Rotors
03-26-2008, 07:30 PM
#7
Junior Member
Join Date: Mar 2008
Location: chandler, az
Posts: 17
Speaking of rotors, has anyone ever heard of the surface of a rotor heating up to the point of producing small specks of slag on the rotor where it contacts the pads? By slag I mean like hot solder being dripped on the surface of the rotor. What would cause something like this???
03-26-2008, 07:55 PM
#8
Member
Join Date: May 2006
Location: Austin, Texas
Posts: 155
It might just be my bad luck but I've gotten two bad rotors from Autozone for the Max. The first was warped from the start and the second had a bump on the surface very close to the edge. They are pretty good about taking defective parts back, but its a major pain to re-do the same job over and over. Anyway, just inspect it carefully before leaving the store.
03-27-2008, 12:40 PM
#13
03-28-2008, 09:05 AM
#17
I would just contact Brembo. Go to the site. The guy from Tire Rack told me about the 4/9 date. He said they have been on back order for over a year. I don't know how true that is though. Good luck man, you should find out for sure and get what you want ....don't settle
peace
04-04-2008, 11:16 PM
#20
Senior Member
Join Date: Jun 2004
Posts: 352
04-07-2008, 06:15 PM
#23
04-07-2008, 07:17 PM
#24
Banned
Join Date: Feb 2005
Posts: 4,269
I changed the pads myself last year now im waiting for new pads rotors and hardware to come in and to do it again with the new rotors (should have changed them in the first place) Do they just tap off after you get the caliper off?
04-08-2008, 04:45 PM
#26
Member
Join Date: Jan 2008
Posts: 35
My opinoin - DO NOT GO WITH POWERSLOT. I'll explain if you care to know why......
I have a 2001 Ford F 150. I purchased Powerslot front and back slotted rotors and Hawk pads from Autoanything.com. $106 each for the front rotors... 14k miles later the front rotors are Warped bad!!! It clearly states on the website that you get a 3 year / 36k mile warranty. So I call autoanything, they call powerslot, powerslot says the warranty does not cover warping. ARE YOU FREAKING KIDDING ME? I'm no expert but I was under the assumption that they are slotted for the simple reason of reducing heat and friction which causes them to warp. I could be wrong here....anyways, powerslot pretty much said go $%*# yourself. I don't know how you can say you have a warranty and not back it up. Apparently it only covered manufacture defects. Like the freaking rotor is going to split in two or something while driving..... Well now for the good news. This customer rep at autoanything took ownership of my problem and refunded me 50% of the purchase price on the front rotors. I'm thankful for the people at autoanything. She also submitted a request to have their website department update the site to show warping is not covered. Only 14k of highway miles man...that's rediculous.....
I have a 2001 Ford F 150. I purchased Powerslot front and back slotted rotors and Hawk pads from Autoanything.com. $106 each for the front rotors... 14k miles later the front rotors are Warped bad!!! It clearly states on the website that you get a 3 year / 36k mile warranty. So I call autoanything, they call powerslot, powerslot says the warranty does not cover warping. ARE YOU FREAKING KIDDING ME? I'm no expert but I was under the assumption that they are slotted for the simple reason of reducing heat and friction which causes them to warp. I could be wrong here....anyways, powerslot pretty much said go $%*# yourself. I don't know how you can say you have a warranty and not back it up. Apparently it only covered manufacture defects. Like the freaking rotor is going to split in two or something while driving..... Well now for the good news. This customer rep at autoanything took ownership of my problem and refunded me 50% of the purchase price on the front rotors. I'm thankful for the people at autoanything. She also submitted a request to have their website department update the site to show warping is not covered. Only 14k of highway miles man...that's rediculous.....
04-08-2008, 08:14 PM
#28
I've got the slotted RTPs from AuToMaX_95... they are great:
http://forums.maxima.org/showthread.php?t=279373
http://forums.maxima.org/showthread.php?t=279373
Zinc plated RTP Cross drill, sloted, dimpled
F/R $186 for full set-- $93 for Front pair or Rear pair
(2002-2006 maxima only)
F/R $186 for full set-- $93 for Front pair or Rear pair
(2002-2006 maxima only)
04-09-2008, 12:02 PM
#30
Senior Member
Join Date: Feb 2008
Location: Baltimore MD
Posts: 387
04-14-2008, 07:57 AM
#31
Member
Join Date: Mar 2008
Location: Green Bay, Wisconsin
Posts: 35
my steering shakes when braking at high speed. Took it to midas for a check. They said that I had to resurface all my four rotors and also change all 4 brake pads. Charging me for $340 for all the works. Is the price ok? I have 2 questions. Qn 1. Must I resurface my rear rotors and change my rear pads? (I see my rear pads still have about half left) Qn 2. Must I change my front pads, it also has about half left. Or is it better to change the pads whenever resurfacing is done....
04-14-2008, 08:57 AM
#32
Member
Join Date: Jan 2008
Posts: 35
my steering shakes when braking at high speed. Took it to midas for a check. They said that I had to resurface all my four rotors and also change all 4 brake pads. Charging me for $340 for all the works. Is the price ok? I have 2 questions. Qn 1. Must I resurface my rear rotors and change my rear pads? (I see my rear pads still have about half left) Qn 2. Must I change my front pads, it also has about half left. Or is it better to change the pads whenever resurfacing is done....
If your steering is shaking when braking it's because your front rotors are warped. Which means you should replace them as well as the front pads. Rear rotors and pads don't wear out as much as they only take in about 20% of braking...Your fronts do most the work. So it sounds like the shop is trying to take you for a ride....But it does depend on how old the rotors are and how many miles are on them. That's just my two cents.......
Last edited by bryguy1822; 04-14-2008 at 09:10 AM.
04-14-2008, 08:58 AM
#33
my steering shakes when braking at high speed. Took it to midas for a check. They said that I had to resurface all my four rotors and also change all 4 brake pads. Charging me for $340 for all the works. Is the price ok? I have 2 questions. Qn 1. Must I resurface my rear rotors and change my rear pads? (I see my rear pads still have about half left) Qn 2. Must I change my front pads, it also has about half left. Or is it better to change the pads whenever resurfacing is done....
I know they call it warped rotors but thats suppose to be distortion from heat, my rotors where worn, maybe Nissan puts soft rotors on and really hard pads, kinda like German cars.
depending on mileage get the fluid replaced
04-14-2008, 09:34 AM
#34
my steering shakes when braking at high speed. Took it to midas for a check. They said that I had to resurface all my four rotors and also change all 4 brake pads. Charging me for $340 for all the works. Is the price ok? I have 2 questions. Qn 1. Must I resurface my rear rotors and change my rear pads? (I see my rear pads still have about half left) Qn 2. Must I change my front pads, it also has about half left. Or is it better to change the pads whenever resurfacing is done....
04-15-2008, 07:13 AM
#35
Member
Join Date: Mar 2008
Location: Green Bay, Wisconsin
Posts: 35
Thanks guys for all the helpful info. Now I am armed with useful info to talk to those guys at midas esp wanting to change my rear pads and turn my rear rotors. I might probably go with new rotors since resurfacing them, the problem might appear again several thousand miles later, and I have to change the pads again. What is the price for a pair of Rotorpros rotors and a good pair of pads? Is there a good website anyone can recommend for my purchase?
Last edited by carcraze28; 04-15-2008 at 07:17 AM.
04-15-2008, 08:00 AM
#36
04-17-2008, 05:33 PM
#37
Member
Join Date: Mar 2008
Posts: 58
Thanks To Dave Mann, Society of Automotive Engineers Professional Member
One of the most common brake system customer vehicle performance complaints is brake roughness, pulsation and vibration. As common as this complaint is very few people, including many service technicians, actually understand the true cause of it and what to do to correct it permanently. This leads to misdiagnosis, unnecessary repairs and parts replaced and the likely re-occurrence of the problem a short time later. Brake roughness can be defined as vibration that is felt in the steering wheel, brake pedal and/or seat during vehicle braking. This does not include the normal pulsation that occurs when anti-lock brakes are activated during a panic stop or when on wet, snow or ice covered roads, which can activate the anti-lock brakes.
What typically happens is the customer experiences this type of vibration and pulsation and thinks something is wrong with their brakes and then takes their vehicle into a repair facility. The customer explains the problem and the repair facility technician or service writer either takes the vehicle out for a test drive to confirm the symptoms or pulls it into the shop and starts right in on the brakes. Then they come out to the customer and inform them that their brake rotors are "warped" and they need new rotors and pads (and sometimes hubs), or they can machine the rotors on their bench lathe if there is enough rotor material remaining to meet the manufacturers minimum thickness requirements.
The problem with this diagnosis and repair procedure is that first of all is that brake rotors do not warp. The second problem is that replacing a brake rotor with a new brake rotor or machining the rotor on a bench lathe will only fix the problem temporary. The problem will almost always re-occur after a period of time, thus necessitating further repairs. Brake rotor disc thickness variation or excessive lateral runout, as well as drums that are out of round can cause vibrations and pulsations in the brake pedal and/or steering wheel. Brake lining material transfer onto the rotor can also have an effect on this as well.
Here's what really occurs: all brake rotors and hubs have an associated Lateral Runout (LRO). LRO occurs when two axes are not parallel to each other, such as the axes of the rotor and the hub or the spindle and the rotor/hub. LRO may be caused by manufacturing tolerances, improperly torqued wheel nuts (uneven or excessive torque), corrosion between the brake rotor and the hub, hub with excessive runout, worn or improperly adjusted wheel bearings or any damage or wear. This is what is commonly referred to as "warped" rotors. These so called "warped" rotors do not in and of themselves cause the vibrations and pulsations. Any machined component, such as brake rotors and hubs, are going to have manufacturing tolerances, which include runout. Typical original equipment new rotor runout specifications are in the range of 0.0015-0.002 in. while low quality aftermarket rotors can be significantly higher. In addition to excessive manufacturing tolerances, cheap, low quality aftermarket rotors can have increased impurities and porosity in the metallurgy. I recommend using either the OEM rotors or a high quality aftermarket rotor.
New rotors and hubs are machined to precision tolerances from the auto manufacturers. Aftermarket rotors and hubs are usually not machined to the same tolerances, as the aftermarket manufacturers do not know the OEM specifications, although some are much better than others. Auto manufacturers will either match mount the rotor and hubs or machine the rotor on the hub unit as an assembly. Match mounting is matching up the low spot on the brake rotor with the high spot on the hub. This match mounting process minimizes the runout of the assembled components, but is only a production process. A service technician cannot effectively determine where the high and low spots are in order to match mount the components. Machining the rotor on the hub (and/or spindle) with the proper on-vehicle machining equipment is the very best method and almost completely eliminates runout. But, if they do not effectively prevent rust and corrosion in the joint, over a period of time it will induce runout and eventually brake roughness.
What can occur over a period of time is that whatever runout is in the system coupled with improperly torqued wheel nuts and/or misadjusted or loose wheel bearings and rust and corrosion forming between the rotor and hub surface leads to increases in runout. As you drive your vehicle without using the brakes, such as on the highway, every rotation of the rotor high spot or multiple high spots contacts your brake linings in the caliper, even when you are not using the brakes and wears the high spot or multiple high spots off the rotor which causes a thin spot or multiple thin spots. Over a period of time this repeated process causes what is called Disc Thickness Variation (DTV). DTV is when the rotor thickness is not the same all the way around the rotor. DTV is typically caused by lateral runout. DTV can only be measured with very specialized laboratory testing equipment or with special on vehicle capacitance probes.
When you apply your brakes, and a brake rotor has DTV, the thick and thin spots on the rotor cause the brake pads to move in and out. This in-and-out pad motion causes increases and decreases in brake system pressure, which the driver can feel in the brake pedal. This in-and-out pad motion causes a varying brake force, which is passed to the steering wheel. As the rotor gets hot, it is much more likely to increase thickness variation, thus increasing pedal pulsations as well as steering wheel and other vehicle vibrations. This phenomenon is what many technicians refer to as "warping", however they actually think the rotor warped and needs replacement.
Typical acceptable values for DTV are around 0.0004 in. That's 4 ten thousandths of an inch! As DTV increases beyond 0.0004 in., brake pedal, steering wheel and vehicle vibrations and pulsations will almost always occur.
Replacing a rotor with excessive DTV with another new rotor will only correct the problem temporarily, because eventually the associated LRO with the new rotor will lead to DTV over a period of time, and the problem repeats itself all over again. Machining a rotor with excessive DTV on a bench lathe will only temporarily correct the problem because the rotor is being machined true to the bench lathes spindle and not the spindle on the car, plus the spindle on the bench lathe has its own runout.
The correct method is to machine the brake rotor on the vehicle using an on-vehicle brake lathe. For applications where the rotor is separate from the hub (loose rotor) make certain that both surfaces are free of rust and corrosion and be sure to put a thin layer of nickel anti-seize on the mating surfaces. This will prevent rust induced increases in LRO over a period of time. Rust can form in-between the mating surfaces and exert tremendous forces which will cause increases in tension of the wheel studs and resulting clamp load variation which creates LRO. The LRO will then eventually lead to DTV, brake roughness and vibration. For vehicles with adjustable wheel bearings, be certain to properly adjust the bearing preload prior to machining the rotor.
Brake drums still must be machined on bench lathes as there is no method to machine a drum on-vehicle. Drum brake systems are less sensitive in terms of tolerancing that can cause vibrations and pulsations. Most newer model vehicles these days have 4-wheel disc brake systems. Both front and rear rotors can be machined on-vehicle. Note that I recommend machining new rotors on vehicle as well. That way you can be 100% assured that the entire assembly (rotor, hub and spindle) is a matched and perfectly machined rotating assembly. In addition, make sure the caliper slides freely on the caliper pins or slide mechanism, which will minimize off-brake contact of the brake pads with the rotor.
The on-vehicle brake rotor machining equipment that I recommend which performs the absolute best job is the Pro-Cut On-Vehicle Brake Lathe. It is simply the absolute best on-vehicle brake lathe on the market; the competition doesn't even come close to the results achieved with the Pro-Cut. The Pro-Cut is recommended and approved by Ford, GM and Daimler-Chrysler as well as many other car companies.
I have measured finished LRO values of less than 0.0005 in. with the Pro-Cut, which is less than the tolerances on new rotors. In addition the Pro-Cut uses special cutting bits that produce the proper non-directional micro-finish. The Pro-Cut lathe attaches to the hub and is computerized in order to measure runout of the entire system automatically and compensate for it prior to machining so that a perfect cut is achieved every time. Do not allow a caliper mounted brake lathe to be used on your vehicle. Caliper mounted brake lathes mount on the caliper mounts which are machined in different planes with different cutting tools, therefore a few thousandths difference at the caliper mount will produce a finished machined rotor with runout machined in which will eventually lead to DTV and brake roughness.
What typically happens is the customer experiences this type of vibration and pulsation and thinks something is wrong with their brakes and then takes their vehicle into a repair facility. The customer explains the problem and the repair facility technician or service writer either takes the vehicle out for a test drive to confirm the symptoms or pulls it into the shop and starts right in on the brakes. Then they come out to the customer and inform them that their brake rotors are "warped" and they need new rotors and pads (and sometimes hubs), or they can machine the rotors on their bench lathe if there is enough rotor material remaining to meet the manufacturers minimum thickness requirements.
The problem with this diagnosis and repair procedure is that first of all is that brake rotors do not warp. The second problem is that replacing a brake rotor with a new brake rotor or machining the rotor on a bench lathe will only fix the problem temporary. The problem will almost always re-occur after a period of time, thus necessitating further repairs. Brake rotor disc thickness variation or excessive lateral runout, as well as drums that are out of round can cause vibrations and pulsations in the brake pedal and/or steering wheel. Brake lining material transfer onto the rotor can also have an effect on this as well.
Here's what really occurs: all brake rotors and hubs have an associated Lateral Runout (LRO). LRO occurs when two axes are not parallel to each other, such as the axes of the rotor and the hub or the spindle and the rotor/hub. LRO may be caused by manufacturing tolerances, improperly torqued wheel nuts (uneven or excessive torque), corrosion between the brake rotor and the hub, hub with excessive runout, worn or improperly adjusted wheel bearings or any damage or wear. This is what is commonly referred to as "warped" rotors. These so called "warped" rotors do not in and of themselves cause the vibrations and pulsations. Any machined component, such as brake rotors and hubs, are going to have manufacturing tolerances, which include runout. Typical original equipment new rotor runout specifications are in the range of 0.0015-0.002 in. while low quality aftermarket rotors can be significantly higher. In addition to excessive manufacturing tolerances, cheap, low quality aftermarket rotors can have increased impurities and porosity in the metallurgy. I recommend using either the OEM rotors or a high quality aftermarket rotor.
New rotors and hubs are machined to precision tolerances from the auto manufacturers. Aftermarket rotors and hubs are usually not machined to the same tolerances, as the aftermarket manufacturers do not know the OEM specifications, although some are much better than others. Auto manufacturers will either match mount the rotor and hubs or machine the rotor on the hub unit as an assembly. Match mounting is matching up the low spot on the brake rotor with the high spot on the hub. This match mounting process minimizes the runout of the assembled components, but is only a production process. A service technician cannot effectively determine where the high and low spots are in order to match mount the components. Machining the rotor on the hub (and/or spindle) with the proper on-vehicle machining equipment is the very best method and almost completely eliminates runout. But, if they do not effectively prevent rust and corrosion in the joint, over a period of time it will induce runout and eventually brake roughness.
What can occur over a period of time is that whatever runout is in the system coupled with improperly torqued wheel nuts and/or misadjusted or loose wheel bearings and rust and corrosion forming between the rotor and hub surface leads to increases in runout. As you drive your vehicle without using the brakes, such as on the highway, every rotation of the rotor high spot or multiple high spots contacts your brake linings in the caliper, even when you are not using the brakes and wears the high spot or multiple high spots off the rotor which causes a thin spot or multiple thin spots. Over a period of time this repeated process causes what is called Disc Thickness Variation (DTV). DTV is when the rotor thickness is not the same all the way around the rotor. DTV is typically caused by lateral runout. DTV can only be measured with very specialized laboratory testing equipment or with special on vehicle capacitance probes.
When you apply your brakes, and a brake rotor has DTV, the thick and thin spots on the rotor cause the brake pads to move in and out. This in-and-out pad motion causes increases and decreases in brake system pressure, which the driver can feel in the brake pedal. This in-and-out pad motion causes a varying brake force, which is passed to the steering wheel. As the rotor gets hot, it is much more likely to increase thickness variation, thus increasing pedal pulsations as well as steering wheel and other vehicle vibrations. This phenomenon is what many technicians refer to as "warping", however they actually think the rotor warped and needs replacement.
Typical acceptable values for DTV are around 0.0004 in. That's 4 ten thousandths of an inch! As DTV increases beyond 0.0004 in., brake pedal, steering wheel and vehicle vibrations and pulsations will almost always occur.
Replacing a rotor with excessive DTV with another new rotor will only correct the problem temporarily, because eventually the associated LRO with the new rotor will lead to DTV over a period of time, and the problem repeats itself all over again. Machining a rotor with excessive DTV on a bench lathe will only temporarily correct the problem because the rotor is being machined true to the bench lathes spindle and not the spindle on the car, plus the spindle on the bench lathe has its own runout.
The correct method is to machine the brake rotor on the vehicle using an on-vehicle brake lathe. For applications where the rotor is separate from the hub (loose rotor) make certain that both surfaces are free of rust and corrosion and be sure to put a thin layer of nickel anti-seize on the mating surfaces. This will prevent rust induced increases in LRO over a period of time. Rust can form in-between the mating surfaces and exert tremendous forces which will cause increases in tension of the wheel studs and resulting clamp load variation which creates LRO. The LRO will then eventually lead to DTV, brake roughness and vibration. For vehicles with adjustable wheel bearings, be certain to properly adjust the bearing preload prior to machining the rotor.
Brake drums still must be machined on bench lathes as there is no method to machine a drum on-vehicle. Drum brake systems are less sensitive in terms of tolerancing that can cause vibrations and pulsations. Most newer model vehicles these days have 4-wheel disc brake systems. Both front and rear rotors can be machined on-vehicle. Note that I recommend machining new rotors on vehicle as well. That way you can be 100% assured that the entire assembly (rotor, hub and spindle) is a matched and perfectly machined rotating assembly. In addition, make sure the caliper slides freely on the caliper pins or slide mechanism, which will minimize off-brake contact of the brake pads with the rotor.
The on-vehicle brake rotor machining equipment that I recommend which performs the absolute best job is the Pro-Cut On-Vehicle Brake Lathe. It is simply the absolute best on-vehicle brake lathe on the market; the competition doesn't even come close to the results achieved with the Pro-Cut. The Pro-Cut is recommended and approved by Ford, GM and Daimler-Chrysler as well as many other car companies.
I have measured finished LRO values of less than 0.0005 in. with the Pro-Cut, which is less than the tolerances on new rotors. In addition the Pro-Cut uses special cutting bits that produce the proper non-directional micro-finish. The Pro-Cut lathe attaches to the hub and is computerized in order to measure runout of the entire system automatically and compensate for it prior to machining so that a perfect cut is achieved every time. Do not allow a caliper mounted brake lathe to be used on your vehicle. Caliper mounted brake lathes mount on the caliper mounts which are machined in different planes with different cutting tools, therefore a few thousandths difference at the caliper mount will produce a finished machined rotor with runout machined in which will eventually lead to DTV and brake roughness.
Last edited by saraara; 04-17-2008 at 05:41 PM.