For the love of pete, please stop using HPS and HP+ pads at the track!

[jml]

Originally Posted by Slapshot9

Disagree with nearly all of your comments in regards to HP+. Not to question your abilities, but a lot of people don't know how to properly brake. IE: dont drag your brakes, change before too thin, etc, etc. Speaking from experience, as well as others posted here, HP+ can be run very effectively all day without issues. Your problems sound like isolated issues that may not be the resut of the HP+ compound. Feel free to share more details (track, length of run, track temp, lap times, etc) so we better understand your problem.

I am not sure where to begin. If you are pushing back because you own these pads or sell them...then please, do your family and conscious a favor and buy a product that is more applicable to track use in the M3. I really hope that you take my advice...and I care and worry that those who are reading this thread are going to listen to you and hurt themselves.

The HP+ has a MOT of 950F, which is about the same as stock pads. It has a very high friction at low temps relative to other street pads, which is why many people like them. A good race pad, like say the DTC70, has a MOT of 1600F+. These are high power, 4000lb cars with virtually zero brake cooling from the factory. It is inevitable that you will exceed 950F between the pad and rotor. If you've ever faded stock pads, or had them melt onto the rotors, then you will reach the MOT of HP+ pads. And the issue is the abrupt nature of what happens after that point. You don't have to take my word for it. Call Dave zeckhausen, or James Clay at Bimmerworld and ask them what a good track pad is for a begineer/novice student...HP+ is not going to be it.

There are a lot of other factors that will drive more or less heat into the brake system. A intermediate to advanced student is going to far exceed the ability of these pads within 5-10 laps in most situations. A begineer could get there as well on a fast track like TWS, or a very bad student ridding the stability system on every corner.......and if you are running these and have not yet had the experience, it's only a matter of time as you get faster - or make a mistake and suddenly need a safety net. I pray that you don't. It's your choice though.

PCA will be sending out a memo to students at some point (this is not the first time this has happened at our events) asking students to not show up to DE events with these pads. We have no way to enforcing it, but the word will spread and a few instructors out there with families will probably decide not to get into your car.

[LittleBlueBMW]

I have run HP+ on all my E36's with no issues in CCA intermediate groups and we currently have a set on the ZO6 with no issues. Just got back from Buttonwillow from a 2 day school and the pads certainly held up well. I certainly will look into an upgrade since the husband is starting to get a little fast and needs stronger brakes. All the cars are on the lighter side but that ZO6 is just so damn fast.

[Richbot]

Please cite sources your MOT numbers, I don't doubt it, just would like to know where to find this information since it's not easy to find on Hawk's webpage or anywhere else.

FWIW, I was using the DTC60 on the miata in my signature, and that was a 130hp, 2300lb car.

[CanAutM3]

Originally Posted by The HACK

Kinetic energy is now growing at an exponential pace due to the constant growth of weight and power, while the ability to dissipate it have not. So the only choice y'all have, is to continue to escalate the capacity to operate under higher and higher MOT.

I don't believe this is entirely true. The weight from and E36 (~3200lb) to a E92 (~3600) increased by about 13% while the disc swept area increased by around 30%. This discs also have greater thickness and mass. So, IMO, the systems ability to dissipate heat has increased more than the weight of the cars.

However, is it enough to overcome the increased kinetic energy due to the higher power? Well that is another question...

[jml]

Originally Posted by Richbot

Please cite sources your MOT numbers, I don't doubt it, just would like to know where to find this information since it's not easy to find on Hawk's webpage or anywhere else.

FWIW, I was using the DTC60 on the miata in my signature, and that was a 130hp, 2300lb car.

When I spoke with Dave Zech. he said they were slightly less than the Ferrodo 2500s, which are 1000F.

Not sure where y'all get 3600lbs for the M3 weight, mine is right under 4K with me in the driver's seat and a full tank on track scales.

[Richbot]

My E90 with a full tank is at 3775lbs with me in it (has a few lighter weight components amounting to about 35lbs of total weight loss). No sunroof, single hump, 6-speed manual, premium and cold weather packages. A fully optioned car weighs at least 100lbs more, probably more like 150. 44lbs for DCT alone.

[Richbot]

Originally Posted by CanAutM3

I don't believe this is entirely true. The weight from and E36 (~3200lb) to a E92 (~3600) increased by about 13% while the disc swept area increased by around 30%. This discs also have greater thickness and mass. So, IMO, the systems ability to dissipate heat has increased more than the weight of the cars.

However, is it enough to overcome the increased kinetic energy due to the higher power? Well that is another question...

Mass is a linear relationship with kinetic energy. Velocity is a squared relationship. The E90 doesn't need more brake because it's fatter, it primarily needs more brake because it's 10-20mph faster at the end of most straights than any M3 before it. So no, the M3's brakes have not increased in size sufficient to compensate for the increase in performance, let alone weight.

From an earlier post of mine:

E46 M3 at 3500lbs with driver braking from 135 mph for a 60 mph corner needs to dissipate approximately 550kcal of kinetic energy. E92 M3 braking from 145mph for the same corner needs to dissipate approximately 705kcal of kinetic energy. That's a ~7% increase in weight and speed and ~45% increase in heat load on the brakes. The E92 brakes are bigger but they aren't 45% bigger, and at bigger tracks the speed gap is even more significant. Faster cars are harder on equipment, k=mv^2. BMW had a choice to provide everything from a setup for a 150mph car with a sensitive driver to manage on track to one that can throw down qualifying laps for a whole race distance on a 100 degree day running 6" from another car's bumper. One is what we have from the factory, the other would probably need to be water cooled to fit under 18" wheels.

[Porschefile]

My car scaled in at 3540 with 1/2 tank with few mods, and my car is a loaded DCT and presumably heavier than a 6MT. The rotor design on the E9X uses a strange mounting design that covers up roughly half of the cooling vanes with tabs. I don't know anyone that drives near the limit and doesn't have major issues with stock brakes. The E9X needs PFC/Hawk/etc. to be reliable on track. Brakes are not the place to skimp.

[Richbot]

DCT adds 44lbs (20kg) vs 6MT according to BMW's literature.

Your car with a full tank (+48lbs) and me in it would weigh about 3780 on those scales. Nowhere near 4000lbs. Of course, "loaded" on an E92 often still means it has a CF roof, which is a 45+lb difference compared to a sunroof

[Porschefile]

Originally Posted by Richbot

DCT adds 44lbs (20kg) vs 6MT according to BMW's literature.

Your car with a full tank (+48lbs) and me in it would weigh about 3780 on those scales. Nowhere near 4000lbs. Of course, "loaded" on an E92 often still means it has a CF roof, which is a 45+lb difference compared to a sunroof

Yep, I meant loaded with the good options . Everything except sunroof. But IIRC premium sound adds weight. The exhaust and wheels and stuff I have probably drop weight slightly. But I don't see any 4000lb E9X happening unless someone throws a roll cage in a car with full interior or something.

[Richbot]

If you use my car as a baseline at 3775 with driver and full tank, add 44lbs for DCT, ~50lbs for sunroof, and ~50lbs for everything else and you're at 3919. Add a big guy driving and you're there, but that's hardly the norm especially for people who track their cars and don't buy cars loaded down with every option and tend to be skinny nerds

[CanAutM3]

Originally Posted by Richbot

Mass is a linear relationship with kinetic energy. Velocity is a squared relationship. The E90 doesn't need more brake because it's fatter, it primarily needs more brake because it's 10-20mph faster at the end of most straights than any M3 before it. So no, the M3's brakes have not increased in size sufficient to compensate for the increase in performance, let alone weight.

From an earlier post of mine:

E46 M3 at 3500lbs with driver braking from 135 mph for a 60 mph corner needs to dissipate approximately 550kcal of kinetic energy. E92 M3 braking from 145mph for the same corner needs to dissipate approximately 705kcal of kinetic energy. That's a ~7% increase in weight and speed and ~45% increase in heat load on the brakes. The E92 brakes are bigger but they aren't 45% bigger, and at bigger tracks the speed gap is even more significant. Faster cars are harder on equipment, k=mv^2. BMW had a choice to provide everything from a setup for a 150mph car with a sensitive driver to manage on track to one that can throw down qualifying laps for a whole race distance on a 100 degree day running 6" from another car's bumper. One is what we have from the factory, the other would probably need to be water cooled to fit under 18" wheels.

I fully agree on the impact of speed.

However I am not sure I follow your math. When I do the calculation using 3500lb and 135mph for the the E46 and 3750 and 145mph for the E92 with both slowing to 60mph I come up with 3.0Mj and 2.3 Mj repectively of dissipated energy. Which is a 28% difference, not 45%. Further, from your own calculation 705kCal/550kCal is also 28% .

Further, my E46 weighed closer to 3600lb (bare bone 6MT) with me and half fuel and my E92 weighs 3750lb with me and half fuel. With this I only come up with a 24% difference. When I compare the swept area of the front rotors, they are about 20% bigger on the E92. This is not that far off...

[Richbot]

You're right, I borked my ratio

Swept area != heat capacity, and more important heat dissipation rate, as you said. It's a big assumption to assume dissipation rate has increased, and probably not a good one as the E9x doesn't have any kind of ducting to speak of from the factory. And in any case, you're still comparing one inadequate brake system to another, neither the E46 nor the E36 before it was suitable for sustained use on a racetrack close to the car's speed potential. I don't doubt there were plenty of drivers who weren't turning lap times anywhere close to that potential who were just fine, but that's the same as always, there are plenty of drivers on here running laptimes that would be lucky to stand up in a ChumpCar race. So as to the Hack's comment, I think it's true, relative to the car's performance and even using your numbers, the upgrades to the M3's brakes for this generation have not kept up with the demands placed on them.

We're quibbling anyway, if the MOT of HP+ is less than 1,000F, they have no business being sold as track pads for a car like ours. MDM and other stability "aids" (more like bandaids) just make it worse

[ortho281]

Originally Posted by jml

A student and I were nearly in a shunt this weekend at TWS because someone told him hawk HPS pads were good dual-use street-track pads. He was put in an advanced run group, so the speeds were moderate. I commented to him that I was pretty sure the pads were not going to hold up. Sure enough, within 3 laps, his brakes TOTALLY failed WITH ZERO notice right behind a C2S going into T4 Clockwise...I don't know how he missed hitting it...mad ninja skillz I guess. There were fine braking into T6....but nothing in T4.

I see vendors in this forum recommending these products as viable on a race course. They are not, and someone is going to get hurt. PCA national is going to be banning these after this weekend's incident. A SURPRISING number of people show up to the track with after market street pads in moderate run groups. I don't understand it - brake pads are a safety device.
Rant over....

+1000
Sorry for not posting earlier, but I'm not on here much and recently stumbled on this thread. Thanks to my instructor (OP) for posting this warning!

Here is the video taken at Sept LSRPCA DE event showing abrupt failure of Hawk HPS street/track pads (BMW E92 M3) in turn 4 going clockwise. Brakes were fine going into turn 6, but then gave up suddenly in turn 4 as I followed a 911 Carrera S. Luck was on my side, as I was able to avoid a collision and regain control of the car. This is not an isolated incident as the PCA instructor (OP) riding with me had the same thing happen to him using the same pads.

These pads were recommended as an alternative to the PFC-06, which I was running previously, but were too noisy for the street. This was my 3rd track day using these pads which were properly bedded in. The brake pedal did not go the floor and I still had a firm pedal, but there was no friction to slow the car. Inspection after removal revealed that pad material had worn very rapidly and was clogging all the holes in the OEM drilled rotors.

PLEASE DO NOT USE THESE PADS ON THE TRACK, FAILURE IS EMINENT!

[dizzyj]

Nice evasive maneuver btw. I'm still surprised that this happens at tws, it seems pretty easy on brakes, but gives a lot of pause for thought.

/edit, op said it was turn 4 cw edit/

[jml]

Another incident this weekend at TWS - 2012 WRX with HP+ pads went off on braking into 10, nearly nailed fence. Very good friend of mine in the passenger seat.

[ortho281]

Very lucky like we were! I'm glad they were able to avoid hitting wall.

[ThunderMoose]

Originally Posted by jml

Another incident this weekend at TWS - 2012 WRX with HP+ pads went off on braking into 10, nearly nailed fence. Very good friend of mine in the passenger seat.

Yep. PDS instructors are going to be asking students which pads they are using.

[jml]

Originally Posted by Richbot

If you use my car as a baseline at 3775 with driver and full tank, add 44lbs for DCT, ~50lbs for sunroof, and ~50lbs for everything else and you're at 3919. Add a big guy driving and you're there, but that's hardly the norm especially for people who track their cars and don't buy cars loaded down with every option and tend to be skinny nerds

At a 35lb infant seat...and some Legos and food on the floor, and you're there.

Really drives the GT3 guys crazy that there is a baby seat in my car....

[1MOREMOD]

Originally Posted by jml

At a 35lb infant seat...and some Legos and food on the floor, and you're there.

Really drives the GT3 guys crazy that there is a baby seat in my car....

you should leave it in for a track day and then park next to a gt3 you passed.

[jml]

Originally Posted by 1MOREMOD

you should leave it in for a track day and then park next to a gt3 you passed.

Oh I do

[1MOREMOD]

Originally Posted by jml

Oh I do

seriously! that is epic. i dont even have a kid and i want to try this.