Warped rotors again
#31
06-06-2011, 02:13 PM
I am not an engineer, nor am I an "expert" but one thing I have done, I have worked the heck out of my trucks and pushed nearly every limit that Detroit has designed into them. I have pulled skid steers, small back hoes, boats etc with Fords, Chevy's and even a dodge. I also do nearly ALL of my own repairs. I can tell you for a FACT, if you have a big load going DOWN the other side of the West Virginia Turnpike and have some soccer ma and pa heading to the beach with their 2.2 kids in their Honda mini van riding the brakes because they are afraid of heights, right in front of you the whole way down, your brakes WILL warp just from trying to not run them over. I have has as much as .084" run-out with a dial indicator. Never mind the damage to the trailer brakes if they are surge brakes. Point is, call it whatever you want, warpage, heat deformation, it DOES happen in extreme cases. Now on the other hand, my wife drives an entire 1.2 miles to work and back every day so she never really heats up her brakes. They FEEL warped but the indicator proves every time that they are as strait as when I put them on. I can usually get rid of the pulse by following the bed in procedure for performance pads but double the stops. Heats them up enough to burn off any oils or greases and re distributes the pad material on the rotor. I have done this more than once on her van.
#32
06-06-2011, 03:47 PM
Wow, we have gone a little off track here. Your first point is wrong as proven by thousands of disk brake users who have suffered from chronic warpage. They change over to drilled/slotted rotors and the problem ends. This is due to the increased ability to quickly dissapate heat. People who live in mountainous areas that carry heavy loads KNOW this.
On your second point, we are talking about Ford trucks here. Not some "economy" car and certainly not race cars. And your characterization "many of the detroit oem's are still cast iron" seems to imply that iron disks are going away is just wrong. Unless some miracle material that is cheaper than cast iron is developed, cast iron will still be the choice of all but the most exotic manufacturers.
On your third point you say "Venting by itself for heavier vehicles is initself a misnomer" I can only guess that your experience is limited to what you read on the internet or car magazines. Vented disks, assuming you know what they are have been around since the sixties and are very common because they are more effective at dissapating heat. And as to your assertion that ANY oem does not recommend their use in ANY application sounds like something you just pulled out of the air. The only reasons that vented disks are not used in more applications is that they do slightly increase unsprung weight and they cost a little more than plain disks.
On your second point, we are talking about Ford trucks here. Not some "economy" car and certainly not race cars. And your characterization "many of the detroit oem's are still cast iron" seems to imply that iron disks are going away is just wrong. Unless some miracle material that is cheaper than cast iron is developed, cast iron will still be the choice of all but the most exotic manufacturers.
On your third point you say "Venting by itself for heavier vehicles is initself a misnomer" I can only guess that your experience is limited to what you read on the internet or car magazines. Vented disks, assuming you know what they are have been around since the sixties and are very common because they are more effective at dissapating heat. And as to your assertion that ANY oem does not recommend their use in ANY application sounds like something you just pulled out of the air. The only reasons that vented disks are not used in more applications is that they do slightly increase unsprung weight and they cost a little more than plain disks.
1. There is no vehicle placing a greater demand on brakes than a Fire engine. San Bernardino Fire Agency (whose repiar facility is in Fontana, Ca), services/maintains the vehicles in the San bernardino Mountains, this includes Lake Arrowhead, Running Springs...all the way up to Big Bear. neither the Fire Agency, nor CHP (who runs hwy 18), nor the SB County Sheriff specs slotted/vented/crossdrilled rotors for any of their vehicles the policve spec vehicles must be capable of providing braking at sustained speeds up to 130 mph, CHP in fact has been involved in numerous high speed pursuits on both hywys 18 & 330....I know of no other roads in the western US that would be more demanding ona 4000 pound vehicle running speeds ranging from 35 to 110 mph on mountain roads.
2. In independent testing (avial on the web) for street vehicles (this included, light trucks, etc.) consistantly demonstrated little no benefit of slotted/drill rotors in street applications- actually, the drilled only rotors actually showed a slight degrease in initial braking capability- In summary, there are very few instances that nessitate benefit to a street-vehicle (not that there aren't a few), but it is the general guidence for 90% of the vehicles.
3. If you contact CarboTech Engineering (who have built brake systems for an incredible array of oems including MB's supercars of the 90's) ART or DC, they will convey the exact reply that I have given you.
CarboTech 877-899-5024
ART 714-527-9400
DC 888-323-8456
#33
06-06-2011, 07:31 PM
#34
06-06-2011, 08:36 PM
Beechkid, you keep trying to broaden the discussion. Is this thread about fire trucks? No. Is it about race cars? No. It is about disk warpage. Or do you want to talk about brakes on 747s.
Police vehicles come with upgraded brakes. So lets exclude them from the discussion unless some of our FTE leos would like to add something here. That would be welcome. I can say that I have seen police pursuit vehicles with drilled and slotted disks.
I have to assume that the "independent testing" that you refer to was testing brake performance, not durability or disk warping.
Congratulations to your dad, his credentials are admirable. You should get some of your own.
Police vehicles come with upgraded brakes. So lets exclude them from the discussion unless some of our FTE leos would like to add something here. That would be welcome. I can say that I have seen police pursuit vehicles with drilled and slotted disks.
I have to assume that the "independent testing" that you refer to was testing brake performance, not durability or disk warping.
Congratulations to your dad, his credentials are admirable. You should get some of your own.
#36
06-06-2011, 09:28 PM
I will say that in within my ownership, my f250 superduty had gone through 4 sets of front brake pads, 3 sets of rear brake pads, 2 sets of front rotors and 3 sets of rear rotors and has only 42K on the odo right now. I tow a race car ocassionally, sometimes a single quad trailer, but my oem brakes and rotors lasted approx 10K miles, Powerslot fronts have been on since. I have used Performance friction, and EBC greenstuffpads. In my shop, i rarely see a superduty have brakes last 20K miles or so, heck, i rarey
see any vehicle come in with brakes that last that long.
#37
06-06-2011, 10:12 PM
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My intent was not to start a rivalry that borders on a Yankees/Red Sox but I got more than I bargained for. This has been very educational. My rims are torqued by my local Ford dealer and I trust they are correct though I cannot confirm this. My first set of rotors did look like material had deposited on the rotor. My truck only sees short trips back and forth to work but I had the same problem with my 2000 Excursion at 26K miles. The X lives inside and is only used for vacation. We don't tow anything except kids. The X has 44K now and the brakes have been fine so far. I'm going to have the rotors turned and make sure I break in the pads. I'll make sure I report back on the outcome.
#38
06-07-2011, 04:25 PM
Beechkid, you keep trying to broaden the discussion. Is this thread about fire trucks? No. Is it about race cars? No. It is about disk warpage. Or do you want to talk about brakes on 747s.
Police vehicles come with upgraded brakes. So lets exclude them from the discussion unless some of our FTE leos would like to add something here. That would be welcome. I can say that I have seen police pursuit vehicles with drilled and slotted disks.
I have to assume that the "independent testing" that you refer to was testing brake performance, not durability or disk warping.
Congratulations to your dad, his credentials are admirable. You should get some of your own.
Police vehicles come with upgraded brakes. So lets exclude them from the discussion unless some of our FTE leos would like to add something here. That would be welcome. I can say that I have seen police pursuit vehicles with drilled and slotted disks.
I have to assume that the "independent testing" that you refer to was testing brake performance, not durability or disk warping.
Congratulations to your dad, his credentials are admirable. You should get some of your own.
By comparison, a typical Fire engine weighs in at about 28,000 to 32,000 pounds, is equipped with disc brakes on both the front and rear axels and have anti-lock, as well as police cars (ex- crown vics) - used extensively by many law enforcement agencies in cluding the highway patrol in california in the San Bernardino Mountains where the peak elevation is around 6,500 feet- high speed pursuits (80 mph) in the mountains is not unusual.
if the theory as previously stated is, because of the weight, size and operational demand (brakes) is so great on the street for many vehicles that it requires the use of cross drilled/slotted rotors to cool the rotors to keep them from warping and enhance braking, then both the oems of these vehicles and service facilities would provide cross drilled/slotted rotors on these vehicles from the production lines or the service facilities would replace the rotors with cross drilled/slotted units during the routine, 90 day (required) safety inspections (when routine part replacement occurs). But they don't. Yes many of the 2010 IIRR and newer police units do have crossdrilled/slotted rotors, they are only recent.....going back to the late 1990's to about 2008 when they 1st began their introduction- which is still mostly limited to Dodge. Fords still do not use them (crown vics) but I suspect the new taurus & F150 pursuit packages will have them. In regards to the size on the crown Vics...they are the same units found on the Crown Vic & merc "Sport packages".......that also have the higher friction brake linings (though not as high as the pursuit packages for dust production and logetivity reasons I suspect)
There is simply no F150 on the street that demands on a daily basis the loads that are placed on these systems by comparison on these vehicles.
My credentials as well in both aftermarket part design although is limited to suspension & carb systems, my numerous builds in SCCA (yes its been a couple of years ago), had restrictions on aftermarket brake components which "we" worked around.......including the use of cryo treated rotors on the TR8 (no, not a mis-print, yes, a TR8 - V8, very limited production roadracing coupe) which most of the testing and prep was done at riverside Raceway (yeah its gone- showing my age again)
Again, there are numerous independent test that have been done, clearing demonstrating in both lab and track based settings, that there is little to no performance benefit to cross drilled/slotted rotors as compared to the same 'plain" rotors.
ART, DC both slot/crossdrill rotors and if you want they will provide at a resonable cost, but each will advise the clients "if they ask", is there a performance benefit for my street-use vehicle, they will respond no....but they will recommend cryo tx of the rotors to increase the hardness which also through others aspects (too long to go into here), reduces heat absorbion slightly and allows increase heat dissipation.....which is what most street driven operators want....
cryo is a tx used for many decades in a variety of hp applications where stresses placed parts into questionable logitivity.......pistions are probably the most common in the racing circuit next to rods, cranks & heads- there are a few who have even done entire engine blocks-
The point here is, there is a definite lack of engineering science behind many claims made by many "experts" who are basing all of the presentation upon some incredible marketing plans...of which i give them 100% credit and recognition.
But as these claims get inflated past the point of creative marketing, it becomes fraudulent selling...of which the FTC has already come down on companies (such as megs Clay Bar ads- previous to the 3M buyout).....
and I actually do have college degrees.........racing experience.........car construstion and a family whose engineering background is well known in the industry and still alive today........some just shake their head at what they see and others just love to meet these "sale-persons" face to face.....and watch the look on their face when they are presented with ASTM test data (and others) ..........their typical response...
"I'm not familiar with that"
"i can't comment on that"
"I don't know what product was used or even if it was one of our products used in that"
When given copies in public, typically, they just go away and then you find another 90-day sales wonder who pops up a few months later with a new pitch, same claim.
A+ for creativity
A+ tenacity
but that's about it....
#39
06-07-2011, 04:47 PM
Ha ha, I agree. Its always funny when someone thinks they are an expert because daddy had a degree.
I will say that in within my ownership, my f250 superduty had gone through 4 sets of front brake pads, 3 sets of rear brake pads, 2 sets of front rotors and 3 sets of rear rotors and has only 42K on the odo right now. I tow a race car ocassionally, sometimes a single quad trailer, but my oem brakes and rotors lasted approx 10K miles, Powerslot fronts have been on since. I have used Performance friction, and EBC greenstuffpads. In my shop, i rarely see a superduty have brakes last 20K miles or so, heck, i rarey
see any vehicle come in with brakes that last that long.
I will say that in within my ownership, my f250 superduty had gone through 4 sets of front brake pads, 3 sets of rear brake pads, 2 sets of front rotors and 3 sets of rear rotors and has only 42K on the odo right now. I tow a race car ocassionally, sometimes a single quad trailer, but my oem brakes and rotors lasted approx 10K miles, Powerslot fronts have been on since. I have used Performance friction, and EBC greenstuffpads. In my shop, i rarely see a superduty have brakes last 20K miles or so, heck, i rarey
see any vehicle come in with brakes that last that long.
using the vehicle maintenance records........
1965 Mustang (been in the family since new), shelby installed velva touch linings...91,000 miles, next set installed 87,000 miles, next set installed 42,000 miles later.....defective brake springs, currently have about 12,000 miles
1990 f150 70/30 city/hwy (work truck), 18,000 miles on oems, new front & rears installed (with cryo tx rotors), 104,000 miles front & rears...sold truck in 2006 with 116,000 miles
1997 Cougar Sport (V8) 100% city, very heavy daily traffic, 12 miles daily round trip, 45 minute duration each way, replaced oem pads & rotors with cryo tx units at 23,000 miles, 53,000 miles on fronts & rears- just replaced last month.
I typically avoid high production line distrbution product lines because they typically have reduced quality to meet price margins. But I also do pay about $140 a set for pads and on the mustang about $200 a set for shoes- but i also triple the wear and I also typically get 100,000+ miles on my rotors- I think the EBC line at Slep Boys is a fraction of that price.
#40
06-07-2011, 04:54 PM
I am not an engineer, nor am I an "expert" but one thing I have done, I have worked the heck out of my trucks and pushed nearly every limit that Detroit has designed into them. I have pulled skid steers, small back hoes, boats etc with Fords, Chevy's and even a dodge. I also do nearly ALL of my own repairs. I can tell you for a FACT, if you have a big load going DOWN the other side of the West Virginia Turnpike and have some soccer ma and pa heading to the beach with their 2.2 kids in their Honda mini van riding the brakes because they are afraid of heights, right in front of you the whole way down, your brakes WILL warp just from trying to not run them over. I have has as much as .084" run-out with a dial indicator. Never mind the damage to the trailer brakes if they are surge brakes. Point is, call it whatever you want, warpage, heat deformation, it DOES happen in extreme cases. Now on the other hand, my wife drives an entire 1.2 miles to work and back every day so she never really heats up her brakes. They FEEL warped but the indicator proves every time that they are as strait as when I put them on. I can usually get rid of the pulse by following the bed in procedure for performance pads but double the stops. Heats them up enough to burn off any oils or greases and re distributes the pad material on the rotor. I have done this more than once on her van.
#41
06-07-2011, 11:04 PM
[quote=Beechkid;10433362]1. The statement was made that trucks (Im assuming f150/250/350), because of their weight, load and harder than passenger car usage requires the use of cross-drilled/slotted rotors to dissipate the heat
Where was that statement made? Not by me! Your imagination is getting you off track again.
By comparison, a typical Fire engine weighs
Not part of the discussion!
if the theory as previously stated is,
You need to learn to read. That was NOT stated by me! And your conclusions are not real world.
.
Again, there are numerous independent test that have been done, clearing demonstrating in both lab and track based settings, that there is little to no performance benefit to cross drilled/slotted rotors as compared to the same 'plain" rotors.
That is overlooking the fact that they do not warp as readily as do solid disks. They were developed by racers to cure the warping problem. And, within reasonable limits they do the job.
ART, DC both slot/crossdrill rotors and if you want they will provide at a resonable cost, but each will advise the clients "if they ask", is there a performance benefit for my street-use vehicle, they will respond no....but they will recommend cryo tx of the rotors to increase the hardness which also through others aspects (too long to go into here), reduces heat absorbion slightly and allows increase heat dissipation.....which is what most street driven operators want....
You keep assuming that people choose drilled/slotted disks to make the vehicle stop better which is wrong, and therefore beside the point. Go back to post #1 to see what this thread is all about.
quote]
Please try to get back to the topic, which is the problem of brake disks warping.
Where was that statement made? Not by me! Your imagination is getting you off track again.
By comparison, a typical Fire engine weighs
Not part of the discussion!
if the theory as previously stated is,
You need to learn to read. That was NOT stated by me! And your conclusions are not real world.
.
Again, there are numerous independent test that have been done, clearing demonstrating in both lab and track based settings, that there is little to no performance benefit to cross drilled/slotted rotors as compared to the same 'plain" rotors.
That is overlooking the fact that they do not warp as readily as do solid disks. They were developed by racers to cure the warping problem. And, within reasonable limits they do the job.
ART, DC both slot/crossdrill rotors and if you want they will provide at a resonable cost, but each will advise the clients "if they ask", is there a performance benefit for my street-use vehicle, they will respond no....but they will recommend cryo tx of the rotors to increase the hardness which also through others aspects (too long to go into here), reduces heat absorbion slightly and allows increase heat dissipation.....which is what most street driven operators want....
You keep assuming that people choose drilled/slotted disks to make the vehicle stop better which is wrong, and therefore beside the point. Go back to post #1 to see what this thread is all about.
quote]
Please try to get back to the topic, which is the problem of brake disks warping.
#42
06-07-2011, 11:46 PM
Join Date: Aug 2007
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Mobile site is not letting quote. But to answer the questions.
No not alot of mountains in new bern. However I'm from Oregon and there are plenty there this truck is currently on it's second trip pulling moderately heavy in the Rockies. I made plenty of trips into the appalacians also.
And I don't check them when the guys at the tire shop do them or when I do. Only explanation I can think of is the guys who do mine are just better then yours. And when I do my own I'm just that good.
But traveling through the
Country currently I just realized I actually don't use my brakes to much unless I'm making a complete stop. Down a 10% grade in the Black Hills did 40mph and touched my brakes twice. Once to get my desired speed and the second time because a vehicle in front of me.
No not alot of mountains in new bern. However I'm from Oregon and there are plenty there this truck is currently on it's second trip pulling moderately heavy in the Rockies. I made plenty of trips into the appalacians also.
And I don't check them when the guys at the tire shop do them or when I do. Only explanation I can think of is the guys who do mine are just better then yours. And when I do my own I'm just that good.
But traveling through the
Country currently I just realized I actually don't use my brakes to much unless I'm making a complete stop. Down a 10% grade in the Black Hills did 40mph and touched my brakes twice. Once to get my desired speed and the second time because a vehicle in front of me.
#43
06-08-2011, 12:13 AM
Mobile site is not letting quote. But to answer the questions.
No not alot of mountains in new bern. However I'm from Oregon and there are plenty there this truck is currently on it's second trip pulling moderately heavy in the Rockies. I made plenty of trips into the appalacians also.
And I don't check them when the guys at the tire shop do them or when I do. Only explanation I can think of is the guys who do mine are just better then yours. And when I do my own I'm just that good.
But traveling through the
Country currently I just realized I actually don't use my brakes to much unless I'm making a complete stop. Down a 10% grade in the Black Hills did 40mph and touched my brakes twice. Once to get my desired speed and the second time because a vehicle in front of me.
No not alot of mountains in new bern. However I'm from Oregon and there are plenty there this truck is currently on it's second trip pulling moderately heavy in the Rockies. I made plenty of trips into the appalacians also.
And I don't check them when the guys at the tire shop do them or when I do. Only explanation I can think of is the guys who do mine are just better then yours. And when I do my own I'm just that good.
But traveling through the
Country currently I just realized I actually don't use my brakes to much unless I'm making a complete stop. Down a 10% grade in the Black Hills did 40mph and touched my brakes twice. Once to get my desired speed and the second time because a vehicle in front of me.
#44
06-08-2011, 10:32 AM
[QUOTE=Bdox;10434685]
It boils down to this......
Slotted/cross drill rotors do dissipate heat any faster than non-modified units in 90% of street appplications- slotting & cross drill in summary is to vent gases produced by racing conditions and (2) to clean contaminent buildup on the brake linings & rotors. There are 2 scientific theories working here regarding heat...
The law of latent heat vaporization and the law of latent heat transfer
Todays oem rotors (in most cases) have a high content of aluminum for the purposes of reducing weight. Although Al does dissipate heat faster than cast iron, it also reaches a point of heating much faster as well- that is why during extended braking periods or excessively heavy braking (or a combination of both), and for great laughs throw in a little water vapor to really speed thing up, the rotors warp - because they are cooling unequally.
Now, cryo tx costs about $10-$15 per rotor, this increase the hardness and reduces the tendency to physically change as a result of thermal conditions, this also enhances the heat transfer over a greater area as a result of the reduction of hot-spots greated on the rotor during application. The cost of this tx is very cheap in comparison to the typical cost of crossdrilled/slotting and actually addresses the issue of heat.
As a mechanic, what you are failing to recognize in the examples given is....
if the theory is solid rotors warp because of their inability to dissipate heat, well, vehicles weighing 6 times that of an F150 run solid rotors and have no issues in extreme operating conditions, well above that which any driver could ever expose their vehicle to.
and secondly, even street vehicles used in racing type conditions on the street (such as the Calif Hwy Patrol) in the San Bernardino Mountains who have been running Crown Vics with solid rotors for over 15 years) going as far back as 1979, ths issue that solid rotors cannot take the heat (so to speak) is just not even in the ballpark of reality.
What is reality is many of the oem rotors are comprised of materials which are marginal at best in terms of the ability to function in the performance capabilities of the vehicles they are on and secondly, the aftermarket, most come from the same (one of 2) chinese foundaries (whether its wagner, TRW, autospecialties, bendix, raybestos, etc.).
If you check with both ART & DC, they will confirm this...they both purchase the highest grades (of the 4 grade specs) of rotors available, QA each rotor, dumping the rejects (salvage sales) into the wholesale market place in most cases and then re-machine & treat as ordered by the customer.
Powerslot rotors come from china as well (IMHO)......a couple of years ago I installed a set (by request) and when I compared them very carefully to a set for the exact same vehicle that I had a set from DC (IIRR) for, guess what...the exact same foundary markings!
Guess what, almost 3 years later, the both vehicles within a couple of months return for routine service....for chuckles I mic the rotors of both vehicles, guess what, the front installed powerslot units have .43 mm more runout than the xryo, non-drilled counter parts. Could this be as a result of driver operations, of course! a variable that really cant be controlled, but in terms of general mileage and condition, both were similar, both had been involved in heavy demand operations, both had the same maintenance and the brake rotor installs were done by the same person...me.
Not only is this reality, but 50 years combined experience between myself and my father in both racing and non-racing conditions. Check out the 3/4 jalopy racing circuits- Today the rules still require 4 wheel drum brakes.....yes chinese made brake drums (the only ones out there) providing stopping power to almost the efficiency of many oem disc brakes, and heat generated well beyond most street vehicles ever even see...
how do we do it...
Cryo tx the drums
organic (my personal preferance) or carbon fiber brake linings with co-efficients well above .50!
I personally suspect you have some relationship with the aftermarket rotor industry...because typically there are two types of people who create such a negative discussion on this aspect of the subject...those who are either selling or buying the marketing.
1. The statement was made that trucks (Im assuming f150/250/350), because of their weight, load and harder than passenger car usage requires the use of cross-drilled/slotted rotors to dissipate the heat
Where was that statement made? Not by me! Your imagination is getting you off track again.
By comparison, a typical Fire engine weighs
Not part of the discussion!
if the theory as previously stated is,
You need to learn to read. That was NOT stated by me! And your conclusions are not real world.
.
Again, there are numerous independent test that have been done, clearing demonstrating in both lab and track based settings, that there is little to no performance benefit to cross drilled/slotted rotors as compared to the same 'plain" rotors.
That is overlooking the fact that they do not warp as readily as do solid disks. They were developed by racers to cure the warping problem. And, within reasonable limits they do the job.
ART, DC both slot/crossdrill rotors and if you want they will provide at a resonable cost, but each will advise the clients "if they ask", is there a performance benefit for my street-use vehicle, they will respond no....but they will recommend cryo tx of the rotors to increase the hardness which also through others aspects (too long to go into here), reduces heat absorbion slightly and allows increase heat dissipation.....which is what most street driven operators want....
You keep assuming that people choose drilled/slotted disks to make the vehicle stop better which is wrong, and therefore beside the point. Go back to post #1 to see what this thread is all about.
quote]
Please try to get back to the topic, which is the problem of brake disks warping.
Where was that statement made? Not by me! Your imagination is getting you off track again.
By comparison, a typical Fire engine weighs
Not part of the discussion!
if the theory as previously stated is,
You need to learn to read. That was NOT stated by me! And your conclusions are not real world.
.
Again, there are numerous independent test that have been done, clearing demonstrating in both lab and track based settings, that there is little to no performance benefit to cross drilled/slotted rotors as compared to the same 'plain" rotors.
That is overlooking the fact that they do not warp as readily as do solid disks. They were developed by racers to cure the warping problem. And, within reasonable limits they do the job.
ART, DC both slot/crossdrill rotors and if you want they will provide at a resonable cost, but each will advise the clients "if they ask", is there a performance benefit for my street-use vehicle, they will respond no....but they will recommend cryo tx of the rotors to increase the hardness which also through others aspects (too long to go into here), reduces heat absorbion slightly and allows increase heat dissipation.....which is what most street driven operators want....
You keep assuming that people choose drilled/slotted disks to make the vehicle stop better which is wrong, and therefore beside the point. Go back to post #1 to see what this thread is all about.
quote]
Please try to get back to the topic, which is the problem of brake disks warping.
Slotted/cross drill rotors do dissipate heat any faster than non-modified units in 90% of street appplications- slotting & cross drill in summary is to vent gases produced by racing conditions and (2) to clean contaminent buildup on the brake linings & rotors. There are 2 scientific theories working here regarding heat...
The law of latent heat vaporization and the law of latent heat transfer
Todays oem rotors (in most cases) have a high content of aluminum for the purposes of reducing weight. Although Al does dissipate heat faster than cast iron, it also reaches a point of heating much faster as well- that is why during extended braking periods or excessively heavy braking (or a combination of both), and for great laughs throw in a little water vapor to really speed thing up, the rotors warp - because they are cooling unequally.
Now, cryo tx costs about $10-$15 per rotor, this increase the hardness and reduces the tendency to physically change as a result of thermal conditions, this also enhances the heat transfer over a greater area as a result of the reduction of hot-spots greated on the rotor during application. The cost of this tx is very cheap in comparison to the typical cost of crossdrilled/slotting and actually addresses the issue of heat.
As a mechanic, what you are failing to recognize in the examples given is....
if the theory is solid rotors warp because of their inability to dissipate heat, well, vehicles weighing 6 times that of an F150 run solid rotors and have no issues in extreme operating conditions, well above that which any driver could ever expose their vehicle to.
and secondly, even street vehicles used in racing type conditions on the street (such as the Calif Hwy Patrol) in the San Bernardino Mountains who have been running Crown Vics with solid rotors for over 15 years) going as far back as 1979, ths issue that solid rotors cannot take the heat (so to speak) is just not even in the ballpark of reality.
What is reality is many of the oem rotors are comprised of materials which are marginal at best in terms of the ability to function in the performance capabilities of the vehicles they are on and secondly, the aftermarket, most come from the same (one of 2) chinese foundaries (whether its wagner, TRW, autospecialties, bendix, raybestos, etc.).
If you check with both ART & DC, they will confirm this...they both purchase the highest grades (of the 4 grade specs) of rotors available, QA each rotor, dumping the rejects (salvage sales) into the wholesale market place in most cases and then re-machine & treat as ordered by the customer.
Powerslot rotors come from china as well (IMHO)......a couple of years ago I installed a set (by request) and when I compared them very carefully to a set for the exact same vehicle that I had a set from DC (IIRR) for, guess what...the exact same foundary markings!
Guess what, almost 3 years later, the both vehicles within a couple of months return for routine service....for chuckles I mic the rotors of both vehicles, guess what, the front installed powerslot units have .43 mm more runout than the xryo, non-drilled counter parts. Could this be as a result of driver operations, of course! a variable that really cant be controlled, but in terms of general mileage and condition, both were similar, both had been involved in heavy demand operations, both had the same maintenance and the brake rotor installs were done by the same person...me.
Not only is this reality, but 50 years combined experience between myself and my father in both racing and non-racing conditions. Check out the 3/4 jalopy racing circuits- Today the rules still require 4 wheel drum brakes.....yes chinese made brake drums (the only ones out there) providing stopping power to almost the efficiency of many oem disc brakes, and heat generated well beyond most street vehicles ever even see...
how do we do it...
Cryo tx the drums
organic (my personal preferance) or carbon fiber brake linings with co-efficients well above .50!
I personally suspect you have some relationship with the aftermarket rotor industry...because typically there are two types of people who create such a negative discussion on this aspect of the subject...those who are either selling or buying the marketing.
