emilio700

iTrader: (3)

I must be spoiled. With the combo I run, I must not be needing more than 60 lbs or so on any of my cars. R18 G-Loc

mekilljoydammit

AP Racing's prop valve datasheets actually illustrate the hysteresis, especially on their sheet for the **** type one. It looks very much like if you tune the thing to get the rear forces right at threshold braking, as you ease off, the rears are going to stay at higher pressure until you get to the knee point. Further, they say it gets worse the further down the pressure curve you put the knee, so even worse for non-boosted masters. All of this sounds not-great to me. Now, it may be that Wilwood and Tilton have better prop valves than AP, but somehow I doubt it.

acedeuce802

iTrader: (1)

I definitely overlooked the fact that dual masters split the pedal force in half at each master. I only validated brake bias with my spreadsheet, and forgot to look at overall pedal force. Dual 5/8" may be doable with a pedal ratio change, but I think I may look at a single master booster delete.

emilio700

iTrader: (3)

Other than the small weight savings, I'm not sure what the current fascination with booster deletes is. Set up properly, you can get a rock solid and consistent pedal using an OEM booster. My guess is there are owners out there that haven't been able to do that and decide to throw the baby out with the bathwater. What I often hear/read is owners wanting to save money by using some inappropriate parts and trying to tune around it. To me, that's like setting up a chassis on worn out tires. Waste of time. Do the homework to figure out what the right setup will be and start saving. Last time I checked, brakes are kinda important on a race car.

acedeuce802

iTrader: (1)

I hate to be that guy, but part of my motivation is cleaning up the bay and freeing up space. My V8 build is leaning towards track car, but it's also a daily driver that's taken to countless meets/shows and I enjoy having a nicely tucked bay.

So if it's between getting a 1" master, and getting a 3/4" master and deleting the booster, I'll choose the booster delete. Cost is relatively the same, and I have the manufacturing ability to make it reliable. Plus I'm not too sure how the booster will like the moderate cam I have planned.

mekilljoydammit

Well, some of us are looking at engines without much manifold vacuum to speak of, but in EProd it was a pain in the *** to make brakes sized for boosted masters work without boosters and this seems like the same story. Good thing they sell Dynalites in different piston sizes...

Dunning Kruger Affect

It's not manual man, it's all about the feeeeeeling, bro. Anything that can be considering a driving aid is bad, this includes power anything (especially windows and mirrors). Driving aid, more like Driving AIDS. I need to feel the raw brake horsepower to fully experience the Jinba Ittai. Also, I have a very strong trunk and things like squats, deadlifts, and leg presses are relatively easy for me and my HUGE *** QUADS.

turbofan

iTrader: (1)

Your *** has quads? Odd.

Props given for seriously thorough brake discussion.

OGRacing

iTrader: (1)

hit the gym Pros in formula cars need 200lbs. if not a little more. manual brakes, small wheels and a ton of aero.

OGRacing

iTrader: (1)

ok i need to clear some stuff up. at PFC we spent 2 months learning about pedal boxes before we where allowed to talk to any customers. my boss was a former tiltion rep.


1 OK manual brakes. we can get manual done. it's not that hard. Yes you want different sized MC's, why? because you want less line pressure to the rear. you want to use the balance bar only to adjust bias while the car is in motion. we do not want to have the biar bar to get maxed out. if it maxxes out you'll need to buy a larger rear mc anyway. so we need to set up the Bias as close to perfect as we can.
1.5 i have yet to pop my head into any race car on any professional level and find the balance bar adjusted correctly. we always find something. so be careful who you take advice from.

2 yes you want more then 4:1 pedal ratio. in the industry we call it cheating to increase the pedal ratio. mostly because it has little to no trade off. you just get extra pedal distance. so when you weld in your willwood balance bar thing. move it up closer to mounting point.

3 i wouldn't do manual brakes with stock sized pistons. the factory miata brakes rely on a ton of vacuum assist. in my car i did the 1.75 Fronts and 1.375 pistons out back all on 11.75" rotors we did 3/4" and 13/16 rear mc. the tilton pedal box has a 5.75;1 ratio. i have 100lbs press @45ish mm to achieve a 1.5g stop.

OGRacing

iTrader: (1)

NEVER EVER RUN A PROP VALVE AND A BALANCE BAR. no stop dont do that, nope stop.

OGRacing

iTrader: (1)

i'll post the spread sheets we use tomorrow. night yall!

codrus

In F1 they adjust the balance for every corner! Well, Schumacher did -- not sure if all the drivers do.

--Ian

OGRacing

iTrader: (1)

i've only gone to Europe on the way to Iraq. haven't had the privilege to get into a F1 car yet.


I can't share too much of this. It has some serious Proprietary information but it demonstrates the effort you'll need to run manual brake with stock Piston sizes and pedal ratio.

it says we will need a Pad of .44mu i cannot express how much Hawk Carbo tech and Padgid Skew their Mu for marketing reasons. a very very high torq pad will be in the .56mu range.




As we can see with a 3/4 - 7/8's combo the balance of the car comes out great, the mu requirement is equal. this will allow us to set the balance bar in the center for maximum adjust-ability. this also gives us adjust-ability for compound choices.

ThePass

iTrader: (3)

Thread about it over on clubroadster has a guy who (apparently?) works at ST telling people that the difference in pad size increases braking torque, thus alleging that the difference between their 11" kit and other's 11.75" kits is negligible. So that's going well.

OGRacing

iTrader: (1)

oh man that's going to be rough... the benefits are going to be from a stronger caliper. not from shorter stopping distances.


ninja edit. I found the thread. lol man that guy is just spewing false information. let's dig shall we.

i've seen as low as 0.1mm and that was from he spokes. i guess airing on the side of caution is good.

11.75" rotors are 299mm if we want to nit-pick. 299-280 that's a 6.35% difference. that is enough to be noticeable in torque.

i dunno what competitor they are talking about but pad area dictates longevity, not friction. so he's squawking out of his butt. and this Kit uses the 7752 pad. same as all the dynalight kits so the pad is exactly the same as almost all of the competitors.

mekilljoydammit

Two more questions. Given a basic caliper layout (call it 2 piece bolted Dynalite size with one bridge bolt) how much scope for stiffer calipers is there *really*? I mean yeah, the STR-42 is going to be more nicely machined than Wilwood's stuff, but it seems like there's limits here. Oh yeah and ******* LOL at the guy claiming the pad size is going to affect things when it's literally using a Dynapro pad.

Secondly, what's a decent back-of-the-envelope friction coefficient to use for something like PF01/11/14? Not asking for the keys to the bank or anything, but if Wilwood and stuff are saying 0.65-0.7ish is a high friction pad, you're saying 0.56 is a high friction pad, what's a value to use for sizing things for a medium friction pad?

OGRacing

iTrader: (1)

We could have a caliper strength debate for hours. what's worth it? strength vs cost vs un-spring weight. the stronger the caliper is the better, as long as it's not t0o heavy. so it'a all a compromise triangle of Cost, Strength, and Weight.

i like to show this video of a standard stoptech st-60 caliper vs a similar sized OEM manufactured Brembo. Both have good names one is just built for mass production and costs are low. the other is built for Motorsports.

Like iv'e said before I've sold calipers that at full speed wouldn't flex more then 0.1mm. those are going to have incredibly low drag, but cost more then 120 bucks.



back of the envelope I cannot tell you what the Mu's are. the reason they are not published is because the numbers can be manipulated easily. Lets look at tires. A tire's mu changes with the surface it interacts with. a tires mu will increase on tarmac, concrete and rubber. in that order. rubber on rubber mu can be over 1.1mu (notice when two tires touch and one car gets flung into orbit), as tarmac it can be as low as .5. we can also manipulate brake Mu with temperature, rotor size. rotor iron consistency. hell we could put a dyno in the arctic circle, a gigantic rotor made from other pads, under vacuum and get .7mu out of a set of xp10. i know PFC's mu numbers and i use PFC charts to pick out pad compounds. both the charts and the pads have the same testing variables. so i know what i'm grabbing off the shelf. sharing that chart is dangerous because everyone thinks "oh i need a .45mu pad", they go over to carbos, buy a pad that says.45 mu, they crash because carbotech inflates their numbers. hawk says the dtc70 get's .9mu. that's enough friction to rip the suspension pick up points out of a car. on an average GT car .45 mu is perfect. it gives us the right about of bight, good modulation and not too much tq that your going to be flatspotting tires.


The short list is PFC doesn't post Mu number because everyone else distorts their Mu numbers. We would either need to be dishonest or just avoid the whole situation altogether.

Jumbosrule

Im on here too - no bad blood though, this is all good discussion. Did not think there was any amount of spewing - just trying to turn the engineering concepts into common language for people that are not embedded in the business. We run in house testing systems on a Link brake dyno and can confirm temperature, torque output, line pressures and deceleration times based on preset vehicle speeds before we go to dynamic, on-car testing. I don't have to tell you how poorly understood braking is to the average enthusiast. Simple concepts are very often tempered by quite a few other factors in the system.

6.35% difference in rotor diameter does not necessarily equate to a torque difference (but it could) if the center lines of the pads on the rotor annulus are different, especially with different pad areas.

The 7752 pad is not used in the StopTech BBK. It is using the FMSI# 8567 (DR22) pad shape. The difference in area between the two is 10mm in pad height for the width of the pad or 5633.6mm^2 as compared to 4646mm^2 so the 8567 pad has 17.5% larger contact area.

http://www.stoptech.com/images/defau...e-pads/d22.jpg
7752 | PFC Brakes - Performance Friction

Totally agree that pad volume speaks to longevity - no argument there. Add to that higher caliper stiffness and differential bores - all contribute to pad life.

Same here. We test all friction relative to each other so numbers are comparative but find the same industry inflation everywhere.

Great video of caliper flex - that demo unit is sitting in our engineering offices.

OGRacing

iTrader: (1)

my mistake. when i talked with stop tech two years ago they mentioned that it would take the same pad as the dynalight. the 7752 shape. the difference in swept area between the dr22 and the 7752 is actually less pad volume going towards the dr22 pad shape.

I would need to disagree that this kit wouldn't "outbreak" a Dynalight 11.75" but what you do have over everyone else is a miles better caliper. Stoptechs claim to fame is bad *** calipers. I would guess that it should have substantially less drag in the system. less drag = longer life, better performance. but with miracle stop #1 i would be surprised to see higher Tq output.