Best bang for the buck brakes!!
04-15-2011, 05:05 PM
#21
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I never said they didn't look good - but as far as performance a cheap drilled or slotted rotor is not your best bet.
It's pretty simple to think about why blanks have advantages in heat transfer theory- what advantage do slotted / drilled have? It's really impossible to prove either way without extensive testing on specific applications with specific parts and driving scenarios.
Regardless, it is my personal opinion that I would much rather have a nice quality set of blanks than a cheaper set of drilled / slotted rotors. Those came on my car and the previous owner had no problem but with my more aggressive driving style they warped in no time at all.
It's pretty simple to think about why blanks have advantages in heat transfer theory- what advantage do slotted / drilled have? It's really impossible to prove either way without extensive testing on specific applications with specific parts and driving scenarios.
Regardless, it is my personal opinion that I would much rather have a nice quality set of blanks than a cheaper set of drilled / slotted rotors. Those came on my car and the previous owner had no problem but with my more aggressive driving style they warped in no time at all.
04-16-2011, 11:20 PM
#22
Check the sticky on here - https://ls1tech.com/forums/suspensio...brake-faq.html - answers the questions being asked. I know I am looking into new breaks and keep debating on what to get.
04-18-2011, 03:08 PM
#23
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I never said they didn't look good - but as far as performance a cheap drilled or slotted rotor is not your best bet.
It's pretty simple to think about why blanks have advantages in heat transfer theory- what advantage do slotted / drilled have? It's really impossible to prove either way without extensive testing on specific applications with specific parts and driving scenarios.
Regardless, it is my personal opinion that I would much rather have a nice quality set of blanks than a cheaper set of drilled / slotted rotors. Those came on my car and the previous owner had no problem but with my more aggressive driving style they warped in no time at all.
It's pretty simple to think about why blanks have advantages in heat transfer theory- what advantage do slotted / drilled have? It's really impossible to prove either way without extensive testing on specific applications with specific parts and driving scenarios.
Regardless, it is my personal opinion that I would much rather have a nice quality set of blanks than a cheaper set of drilled / slotted rotors. Those came on my car and the previous owner had no problem but with my more aggressive driving style they warped in no time at all.
04-18-2011, 03:28 PM
#24
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Because I sell them for a living? I've said it before and I'll repeat, I'm not opposed to people using blanks for race applications (or street for that matter). I just will not tolerate ill informed people perpetuating the false notion that drilled rotors serve no functional purpose. Audi, Mercedes, BMW, Lamborghini, Lotus, Porsche, Lexus & Aston Martin have been and currently are equipping their road going vehicles with cross-drilled rotors because they work - not because they are pretty and crack, as the majority of forum members would have you believe.
04-18-2011, 03:35 PM
#25
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Check the sticky on here - https://ls1tech.com/forums/suspensio...brake-faq.html - answers the questions being asked. I know I am looking into new breaks and keep debating on what to get.
04-18-2011, 04:48 PM
#26
Please explain how or why a blank rotor has an advantage in heat transfer theory? It's not impossible to prove and it has been proven in SAE published white papers by reputable GM engineers who compiled and interpreted data collected for over a decade. The only thing the internet nay sayers have is an opinion - never a legitimate counter argument or proof to back up their claims.
That link you toss aside and internet folklore cites white papers by just as professional engineers ... engineers that designed products the government didn't have to bail out.
Last word from me is ... It's ludicrous to compare an F-Car to R8s, SLK/SLRs, GT3s or Virages even though it's done by carnival hawkers all the time.
04-18-2011, 06:42 PM
#27
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Please explain how or why a blank rotor has an advantage in heat transfer theory? It's not impossible to prove and it has been proven in SAE published white papers by reputable GM engineers who compiled and interpreted data collected for over a decade. The only thing the internet nay sayers have is an opinion - never a legitimate counter argument or proof to back up their claims.
Surface area, strength, expansion and contraction, etc etc. Not to mention it's the simplest machine design to see that holes create huge stress concentrations.
And actually it is pretty damn hard to prove. Have you ever studied heat transfer? It's a highly complex subject. **** - people write thesis papers hundreds of pages long on how to analyze a finned tube heat exchanger (like a cheap simple oil cooler). It isn't really that easy....
I said specific applications and parts vary GREATLY. It's impossible to say that because a study was done on one thing that it applies to everything.
The above mostly applies to rotors that are drilled. While I don't think its there for anything more than looks (even aggressive street pads don't need to be cleaned off or alleviate gases anymore) slots aren't nearly as bad. They will wear your pads more, which kind of defeats the purpose of budget, but they won't be near as bad drilled rotors. The next point though, that applies to both.
Additionally - most of the stuff I see marketed to Fbody guys as high quality cross drilled / slotted rotors is a freaking joke - not the stuff Ferrari - etc is using. The stuff is just junky parts designed to look cool. I am not saying that is what you are selling (I haven't even looked) - but I am saying that is what I have seen in the past lots of places.
The vast majority of slotted / drilled rotors are done for looks alone.
It is why you see something like this:
http://www.0-60mag.com/wp-content/up...treet-disc.jpg
It is a dimpled rotor to still have some of that cool look while maintaining the most mass and surface area for stopping power.
Last edited by ThumperNC24; 04-18-2011 at 07:00 PM.
04-19-2011, 10:39 AM
#28
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Then why wouldn't GM install holes and grooves in rotors on their HD line of trucks? Nothing is as hard on brakes as an 8K lb vehicle towing 15K lb and trying to panic stop.
That link you toss aside and internet folklore cites white papers by just as professional engineers ... engineers that designed products the government didn't have to bail out.
Last word from me is ... It's ludicrous to compare an F-Car to R8s, SLK/SLRs, GT3s or Virages even though it's done by carnival hawkers all the time.
That link you toss aside and internet folklore cites white papers by just as professional engineers ... engineers that designed products the government didn't have to bail out.
Last word from me is ... It's ludicrous to compare an F-Car to R8s, SLK/SLRs, GT3s or Virages even though it's done by carnival hawkers all the time.
04-19-2011, 10:46 AM
#29
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more mass = more heat capacity for one.
Surface area, strength, expansion and contraction, etc etc. Not to mention it's the simplest machine design to see that holes create huge stress concentrations.
And actually it is pretty damn hard to prove. Have you ever studied heat transfer? It's a highly complex subject. **** - people write thesis papers hundreds of pages long on how to analyze a finned tube heat exchanger (like a cheap simple oil cooler). It isn't really that easy....
I said specific applications and parts vary GREATLY. It's impossible to say that because a study was done on one thing that it applies to everything.
The above mostly applies to rotors that are drilled. While I don't think its there for anything more than looks (even aggressive street pads don't need to be cleaned off or alleviate gases anymore) slots aren't nearly as bad. They will wear your pads more, which kind of defeats the purpose of budget, but they won't be near as bad drilled rotors. The next point though, that applies to both.
Additionally - most of the stuff I see marketed to Fbody guys as high quality cross drilled / slotted rotors is a freaking joke - not the stuff Ferrari - etc is using. The stuff is just junky parts designed to look cool. I am not saying that is what you are selling (I haven't even looked) - but I am saying that is what I have seen in the past lots of places.
The vast majority of slotted / drilled rotors are done for looks alone.
It is why you see something like this:
http://www.0-60mag.com/wp-content/up...treet-disc.jpg
It is a dimpled rotor to still have some of that cool look while maintaining the most mass and surface area for stopping power.
Surface area, strength, expansion and contraction, etc etc. Not to mention it's the simplest machine design to see that holes create huge stress concentrations.
And actually it is pretty damn hard to prove. Have you ever studied heat transfer? It's a highly complex subject. **** - people write thesis papers hundreds of pages long on how to analyze a finned tube heat exchanger (like a cheap simple oil cooler). It isn't really that easy....
I said specific applications and parts vary GREATLY. It's impossible to say that because a study was done on one thing that it applies to everything.
The above mostly applies to rotors that are drilled. While I don't think its there for anything more than looks (even aggressive street pads don't need to be cleaned off or alleviate gases anymore) slots aren't nearly as bad. They will wear your pads more, which kind of defeats the purpose of budget, but they won't be near as bad drilled rotors. The next point though, that applies to both.
Additionally - most of the stuff I see marketed to Fbody guys as high quality cross drilled / slotted rotors is a freaking joke - not the stuff Ferrari - etc is using. The stuff is just junky parts designed to look cool. I am not saying that is what you are selling (I haven't even looked) - but I am saying that is what I have seen in the past lots of places.
The vast majority of slotted / drilled rotors are done for looks alone.
It is why you see something like this:
http://www.0-60mag.com/wp-content/up...treet-disc.jpg
It is a dimpled rotor to still have some of that cool look while maintaining the most mass and surface area for stopping power.
04-19-2011, 12:18 PM
#30
Uhm, actually as a physical chemist the mass of material defiantly plays a roll in heat capacity, and for sure isn't an engineering myth. Weather its significant or not is a different story.
04-19-2011, 12:50 PM
#31
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Extrapolate for me then the loss of thermal conduction capacity by removing .2lbs of mass from a 20 lb iron rotor. I'm not arguing that loss of mass has zero effect on thermodynamics (obviously it does) I'm arguing that the impact is negligible in the case of cross drilling rotors. As is the claim that the reduction in surface area makes even a modicum of difference in the actual brake torque produced.
04-19-2011, 01:45 PM
#32
Extrapolate for me then the loss of thermal conduction capacity by removing .2lbs of mass from a 20 lb iron rotor. I'm not arguing that loss of mass has zero effect on thermodynamics (obviously it does) I'm arguing that the impact is negligible in the case of cross drilling rotors. As is the claim that the reduction in surface area makes even a modicum of difference in the actual brake torque produced.
Same with the surface area deal on the brake pads, you obviously lose some area=lost friction, but it would depend on the proportion of the slot to brake pad size and frequency of the slots and on and on. Im not sure either way makes a big difference for 99% of drivers, and that one is simply better than the other.
Either way, loss in material=loss in heat capacity. Loss in surface area=loss in friction.
Is it significant? Probably not.
04-19-2011, 02:35 PM
#33
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Id need some data points to start with, hence the "weather its significant or not" point.
Same with the surface area deal on the brake pads, you obviously lose some area=lost friction, but it would depend on the proportion of the slot to brake pad size and frequency of the slots and on and on. Im not sure either way makes a big difference for 99% of drivers, and that one is simply better than the other.
Either way, loss in material=loss in heat capacity. Loss in surface area=loss in friction.
Is it significant? Probably not.
Same with the surface area deal on the brake pads, you obviously lose some area=lost friction, but it would depend on the proportion of the slot to brake pad size and frequency of the slots and on and on. Im not sure either way makes a big difference for 99% of drivers, and that one is simply better than the other.
Either way, loss in material=loss in heat capacity. Loss in surface area=loss in friction.
Is it significant? Probably not.
The data points for the reduced surface area problem could be completely arbitrary and as long as the only variables in the equation are (X) and (X -.2) the results will prove the point, which is; that the reduction in conductive heat transfer capacity is so negligible that it's not a valid criticism of drilled rotors.
04-19-2011, 03:38 PM
#34
Not sure why youre still "countering" me on this, as I keep saying it isn't significant. Except you are right with the pad thing, i forgot Ff=umg where mg in this case would be the force applied by the piston.
As for the heat capacity problem (not surface area problem as stated) even if the values are arbitrary, heat capacity is not only a function of mass, but a function of mass and temperature. So in a hypothetical situation assuming that the only variable is mass (x-0.2) works fine producing a linear output, but in a real world situation (brakes especially) as the temperature increases heat capacity decreases, producing a exponential output. As you build up temperature from braking, the materials ability to absorb heat (or its specific heat capacity) decreases, ect ect. Ceramic is great for this because it has a huge specific heat capacity which changes tiny amounts across temperature until its melting point. Its just a matter as to at what point does it matter.
For my car I say it doesn't, so I go with drilled/slotted anyways because they look dandy and will do all the braking I need.
As for the heat capacity problem (not surface area problem as stated) even if the values are arbitrary, heat capacity is not only a function of mass, but a function of mass and temperature. So in a hypothetical situation assuming that the only variable is mass (x-0.2) works fine producing a linear output, but in a real world situation (brakes especially) as the temperature increases heat capacity decreases, producing a exponential output. As you build up temperature from braking, the materials ability to absorb heat (or its specific heat capacity) decreases, ect ect. Ceramic is great for this because it has a huge specific heat capacity which changes tiny amounts across temperature until its melting point. Its just a matter as to at what point does it matter.
For my car I say it doesn't, so I go with drilled/slotted anyways because they look dandy and will do all the braking I need.
04-19-2011, 04:36 PM
#35
Just quoting this because gives starting pts for my post...
This is true for strictly the force of friction between the pad and the rotor. However it is clear that this is not strictly related to the braking force of the system. Brake pads apply force through friction and adhesion, the actual pad design/materials determine the proportion of each force. Most street pads are mostly friction. You also get some shearing of the pad material as it is compressed into the holes or slots which reduces the pad life, but may improve bite at low temp and reduce glazing (if that is a problem with your particular pad compound).
The actual thermal performance is definitely going to be difficult to model and will be system specific...
The one SAE paper that gets some attention by the two GM engineers had three different brake system models with vented blanks versus cross drilled rotors. Honestly their experimental models leave a lot to be desired but since it keeps getting brought up then I suppose we should talk about it.
If I remember correctly, the System 1 was allegedly for a performance sedan and used semi-metallic brake pads and nearly all of the braking force came from the front brakes. It had pillar-post vanes front and straight vanes rear. System 2 was for a performance car and could have easily been a C5 braking model although not listed... it had curved vanes front and pillar post rear (there was also internet speculation that in fact System 1 was Corvette and System 2 was a 911, but I think that is actually unlikely for a variety of reasons and think that not only were they probably testing GM cars, but that System 2 is more similar to Corvette than 911 anyway, and System 1 isn't really either car. I also want to say that both 1 and 2 had dual piston floating calipers front and single piston floating rears). System 3 was the odd one in which they still compared blanks to drilled, but the blanks were slightly smaller in diameter to the drilled and they used organic pads.
Out of order, System 3 showed better performance with blanks at all temps. The other two systems were better with the drilled at high temps and the blanks at low temps. As far as temps are concerned, at low speed the rear drilled rotors of System 1 ran hotter than the blanks.
They otherwise had a "cooling capacity" (hA) that they generated in the following manner:
h = convective heat transfer coefficient
A = working area of brake rotor
They came up with this because they wanted to compare rotors of dissimilar masses.
It's derived from the equation h*A=b*c*M where
M=working mass of rotor
c=specific heat capacity of rotor material
b=cooling coefficient of brake rotor
The cooling coefficient (b) comes from:
b= (1/t)*ln[(T-TsubS)/(TsubI-TsubS)] where
t=time
T=rotor temperature
TsubI=rotor intial temperature
TsubS=rotor stabilization temperature
For drilled versus blank for System 1 tests at 50kph, 100kph, and 160kph, showed an increase of cooling values (hA) of 8.8%, 12.1%, and 20.1% on the front and -3.2%, 1.9%, and 8.5% on the rear. For System 2, the test derived cooling capacity values at 50kph, 110kph, and 140kph are 7.8%, 10.4%, and 12.1% for the front and 4.1%, 7.7%, and 13.4% rear. Also of note is that the System 2's blank disk setup significantly outperformed both blank and drilled versions of System 1. The raw hA numbers are also interesting. At 160kph, the average hA for the front rotors of System 1 is 19.26 for the plain rotors and 23.13 for the cross-drilled. By comparison, the System 2 values at 140kph are 23.35 for the plain rotors and 26.18 for the drilled.
The way they generated this data was to mildly apply the brakes till they hit 450-500C then release and monitor the temp as it dropped. System 3 had weird values in this test and and under repeated stops the cross drilled brakes started to seriously spike in temp.
Other tidbits: Pad wear on cross-drilled rotors was also shown to be up to up to 50% greater under hard use, and about 25 to 30% greater under street use. They did not observe any significant difference in wet braking with cross drilled versus blanks (despite Porsche's claim, but again not necessarily the same system). They did not observe pad out-gassing and did not believe it to be a factor for a modern street car. Thermal fatigue life was less in a cross drilled rotor, and in System 1 was estimated to be up to 50% reduction in rotor life for the front.
All in all it was a study of 3 specific systems. Based on the way it was conducted, I am not sure all of it is 100% generalizable. Ah well. At least we see that you need to pay attention to the entire system and its use.
I hate bring out the "what racecars run" argument but there aren't very many cross drilled rotors in sports car racing. In the classes with iron rotors, the cars are running the j-slots. Even the cars that run drilled from the factory in street form. This is of course apples-oranges: they run gigantic diameter disks that are multipiece and have little to do with what I need to drive down to Walmart.
That's a fair statement. If you like the way they look then go for it. Don't expect any miraculous performance without any downsides. You can't pull a rabbit out of a rotor hat.
As for the heat capacity problem (not surface area problem as stated) even if the values are arbitrary, heat capacity is not only a function of mass, but a function of mass and temperature. So in a hypothetical situation assuming that the only variable is mass (x-0.2) works fine producing a linear output, but in a real world situation (brakes especially) as the temperature increases heat capacity decreases, producing a exponential output. As you build up temperature from braking, the materials ability to absorb heat (or its specific heat capacity) decreases, ect ect. Ceramic is great for this because it has a huge specific heat capacity which changes tiny amounts across temperature until its melting point. Its just a matter as to at what point does it matter.
The one SAE paper that gets some attention by the two GM engineers had three different brake system models with vented blanks versus cross drilled rotors. Honestly their experimental models leave a lot to be desired but since it keeps getting brought up then I suppose we should talk about it.
If I remember correctly, the System 1 was allegedly for a performance sedan and used semi-metallic brake pads and nearly all of the braking force came from the front brakes. It had pillar-post vanes front and straight vanes rear. System 2 was for a performance car and could have easily been a C5 braking model although not listed... it had curved vanes front and pillar post rear (there was also internet speculation that in fact System 1 was Corvette and System 2 was a 911, but I think that is actually unlikely for a variety of reasons and think that not only were they probably testing GM cars, but that System 2 is more similar to Corvette than 911 anyway, and System 1 isn't really either car. I also want to say that both 1 and 2 had dual piston floating calipers front and single piston floating rears). System 3 was the odd one in which they still compared blanks to drilled, but the blanks were slightly smaller in diameter to the drilled and they used organic pads.
Out of order, System 3 showed better performance with blanks at all temps. The other two systems were better with the drilled at high temps and the blanks at low temps. As far as temps are concerned, at low speed the rear drilled rotors of System 1 ran hotter than the blanks.
They otherwise had a "cooling capacity" (hA) that they generated in the following manner:
h = convective heat transfer coefficient
A = working area of brake rotor
They came up with this because they wanted to compare rotors of dissimilar masses.
It's derived from the equation h*A=b*c*M where
M=working mass of rotor
c=specific heat capacity of rotor material
b=cooling coefficient of brake rotor
The cooling coefficient (b) comes from:
b= (1/t)*ln[(T-TsubS)/(TsubI-TsubS)] where
t=time
T=rotor temperature
TsubI=rotor intial temperature
TsubS=rotor stabilization temperature
For drilled versus blank for System 1 tests at 50kph, 100kph, and 160kph, showed an increase of cooling values (hA) of 8.8%, 12.1%, and 20.1% on the front and -3.2%, 1.9%, and 8.5% on the rear. For System 2, the test derived cooling capacity values at 50kph, 110kph, and 140kph are 7.8%, 10.4%, and 12.1% for the front and 4.1%, 7.7%, and 13.4% rear. Also of note is that the System 2's blank disk setup significantly outperformed both blank and drilled versions of System 1. The raw hA numbers are also interesting. At 160kph, the average hA for the front rotors of System 1 is 19.26 for the plain rotors and 23.13 for the cross-drilled. By comparison, the System 2 values at 140kph are 23.35 for the plain rotors and 26.18 for the drilled.
The way they generated this data was to mildly apply the brakes till they hit 450-500C then release and monitor the temp as it dropped. System 3 had weird values in this test and and under repeated stops the cross drilled brakes started to seriously spike in temp.
Other tidbits: Pad wear on cross-drilled rotors was also shown to be up to up to 50% greater under hard use, and about 25 to 30% greater under street use. They did not observe any significant difference in wet braking with cross drilled versus blanks (despite Porsche's claim, but again not necessarily the same system). They did not observe pad out-gassing and did not believe it to be a factor for a modern street car. Thermal fatigue life was less in a cross drilled rotor, and in System 1 was estimated to be up to 50% reduction in rotor life for the front.
All in all it was a study of 3 specific systems. Based on the way it was conducted, I am not sure all of it is 100% generalizable. Ah well. At least we see that you need to pay attention to the entire system and its use.
I hate bring out the "what racecars run" argument but there aren't very many cross drilled rotors in sports car racing. In the classes with iron rotors, the cars are running the j-slots. Even the cars that run drilled from the factory in street form. This is of course apples-oranges: they run gigantic diameter disks that are multipiece and have little to do with what I need to drive down to Walmart.
For my car I say it doesn't, so I go with drilled/slotted anyways because they look dandy and will do all the braking I need.
04-19-2011, 05:07 PM
#36
Do you know what the ventilation was like on the rotors? As in were the enclosed under a wheel/tire, or were they on an open spindle with no wheel/tire? The cooling aspect of it adds a ton of extra variability that is defiantly beyond me, but that equation for a cooling coefficient looks pretty solid, im just not sure how they derived it.
Edit: After re-reading I think it would have to be on a stand, not on car, just for the fact that they were able to keep it spinning with break pressure until temps were reached, and monitor the drop.
Im not sure how wheels effect airflow around the brake rotor? I would think they prevent good airflow (unless you had rims that fanned the rotors, or a seperate venting system) but if you were able to add air flow over a blank disc i could see the cooling coefficient become very significant.
Either way, that side of the dynamics is way beyond me at this point.
Im not on either side for the drilled vs blank debate, just the fundamentals and basics sides of things.
Edit: After re-reading I think it would have to be on a stand, not on car, just for the fact that they were able to keep it spinning with break pressure until temps were reached, and monitor the drop.
Im not sure how wheels effect airflow around the brake rotor? I would think they prevent good airflow (unless you had rims that fanned the rotors, or a seperate venting system) but if you were able to add air flow over a blank disc i could see the cooling coefficient become very significant.
Either way, that side of the dynamics is way beyond me at this point.
Im not on either side for the drilled vs blank debate, just the fundamentals and basics sides of things.
Last edited by BigBadWhitey; 04-19-2011 at 05:17 PM.
04-19-2011, 05:24 PM
#37
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Actually I have ~23 Days left until I graduate with my Degree from Purdue in Mechanical Engineering. Oh and btw, I had my 5 term co-op (about 2 years experience) with an automotive brake supplier.
Even if you through out all other concerns, my biggest one still remains - strength. I destroyed a set of powerslot drilled / slotted rotors with pure street driving. I'll never own another set, they came on the car and that is the only reason why I had them in the first place. They had stress cracks everywhere and were warped like crazy. Kind of nuts I have have 0 problems with my blanks and even more aggressive pads...
I do believe that the affects from heat transfer weight etc are very small. No doubt, but they do exist. I believe it is mostly the quality of the piece that makes the biggest difference. Also as far as stopping distance for a one time stopping even - no difference I bet. I still stand by the fact that the only reason they do drilled / slotted is for looks.
If you don't drive really aggressively and want the looks - by all means go for them. Not for me though.
and for the surface area - yes the FORCE of the friction is not affected by the area in the purely theoretical realm, but you still need more surface area to apply that force. Ex: Why do people run wide tires if friction is not affected by area?
Also took a look over at your other thread. ChrisB knows what he is talking about for race cars - but we were talking about budget street applications here.
You aren't really addressing the point of what I was saying anyway so it doesn't really matter. I have some real projects to finish up and it isn't worth doing the immense amount of calculations to even come up with some basic theory argument for this - so I am just going to stop now. I'll go back to internet engineering somewhere else.
Even if you through out all other concerns, my biggest one still remains - strength. I destroyed a set of powerslot drilled / slotted rotors with pure street driving. I'll never own another set, they came on the car and that is the only reason why I had them in the first place. They had stress cracks everywhere and were warped like crazy. Kind of nuts I have have 0 problems with my blanks and even more aggressive pads...
I do believe that the affects from heat transfer weight etc are very small. No doubt, but they do exist. I believe it is mostly the quality of the piece that makes the biggest difference. Also as far as stopping distance for a one time stopping even - no difference I bet. I still stand by the fact that the only reason they do drilled / slotted is for looks.
If you don't drive really aggressively and want the looks - by all means go for them. Not for me though.
and for the surface area - yes the FORCE of the friction is not affected by the area in the purely theoretical realm, but you still need more surface area to apply that force. Ex: Why do people run wide tires if friction is not affected by area?
Also took a look over at your other thread. ChrisB knows what he is talking about for race cars - but we were talking about budget street applications here.
You aren't really addressing the point of what I was saying anyway so it doesn't really matter. I have some real projects to finish up and it isn't worth doing the immense amount of calculations to even come up with some basic theory argument for this - so I am just going to stop now. I'll go back to internet engineering somewhere else.
Last edited by ThumperNC24; 04-19-2011 at 06:09 PM.
04-19-2011, 07:14 PM
#38
One of the things that makes it seem like wider tires enhance traction is similar to the effect that people are attributing to rotor changes when they upgrade rotors and pads... focusing on one thing and ignoring other variables. Many times guys that go wider are also ending up with better tire compound which enhances grip all throughout the traction circle.
04-19-2011, 10:15 PM
#40
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Some of it was done on car, some on a brake dynometer. I don't have the paper in front of me and I don't remember what all was done where.
I'm not a tire expert but I think tires are a complicated subject that is misunderstood and one of the more common misconceptions is that wider tires enhance "traction." Wider tires do not increase grip as far as straight line acceleration or braking is concerned. They do increase the limit of lateral grip, but they also break away more abruptly when they hit the limit. The contact patch length in the direction of acceleration (forward, backwards, or to the side) affects the grip because of shearing. There is a surface area effect from adhesion that depends on contact patch area, but contact patch area does not change when you go to a wider tire with the same air pressure... it just gets wider left to right and shorter front to back.
One of the things that makes it seem like wider tires enhance traction is similar to the effect that people are attributing to rotor changes when they upgrade rotors and pads... focusing on one thing and ignoring other variables. Many times guys that go wider are also ending up with better tire compound which enhances grip all throughout the traction circle.
I'm not a tire expert but I think tires are a complicated subject that is misunderstood and one of the more common misconceptions is that wider tires enhance "traction." Wider tires do not increase grip as far as straight line acceleration or braking is concerned. They do increase the limit of lateral grip, but they also break away more abruptly when they hit the limit. The contact patch length in the direction of acceleration (forward, backwards, or to the side) affects the grip because of shearing. There is a surface area effect from adhesion that depends on contact patch area, but contact patch area does not change when you go to a wider tire with the same air pressure... it just gets wider left to right and shorter front to back.
One of the things that makes it seem like wider tires enhance traction is similar to the effect that people are attributing to rotor changes when they upgrade rotors and pads... focusing on one thing and ignoring other variables. Many times guys that go wider are also ending up with better tire compound which enhances grip all throughout the traction circle.