Straight talk about brake rotors
01-04-2015, 02:52 AM
#1
4th Gear Member
Thread Starter
Join Date: Mar 2006
Location: CA
Posts: 1,313
Straight talk about brake rotors
I wanted to start a friendly conversation about the utility of upgrading/using higher quality brake rotors.
I recently returned from running at Laguna Seca last weekend and it was awesome to say the least. I had upgraded my front brake set up to GT500 14" brembo calipers and rotors. For the street I had a generic auto zone ceramic pad that came with the calipers as well as vented and slotted auto zone rotors. For the track day I switched in some PFC 08 racing pads a couple days before to get them seated. They were phenomenal on the track and wore exceptionally well. The rotors did get scorched in places and seemed to lay down uneven brake pad material. I switched back to my street pads and they seem fine. The rear set up is stock rotors with Hawk HPS pads and I had no issues at the track.
The discussion I want to get into is replacement rotors, their utility, benefits, etc.
Shopping around, I can find the vented 14" rotor from AutoZone for $59 for the pair. Ford replacement rotors for $89. Power Slots, Stop Tech, Baer two piece rotors, etc at costs closers to $300 a pair and higher. Some are plain, some are slotted, some drilled, some slotted and drilled. Some cryo, some zinc coated, etc etc.
It seems like most rotors these days can't be turned if they warp so they are pretty much a one time use.
I understand the debate between using a flat rotor vs a slotted or drilled. On the one hand you lose surface area but may gain better heat dissipation. And its the heat that can warp a rotor.
My question is from a cost vs performance issue what is the rotor to go with? Why do certain rotors cost more? Is is the type or quality of the materials, the thickness, the weight, the name? Is a two piece lighter weight rotor that is drilled actually provide better performance than a $59 AutoZone rotor from China? With all things else staying constant, no brake cooling ducting, track pads, Motul 600 fluid, ss lines, same tires, etc. Which type of rotor will outperform the cheap ones? Will they last longer, resist warping better, stop shorter? Or is it just they look nicer and have a brand name?
I'm asking myself if I can have 3 sets of plain vented rotors for the cost of a two piece lighter weight rotor, will I actually see a difference at the track?
I'm hoping the track rats and autocross people or anyone with significant knowledge will chime in.
Thanks
I recently returned from running at Laguna Seca last weekend and it was awesome to say the least. I had upgraded my front brake set up to GT500 14" brembo calipers and rotors. For the street I had a generic auto zone ceramic pad that came with the calipers as well as vented and slotted auto zone rotors. For the track day I switched in some PFC 08 racing pads a couple days before to get them seated. They were phenomenal on the track and wore exceptionally well. The rotors did get scorched in places and seemed to lay down uneven brake pad material. I switched back to my street pads and they seem fine. The rear set up is stock rotors with Hawk HPS pads and I had no issues at the track.
The discussion I want to get into is replacement rotors, their utility, benefits, etc.
Shopping around, I can find the vented 14" rotor from AutoZone for $59 for the pair. Ford replacement rotors for $89. Power Slots, Stop Tech, Baer two piece rotors, etc at costs closers to $300 a pair and higher. Some are plain, some are slotted, some drilled, some slotted and drilled. Some cryo, some zinc coated, etc etc.
It seems like most rotors these days can't be turned if they warp so they are pretty much a one time use.
I understand the debate between using a flat rotor vs a slotted or drilled. On the one hand you lose surface area but may gain better heat dissipation. And its the heat that can warp a rotor.
My question is from a cost vs performance issue what is the rotor to go with? Why do certain rotors cost more? Is is the type or quality of the materials, the thickness, the weight, the name? Is a two piece lighter weight rotor that is drilled actually provide better performance than a $59 AutoZone rotor from China? With all things else staying constant, no brake cooling ducting, track pads, Motul 600 fluid, ss lines, same tires, etc. Which type of rotor will outperform the cheap ones? Will they last longer, resist warping better, stop shorter? Or is it just they look nicer and have a brand name?
I'm asking myself if I can have 3 sets of plain vented rotors for the cost of a two piece lighter weight rotor, will I actually see a difference at the track?
I'm hoping the track rats and autocross people or anyone with significant knowledge will chime in.
Thanks
01-04-2015, 08:29 AM
#2
1st Gear Member
Join Date: Nov 2013
Location: New Hampshire
Posts: 66
The stock rotors are fine unless you are road racing for trophies. And then you will want more suspension work based on you sig. For track days on street tires the suspension you have is nice.
So just Pads and cooling are key.
I run JLT brake cooling. Inexpensive and worked well but would look at Vorschlag kit if doing cooling kit again as I like their latest design.
Rear rotor covers removed.
Carbotech pads are superb. After discussion with the Carbotech tech line I use XP24 front and XP12 rear. With street tires not sure you can get enough heat in the XP24. So call the tech line. You may be better with XP12 on the front and XP8 rear. With that combo you may be able to run street and track without damaging rotors but ask the tech line. My XP12 rears are left on the car for street and track. The front I switch to the street Bobcat Carbotech. Staying with the Carbotech family for track and street there is no need now to clean or change from rotors for the track as the Bobcat is same family of material. Tech said the XP24 is the endurance pad and is longer lasting so worth the small higher price.
I was using Nitto NT01 tires and run very hard in the Instructo/Advance group.
So just Pads and cooling are key.
I run JLT brake cooling. Inexpensive and worked well but would look at Vorschlag kit if doing cooling kit again as I like their latest design.
Rear rotor covers removed.
Carbotech pads are superb. After discussion with the Carbotech tech line I use XP24 front and XP12 rear. With street tires not sure you can get enough heat in the XP24. So call the tech line. You may be better with XP12 on the front and XP8 rear. With that combo you may be able to run street and track without damaging rotors but ask the tech line. My XP12 rears are left on the car for street and track. The front I switch to the street Bobcat Carbotech. Staying with the Carbotech family for track and street there is no need now to clean or change from rotors for the track as the Bobcat is same family of material. Tech said the XP24 is the endurance pad and is longer lasting so worth the small higher price.
I was using Nitto NT01 tires and run very hard in the Instructo/Advance group.
Last edited by todcp; 01-04-2015 at 08:32 AM.
01-04-2015, 10:34 AM
#3
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
Lighter rotor mass is irrelevant at this stage.
Drilled holes are as apt to create places for cracks to start as provide any significant benefit with most current pad compounds. Air is not particularly inclined to flow through the holes, since the internal vanes in the rotors actually behave like the impellers of a centrifugal pump by accelerating the air from the center inlets to the outer diameters of the rotors. There is no compression going on to force the air out the holes. The original reason for holes was to provide an escape for pad "outgassing", which used to be a serious issue.
Slots are somewhat better approaches to the offgas issue, and at least provide dirt and grit a place to go instead of sitting there trapped under a pad and scoring up the rotor. This is really more of a street driving concern, as track levels of hard braking are better at dislodging such debris than typical street braking ever is or should have to be on any regular basis.
I do think I'd step past Wearever or whatever over the counter rotors are that are really only expected to see street use. I've run plain Centrics (Tire Rack). With the small 12.4" GT front brakes and XP8 pads, I managed to develop a pretty strong heat-check pattern in the front Centrics (which might pass a very casual fingernail test but not a thorough one). So the front now has some DBA 4000 (slotted) rotors on (got them on a closeout deal even before buying the Centrics), and those have been on the car for possibly as many as 6 track days. XP10's. Between not having a garage usable for repair & maintenance, cold, rainy weather, and me being a bit under the weather myself, I don't know how close I am to needing either pads or rotors - I did get to beat up on them at my home track one last time in 2014 right after Christmas.
FWIW, I run solo, and for the last couple of track days I've been moved up into the combined Advanced/Instructor run group.
Norm
Drilled holes are as apt to create places for cracks to start as provide any significant benefit with most current pad compounds. Air is not particularly inclined to flow through the holes, since the internal vanes in the rotors actually behave like the impellers of a centrifugal pump by accelerating the air from the center inlets to the outer diameters of the rotors. There is no compression going on to force the air out the holes. The original reason for holes was to provide an escape for pad "outgassing", which used to be a serious issue.
Slots are somewhat better approaches to the offgas issue, and at least provide dirt and grit a place to go instead of sitting there trapped under a pad and scoring up the rotor. This is really more of a street driving concern, as track levels of hard braking are better at dislodging such debris than typical street braking ever is or should have to be on any regular basis.
I do think I'd step past Wearever or whatever over the counter rotors are that are really only expected to see street use. I've run plain Centrics (Tire Rack). With the small 12.4" GT front brakes and XP8 pads, I managed to develop a pretty strong heat-check pattern in the front Centrics (which might pass a very casual fingernail test but not a thorough one). So the front now has some DBA 4000 (slotted) rotors on (got them on a closeout deal even before buying the Centrics), and those have been on the car for possibly as many as 6 track days. XP10's. Between not having a garage usable for repair & maintenance, cold, rainy weather, and me being a bit under the weather myself, I don't know how close I am to needing either pads or rotors - I did get to beat up on them at my home track one last time in 2014 right after Christmas.
FWIW, I run solo, and for the last couple of track days I've been moved up into the combined Advanced/Instructor run group.
Norm
01-04-2015, 05:10 PM
#4
4th Gear Member
Thread Starter
Join Date: Mar 2006
Location: CA
Posts: 1,313
The stock rotors are fine unless you are road racing for trophies. And then you will want more suspension work based on you sig. For track days on street tires the suspension you have is nice.
So just Pads and cooling are key.
I run JLT brake cooling. Inexpensive and worked well but would look at Vorschlag kit if doing cooling kit again as I like their latest design.
Rear rotor covers removed.
Carbotech pads are superb. After discussion with the Carbotech tech line I use XP24 front and XP12 rear. With street tires not sure you can get enough heat in the XP24. So call the tech line. You may be better with XP12 on the front and XP8 rear. With that combo you may be able to run street and track without damaging rotors but ask the tech line. My XP12 rears are left on the car for street and track. The front I switch to the street Bobcat Carbotech. Staying with the Carbotech family for track and street there is no need now to clean or change from rotors for the track as the Bobcat is same family of material. Tech said the XP24 is the endurance pad and is longer lasting so worth the small higher price.
I was using Nitto NT01 tires and run very hard in the Instructo/Advance group.
So just Pads and cooling are key.
I run JLT brake cooling. Inexpensive and worked well but would look at Vorschlag kit if doing cooling kit again as I like their latest design.
Rear rotor covers removed.
Carbotech pads are superb. After discussion with the Carbotech tech line I use XP24 front and XP12 rear. With street tires not sure you can get enough heat in the XP24. So call the tech line. You may be better with XP12 on the front and XP8 rear. With that combo you may be able to run street and track without damaging rotors but ask the tech line. My XP12 rears are left on the car for street and track. The front I switch to the street Bobcat Carbotech. Staying with the Carbotech family for track and street there is no need now to clean or change from rotors for the track as the Bobcat is same family of material. Tech said the XP24 is the endurance pad and is longer lasting so worth the small higher price.
I was using Nitto NT01 tires and run very hard in the Instructo/Advance group.
You basically say that "at my level" stock rotors are fine. I would rather discuss why you think stock rotors are fine. Is it because the amount of friction and heat dissipation will not be detrimental due to the lack of adhesion that can be accomplished with street tires? Or are you saying that the pads optimal operating temperature will not damage the stock rotor?
If we take the two piece, drilled, slotted rotors off the table, and just look at stock appearing rotors, is there a difference in performance and longevity between a Ford OEM replacement rotor, a stop tech rotor, a powerslot rotor, DBA rotor, or an off brand AutoZone/NAPA rotor? How much does the vein design matter in vented rotors? Are these rotors made differently or have different tolerances?
Thanks
01-04-2015, 07:17 PM
#5
4th Gear Member
Thread Starter
Join Date: Mar 2006
Location: CA
Posts: 1,313
Lighter rotor mass is irrelevant at this stage.
Drilled holes are as apt to create places for cracks to start as provide any significant benefit with most current pad compounds. Air is not particularly inclined to flow through the holes, since the internal vanes in the rotors actually behave like the impellers of a centrifugal pump by accelerating the air from the center inlets to the outer diameters of the rotors. There is no compression going on to force the air out the holes. The original reason for holes was to provide an escape for pad "outgassing", which used to be a serious issue.
Slots are somewhat better approaches to the offgas issue, and at least provide dirt and grit a place to go instead of sitting there trapped under a pad and scoring up the rotor. This is really more of a street driving concern, as track levels of hard braking are better at dislodging such debris than typical street braking ever is or should have to be on any regular basis.
I do think I'd step past Wearever or whatever over the counter rotors are that are really only expected to see street use. I've run plain Centrics (Tire Rack). With the small 12.4" GT front brakes and XP8 pads, I managed to develop a pretty strong heat-check pattern in the front Centrics (which might pass a very casual fingernail test but not a thorough one). So the front now has some DBA 4000 (slotted) rotors on (got them on a closeout deal even before buying the Centrics), and those have been on the car for possibly as many as 6 track days. XP10's. Between not having a garage usable for repair & maintenance, cold, rainy weather, and me being a bit under the weather myself, I don't know how close I am to needing either pads or rotors - I did get to beat up on them at my home track one last time in 2014 right after Christmas.
FWIW, I run solo, and for the last couple of track days I've been moved up into the combined Advanced/Instructor run group.
Norm
Drilled holes are as apt to create places for cracks to start as provide any significant benefit with most current pad compounds. Air is not particularly inclined to flow through the holes, since the internal vanes in the rotors actually behave like the impellers of a centrifugal pump by accelerating the air from the center inlets to the outer diameters of the rotors. There is no compression going on to force the air out the holes. The original reason for holes was to provide an escape for pad "outgassing", which used to be a serious issue.
Slots are somewhat better approaches to the offgas issue, and at least provide dirt and grit a place to go instead of sitting there trapped under a pad and scoring up the rotor. This is really more of a street driving concern, as track levels of hard braking are better at dislodging such debris than typical street braking ever is or should have to be on any regular basis.
I do think I'd step past Wearever or whatever over the counter rotors are that are really only expected to see street use. I've run plain Centrics (Tire Rack). With the small 12.4" GT front brakes and XP8 pads, I managed to develop a pretty strong heat-check pattern in the front Centrics (which might pass a very casual fingernail test but not a thorough one). So the front now has some DBA 4000 (slotted) rotors on (got them on a closeout deal even before buying the Centrics), and those have been on the car for possibly as many as 6 track days. XP10's. Between not having a garage usable for repair & maintenance, cold, rainy weather, and me being a bit under the weather myself, I don't know how close I am to needing either pads or rotors - I did get to beat up on them at my home track one last time in 2014 right after Christmas.
FWIW, I run solo, and for the last couple of track days I've been moved up into the combined Advanced/Instructor run group.
Norm
When you say the Wherever, Whenever rotors are only meant for street use, what do you mean? Are you saying their vein design and tolerances make them prone to warping or cracking under track level use? Have you noticed any brands of rotors that are thicker implying they are better heat soaks? How long were your stock rotors lasting if your current set up has lasted 6 events?
01-04-2015, 07:38 PM
#6
1st Gear Member
Join Date: Nov 2013
Location: New Hampshire
Posts: 66
Norm is correct. Centric rotors are very good as are the stock rotors. I can't speak to changes in rotor venting vanes design but the centric and stock work well. And Norm is correct on drilled rotors not a good idea for track. I cannot speak to other rotor brands as I have not seen a need to use any rotor other than stock or Centric.
Correct on street tires. They put less heat into the rotors and pads due to the fact that they grip less than the Nitto NT01 or Dot R tires. In my case I see no reason to switch rotors even on the Nitto NT01 as the stock rotor is holding up well and braking is terrific on the Nitto NT 100 wear rating. Cooling ducts are needed with the NT01. A track day friend found cooling ducts to be needed as he progressed on sticky street tires. He is Dmichaels on the forums.
To your desire to not cut the lower front grill...Not sure but the Vorschlag ducts, from the pics on their website, they may sit behind the grill vs my JLT that require two holes in the grill.
Correct on street tires. They put less heat into the rotors and pads due to the fact that they grip less than the Nitto NT01 or Dot R tires. In my case I see no reason to switch rotors even on the Nitto NT01 as the stock rotor is holding up well and braking is terrific on the Nitto NT 100 wear rating. Cooling ducts are needed with the NT01. A track day friend found cooling ducts to be needed as he progressed on sticky street tires. He is Dmichaels on the forums.
To your desire to not cut the lower front grill...Not sure but the Vorschlag ducts, from the pics on their website, they may sit behind the grill vs my JLT that require two holes in the grill.
01-05-2015, 09:34 AM
#7
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
Thanks Norm,
When you say the Wherever, Whenever rotors are only meant for street use, what do you mean? Are you saying their vein design and tolerances make them prone to warping or cracking under track level use? Have you noticed any brands of rotors that are thicker implying they are better heat soaks? How long were your stock rotors lasting if your current set up has lasted 6 events?
When you say the Wherever, Whenever rotors are only meant for street use, what do you mean? Are you saying their vein design and tolerances make them prone to warping or cracking under track level use? Have you noticed any brands of rotors that are thicker implying they are better heat soaks? How long were your stock rotors lasting if your current set up has lasted 6 events?
I've had rotors come with significant variations in the thicknesses of the rotor 'cheeks' - eyeball visible brand new right out of the box - and the lower you go on the scale (either absolutely on price or relatively in some cases to the claimed "name") the more likely it is that you'll encounter something similar.
Norm
01-26-2015, 08:20 PM
#8
3rd Gear Member
Join Date: Sep 2006
Location: Indianapolis
Posts: 770
brakes don't warp from heat.
even tirerack gets this wrong:
"Brake rotors don’t warp unless overheated. It’s very common to misdiagnose brake problems and attribute them to a warped brake rotor. Warping is caused by excessive heating of the brake rotor and the resulting distortion of the cast iron."
http://www.tirerack.com/FAQ/results.jsp?category=Brakes
but the manufacturers will tell you otherwise:
stoptech:
With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification, in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc.
http://stoptech.com/technical-suppor...nd-other-myths
raybestos brake tech school:
(from police fleet manager) "Brake rotors do not warp from heat, even when driven by the most aggressive traffic officer. Instead, they wear unevenly. This uneven wear is caused by the brake pads themselves as they intermittently touch an out-of-true rotor. The root cause of the uneven wear is one of two things: either the rotor was installed out-of-true with the hub, or the tire was improperly torqued to the hub during the last tire change."
http://www.hendonpub.com/resources/a...etails?id=1787
-----------------------
regarding rotor design and the benefits of going aftermarket you might find the following article interesting:
http://www.essexpartsblog.com/news/c...y-track-worthy
while not specific to mustangs you can see an in-depth look at stock vs aftermarket differences when it comes to rotors.
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