake pulsation
It is generally a better idea to replace warped rotors than to resurface them. If a rotor has warped the warping stress exists all through the metal, not just the surface. Resurfacing will seem to fix it initially but they will most likely "re-warp" relatively soon when the stress inside gets heated and cooled during normal use. Rotors are easy to replace yourself and not that expensive either. If you go so far as to get the brake pads off, not a hard job in and of itself if you have the right wrenches and sockets, then you can get the rotors off. It is usually just a couple additional bolts to get the bracket off that holds on the caliper on and you just pop off the rotors. If they're stuck on tap them lightly on the side with a hammer. There are other methods to get off stuck rotors but if you are going to discard them anyway, tapping with a hammer is the quickest and easiest IMHO. There are a lot of YouTube videos from car mechanics like Scotty Kilmer, ChrisFix and NutzAboutBolts that can show you exactly how to do it.
03-14-2016, 10:10 AM
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Re: diagnose brake pulsation
you have no idea what you are talking about user456101. honda RECOMMENDS to resurface rotors until there specified minimum thickness in the service manual.
03-14-2016, 10:15 AM
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Re: diagnose brake pulsation
I don't want to replace the rotors if something like a sticky caliper, or some other issue exists.
03-14-2016, 10:32 AM
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Re: diagnose brake pulsation
if the caliper piston goes back its not a caliper issue, a lot of people pad slap cars (putting new pads on old glazed over or rusty rotors) which can almost guarantee either absolute crap braking performance or a pulsation or both lol. this is because as stated already the pads dont seat correctly into the rotor. so to answer your question yes it could have been caused by a poor/ incorrect brake job and or crappy brake pads.
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03-14-2016, 02:42 PM
#8
Honda-Tech Member
Re: diagnose brake pulsation
It is generally a better idea to replace warped rotors than to resurface them. If a rotor has warped the warping stress exists all through the metal, not just the surface. Resurfacing will seem to fix it initially but they will most likely "re-warp" relatively soon when the stress inside gets heated and cooled during normal use. Rotors are easy to replace yourself and not that expensive either. If you go so far as to get the brake pads off, not a hard job in and of itself if you have the right wrenches and sockets, then you can get the rotors off. It is usually just a couple additional bolts to get the bracket off that holds on the caliper on and you just pop off the rotors. If they're stuck on tap them lightly on the side with a hammer. There are other methods to get off stuck rotors but if you are going to discard them anyway, tapping with a hammer is the quickest and easiest IMHO. There are a lot of YouTube videos from car mechanics like Scotty Kilmer, ChrisFix and NutzAboutBolts that can show you exactly how to do it.
03-14-2016, 03:36 PM
#9
MM Gruppe B
Re: diagnose brake pulsation
From either or both.
Go to your local parts store and pickup whatever set of semi-metallic pads they have, $20 Semi-Metallics will outbrake uber $50+ Ceramic pads. Ceramics suck. All. The. Time. And they will never bed-in properly, by the time you get them hot enough to bed-in they fade. They offer a very strange pedal and brake performance. Brake modulation is not good with ceramics.
The muppet behind the counter may ask you if you have a sedan or coupe, but being a 94-97 it only matters if your car is a 2.2 or V6/Wagon. Only two types of pads.
Find a stretch of road you can safely get up to 60MPH that has little/no traffic on it. I prefer after 1PM on the freeway, usually lunch traffic is gone.
You will want to do at three to five slow downs. Similar to getting off at a short offramp. You want to get the rotors hot but not cooking. You don't want to bake your brakes.
Go from 60-10MPH and then accelerate away, rinse repeat. You don't want to kill your pedal, if the pedal gets spongey then either you have overheated the fluid or it is time to replace the fluid anyway.
With semi-metallics you can usually tell when the heat kicks in as they bite harder with more friction but the same pedal pressure. So don't freak out when they bite, just hold the pedal steady til you get down to 10 and then accelerate away to cool off the rotors. Don't stop until you have completed the bed-in procedure and driven the car after the final bed-in to make sure the rotors/pads/calipers are cooled down. If you stop with the brakes hot, you can actually bake the rotor and create a hard-spot on the rotors. That would require rotor replacement to fix, it cannot be machined.
If the brake pedal starts pulsing while bedding in the pads, keep going. This is caused by one of two things.
Rotors too thin and you are actually feeling the unsupported swept surface of the rotor collapsing into the vanes, there is no fixing this the rotors just need to be replaced.
Or
There is an excessive build up of pad material or high spot on the rotor and you will need to try to wipe it clean by bedding in the pads properly.
Usually what happens is the pulsing gets worse, then it begins to taper off. When it tapers off just keep bedding in the pads until the pulsing goes away.
If the pulsing continues to get worse then there probably is already a hard spot on the rotor and they will just need to be replaced, or they are too thin and need to be replaced.
One thing you cannot do is over bed-in pads/rotors. They are either bed-in or not. Even after the initial bed-in, from time to time the pads/rotors may need to be re-bed-in again if the car is driven sedately.
When bedding in rotors/pads there are three things that happen.
Machining the pad to rotor interface for maximum surface to surface contact.
Transferring pad material to the rotor(actual 'bed-in')
Heating up the pads to burn off the 'green' and mould release that some pads may have. Even pads that are 'pre scorched' will still need to be heated to burn off any excess binders/glue that may be on the surface.
Verify your tire pressures are correct before going out, this will allow better brake control while bedding in.
Go to your local parts store and pickup whatever set of semi-metallic pads they have, $20 Semi-Metallics will outbrake uber $50+ Ceramic pads. Ceramics suck. All. The. Time. And they will never bed-in properly, by the time you get them hot enough to bed-in they fade. They offer a very strange pedal and brake performance. Brake modulation is not good with ceramics.
The muppet behind the counter may ask you if you have a sedan or coupe, but being a 94-97 it only matters if your car is a 2.2 or V6/Wagon. Only two types of pads.
Find a stretch of road you can safely get up to 60MPH that has little/no traffic on it. I prefer after 1PM on the freeway, usually lunch traffic is gone.
You will want to do at three to five slow downs. Similar to getting off at a short offramp. You want to get the rotors hot but not cooking. You don't want to bake your brakes.
Go from 60-10MPH and then accelerate away, rinse repeat. You don't want to kill your pedal, if the pedal gets spongey then either you have overheated the fluid or it is time to replace the fluid anyway.
With semi-metallics you can usually tell when the heat kicks in as they bite harder with more friction but the same pedal pressure. So don't freak out when they bite, just hold the pedal steady til you get down to 10 and then accelerate away to cool off the rotors. Don't stop until you have completed the bed-in procedure and driven the car after the final bed-in to make sure the rotors/pads/calipers are cooled down. If you stop with the brakes hot, you can actually bake the rotor and create a hard-spot on the rotors. That would require rotor replacement to fix, it cannot be machined.
If the brake pedal starts pulsing while bedding in the pads, keep going. This is caused by one of two things.
Rotors too thin and you are actually feeling the unsupported swept surface of the rotor collapsing into the vanes, there is no fixing this the rotors just need to be replaced.
Or
There is an excessive build up of pad material or high spot on the rotor and you will need to try to wipe it clean by bedding in the pads properly.
Usually what happens is the pulsing gets worse, then it begins to taper off. When it tapers off just keep bedding in the pads until the pulsing goes away.
If the pulsing continues to get worse then there probably is already a hard spot on the rotor and they will just need to be replaced, or they are too thin and need to be replaced.
One thing you cannot do is over bed-in pads/rotors. They are either bed-in or not. Even after the initial bed-in, from time to time the pads/rotors may need to be re-bed-in again if the car is driven sedately.
When bedding in rotors/pads there are three things that happen.
Machining the pad to rotor interface for maximum surface to surface contact.
Transferring pad material to the rotor(actual 'bed-in')
Heating up the pads to burn off the 'green' and mould release that some pads may have. Even pads that are 'pre scorched' will still need to be heated to burn off any excess binders/glue that may be on the surface.
Verify your tire pressures are correct before going out, this will allow better brake control while bedding in.
03-14-2016, 03:44 PM
#10
MM Gruppe B
03-14-2016, 03:50 PM
#11
Honda-Tech Member
Re: diagnose brake pulsation
FWIW, on 'warped' rotors...
Warped brake disc and other myths.
Warped brake disc and other myths.
03-14-2016, 03:55 PM
#12
Honda-Tech Member
Re: diagnose brake pulsation
From either or both.
Go to your local parts store and pickup whatever set of semi-metallic pads they have, $20 Semi-Metallics will outbrake uber $50+ Ceramic pads. Ceramics suck. All. The. Time. And they will never bed-in properly, by the time you get them hot enough to bed-in they fade. They offer a very strange pedal and brake performance. Brake modulation is not good with ceramics.
The muppet behind the counter may ask you if you have a sedan or coupe, but being a 94-97 it only matters if your car is a 2.2 or V6/Wagon. Only two types of pads.
Find a stretch of road you can safely get up to 60MPH that has little/no traffic on it. I prefer after 1PM on the freeway, usually lunch traffic is gone.
You will want to do at three to five slow downs. Similar to getting off at a short offramp. You want to get the rotors hot but not cooking. You don't want to bake your brakes.
Go from 60-10MPH and then accelerate away, rinse repeat. You don't want to kill your pedal, if the pedal gets spongey then either you have overheated the fluid or it is time to replace the fluid anyway.
With semi-metallics you can usually tell when the heat kicks in as they bite harder with more friction but the same pedal pressure. So don't freak out when they bite, just hold the pedal steady til you get down to 10 and then accelerate away to cool off the rotors. Don't stop until you have completed the bed-in procedure and driven the car after the final bed-in to make sure the rotors/pads/calipers are cooled down. If you stop with the brakes hot, you can actually bake the rotor and create a hard-spot on the rotors. That would require rotor replacement to fix, it cannot be machined.
If the brake pedal starts pulsing while bedding in the pads, keep going. This is caused by one of two things.
Rotors too thin and you are actually feeling the unsupported swept surface of the rotor collapsing into the vanes, there is no fixing this the rotors just need to be replaced.
Or
There is an excessive build up of pad material or high spot on the rotor and you will need to try to wipe it clean by bedding in the pads properly.
Usually what happens is the pulsing gets worse, then it begins to taper off. When it tapers off just keep bedding in the pads until the pulsing goes away.
If the pulsing continues to get worse then there probably is already a hard spot on the rotor and they will just need to be replaced, or they are too thin and need to be replaced.
One thing you cannot do is over bed-in pads/rotors. They are either bed-in or not. Even after the initial bed-in, from time to time the pads/rotors may need to be re-bed-in again if the car is driven sedately.
When bedding in rotors/pads there are three things that happen.
Machining the pad to rotor interface for maximum surface to surface contact.
Transferring pad material to the rotor(actual 'bed-in')
Heating up the pads to burn off the 'green' and mould release that some pads may have. Even pads that are 'pre scorched' will still need to be heated to burn off any excess binders/glue that may be on the surface.
Verify your tire pressures are correct before going out, this will allow better brake control while bedding in.
Go to your local parts store and pickup whatever set of semi-metallic pads they have, $20 Semi-Metallics will outbrake uber $50+ Ceramic pads. Ceramics suck. All. The. Time. And they will never bed-in properly, by the time you get them hot enough to bed-in they fade. They offer a very strange pedal and brake performance. Brake modulation is not good with ceramics.
The muppet behind the counter may ask you if you have a sedan or coupe, but being a 94-97 it only matters if your car is a 2.2 or V6/Wagon. Only two types of pads.
Find a stretch of road you can safely get up to 60MPH that has little/no traffic on it. I prefer after 1PM on the freeway, usually lunch traffic is gone.
You will want to do at three to five slow downs. Similar to getting off at a short offramp. You want to get the rotors hot but not cooking. You don't want to bake your brakes.
Go from 60-10MPH and then accelerate away, rinse repeat. You don't want to kill your pedal, if the pedal gets spongey then either you have overheated the fluid or it is time to replace the fluid anyway.
With semi-metallics you can usually tell when the heat kicks in as they bite harder with more friction but the same pedal pressure. So don't freak out when they bite, just hold the pedal steady til you get down to 10 and then accelerate away to cool off the rotors. Don't stop until you have completed the bed-in procedure and driven the car after the final bed-in to make sure the rotors/pads/calipers are cooled down. If you stop with the brakes hot, you can actually bake the rotor and create a hard-spot on the rotors. That would require rotor replacement to fix, it cannot be machined.
If the brake pedal starts pulsing while bedding in the pads, keep going. This is caused by one of two things.
Rotors too thin and you are actually feeling the unsupported swept surface of the rotor collapsing into the vanes, there is no fixing this the rotors just need to be replaced.
Or
There is an excessive build up of pad material or high spot on the rotor and you will need to try to wipe it clean by bedding in the pads properly.
Usually what happens is the pulsing gets worse, then it begins to taper off. When it tapers off just keep bedding in the pads until the pulsing goes away.
If the pulsing continues to get worse then there probably is already a hard spot on the rotor and they will just need to be replaced, or they are too thin and need to be replaced.
One thing you cannot do is over bed-in pads/rotors. They are either bed-in or not. Even after the initial bed-in, from time to time the pads/rotors may need to be re-bed-in again if the car is driven sedately.
When bedding in rotors/pads there are three things that happen.
Machining the pad to rotor interface for maximum surface to surface contact.
Transferring pad material to the rotor(actual 'bed-in')
Heating up the pads to burn off the 'green' and mould release that some pads may have. Even pads that are 'pre scorched' will still need to be heated to burn off any excess binders/glue that may be on the surface.
Verify your tire pressures are correct before going out, this will allow better brake control while bedding in.
A simple 10-15 stops with moderate brake pressure, from 30 mph will do just fine.
03-14-2016, 04:04 PM
#13
MM Gruppe B
Re: diagnose brake pulsation
If everything was new, maybe. Ceramics and Organics don't take much to bed in.
Semi-metallics do need some loving with the pedal. 30MPH will not generate enough heat to have a nice transfer layer. The higher speed/heat created will also show up any other problems that the system has. Rather find a problem now during testing/bedding than when you need the brakes to work 40' ago.
Semi-metallics do need some loving with the pedal. 30MPH will not generate enough heat to have a nice transfer layer. The higher speed/heat created will also show up any other problems that the system has. Rather find a problem now during testing/bedding than when you need the brakes to work 40' ago.
03-14-2016, 09:23 PM
#14
Re: diagnose brake pulsation
It is generally a better idea to replace warped rotors than to resurface them. If a rotor has warped the warping stress exists all through the metal, not just the surface. Resurfacing will seem to fix it initially but they will most likely "re-warp" relatively soon when the stress inside gets heated and cooled during normal use. Rotors are easy to replace yourself and not that expensive either. If you go so far as to get the brake pads off, not a hard job in and of itself if you have the right wrenches and sockets, then you can get the rotors off. It is usually just a couple additional bolts to get the bracket off that holds on the caliper on and you just pop off the rotors. If they're stuck on tap them lightly on the side with a hammer. There are other methods to get off stuck rotors but if you are going to discard them anyway, tapping with a hammer is the quickest and easiest IMHO. There are a lot of YouTube videos from car mechanics like Scotty Kilmer, ChrisFix and NutzAboutBolts that can show you exactly how to do it.
Whenever I have went with cheapo rotors in the past, after some hard breaking they tend to pulsate, which I believe to be related to the rotor warping. Even after resurfacing the warpage comes right back. If it was just residual brake pad material, then the issue shouldn't be coming back since you've removed that suspect material.
If you've ever used a cheapo pan in the oven and after a few minutes you hear it warp to the side you can get an idea of what appears to be going on.
You'll notice this doesn't occur with Honda or high quality name brand rotors. It seems the dark colored rotors are the way to go. Light colored rotors I've found just aren't as strong or able to hold up to the 800 or so degrees that brake rotors get up to. Atleast that's what I've found.
Another thing to keep in mind is that rotors that appear to be warped are never in their warped position until they get good and hot so if someone is testing them for warpage they would need to heat them up to 500 or so minimum to be able to test them accurately. When you first drive a car from cold they don't pulsate until they get hot enough.
03-15-2016, 05:02 AM
#15
Re: diagnose brake pulsation
I have use the Akebono ProACT pads, which I think are ceramic, for some time with excellent results. These pads need to be warmed up before they bite really well, and seem to exhibit the characteristics for the metallic pads as described above. Are these pads different from the average ceramic pad?
03-15-2016, 08:24 AM
#16
Honda-Tech Member
Re: diagnose brake pulsation
If everything was new, maybe. Ceramics and Organics don't take much to bed in.
Semi-metallics do need some loving with the pedal. 30MPH will not generate enough heat to have a nice transfer layer. The higher speed/heat created will also show up any other problems that the system has. Rather find a problem now during testing/bedding than when you need the brakes to work 40' ago.
Semi-metallics do need some loving with the pedal. 30MPH will not generate enough heat to have a nice transfer layer. The higher speed/heat created will also show up any other problems that the system has. Rather find a problem now during testing/bedding than when you need the brakes to work 40' ago.
03-15-2016, 08:30 AM
#17
Honda-Tech Member
Re: diagnose brake pulsation
Of course you do.
The rotor is not warping.
LoL not even close to being the same thing.
The stupidity of your comments never fail to entertain. Do you practice in front of a mirror?....
Whenever I have went with cheapo rotors in the past, after some hard breaking they tend to pulsate, which I believe to be related to the rotor warping. Even after resurfacing the warpage comes right back. If it was just residual brake pad material, then the issue shouldn't be coming back since you've removed that suspect material.
Another thing to keep in mind is that rotors that appear to be warped are never in their warped position until they get good and hot so if someone is testing them for warpage they would need to heat them up to 500 or so minimum to be able to test them accurately. When you first drive a car from cold they don't pulsate until they get hot enough.
03-15-2016, 08:42 AM
#18
Honda-Tech Member
Re: diagnose brake pulsation
I have use the Akebono ProACT pads, which I think are ceramic, for some time with excellent results. These pads need to be warmed up before they bite really well, and seem to exhibit the characteristics for the metallic pads as described above. Are these pads different from the average ceramic pad?
03-15-2016, 12:29 PM
#19
Re: diagnose brake pulsation
I don't just read out of a book, I actually use my brain.
03-15-2016, 02:38 PM
#20
Honda-Tech Member
Re: diagnose brake pulsation
LoL, now youre making up posts. Oh **** what a true clown you are!
I never EVER made that post about saying you were wrong. Post a link to that thread and prove otherwise
I never EVER made that post about saying you were wrong. Post a link to that thread and prove otherwise
03-15-2016, 03:50 PM
#22
Re: diagnose brake pulsation
Satire | Definition of Satire by Merriam-Webster
03-15-2016, 06:53 PM
#23
MM Gruppe B
03-17-2016, 08:50 AM
#24
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Re: diagnose brake pulsation
There is so much incorrect information in this thread, I don't even know where to start. DCFIVER, have you ever resurfaced a disk? As in put the disk on the machine, and turned it down? The thickness is typically not what varies. The rotor warps side to side, in other words the pad surface is no longer true to the surface against the hub. So as it rotates, the pad surface moves slightly side to side. This causes that annoying shake everyone experiences in the steering wheel with warped rotors.
03-19-2016, 03:27 PM
#25
Honda-Tech Member
Re: diagnose brake pulsation
There is so much incorrect information in this thread, I don't even know where to start. DCFIVER, have you ever resurfaced a disk? As in put the disk on the machine, and turned it down? The thickness is typically not what varies. The rotor warps side to side, in other words the pad surface is no longer true to the surface against the hub. So as it rotates, the pad surface moves slightly side to side. This causes that annoying shake everyone experiences in the steering wheel with warped rotors.
