Jim Devine

Call these guys- they make the stuff, even some of the goobers in NASCAR use them.
http://www.raybestosbrakes.com/magno...formation.html

Might want to speak to them about front/ rear balance & line pressures etc.
Lots of free help & engineering available, they want their products to work.

IcemanG17

interesting thread.......as always..... granted my racer is lighter with much less power than MK and blown up.... :>)

However....from experience building endurance race 928's (8+ hours straight) what I know is this....the race shop I trusted to build the car (evil genius) said "Raybestos St43" since it was a lower powered car....a shop that WON their class in the NASA 25 hour a couple times....without changing brake pads... The person that I sold the car too still uses the EXACT same setup...with even better success than I had.... http://blog.caranddriver.com/24-hour...g-the-winners/

Same car MK raced, Anderson, Sean, Jeff, Rick, umm everyone...

Then I met Jeff here...he said the EXACT same thing....then when I bumped to a more powerful 928 racer with bigger brakes Jeff and Evil Genius said St41 front St43 rear...so that is what I did, as did Sean....AMAZING....unreal brake power with minimal wear at just under 300whp/2850lbs on Seans racer a bit less on mine...

While MK's experience is HIS experience....many have tried, nobody who currently races has matched his success.... not a single one....but that is another story...

I am 100% sure that my old 84 "estate" has by far the most on track hours of ANY race 928 in history..... over 100 when I sold it.....many races more now....maybe 200 hours on track.... It has blown engines (3), and other issues...BUT NEVER-EVER had a single brake issue running just "S" brake...nor a transmission issue (automatic)................Kibort has blown transmissions along with everyone else...and had brake issues...

stuartbrs

Um.. those discs (rotors) don't look safe...

mark kibort

I never had a brake issue either. you seem to forget this. the only brake issue I ever had was when I bolted on the larger motor and got 50 extra hp. that 10mph was a KE that is off the chart difference slowing from 130 to 45mph vs 120 to 45mph . the only brake issue I ever had was with the blown line.... my fault.

you seemed to forget my car on TV running up to Derek bell under braking (using S brakes by the way) into the hard braking zone of turn 11 laguna. the announcer said... "look at the braking power of that 928"

I blew one transmission, the holbert after 120hours of racing. broke 5th gear teeth. the 84 broke on the dyno after I left the ebrake on . the vibration broke the input shaft to the transmission.

brian... im not doing anything that different. im beating the snot out of the car and redlining it on every shift, but also not abusing the car either for no performance gain. watch the next video im going to post while im down on power for some reason, and needed to hit the rev limiter a lot during the 2 race weekend.

getting some new rotors for the new 2 piece set up and should be good to go for the runoffs if I get the power issue resolved.

mark kibort

video up..... from a nascar like competitor. go to 10mins in the video and onward.

mark kibort

mark kibort

and a corkscrew view from someone's spotter on the track.

soltino

Great Stuff.

Really enjoyed the Hi-Tech Straw in the first one and the in the Wine sound of the Corkscrew one.

tino

mark kibort

that's mark Ruden in the nascar like beast. he is following me at about 13min in the video

GregBBRD

According to Mark Kibort, I'm just a dumb mechanic and my 40 years of experience at race tracks (thirty of which were also driving) means that I know absolutely nothing about racing.

Because I'm just a dumb mechanic and can barely attach two male and female threaded objects together, on my own, I'm certainly not going to claim to know much about Physics....

And I'm certainly at the point where I will never, ever remotely suggest anything ever again to Kibort and be insulted by him for making a suggestion...

I do have one simple question regarding this thread.

If the amount of Kinetic energy that needs to be dissipated over the same amount of time is not altered.....and the system that removes the Kinetic energy is not altered....doesn't the amount of Kinetic energy transformed into heat at the front brakes remain the same....regardless of what friction material is used?

More simply.....just so I understand it....

I don't see how the front rotors get cooler, (regardless of what friction material is used) unless:

1. The heat removal from the front rotors is increased. (more airflow? spray water?)
2. The front brake pads allow more heat to be transferred to the caliper (a terrible idea)
3. The rear brakes do more work. (impossible.....according to Kibort.)
4. The mass of the vehicle is decreased. (Remove weight? Where/how?)
5. The braking time is increased (allowing for more heat dissipation....and slower lap times)

BTW....I'm now one of the people sitting back shaking my head in dismay.

mark kibort

Greg, you have read what I have to say carefully here. (insult removed) (edit: sorry Greg you didn't deserve that)

1. Heat removal from the rotor is increased with the aluminum hat, aluminum sheds heat MUCH quicker than steel. plus there is 4% more mass to dissipate heat, and 4% more leverage. 4% less pedal pressure can produced the same stopping
force. this could have been the reason alone.
2. the drilled rotors give the hot gasses an escape path. the feel of drilled vs holed was always an obvious difference to me in these parts of tracks.

3. the rear brakes can only apply what the weight of the car is on them, and during a 1.5g decal, that's 300lbs a wheel. ive proved that the engine braking alone can provide this at 6-4krpm, plus what is provided by the bias in the car today. if you have a suggestion of how this is underestimating the rear braking performance, I would love to hear it. PLUS, I can also prove to you how much stopping power would be provided. Best case, there would be a slight change in slowing distance, but not enough to change KE values all that much. if you can put up some numbers here, love to see it.
ive already shown my braking system in the rear under moderate pressure can produced 350ft-lbs at the crank, or over 1000ft-lbs at the wheels (500ft-lbs per tire in 3rd gear)

4. Lower mass in the vehicle would NOT help KE. actually make it worse. less mass means top speed might go up 1/2 of the % you decreased weight (e.g. 7% less mass might mean 3% increased top speed) this would actually net you more KE to dissipate for a 120mph vs 125mph slow down starting speed.

5. always a possibility, but not likely, and confirmed by the video and comparison videos.

The only changes were going to a larger diameter rotor with 4% more mass and diameter to it. Its holes could have helped, as do slots in other ways, and the aluminum hats shed heat at a much faster rate.

Now, greg... we are all friends here and I do consider you the master.... a little stubborn at times, but still much respect goes out to you. remember the intermediate plate discussion.... you were so emphatic that you knew where the forces were, but you were dead wrong. admitted it and gained even more knowledge. sometimes things are not always as they first seem. I like to dig in to the issues and prove things empirically, with closer analysis, or with the physics.

GregBBRD

So, you are in great shape and that 1400 degree front rotor temperature was from before, not now with your "new rotors". Amazing how clever you are, in photoshop. You made that 1400 degree reading look like it was on the rotor with the aluminum hat!

Here's as simple as I can make it.

If you change nothing....and you reject every single suggestion anyone has...how do you plan to reduce the front rotor temperature, genius?

BTW....The aluminum (that those hats in the picture are made from) melts at 1600 degrees....and is getting very close to "fluid" at 1400 degrees....you might think it's great....but no one I know, in the racing world, would ever allow that aluminum to get that close to the melting point, or would ever reuse the hats, after getting that close to the melting point. You turned those hats into junk!

And perhaps more to the point....if you reject everything anyone has to suggest, why do you bother posting anything?

KaiB

Until Mark gets his suspension in order, all bets regarding weight transfer and rear bias are OFF.

mark kibort

Greg, (and I wont call you "genius" ) you cant make up stuff..... its so distracting. nothing is photoshopped.

And by the way Greg, im only insulting because you are firing off on me..... keep this respectful and ill return the favor.
(BTW..... I removed my comments to you. that was uncalled for on my part... sorry)

those rotors are the 2 piece and I measured the temp this outing at Laguna last weekend. they are the two piece. the hats didn't get near that temp, as proven by the line of paint from rotor to hub.
So, why do you think the aluminum got to 1400F ?? again, put down the hammer and think clearly about this one. that's funny you think I photo shopped it.

now Greg, the rotor has 4% more mass now. 4% more diameter , this means 4% more material to dissipate the same stopping power , which means a significant temp drop. also, there is thermal run away factors too. the more I push with the fading rotor, the more the friction goes up in heat , and not stopping force. if I don't fade, that doesn't happen. the pads are only at the edge of fade at the very end of the stopping sequence. a fraction of a second, and only one place on the track. With the new rotors, with aluminum hats and holes, as well as a 4% greater diameter , many factors are changed

Did you see the temp stripe on the rotor that went through the hat? rotors where hot, hat... not so much. calipers not so much either.

again, what I changed was a significant element of the rotor. its diameter and mass, along with heat dissipating qualities. (aluminum hat).

mark kibort

That would effect handling, but not weight transfer in the slow down scenario. it would effect how fast I can apply the brakes, but once the chassis has compressed up front, the rear shocks don't do much here on a smooth surface and constant braking force.

trying to get that taken care asap!