Need track day advice

[Wertles]

I'm just about to order rotors and pads. After talking with a salesman, he recommended the following.

SP slotted rotors
http://www.bestbrakes.com/c/car-item...MW%20M%20Coupe

Hawk DTC-60 pads for the front
http://www.bestbrakes.com/c/car-seri...9+BMW+M+Coupe+

Hawk HP plus pads for the rear
http://www.bestbrakes.com/c/car-seri...9+BMW+M+Coupe+

He likes the quality of these rotors over most others for the value, since I am trailering the car, the race pads in the front (he states they will perform better hotter and last longer than HP Plus pads) and the HP Plus pads for the rear because I won't be able to keep the rears hot enough for the race pads to work well. That, and they will have good cold bite until the fronts get above 150 degrees or so. He states the difference between stopping power between the pads is small and shouldn't affect the balance of the car.

What say you?

[BMWBergy]

Chris, this may just be my opinion, but since this is your first HPDE, you may be doing a little thing called 'overkill.' I think that on street tires, and as a first-timer, HP+ will be more than enough brake pad for the front axle. If you were running R-Comps, maybe race pads would be justified... and you really should not try to go out there as a beginner on R-Comps...

To follow that argument a bit further, I say go out there and learn your car with its current capabilities, augmented with HP+ pads, then incrementally step up the performance gadgets as you drive more events. That way, you will be more familiar with the feel and characteristics of your vehicle when you first take to the tarmac during your first-ever session. You may be a complete superman, but in all likelihood, you will have your hands (and brain) full trying to find the right line and be smooth with your steering, braking, up- and down-shifts, weight transfer, etc.... modulation of the brake pedal with race pads may be a bit too much.

I'm not trying to steer you away from spending your money... I just think that for ~$240 you can have a full set of new rotors, and for $220 you can have HP+ front and rear. That's $460. Your links add up to what? $688?

As a disclaimer, I've never driven the Glen.
As an FYI, for Laguna Seca I'm going to be on fresh street tires, fresh OEM rotors, HP+ front pads and Porterfield R4S rear pads.

[Aw0802]

for first time, remember to bring your helmet....

[Wertles]

for first time, remember to bring your helmet....

Check



Just ordered the Hawk HP Plus pads front and rear. I figured the others were just overkill but wanted to check. I did splurge the little extra for the slotted rotors. If nothing else, they look cool. If they suck for the track, they will just become my daily rotors.

[BMWBergy]

Just ordered the Hawk HP Plus pads front and rear. I figured the others were just overkill but wanted to check. I did splurge the little extra for the slotted rotors. If nothing else, they look cool. If they suck for the track, they will just become my daily rotors.

Good call, Chris.

[vanne]

Wow, great thread!

I'll be looking for my first track day next season when it cools down here.
So keep the advise coming as I am taking notes. By the way, will I be able to use my arai motorcycle helmet for these track days? It's only a year old?

Cheers

[Wertles]

The school I am attending requires Snell 2010. My motorcycle helmet was Snell 2000 so a little out of date. I was planning on a new one this year anyway, this just sped up the process.

[rf900rkw]

Need to check if they will accept a motorcycle helmet. Snell M2010 and SA2010 are not the same certification.

- - - Updated - - -

BTW, I answered your PM in the referenced thread. I know you've been busy with this, don't know if you saw it.

[BMWBergy]

Wow, great thread!

I'll be looking for my first track day next season when it cools down here.
So keep the advise coming as I am taking notes. By the way, will I be able to use my arai motorcycle helmet for these track days? It's only a year old?

Cheers

The organization running specific HPDE or Auto-X events will have distinct requirements for safety equipment (particularly helmets), so it's always best to consult with their documentation. And as Randy said, some organizations may not accept Snell M2005 or M2010 (the 'M' is designation for their motorcycle certification).

[bimmerhhi]

My best advice is to focus on learning how to drive the correct way - good technique. Driving at speed is very, very, very different than driving (on the street), and you are there to learn. Learning takes time. Start slow. Ok, not "slow", but run your car at a quick, but comfortable speed to give your brain time to learn what you are being taught. The speed will come, but if you're just trying to drive fast, your brain will be spending 100% of its time trying to not crash and you won't really be learning much.

College quarterbacks transitioning to the NFL often talk about how fast the game is, but that after a year or two, the game seems to slow down. In reality, the game is just as fast, but after playing in the league for awhile, their brains learn to process what's happening on the field more quickly, giving them more time to make smart decisions. The exact same thing happens on the track. During your first 50 laps, it will feel like everything is happening very fast and most of your attention will be on the 25 feet in front of your car. During your next 50 laps, and the 50 after that, etc., things will seem to slow down, giving you more time to look around, see the flags, think about your lines and shifting strategies, etc. And even though things will seem slower, you will be driving faster. But it takes time… There are no shortcuts. In order for the NFL game to slow down, the quarterback needs to be in the game, play after play after play… In order for the track to slow down, your butt needs to be in the seat, lap after lap after lap…

Listen to your instructor, even if it doesn't seem to make sense, and let your brain be open to to learning. Many things your instructor will be telling you will be counter-intuitive, but they have learned what works on the track. Listen to them. The first time my instructor taught me about threshold braking, I thought he was crazy, but after learning about contact patches and the (massive) weight shift toward the front of the car during braking, and after actually doing it 100 times, it made sense. It was just very, very, very different than what I was used to with normal street driving. Slow in, fast out WORKS, but when you are on the track, it is very counter-intuitive. Listen to your instructor.

Lastly, the main difference between driving on a track and driving on the street is that driving on a track is mostly about controlling the balance of your car. During normal street driving, it is extremely rare to put your car out of balance. On the track, it happens constantly. Just about every decision you make on the track, such as when to brake, how hard to brake, when to accelerate, how quickly to accelerate, when to turn in, how sharply to turn in, when, and how aggressively, to go for the apex, tracking out, shifting, etc., will be based on controlling the balance of your car. Some people think that driving on a track is about going as fast as you can and getting an adrenaline rush. That "rush" usually comes from your car being out of balance, which is another way of saying out of control, or about to be. Those people are wrong. The way to drive a car around a track as quickly as possible is to control every aspect of your car's existence in the universe (track position, angle of attack, speed, acceleration, weight distribution, wheel slip) at all times, and the only way to do that is to control the balance of your car, and the only way to do that is to learn the proper techniques for driving on a track. Slow is smooth. Smooth is fast. Listen to your instructor. :-)

[BenFenner]

I know I'm coming in here way late, but I just wanted to say the slotted rotors, while probably not completely necessary, were a decent choice. They do provide some benefit to blank rotors on the track, and don't have any real negatives. I'm just so glad you didn't do a drilled rotor or rotor with holes. Those are awful for performance driving. If anyone wants citations, here yah go: http://www.sr20-forum.com/members-ri...tml#post167293


Edit: Citations reproduced here since it is behind a registration wall. I made this post showing citations and research after a long, protracted argument with another forum member over the performance benefits of slotted and drilled rotors. These citations are for those who want to see what industry insiders say about the topic.

I don't shun holes in rotors and promote slotting because it makes me feel warm and fuzzy inside.

Source 1:

Contrary to popular belief, they don't lower temperatures. In fact, by removing weight from the rotor, the temperatures can actually increase. The holes can actually create stress risers, allowing the rotor to crack sooner...

Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time. This, in turn, helps to reduce the “glazing” often found during high-speed use, which can lower the coefficient of friction.

Source 2:

Which one is better? This is a common question and naturally, each of them have their benefits and drawbacks. For any performance applications we recommend our AB SELECT rotors. Slots clean the brake pad surface which helps to increase brake "bite". Drilled rotors have the same benefit of cleaning the brake pad surface, but under heavy braking, such as a racing environment they are prone to cracking. For most people drilled rotors provide the desired look yet we only recommend them for street applications with mild braking situation. Slotted rotors are also a good addition to any vehicle that is used for towing, as the benefit is the increased "bite" that you get from the slots.

Source 3:

Anyone that tells you that drilling makes the disc run cooler is smoking crack.

Source 4:

At one time the conventional wisdom in racing circles was to cross-drill brake rotors to aid cooling and eliminate the gas emitted by brake pads. However, today's elite teams in open wheel, Indy and Trans Am racing are moving away from crack prone, cross-drilled brake rotors in favor of rotors modified with a fatigue resistant slotting process.

Source 5:

StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors.

(Note that even though Stop Tech sells both drilled and slotted rotors they do not recommend drilled rotors for severe applications.)

Source 6:

Q: Why are some rotors drilled or slotted?
A: Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity.

Source 7:

If you cross drill one of these vented rotors, you are creating a stress riser that will encourage the rotor to crack right through the hole. Many of the rotors available in the aftermarket are nothing more than inexpensive offshore manufactured stock replacement rotors, cross drilled to appeal to the performance market. They are not performance rotors and will have a corresponding high failure rate.

(Warren Gilliland is a well-known brake engineer in the racing industry and has more than 32 years experience in custom designing brake systems ...he became the main source for improving the brake systems on a variety of different race vehicles from midgets to Nascar Winston Cup cars.)

Source 8:

What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors? In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today's race pad technology, 'outgassing' is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer's offerings.

Source 9:

Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause
temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean
the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

Source 10:

Grooves improve 'cleaning' of the pad surfaces and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs.

Sources 3-10: What Kind of Rotors Should I Get?

[lokijibber]

I know I'm coming in here way late, but I just wanted to say the slotted rotors, while probably not completely necessary, were a decent choice. They do provide some benefit to blank rotors on the track, and don't have any real negatives. I'm just so glad you didn't do a drilled rotor or rotor with holes. Those are awful for performance driving. If anyone wants citations, here yah go: http://www.sr20-forum.com/members-ri...tml#post167293

But they look cool

[Scarceas]

I know I'm coming in here way late, but I just wanted to say the slotted rotors, while probably not completely necessary, were a decent choice. They do provide some benefit to blank rotors on the track, and don't have any real negatives. I'm just so glad you didn't do a drilled rotor or rotor with holes. Those are awful for performance driving. If anyone wants citations, here yah go: http://www.sr20-forum.com/members-ri...tml#post167293

The link you provided requires registration to view, but I'm interested in hearing the logic behind your statements. I want to clarify that I'm not saying you're wrong--I am trying to learn. So let's start out with me explaining what I've heard and read and what makes sense to my simple mind.

OK, first up my understanding of cross-drilled rotors was that they were of benefit "back in the day" when the pad compounds released gas as they were used up. The gas built up in a layer between the rotor and pad, reducing brake efficiency. By putting holes in place, the gas was pushed in to the holes, allowing the pad to contact the rotor more effectively.

However, I also have read that today's pads do not release gasses, therefore the cross drilled rotors are not necessary. They remove surface area for the pads to contact, and with less metal they are less effective at heat dissipation. The holes reduce structural integrity and perhaps cause the rotors to warp more easily. The only benefit I have read that makes sense to me is that debris or water caught on the rotor can be pushed into the holes and that may mean more pad on the rotor.

Finally, cross drilled or slotted, I thought both designs pretty much did the same thing? The slotted I would think removes less material, so it should have some heat dissipation advantage over cross-drilled, and perhaps some increased resistance to warping since there are no actual holes?

Does the benefit of slotted rotors though, really just boil down to keeping the bite surface cleaner than a "blank"?

[BimmerBreaker]

I am also curious what is to be said about this because I was told not only to stay away from cross drilled, but from slotted too - and that blank/vented were best. I have even heard some people say the blank/vented dissipate heat more effectively because of the larger surface area and increased mass (which physics agrees with) - with F1 and other classes of race cars being cited as proof of this. I am curious if race cars use blank/vented rotors due to regulation, strength, or heat dissipation. Its not a direct comparison because the materials those braking systems are made out of are different, but if blank is better for heat dissipation on those materials, I imagine its the same for our rotors.

From what little I do know I have been told that slotted and cross drilled/dimpled rotors were a gimmick on modern cars and may actually negatively impact performance, potentially even becoming a safety hazard. I was under the impression that people use slotted/cross drilled for (perceived) improved heat dissipation even though this is not the case and these rotor designs were originally used in race cars to, as Scarceas said, give the gas from the pad a place to escape. So if modern pads dont release significant amounts of gas, the question becomes, why do we still use these rotors? (not a hypothetical question, I am really asking and hoping someone knows)

And a bit off topic maybe but is it logical to assume that the below failures happen because of the different temperatures in different areas of the metal causing premature fatigue leading to failure? So its cooler near the dimple, and without any room to expand or contract like a slotted rotor would give (or expanding/contracting as a whole like a blank), the metal fatigues. Then eventually through a few heating/cooling cycles, the metal is so fatigued it cracks. These images though, do make me a bit concerned for the strength of the metal in a slotted system.

Grabbed this picture from Google and it was said this was from under one hour of use:


Another failure:


I am curious what some of our more knowledgeable people say about this. I do believe slotted/drilled rotors on modern cars are a cosmetic thing more than anything else, but hope someone can prove me wrong because I would love to justify some cool looking rotors for myself

[Wertles]

From my research, cross drilled are for looks only. They dissipate heat faster due to less mass but also heat up faster due to less mass. Most cheap drilled are not good as proof of the above pictures. There are many different ways of cross drilling. Some just drill, leaving 90 degree edges around each hole while some chamfer the edges. Cheap companies drill right through the cooling vanes hence leading to a weaker rotor.

Since I work at Watkins Glen on the weekends, many, including the Indy car series, all run slotted rotors. There isn't much mass removed, structural integrity on properly slotted rotors is preserved. I'm not sure the Hawk HP Plus brakes produce any gas, but if they do, I'm covered. Again, if they suck, I will go back to blanks and these will just be bling for daily driving.

[rf900rkw]

Yes, slotted/drilled rotors are for wiping the fire band from the pad. This is something that happens right on the edge of the limits, and thus has absolutely no place on a street car. There are correct ways to drill, and incorrect ways. This is especially true on vented rotors.

Failiure analysis is a detailed microscopic art. Casual comment based on two pics is silly. But this is bimmerforums. With the pics above, there are far more questions than answers presented. The two things I would hazard to guess are both cracks were started by uneven stress caused by uneven mounting; such as a piece of dirt/rust under the hat. The second is the if the top pic is from one axle (they appear to be unvented rears), why are they not drilled mirror image. Oh, and thats an awful lot of rust and wear for a mere hour of running

[lokijibber]

I can say from EXPERIENCE that drilled rotors greatly extended pad life in my previous DD. I'm sure there are issues under the duress of track use, but for a street driven car they did wonders.

[BenFenner]

The link you provided requires registration to view, but I'm interested in hearing the logic behind your statements.

I've edited my original post to include the citations since apparently it is behind a registration wall (I was not aware of that when I posted it).

OK, first up my understanding of cross-drilled rotors was that they were of benefit "back in the day" when the pad compounds released gas as they were used up. The gas built up in a layer between the rotor and pad, reducing brake efficiency. By putting holes in place, the gas was pushed in to the holes, allowing the pad to contact the rotor more effectively.

However, I also have read that today's pads do not release gasses, therefore the cross drilled rotors are not necessary. They remove surface area for the pads to contact, and with less metal they are less effective at heat dissipation. The holes reduce structural integrity and perhaps cause the rotors to warp more easily. The only benefit I have read that makes sense to me is that debris or water caught on the rotor can be pushed into the holes and that may mean more pad on the rotor.

Finally, cross drilled or slotted, I thought both designs pretty much did the same thing? The slotted I would think removes less material, so it should have some heat dissipation advantage over cross-drilled, and perhaps some increased resistance to warping since there are no actual holes?

Does the benefit of slotted rotors though, really just boil down to keeping the bite surface cleaner than a "blank"?

Your assessment of the history and pros/cons is pretty close to correct. (As are the other posts made since in this thread.) I could get much deeper into the analysis if you'd like, but we might be better off in a new thread with how specific the brake rotor discussion could get.

To answer your direct question, slotted rotors avoid sudden and complete brake fade caused by pad outgassing by allowing for rejection of the gas between the pad and rotor. This risk has been reduced with modern pads but still exists. Slots also aid in initial "bite" upon pedal application. They also clean and condition the pads resulting in slightly longer pad life. They inhibit pad glazing as well.

A side-effect is a sweeping noise especially at lower speeds.

There are correct ways to drill, and incorrect ways. This is especially true on vented rotors.

Seriously trying to avoid a devolution into brake rotor tech in this more broad thread, but I'll say while this is true (there are "correct" ways to put holes in a rotor), there are no good [cast iron] rotors with holes as far as performance is concerned.

I am curious what some of our more knowledgeable people say about this. I do believe slotted/drilled rotors on modern cars are a cosmetic thing more than anything else, but hope someone can prove me wrong because I would love to justify some cool looking rotors for myself

Holes in rotors are cosmetic only, and a horrible trade-off in my opinion. If you want the look of holes, go with dimples instead. These days dimpled rotors (with slots too) are easy enough to come by for people wanting the look of holes but without all the downsides.

[Wertles]

Brake job, check.



The coating will come off the braking surface during the bed in process leaving the rust preventative coating on the rest of the rotor. Hawk pads slid in well. I will flush the system tonight. Oil change and changing my midpipe to the one I have with higher flow cats are the only things left on the list besides packing tools, spares etc.

[jajou318]

Looks fake.

I was always told to clean rotors w/ brake cleaner before installing them to get off the rust preventative stuff that's on them (for storage and shipping), is this not required?

[Wertles]

Looks fake.

I was always told to clean rotors w/ brake cleaner before installing them to get off the rust preventative stuff that's on them (for storage and shipping), is this not required?

I always did that as well but every other rotor was covered in an oily film for rust protection. This is almost like a dry paint job. I read the directions twice. Only use an abrasive cleaner if you get oil or grease on the rotor during installation.

Yes, it definitely looks fake. However, the coating goes all the way through the vents so hopefully they will stay nice and rust free for a long time.

[BMWBergy]

Zimmerman now sells 'Z-coated' rotors that have that same sort of treatment on them. As Chris said, this is NOT supposed to be cleaned off with chems or other abrasives, rather it will get scrubbed off by the pads. I recommend pulling the pads after the rotor surface turns shiny, and cleaning out the groove in the middle of the pads.

As you can see, the ENTIRE disc, including the venting vanes and tophat are coated in this material, which is meant to prevent rust. I do wonder if it has any negative impact on cooling...

After break-in (1).JPGIMG_0012.JPGIMG_0020.JPG

[Bcar]

Some good info here on brakes, but there is also still alot of debate on holes vs. slots. Ivedone a lot of brake development for non street vehicles working with Brembo(best IMO, spend by FAR the most $$ on R&D), Wilwood, and Stoptech. Holes reduce the thermal mass, but if thehole pattern/vanes are designed correctly and there is air ducting to therotor, they do increase cooling, even counting the reduction in mass. If you look at the latest top of the linebrembo products for street cars (ZR1 etc.), they have holes (cast vs. drilledholes are a different topic! Cast=better though). The other key is iron/steel vs. compositerotors, they shed and store heat in VERY different ways.

I would disagree that slots/holes "clean" thepads though, maybe if you were driving in mud, but that is not the case onstreet or track. Even new technology padscan 'gas' out, but this really only happens when you're near or above the padstemp limit, then the material at the surface is superheated and turns from solidto gas and acts as an air or gas cushion/hovercraft between the rotor and pad. Slotting, or holes, prevent this. But again,only when you've overcooked the brakes.

My car came with slotted and drilled fronts and drilledrears, when they die, I'll be going with slotted only, but not a full slotting,just a few on each rotor, 4-6 probably.

Here's some good whitepaper info from stoptech, for sureworth a read.
http://www.stoptech.com/technical-su...nd-other-myths

Wertles, good choice on pads and rotors. You'll most likely find that the allure of topspeed on the straights wears off because of the brakes (and if something goeswrong...). I'll skip up-shift a lot onsome straights, top end speed is not what most of us are after on the trackanymore, those high speed braking zones are what really wear/heat up brakes, ifyou're 10mph slower, you'll most likely not have to worry about pads/brake tempfor the rest of the lap.

Soooooo....How was your event!?!?

[BenFenner]

If you look at the latest top of the linebrembo products for street cars (ZR1 etc.), they have holes (cast vs. drilledholes are a different topic! Cast=better though).

I didn't want to go here, but there are no such thing as cast iron rotors with holes cast in them. All holes in cast iron rotors are drilled. There is a tech insider who has been offering $500 for the past 10 years for proof of a rotor with holes cast into them and so far he's not had to pay out yet.

Also, just because a ZR1 or Porsche or whatever runs drilled rotors, does not mean they are there for performance.

The link on the myth of warped rotors is a good one, and has been in The Manifesto from the beginning.

Another useful link since we're on the topic: How to properly install plain, slotted, or drilled brake rotors

[Bcar]

I didn't want to go here, but there are no such thing as cast iron rotors with holes cast in them. All holes in cast iron rotors are drilled. There is a tech insider who has been offering $500 for the past 10 years for proof of a rotor with holes cast into them and so far he's not had to pay out yet.

Also, just because a ZR1 or Porsche or whatever runs drilled rotors, does not mean they are there for performance.

The link on the myth of warped rotors is a good one, and has been in The Manifesto from the beginning.

Another useful link since we're on the topic: How to properly install plain, slotted, or drilled brake rotors

"Casted" in some chopped fiber composite rotors, not iron, sorry, should have stated that better. They're drilled in laminate composite rotors (nice and cheap drill bits LOL). I've seen the CFD model results for various brembo rotors, and have done a ton of brake dyno testing at Link. They wouldn’t add cost and complexity to the process if it didn’t work/do anything, and the physical testing results Ive seen/performed state differently. The key is directed airflow, without it, not much change. Thermal mass is not nearly as important on composite rotors vs. iron. nearby components will melt/catch on fire before the rotors get too hot.

Racing is a different animal with vastly different materials when you start taking F1.