New Akebono brakes and wow what a difference!
11-17-15, 02:22 PM
#31
Pole Position
From my own observations it's not that rotors need to be replaced. If don't have any pulsing from the brakes depending on the pads you can turn the rotors and add another set of pads. Some people take a chance and just replace a set of pads without any ill effects although it's better to have them resurfaced so that they match the pads as they break in.
As long as you have enough meat on the rotors there is no reason why you need to replace them however in the most recent times the influx of cheap rotors coming from China makes replacing good rotors vs the cost of resurfacing them a lot more narrow to go through the trouble considering you don't have any down time.
Depending on the car I have found that you can go though two sets of pads before you need to change the rotors.
Regarding the so called warping. The pad material is not the direct source of the high spot. It's the chemical reaction that changes the metal due to hot spots caused by uneven pad deposition which causes the high spots and it's not just pad material that is removed, It's primarily metal.
As long as you have enough meat on the rotors there is no reason why you need to replace them however in the most recent times the influx of cheap rotors coming from China makes replacing good rotors vs the cost of resurfacing them a lot more narrow to go through the trouble considering you don't have any down time.
Depending on the car I have found that you can go though two sets of pads before you need to change the rotors.
Regarding the so called warping. The pad material is not the direct source of the high spot. It's the chemical reaction that changes the metal due to hot spots caused by uneven pad deposition which causes the high spots and it's not just pad material that is removed, It's primarily metal.
Here's a stoptech whitepaper: (excellent read!)
http://www.stoptech.com/technical-su...nd-other-myths
Here is another great article about this subject: (check paragraphs 1,3,4,5,& 6)
http://www.hendonpub.com/resources/a...etails?id=1787
As a side note, one time in my wife's car I had to make a panic stop and brake real hard...and yep had the pedal shimmy right afterwards where there was none before. One gentle pass on the lathe just to clean off the deposits that had bonded on the surface, was all it took to get rid of the pulsation. But I digress...
Last edited by 1BlinkGone; 11-17-15 at 02:46 PM.
11-17-15, 02:48 PM
#32
devh- I come from more than a few decades of past involvement in the Fleet Svc industry as a mechanic and svc tech. There is quite a comprehensive primer on this subject on the Raybestos website. While I agree that just installing new pads is acceptable (and I have done that many times); oftentimes when peeps get that pulsation in the pedal and they think it's a warped rotor, it's simply excess pad in a "high spot"...many times from heated brakes that didn't have a chance to cool down and the parking break set...and sometimes from panic stops when the pulsing isn't caused by this, it's usually from improper torquing techniques that warp the rotor, or uneven pad contact due to an out of true rotor (again, usually from improper torquing procedures). Having said that, Improper torque procedures are probably the #1 culprit of pedal pulsation...followed by rotors with runout "out of spec", or deposits on the rotor surface as I state earlier. Things have changed in the auto industry regarding brakes and today if you're not using a dial indicator to check rotor run-out when installing, you're asking for trouble. This is a grossly misunderstood topic. But let's NOT forget that today's industry doesn't generally make a rotor that you can "turn" a few brake pads worth of jobs anymore. They are simply throwaway parts...this became really prevalent in the early 90's.
Here is a great article about this subject: (check paragraphs 1,3,4,5,& 6)
http://www.hendonpub.com/resources/a...etails?id=1787
Here is a great article about this subject: (check paragraphs 1,3,4,5,& 6)
http://www.hendonpub.com/resources/a...etails?id=1787
Edit: also improper seating of the rotor which wears the rotor unevenly causing a cascading effect that permeates the metal integrity of the rotor.
In regard to the high and low spots I could not understand how it's simply a case of pad deposition that is the source the of the high spot when I could clearly Identify the metal as the source on the rotor face so when this information was brought to my attention by Nick I looked into it and found what is actually happening.
Once I found this link It made a lot more sense to me then simply stating pad deposition.
http://www.autotrackdaymonthly.com/i...-warped-rotors
It gets worse! Once you have the development of DTV the surface of the rotor will begin to heat
unevenly. The high spots will get extremely hot compared to the rest of the rotor. When the temperature
around these high spots reaches 1200 – 1300°F. the cast iron in that area will change structurally and
transform into a material called Cementite. Cementite is far harder than the cast iron of the unaffected
parts of the rotor and will therefore wear considerably less as the rotor wears down with use. Cementite
also has very poor heat sink properties and will therefore continue to run extremely hot resulting in the
rapid spread of the Cementite formation deeper and deeper into the rotor. As a result the DTV will get
progressively worse with time until it becomes literally unbearable under braking. Depending on the
pads used and the driving style of the vehicle owner this process could take 1500 and 3500 miles to
develop and, no, the initial run-out will not necessarily be felt by the driver immediately. Hence the
confusion and clinging to the concept of brake rotors that “warp”.
The rotor has now entered a destructive spiral that will very quickly become irreversible. Rotor
‘skimming’ will only help if the formation of Cementite has just begun on the rotor surface. Once the
formation of the Cementite has spread deeper into the rotor material, skimming will only remove the
surface layer but the DTV (and vibration) will return as the areas of Cementite wear less than the
surrounding cast iron.
unevenly. The high spots will get extremely hot compared to the rest of the rotor. When the temperature
around these high spots reaches 1200 – 1300°F. the cast iron in that area will change structurally and
transform into a material called Cementite. Cementite is far harder than the cast iron of the unaffected
parts of the rotor and will therefore wear considerably less as the rotor wears down with use. Cementite
also has very poor heat sink properties and will therefore continue to run extremely hot resulting in the
rapid spread of the Cementite formation deeper and deeper into the rotor. As a result the DTV will get
progressively worse with time until it becomes literally unbearable under braking. Depending on the
pads used and the driving style of the vehicle owner this process could take 1500 and 3500 miles to
develop and, no, the initial run-out will not necessarily be felt by the driver immediately. Hence the
confusion and clinging to the concept of brake rotors that “warp”.
The rotor has now entered a destructive spiral that will very quickly become irreversible. Rotor
‘skimming’ will only help if the formation of Cementite has just begun on the rotor surface. Once the
formation of the Cementite has spread deeper into the rotor material, skimming will only remove the
surface layer but the DTV (and vibration) will return as the areas of Cementite wear less than the
surrounding cast iron.
Last edited by Devh; 11-17-15 at 04:23 PM.
11-17-15, 06:17 PM
#33
Pole Position
devh- yup failure to properly seat a rotor flush would be a culprit...that would be exposed in the dial indicator procedure which many traditionalists might avoid due to stubbonrness. The actual variance allowed is far less than the eye can see so it's not about just eyeballing it anymore. Today's rotors just aren't as forgiving of ignorance as they were when they were more uh, robustly built. lol...
My oroginal point was the whole "warped rotor" thing is often a misdiagnoses...which all these missives you and I posted, clearly support. hehehe
the cementite phenomena as described in your post is a new one on me. I must go look that up some more... I will say I've never run into a rotor that couldn't be "saved" if they were well within spec. Again, I got out of Automotive in 2000. Perhaps today's metallurgy regarding rotor formulas has played a role in this cementite situation... thanks brudda!
My oroginal point was the whole "warped rotor" thing is often a misdiagnoses...which all these missives you and I posted, clearly support. hehehe
the cementite phenomena as described in your post is a new one on me. I must go look that up some more... I will say I've never run into a rotor that couldn't be "saved" if they were well within spec. Again, I got out of Automotive in 2000. Perhaps today's metallurgy regarding rotor formulas has played a role in this cementite situation... thanks brudda!
Last edited by 1BlinkGone; 11-17-15 at 06:41 PM.
11-17-15, 06:46 PM
#34
devh- yup failure to properly seat a rotor flush would be a culprit...that would be exposed in the dial indicator procedure which many traditionalists might avoid due to stubbonrness. The actual variance allowed is far less than the eye can see so it's not about just eyeballing it anymore. Today's rotors just aren't as forgiving of ignorance as they were when they were more uh, robustly built. lol...
the cementite phenomena as described in your post is a new one on me. I must go look that up some more... I will say I've never run into a rotor that couldn't be "saved" if they were well within spec. Again, I got out of Automotive in 2000. Perhaps today's metallurgy regarding rotor formulas has played a role in this cementite situation... thanks brudda!
the cementite phenomena as described in your post is a new one on me. I must go look that up some more... I will say I've never run into a rotor that couldn't be "saved" if they were well within spec. Again, I got out of Automotive in 2000. Perhaps today's metallurgy regarding rotor formulas has played a role in this cementite situation... thanks brudda!
The cementite phenomenon is something new to me as well. I have read the Stoptech article that you linked as it was linked in another discussion which also mentions the cementite but it did a poor job of explaining the process, to me at least until I looked further.
I did come across a bum rotor that could not be cured and after two attempts I replaced it.
At the time I thought it was more prone to "warp" and after reading the article I now know why.
11-17-15, 07:41 PM
#35
Pole Position
A mentor I had long ago made sure I scrubbed the hub where the rotor meets of any rust with brake cleaner and a metal brush. Now I know the reason and I will incorporate that into my process once more.
The cementite phenomenon is something new to me as well. I have read the Stoptech article that you linked as it was linked in another discussion which also mentions the cementite but it did a poor job of explaining the process, to me at least until I looked further.
I did come across a bum rotor that could not be cured and after two attempts I replaced it.
At the time I thought it was more prone to "warp" and after reading the article I now know why.
The cementite phenomenon is something new to me as well. I have read the Stoptech article that you linked as it was linked in another discussion which also mentions the cementite but it did a poor job of explaining the process, to me at least until I looked further.
I did come across a bum rotor that could not be cured and after two attempts I replaced it.
At the time I thought it was more prone to "warp" and after reading the article I now know why.
Cheers!
AHEM...SORRY FOR THE DERAIL, OP!!!
11-19-15, 11:01 PM
#36
Driver School Candidate
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Location: Ontario
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Does anyone know what the proper model number is for the Centric rotors that will fit both front and rear on my 2010 LS 460L. I have looked on Amazon but have not been able to pin it down on which is the right rotors. I have the Akebono pads for both front and rear with new hardware kits and just need to get the new rotors.
Thanks
Dennis
Thanks
Dennis
11-19-15, 11:19 PM
#37
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Hey guys, so I'll be doing the front brakes this weekend with Akebono Pro-Act pads with new Centric rotors. I was doing some research on the internet looking for the proper bedding procedure when I came across this article 'Proper breaking of Akebono pads'. I was hoping to get everyones thoughts on this. I thought bedding in new pads was necessary for proper wear and preventing premature warping of rotors??
http://www.bimmerforums.com/forum/sh...f-Akebono-pads
http://www.bimmerforums.com/forum/sh...f-Akebono-pads
I just installed centric and akebono up front yesterday, what a difference in ride quality as my oem set was really bad - car is smoother than butter now
Did a typical bed in procedure that I do with my racing brake XT910 pads but doubt it is needed, although it really can't hurt so why not! I believe the type of pad really determines how important this procedure is. I know for sure the OEM pad is much grabbier initially and most likely more prone to build up/deposits on the disks. To me this may very well be the main culprit in the nasty rotor runout that was ruining the driving experience in the vehicle.
11-20-15, 05:36 AM
#38
Pole Position
halfcut
Thanks for the part chart
Dennis
Thanks for the part chart
Dennis
11-20-15, 05:39 AM
#39
new rotors
new rotors are not that expensive, it's around $60 each piece.
and an indy shop can do the whole replacement for $150.
and an indy shop can do the whole replacement for $150.
11-23-15, 05:19 AM
#40
Driver School Candidate
Thread Starter
Quick update since it has been a year since I changed the pads. I love these pads compared to the OEM's because the brakes are no longer grabby and are now very linear. I wish I had changed my rotors because once again the brakes are pulsating. After I changed the pads, I stopped using the auto parking brake which may have extended the rotor warping interval. I also do no not brake hard so I wonder why I am still having this issue unless the Toyota dealer torqued the lug nuts too much.
Also noticed that the brake dust has settled down after the initial month or two and is no longer an issue.
Quick question, if I changed rotors now, do I need to get new pads again as I only have approximately 12,000 miles on these?
Also noticed that the brake dust has settled down after the initial month or two and is no longer an issue.
Quick question, if I changed rotors now, do I need to get new pads again as I only have approximately 12,000 miles on these?
11-23-15, 07:57 AM
#41
Lexus Fanatic
Quick question, if I changed rotors now, do I need to get new pads again as I only have approximately 12,000 miles on these?
07-24-18, 09:10 PM
#42
Driver School Candidate
Quick update now that I have had the new pads for several weeks. The pads are every bit as good as the OEM pads. The brakes are much more linear and they are no longer grabby. The only drawback is they do put out more brake dust than the OEM pads in my opinion. I would still highly recommend them.
08-01-18, 07:06 AM
#43
Driver School Candidate
Thread Starter
I'm trying to better understand your description. The issue I have is I've driven a lot of Porsche cars and when you push on the brakes, it doesn't take much pressure and you don't need to move then more than a few inches and the whole world stops. With the Lexus you have to push it a long distance, the brakes aren't world-stopping, and rather than being linear it's like an EKG reading. And then when you are stopped fully at a red light, I keep "sliding forward" if I don't keep the brake pushed down VERY hard. Again, I know its muscle memory but with the Porsche at a red light all I had to do was put a bit of pressure on the brakes and I stayed put. With the Lexus I feel like I'm stepping on the head of a person resisting arrest, meaning if I don't exert full pressure constantly I will be in trouble. Do these pads fix any of these symptoms?
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