Anyone have any brake questions? - Page 41 - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 06-30-2016, 09:55 AM   #801
Supporting Vendor
iTrader: (3)
 
emilio700's Avatar
 
Join Date: May 2005
Posts: 4,603
Total Cats: 857
Default

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
emilio700 is offline   Reply With Quote
Old 06-30-2016, 10:01 AM   #802
Junior Member
 
Join Date: Jun 2016
Location: Dousman, WI
Posts: 72
Total Cats: 9
Default

Quote:
Originally Posted by Leafy View Post
killjoy, the balance bar and prop valve do different things. The balance bar changes the brake balance at all amounts of braking force while the prop valve only changes it at high forces. You need to tune for both unless you want to suck at trail braking.
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.
mekilljoydammit is offline   Reply With Quote
Old 06-30-2016, 12:00 PM   #803
Senior Member
iTrader: (1)
 
Join Date: Dec 2010
Location: Farmington Hills, MI
Posts: 625
Total Cats: 45
Default

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.
acedeuce802 is offline   Reply With Quote
Old 06-30-2016, 12:09 PM   #804
Supporting Vendor
iTrader: (3)
 
emilio700's Avatar
 
Join Date: May 2005
Posts: 4,603
Total Cats: 857
Default

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.
emilio700 is offline   Reply With Quote
Old 06-30-2016, 12:22 PM   #805
Senior Member
iTrader: (1)
 
Join Date: Dec 2010
Location: Farmington Hills, MI
Posts: 625
Total Cats: 45
Default

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.
acedeuce802 is offline   Reply With Quote
Old 06-30-2016, 12:28 PM   #806
Junior Member
 
Join Date: Jun 2016
Location: Dousman, WI
Posts: 72
Total Cats: 9
Default

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...
mekilljoydammit is offline   Reply With Quote
Old 06-30-2016, 01:30 PM   #807
Senior Member
 
Join Date: Sep 2013
Posts: 900
Total Cats: 59
Default

Quote:
Originally Posted by emilio700 View Post
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.
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.
Dunning Kruger Affect is offline   Reply With Quote
Old 06-30-2016, 06:01 PM   #808
I take big bites
iTrader: (1)
 
turbofan's Avatar
 
Join Date: Sep 2010
Location: Portland, OR
Posts: 6,083
Total Cats: 424
Default

Your *** has quads? Odd.

Props given for seriously thorough brake discussion.
turbofan is online now   Reply With Quote
Old 06-30-2016, 06:35 PM   #809
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

Quote:
Originally Posted by Leafy View Post
140 pounds of leg force is ******* steep. Thats 1950's no power booster full sized car on 4 wheel drums **** right there. Pull up on the steering wheel and give her all she's got in every braking zone doesnt sound fun.

killjoy, the balance bar and prop valve do different things. The balance bar changes the brake balance at all amounts of braking force while the prop valve only changes it at high forces. You need to tune for both unless you want to suck at trail braking.
hit the gym Pros in formula cars need 200lbs. if not a little more. manual brakes, small wheels and a ton of aero.
OGRacing is offline   Reply With Quote
Old 06-30-2016, 06:52 PM   #810
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

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 is offline   Reply With Quote
Old 06-30-2016, 06:56 PM   #811
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

NEVER EVER RUN A PROP VALVE AND A BALANCE BAR. no stop dont do that, nope stop.
OGRacing is offline   Reply With Quote
Old 06-30-2016, 06:57 PM   #812
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

i'll post the spread sheets we use tomorrow. night yall!
OGRacing is offline   Reply With Quote
Old 06-30-2016, 08:26 PM   #813
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 3,015
Total Cats: 222
Default

Quote:
Originally Posted by OGRacing View Post
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.
In F1 they adjust the balance for every corner! Well, Schumacher did -- not sure if all the drivers do.

--Ian
codrus is offline   Reply With Quote
Old 07-01-2016, 01:24 PM   #814
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

Quote:
Originally Posted by codrus View Post
In F1 they adjust the balance for every corner! Well, Schumacher did -- not sure if all the drivers do.

--Ian
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.
Attached Thumbnails
Anyone have any brake questions?-80-stock_miata_with_balance_bar__79b33985558d6a6ca0d2f3a85f2aa2125ac73b2d.png  
OGRacing is offline   Reply With Quote
Old 07-01-2016, 01:45 PM   #815
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,589
Total Cats: 256
Default

Quote:
Originally Posted by aidandj View Post
No deets. But new kit on the market.

StopTech Big Brake Kit for Mazda Miata | Garage Star
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.
ThePass is offline   Reply With Quote
Old 07-01-2016, 02:00 PM   #816
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

Quote:
Originally Posted by ThePass View Post
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.
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.

Quote:
Yes, we maximized clearance inside of a 6UL and left 3mm between the caliper and wheel barrel. That is our minimum clearance requirement.
i've seen as low as 0.1mm and that was from he spokes. i guess airing on the side of caution is good.

Quote:
Does this difference matter? No, not compared to the StopTech BBK. The 11.75' rotor is 298.45mm. The difference in diameter is 298-280 = 18mm, which means the difference in radius is 9mm. This gives the competitive rotor a slight advantage in brake torque IF both brake pads were identical but in this case they are not.
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.

Quote:
The contact area of the brake pad on the rotor is larger in the StopTech kit, effectively increasing brake torque compared to the competitor. This increase completely offsets any disadvantage in the 9mm rotor radius difference. This also makes the StopTech rotor lighter by a fraction.
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.

Last edited by OGRacing; 07-01-2016 at 03:00 PM.
OGRacing is offline   Reply With Quote
Old 07-01-2016, 02:29 PM   #817
Junior Member
 
Join Date: Jun 2016
Location: Dousman, WI
Posts: 72
Total Cats: 9
Default

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?
mekilljoydammit is offline   Reply With Quote
Old 07-01-2016, 04:00 PM   #818
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

Quote:
Originally Posted by mekilljoydammit View Post
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?
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.
OGRacing is offline   Reply With Quote
Old 07-01-2016, 04:57 PM   #819
Newb
 
Join Date: Apr 2013
Location: Redondo Beach, CA
Posts: 37
Total Cats: 1
Default

Quote:
Originally Posted by OGRacing View Post

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.

pad area dictates longevity, not friction. And this Kit uses the 7752 pad. same as all the Dynalite kits so the pad is exactly the same as almost all of the competitors.
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.

Quote:
Originally Posted by OGRacing View Post
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.
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.

Last edited by Jumbosrule; 07-01-2016 at 05:18 PM.
Jumbosrule is offline   Reply With Quote
Old 07-01-2016, 05:26 PM   #820
Supporting Vendor
Thread Starter
iTrader: (1)
 
OGRacing's Avatar
 
Join Date: May 2014
Posts: 1,599
Total Cats: 74
Default

Quote:
Originally Posted by Jumbosrule View Post
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.

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.

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.
OGRacing is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 53 12-07-2016 05:52 PM
1994 Spec Miata Race Car SM/SM2/SSM For Sale Quinn Cars for sale/trade 6 10-23-2016 08:58 AM
15x10 - 15x11 6UL @ 949 Racing emilio700 Wheels and Tires 143 05-21-2016 06:48 PM
Raleigh: Fiberglass headlight scope, 1.6L ECU, AFM, Hardtop latches, more bigmackloud Miata parts for sale/trade 9 11-08-2015 12:58 AM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 07:32 PM.