OGRacing

iTrader: (1)

To get a little personal here. Brake marketing is an interesting marketing technique. most manufacturers avoid displaying hard numbers and testing results. instead, they go straight for "Telling you what you want to hear". To the credit of manufacture, the ones that do display raw data are certainly overlooked by consumers. I know one manufacturer that displays everything and consumers don't really give them a second look. it's excellent for me because I know what I'm looking at and can recommend their products easily. I'm referring to Padgid.

mekilljoydammit

I used to assume PFC naming convention referred to year of introduction, ala Soviet tanks, based on no actual knowledge whatsoever.

Current car I'm sharing (so both drivers are pretty green) is for SCCA T4, so sort of like a grown up Spec Miata on 225 wide R6s; we're running DTC-60s in a "well, a competent shop recommended it" sense but I came to the realization that using publicly available info, it's hard for me to verify that's anything other than "a reasonable choice in Hawk's line because they use similar verbiage to what PFC says about the 01/11". I'm a test engineer in my day job, so that bothers me, and while I'm sure I could build a brake pad dynamometer, I don't really want to as an engine dyno project is crazy enough.

*quickedit* What I mean is, it bothers me in the sense where it doesn't seem like the data I want is just available. I can figure out roll centers, ride frequency, basic shock valving, etc etc etc ad nauseum, but it seems like "this pad does X better, this pad does Y better", the data's mostly not out there.

Hadn't heard much about Pagid - but poking at their literature, I'm assuming that their friction numbers are ... less suspect than Hawk's advertised numbers heading towards a Mu of 0.8 or so. The RSL29 and RSL19 look like pretty reasonable options assuming I'm reading the catalog right... might have to try to find some for after this set of Hawks goes away.

Steve Dallas

I have deep grooves I can't feel with my fingernail? Weird!

The friction layer is fine. After the first few laps on the track, it evens out after everything reaches operating temperature. On the drive home, while running too cool thanks to the ducts, the friction layer is knocked off in rings, but there is still plenty of stopping power for street driving. This "problem" is self-correcting and not a real issue.

The studs are fine. I check every aspect of my brakes after every track day, and there are no signs of stud damage.

Thank you for your concern, however.

OGRacing

iTrader: (1)

Completely understand your frustration. I am not a graduate engineer but I've taken a lot of the classes. math is fun for me. Padgid lists the heat to Tq numbers. they appear to be accurate, and are backed up with results seen at the track.

mekilljoydammit

Well, like I implied anyway, I'll give you a ring once we're out of pads. Thanks for the help; maybe I should do a brake dyno, heh heh.

OGRacing

iTrader: (1)

if you want to I got a set of PFC 7752 in 97 and 01 ready to go. plenty of places will dyno them. pro-systems in NC comes to mind.
even fewer manufacturers will offer them to test.

Leafy

iTrader: (1)

That looks like normal gap to me, these look larger because the insides of the holes are black. If the rotor is moving once the wheels are torqued your lug torque spec is too low.

mekilljoydammit

That actually gives me an idea. I'm going to see what they charge because I don't have any idea whatsoever.

OGRacing

iTrader: (1)

it's not cheap. and i know you need to provide the caliper and a rotor for each pad.

mekilljoydammit

Yeah, I'll see what "not cheap" is. It has to be less than the cost of making my own test rig though, maybe.

OGRacing

iTrader: (1)

exactly. when I was at PFC we had an entire wing dedicated to brake dynos. took the space of a 2 car garage for each one. chances are pro-systems has already tested most compounds. they cannot disclose the data without payment, but they can tell you about different compounds. it's going to be very similar to what I report. as john is my primary source for information on products that I haven't seen the testing.

mekilljoydammit

Yeah, from doing customer testing in other fields, I have no expectation of getting data from a 3rd party test lab unless I'm sending them the pieces to test it - I'd expect that everyone who sent parts in to have tested owns their data and has NDAs etc. I kinda have some high-minded idea of, in the spirit of this place and sharing info, organizing a crowdfunded test using sizes and compounds that are relevant to Miata stuff, but I haven't gotten a response back on even ballpark pricing (mind, it's been less than 24 hours)

Do you have any experience with how big of a drive motor you'd need on a brake dyno? I mean, I know to simulate a braking event it's going to be a lot, but I wonder if 10-20hp might be adequate for a slower analysis of mu vs temperature or if the fidelity would be too far off.

... ugh. Need to finish the engine dyno project first.

OGRacing

iTrader: (1)

the ones we used were huge! i guess 100+ hp. they needed to simulate worst possible conditions so slowing 4000lbs NASCAR from 200-160mph for 3 hours.

mekilljoydammit

Makes sense; the higher up the hierarchy you're getting, the closer you're going to want to get to full scale for everything.

*edit* I don't expect an answer to this, I'm just thinking, if you restricted airflow to the rotor so that the temperature climbed through the test range, maybe you could get a mu vs temperature curve that's still accurate enough for apples to apples comparison on the same test rig with a much lower power input. Might try it; the DAQ is the most expensive part and I already have that.

codrus

Why use a 100 hp brake dyno when you can use a 100 hp Ford Fiesta? Well, OK, probably a 60 hp Ford Fiesta, but...


--Ian

mekilljoydammit

Well, it's hard to get repeatable data out of that, I'd imagine...

OGRacing

iTrader: (1)

i <3 ultimate car brake test video

MrJon

I literally laughed out loud when I saw he was wearing a plastic face shield inside the car.

At about 6:50 "Yeah, this went really well!" bwahahahaha.

Steve Dallas

"Holy sheet! I do accidental burnout!"

I'm glad I was just drinking water then.

OGRacing

iTrader: (1)

They are a company that's easy to work with to get custom sizes. You'll see a lot of little shops offering "Company xyz selling xyz rotors" those are often Coleman. the reports i've gotten back from customers that have tried them. they did pick up life and speed over willwood, but they did not outlast the PFC. generally, people that used a PFC rotor went back to it. if I was looking to build a rear kit I would use Colman's without worry. a front kit I would pick something with better life.