Anyone have any Brake Questions?

[OG_Racing]

Johnny C is the majority of my real name. I'm a "brake guy" by profession and by hobby. I have an obnoxious amount of brake tech swirling around my noodle. If I crammed that info into a Book, nobody would read it. It's some of the driest information anyone could imagine. If and only if you have an issue with your brakes would you pay attention.



About me: I'm a former PFC factory Rep. I've worked with top racing teams like Joe gibbs racing, Ganassi, Rum bum, Irish mikes, so on, and so on. I've been in the motorsports world professionally starting in 2006. I've worked hand and had with teams and engineers to build braking systems and to fix issues with braking systems.

If you having an issue with your brakes, please ask. Or if you are looking to upgrade your brakes, please ask. The majority of club racing related braking issues I come across, are from individuals who tried to upgrade their system.

[Stupidnewbie]

I'll go first. What do you think of my projected brake setup? In the front, I plan to run Z51 340mm rotors with standard 2-piston C6 calipers on my AFX spindles. I have a ford 9" rear axle with 12.19" x 1.25" rotors, using GM III 2.75" single-piston calipers. Is this going to be a good front/rear balance for braking power?

[Buryingthesun]

I might bug you soon seeing you are local, Thanks for offering to share your knowledge not many people offer to do this.

[OG_Racing]

I might bug you soon seeing you are local, Thanks for offering to share your knowledge not many people off this.

90% of my colleagues that know the same information won't offer what they know. because there are so many brake myths it takes 3/4 of the conversation just repeating yourself. Example drilled rotors, cheap made brake kits so on. we would rather just talk to other people that get it, or the one ones that say "here are the keys, take the wheel, and build me a kit".

[OG_Racing]

I'll go first. What do you think of my projected brake setup? In the front, I plan to run Z51 340mm rotors with standard 2-piston C6 calipers on my AFX spindles. I have a ford 9" rear axle with 12.19" x 1.25" rotors, using GM III 2.75" single-piston calipers. Is this going to be a good front/rear balance for braking power?

I'm going to need to Know allot more. i still want to help what are the specs on the chassis. i need to know Chassis Lbs, Horsepower, tire kind, tire size, tire age, shock choice, spring rate...


Most people think that the main thing you need in a system is brake TQ. HIGH TQ is all i hear. That couldn't be further from the truth. Brakesing Tq and horsepower couldn't be anymore different. Don't think that More Brake Tq is good like more Horsepower is good. When I give classes start off asking the Question "What stops the car?". 9/10 i get an answer of "the brakes" to that I reply with "WRONG, the tire stops the car." if you have a car that hit the Curbing on a racetrack and two tires are airborn, how much traction does that car have? how will it be able to stop with 2 tires in the air? the answers are, traction is less than 50% of having 4 tires on the ground and It won't be able to stop. Hitting the brakes with t tires in the air the wheels are fully stopped, and that car's speed won't be decreased. Remember in a braking system "more" is not better, it's just more. Taking a caliper from one car, and adapting to the other is just playing with legos. what we are trying to do is engineer a complete a braking package. before you do this you need to take some considerations into account. piston area in the calipers, Rotor offset, and overall braking balance.

Piston area.

Brake Tq can only be changed by 3 Dynamics in a brake system, Rotor Size, Pad compound, and hydraulic advantage. Hydraulic advantage the difference in size between your master cylinder, and your caliper pistons. if you want more Tq increase your pistons, less decrease your pistons. same goes for the master cylinder. you want more TQ? decrease your Master cylinder size. it will increase your hydraulic advantage. ***before we go out messing with master cylinder sizes and piston sizes there is a point of no return.*** the aspect that nobody thinks about but is important has to do with the brake pedal. As a pedal travels thru it's motion you do lose some advantage the further away from the driver it gets. We find at almost 90* on most pedal assemblies the driver would lose leverage. loss of that leverage would make the pedal harder to push. by decreasing the master cylinder size, or increasing piston size you're increasing the distance the pedal needs to travel. so it will take less effort from your foot to stop, but your trading that effort for pedal distance. try and keep the sweet spot of the pedal (@90*) at the point of where you start to modulate your brakes.


Rotor offset

Declaration happens exponentially faster than acceleration. think of our cars, with 800hp almost every stock component will snap under that much power and acceleration. every car should be able decelerate 4x faster than a 800 hp car can accelerate. the idea that i'm trying to put into everyones mind is 3200hp but in reverse. Everyone would agree that is allot of force. that's the force your braking components are under. When we design a big brake kit, the rotor needs to be squarely centered in between the hub bearings in order to stop the bearing from getting torn to shreds. as an example of what not to do, I bring up the "unnamed unethical corvette shop". (this is a real shop that i used to work with that i have decided that i'm not going to do business with anymore due to unethical practices.) They built their own big brake kit for c5/c6 corvettes and proclaimed it was "better than brembo.". that was a fed flag for me because brembo is a multi billion dollar a year brake company, and these guys are 4 idiots with a cnc machine. first question i asked them was "did you center the rotors in between the wheel bearings?" they answered with "why?", to me that means 'NO we didn't think of that'. every kit they installed on peoples cars blew out one skf corvette wheel bearing ($300-$500ea), this happens at every event. so make sure when you go to an non-oem rotor that the rotor offset is identical.

Overall balance

Big piston calipers, huge rotors can make your braking system feel like complete garbage. A personal example. before i was a brake rep or knew anything about brakes, i did a track day. i took a set of porter fields street pads out and burned them up. I absolutely cooked the snot out of them. They didn't like to work, but they would slow the car down. I knew the pads where toast, so i ordered a set of hp+ pads. I couldn't tell you why i ordered fronts only, and left the toasted porterfield pads in the back. I beaded in the hp+ on the street and thought "man these feel much better.". I went to an auto cross the next weekend. The track started with a long straight followed by a sweeping right turn. first run, I charged hard, came to the braking Zone, reached for the brakes, and there was nothing but white smoke. I flew 10 yards off the track and into a berm. Two big black marks from my front tires lead all the way off the track. My Front tires had all the braking power in the world, the rears were nowhere to be found. to put it into engineering terms the Fronts where at 90% braking and the rears were around 10%. the new pads had an increase of 30% more TQ, to yield to 90% worse overall performance. Although i had "upgraded" the Front brakes, it gave me worse performance than if i had left the burnout pads on the car. Yes you can increase the caliper sizes and get more torque out of the front wheels, but without balancing that increased TQ to the rear you're going to make the braking performance (ability to slow the car) worse. the Idea out of a braking system is that you want to use 100% of the tires. 100% of all 4 tires to slow the car. as the car stops weight is transmitted forward. at this point the rear tires have less weight on them and less traction. my point is that,it is not hard to upgrade rear braking components to handle the lightened traction. but everyone seems to forget that we do have brakes on the rear of the cars that need love too.



to answer your question. yes, you can bolt allot of equipment onto "other" hubs. without balancing the equipment out F->R then you're not really building a better braking system. make sure those rotors are centered. or the money you save avoiding an engineered brake kit will go toward wheel bearings. watch out for how much you increase piston area or you might need more pedal stroke than is available to you.

[minendrews68]

Wow, I'm betting a lot of people will appreciate this..

[Stupidnewbie]

Much of this is still in the planning stages, so things can change as is needed, but here are more details: '68 Firebird, roughly 3200 lbs, stock front subframe, weld-in subframe connectors, G-Bar rear suspension, 800lb front springs, whatever comes with the G-Bar in the rear. The rear axle is a full-floater so the rotor offset shouldn't be a problem on the wheel bearings. The front brakes will be all factory GM parts. I plan to run 275/35/18's up front, 315/30/18 in the rear. Motor is a 389 bored/stroked to 432c.i., should be pushing about 470HP and 500ft/lb of torque. 700r4 transmission. I was planning to use a hydroboost, as well.

[Shootstraight]

Here's a question I haven't gotten an answer for yet. I put a Currie Ford nine inch rear in my 72 Elcamino, for brakes I used Baer iron Sport disc brakes (basically a Mustang caliper). What type of E brake cable do I use that will tie into my factory intermediate cable or do I have to have one made custom? Any clue who does that type of thing?

[TheJDMan]

inlinetube.com can make your custom E brake cables.

[andrewb70]

Thank you for starting this thread.

I'd be interested in a recommendation for a brake package for my 1967 Cougar that has 4 wheel drums now. My only requirement is that the system must fit inside a 15" wheel. This won't be a road racing car. It'll be mostly street driven with an occasional trip to the drag strip.

Thank you in advance.

Andrew

[72Z/28]

Hi

I have Wilwood 4 piston Forged Dynolite calipers and realized they are centered on the brake rotor. Both passenger and driver sides rear calipers are not centered. In fact, both of them are more towards the inboard side or the center of the car as shown in the below pictures.





I thought shims would help to center the calipers but I was wrong as you will notice from the second pic that the outboard side of the caliper is almost rubbing against the rotor.

I have a ford 9" supplied by Speedtech, which is set up for their suspension kit. I measured the axle offset and it is approximately 2.6in.I don't about the offset for the rear brake kit.
However, I did measure the offset for the rotor and is 1.91. The spacer between the caliper bracket and the backing plate is 0.487 thick





URL=http://s218.photobucket.com/user/72Z28/media/image_zpsf4cabc79.jpg.html][/URL]


I have looked up wilwood site and found a rotor with 2.31 offset and wondering if that itself resolves the issue as by having a bit more offset will move the rotor more inboard and center the caliper.



I need your input on how to solve this issue.

[OG_Racing]

Much of this is still in the planning stages, so things can change as is needed, but here are more details: '68 Firebird, roughly 3200 lbs, stock front subframe, weld-in subframe connectors, G-Bar rear suspension, 800lb front springs, whatever comes with the G-Bar in the rear. The rear axle is a full-floater so the rotor offset shouldn't be a problem on the wheel bearings. The front brakes will be all factory GM parts. I plan to run 275/35/18's up front, 315/30/18 in the rear. Motor is a 389 bored/stroked to 432c.i., should be pushing about 470HP and 500ft/lb of torque. 700r4 transmission. I was planning to use a hydroboost, as well.

Stupid newbie, (Love the name)
what are your plans for the Camaro?I would need to know that in order to Suggest the correct brake compounds. Looking at Your set-up I highly advise against using the two and three-quarter inch single Pistons in the back of the car. If we look at the C5 C6 base calipers we will see that they have a 3.9 in.² area. The 2.75 Pistons have a 5.94 in.² area. The older GM calipers will have 41% more piston area. Allow me a moment to explain why the increased piston area is going to be a headache. There are only three ways you can change brake torque in the system; hydraulic advantage (Difference in size between master cylinder and caliper piston size), rotor diameter, and brake pad compound. By varying the piston-size/master-cylinder ratio we can actually adjust the amount of torque in the system. On our road race cars we use what is called a dual master cylinder unit. With a Dual master cylinder system we can actually Change the amount of torque in a braking system. This gives us the added benefit to use the exact same calipers (front and rear) and adjust for the brake torque. In your chassis being a be a single master cylinder unit we need to be very careful about piston sizes. Instead of the 2.75 inch calipers I recommend running the 45 mm C5/C6 rear calipers. I would also recommend running the standard C5 front rotors. Generally I've seen a heavy front brake bias when using C5 C6 brake components with a single master cylinder booster unit. I compensate for this Bias by running the z51 rear rotors in the back of the car. In order to pick out the correct master cylinder size I would need to know the center of gravity in the chassis. It appears of the master cylinder for C5 C6 Corvette is at 1 inch with the booster. The one-inch master cylinder would be a good Place to start. In order to get you optimal braking I would need to know center of gravity. When picking out rotors make sure you find a Curved vane rotor that is manufactured in the US. A lot of manufacture the title the curved vanes "to improve airflow" out of the rotors, but I've also seen them give an increase in rotors' stability.


From the OG racing blog.

there are allot of different aspects when it comes to a rotor.
What is it made from (Iron, Steel, Aluminum, Carbon ceramic, Carbon Carbon)
Where is it made
Is it 2 piece (hat made from aluminum, Rotor ring made from iron)
if it is 2 piece does it float?

Not wanting to spend all day i'll try to keep the answer short. and focus on the standard parts store rotor.
Standard rotors that you find on Rockauto, Autozone, and so on come from china. They are covered and machined with oil, the material to make them is not as pure as it should be, and are never made engineered for racing. allow me to explain.

The machining process for Chinese rotors involves blasting the machining surface and tools with a oil to keep them cool, this lowers maintenance costs on machines. Then factory workers will warp the rotors with an oil impregnated paper. This oil is in an attempt to prevent rust, at that it works well. The problem with using so much oil is that, it will impregnate itself into the iron. once that iron is impregnated the oils will come out under extreme braking. Most of the time when you see issues creating and keeping a transfer layer, the oil inside the iron is causing that issue. It impurities in the rotor are kicking the transfer layer off. Racing companies like PFC, Brembo, AP, will cut the rotors "dry". Dry means to machine the parts without any oil. it is more expensive to do this but will increase the rotors ability to obtain and keep a transfer layer.

Next is what it's made from. Iron is easily one of the best materials used for rotors. Size for size an iron rotor will outperform a carbon ceramic rotor. if you have 14" rotors one in carbon ceramic and one in iron, the iron one will generate a more consistent and higher TQ output. Not to go too off track but that is why you see 15-16" carbon ceramic rotors on oem vehicles. The oem manufacturers need the increased size to get the performance. but Carbon ceramics will outlast a iron rotor. ...sorry back on topic, right iron.. Iron is one of the densest materials in the universe. also how pure it is in the casting for a rotor makes a considerable margin in braking performance. rotors that are casted in china are known to have quite a few impurities, and are labeled incorrectly. anyone that has dealt with 304 *chinese* stainless will know what i'm talking about. these impurities will have a decreased effect on braking performance. I like to find Rotors manufactured and casted in the usa. the us has a higher standard of casting. again PFC, AP, and brembo all are manufactured in the USA, GB, or Italy.

finally the engineering in the rotors could take year to explain, so i'll focus on balancing only. when a rotor gets hot it cones, it beds, and it looks like a wave. it's never still. The material is constantly flexing. think about a top fuel dragster tire in slow motion.. it's not 100% the same but it is close. that rotor is constantly trying to keep itself together and not explode. in order to stop a rotor from shaking the wheel all manufacturers will balance them. Top Motorsports brake manufacturers will balance the rotor by cutting the entire outer perimeter of the rotor on a lathe. this ensures that when a rotor is at thermal capacity, there will be no places of excess or minimal material. it makes the rotor stronger, and more resistant to cracking. part store rotors balance the rotors by finding the heavy spot on the rotor and cutting that off.

what not to do. "mill ballance"


In motorsports this is a huge no-no. the hard edges give a place for cracks to start, the material has a thin spot on the rotor, and it means that the material that is spinning is not balanced through the assembly. it can lead to a cracked rotor and can lead to problems with a long pedal.

In conclusion, :P. is high quality rotors a waist? Like tools good quality parts are never a waste. On average a motorsports rotor will outlast a parts store rotor long enough to justify the price. Parts store rotors can work, they also let allot of people down. If it was my money, paying for my track day, i'm putting the parts on my car that will insure that i have a fun weekend. i'm not looking not fight the $30 rotor that costed me $800 of track time. Allot of people might say "they worked fine for me". Truth of the matter is 80% of the motorsports population knows how to build a motor, 10% know how to build a braking system. when the brakes that they said "worked fine" didn't work "fine", and that person has no idea what the problem actually is.

[OG_Racing]

Hi

I have Wilwood 4 piston Forged Dynolite calipers and realized they are centered on the brake rotor. Both passenger and driver sides rear calipers are not centered. In fact, both of them are more towards the inboard side or the center of the car as shown in the below pictures.

I need your input on how to solve this issue.

72Z/28,
Tell me about your axle. I have a lot of guys who club race on those GM10 bolts and Ford 9 inches. To use a non-floating caliper in the rear the car we need to use a floating hub. Even the pressed in bearings used to remove C-clips have a tendency to walk around under lateral loads. This makes running non floating caliper like A Dinalight almost impossible. The rotor wanders around inside of the caliper housing causing drag. The rotors just won't stay centered enough to make clearances and tolerances work with That kind of caliper. So we have two options. We can change the axle out to a full floating unit, or we can put a floating caliper on the rear end. I'm afraid adding shims won't get us there.


I'm going to include a fixed first floating caliper picture those crudely drawn and Microsoft paint. Just in case there is someone who doesn't know the differences.

[TheJDMan]

Johnny C,
Can you talk a little about pad composition for track vs street use. I'm currently running Hawk Ceramic pads in C6/Z06 6 piston front 4 piston rear calipers w/14" and 13" rotors respectively and a 7/8" Willwood MC with no power assist. This system requires a moderate amount of pedal pressure to operate, is very well balanced and will lock all four wheels if pushed that far without showing any tendency to lock front or rears only. I chose the Hawk ceramic puck style pads primarily for reduced dusting on the street. But I also realize that these pads rank toward the bottom of grip level compared to what is available with more aggressive pads. My specific question is, which Hawk pads would you recommend for track day/autox use and why?

[OG_Racing]

Johnny C,
Can you talk a little about pad composition for track vs street use. I'm currently running Hawk Ceramic pads in C6/Z06 6 piston front 4 piston rear calipers w/14" and 13" rotors respectively and a 7/8" Willwood MC with no power assist. This system requires a comfortable amount of pedal pressure to operate, is very well balanced and will lock all four wheels if pushed that far without any tendency to lock front or rears. I chose the Hawk ceramic individual puck style pads primarily for the reduced dusting on the street but I realize that these are toward the bottom of the grip level that is available with more aggressive pads. My specific question is, which Hawk pads would you recommend for track day/autox use and why?

Thank you for the well-rounded question, and complements on the brake kit. It is beautiful.


Autocross and track day or two different things. A compound that'll work really well in autocross has the ability to work well on the street. This is due to the lower amounts of heat generated during a 30sec run. For those kinds of applications I recommend the PFC Z rated. Has a low operating temperature and is the common street pad. It being a street pad will result in less squeaking and lower dust. For track day pad I always recommend full race pads. We when you attend a track day you can easily invest over thousand dollars in each event. The number one failure component on a streetcar on a race track is the brake pads. No street pad is able to keep up with it elevated temperatures required, especially of the Pro touring cars. Procuring cars have a tendency to be heavy and that added weight generates even more heat into the brakes.But in order to recommend a brake pad I need to know what kind of tire you are running during track days.


What pad is best for me in my application?

Pad compounds are not just about "this will lock up a tire". Finding the right compound relies heavily on factors like, tire compound, tire size, weight distribution, rotor size(in general and front vs rear), the ratio of caliper piston diameter to master cylinder size. but before we start talking about that we bad is best we need to cover the basics. Brake pads can be broken up into the 3 phases of how they work. Initial bite, TQ output, and modulation.

number one Initial bite. this is the characteristic of a pad on first contact with the rotor. if you where to look at a brake dyno you would see a spike at initial contact followed by the Tq level and then how the pad modulates off. this is spike in the duno is considered "initial bite" Or "bite". Initial bite is purely driver preference. Manufacturers have a tendency to keep that characteristic throughout their pad offerings. hawk has a tendency to have a very high initial bite. PFC and pagid are a more mild initial bite. Allot of Club racers like a High initial bite. I hear things like "I want to get thrown into the harness". That sounds fun and all, but professional drivers (the really fast guys, not the pay to play guys) like a low or mild initial bite. the really fast guys like a mild initial bite because it helps the tire keep cohesion with the track. this will allow you to brake harder and deeper into the turn. giving you a few extra tenths. It also lowers the amount you need to "fight" with the car to get it to slow down. a lower initial bite is easier to drive on. i recommend a full GT pad for beginners. because of the ease it engages the rotor allows them to focus on turn in. Drifters. I always recommend hawk to drifters as the initial bite is so high it helps them break the back tires loose to start a slide.


Torque output or "Mu". This is the part when guys get really excited.. i get requests for "i want the highest MU pad you got.." unless you have one of chip ganassi's old indy cars this would be a very bad idea. Pad Tq is not in any way like Horsepower-"more is good!". the Tq of a pad needs to be matched to your application. Brake Tq in a pad has another characteristic, Consistency. General conception that a pad that a professional uses is harder to drive on. i mean they are professionals right? the pro cars are insanely hard to drive. when it comes to horsepower and crazy over steer that is true. it's not true when it comes to the brakes. in fact it's the opposite. a world class pad is insanely consistent throughout it's entire temperature range. this means when a driver is leaving the pits or diving into turn 10A at road atlanta the pedal will feel exactly the same. that cannot be said for a low price economy race pad. even the HP+ has a strange tq rise with heat. ( i Know i'm getting some nodding heads from people that know the hp+). When i'm setting up a car for a beginner I encourage them to spend the extra $$ on a pro set of race pads. It makes the learning experience that much easier for them. When I say pro-pads i don't mean super high Tq pads (i'm talking about the pads pro's use, PFC & Pagid). The higher the Tq is, the less forgiving a pad becomes. If you have an insanely high tq pad on a car that isn't set up with slicks and downforce you're going to overload a tire easily. The Bite of the pads will become very hard to drive , the tq will overload the tires, you'll never get any heat , and you can forget about the transfer layer. the pad compound needs to be matched to the chassis. That key in difficult driving leads me on to modulation..

Modulation! modulation is also known as release characteristics. What it feels like to release the brake pedal. Modulation is generally linked between pad TQ and chassis set up. for example we will look at the PFC 07 compound. the 07 is a very high tq Compound. On a indy car (the chassis the 07 was made for) with huge slicks and tons of downforce. the 07 will feel normal, you'll be able to ease off the brakes. the brakes would still give you a good linear release. on a lemons car, 200qutg tire, no aero. The 07 will feel like a light switch, Linear Fell would be a dream with that setup. lets reverse it. if you where to install a 97 compound (good for a underpowered gt car or a rally racer) on to an indy car. The modulation would be wonderful, you could modulate all day. but you would not have significant tq to adequately slow the vehicle down.


what should you take away from pads? have the correct pad for the chassis you're using. More brake Tq is not better brake Tq. When considering new pads rate your's on Bite, Tq and Modulation. More TQ is not always a good thing. having the highest Tq pads on the block doesn't mean your the fastest guy around. Chicks don't care about how much brake Tq you have... have i mentioned don't over do the Tq.'

[79-TA]

Hi and thanks for trying to tackle all kinds of braking questions.

I tend to cringe at these sort of threads as they throw out a ton of information in an unorganized fashion. I generally tell people to read a book or read the StopTech white papers. Most people don't really understand what makes a braking system good, so best of luck.

http://www.amazon.com/High-Performan.../dp/1613250541

http://www.stoptech.com/technical-su...l-white-papers

Piston area.

Brake Tq can only be changed by 3 Dynamics in a brake system, Rotor Size, Pad compound, and hydraulic advantage. Hydraulic advantage the difference in size between your master cylinder, and your caliper pistons. if you want more Tq increase your pistons, less decrease your pistons. same goes for the master cylinder. you want more TQ? decrease your Master cylinder size. it will increase your hydraulic advantage. ***before we go out messing with master cylinder sizes and piston sizes there is a point of no return.*** the aspect that nobody thinks about but is important has to do with the brake pedal. As a pedal travels thru it's motion you do lose some advantage the further away from the driver it gets. We find at almost 90* on most pedal assemblies the driver would lose leverage. loss of that leverage would make the pedal harder to push. by decreasing the master cylinder size, or increasing piston size you're increasing the distance the pedal needs to travel. so it will take less effort from your foot to stop, but your trading that effort for pedal distance. try and keep the sweet spot of the pedal (@90*) at the point of where you start to modulate your brakes.

Please make sure you're describing things clearly, thoroughly and accurately. Lots of people find these kind of threads and use them as references.

Your initial summary should include the the mechanical leverage of the brake pedal with respect to the direction force is applied. You do mention the pedal later and I appreciate that you talk about keeping the pedal at or near 90 degrees. Line pressure is also increased by the master cylinder and by other outside means like vacuum or hydraulic assist systems. "Rotor diameter" should be replaced with effective radius. The placement of the pistons and shape of the swept area of the pad will determine the effective radius. Yes, for most cases the rotor size will define the other components people will use. People often don't realize that a smaller annulus pad can be used to increase the effective radius of the system. It's a common trick for dyno testing. These are all small, differences, but I feel they are important for better understanding.

I like the following StopTech explanation that goes through the system in a serial manner:

"1) Line pressure can only be increased by either increasing the mechanical pedal ratio or by decreasing the master cylinder diameter. In either case the pedal travel will be increased.

2) Clamping force can only be increased either by increasing the line pressure or by increasing the diameter of the caliper piston(s). Increasing the size of the pads will not increase clamping force. Any increase in caliper piston area alone will be accompanied by an increase in pedal travel. The effectiveness of a caliper is also affected by the stiffness of the caliper body and its mountings. It is therefore possible to reduce piston size while increasing caliper stiffness and realize a net increase in clamping force applied. This would typically improve pedal feel.

3) Only increasing the effective radius of the disc, the caliper piston area, the line pressure, or the coefficient of friction can increase brake torque. Increasing the pad area will decrease pad wear and improve the fade characteristics of the pads but it will not increase the brake torque."



Your overall balance sections reads confusingly. In your example, it sounds like the more immediate issue was that you locked up your front brakes (two black marks, right?) I realize this was just sort of an introductory summary, but it was not made clear that the front brakes should perform a balanced amount of work that is proportional to the normal force on the front tires (assuming equal coefficients of friction for front and rear tires.) A discussion of weight transfer must include the consideration of the height of the center of gravity, wheel base, and the expected maximum rate of deceleration as determined by the coefficient of friction between the ground and tires. I'm sure you'll get it all covered though. A discussion about dynamic brake balance and Z-critical would be impressive.

It's not my goal to discourage or be a pedant and pester this thread with small additions. Just please do a good and thorough job in your explanations. It sounds like you have a good foundation and lots of practical experience to help people with. I think this can be a really good thread.



In evaluating brake systems, I encourage people to look at three questions.

Is the amount of brake torque at a given pedal effort appropriate to stop my car?

Is the system balanced or can it be balanced?

Does my brake system have sufficient thermal capacity for my car's intended use?


And perhaps as a corollary,

Is it not terrible? (avoids excessive knockback, terrible pedal feel, being unreliable or unsafe, etc)

[andrewb70]

No thoughts on my little Cougar project? LOL

Andrew

[72Z/28]

72Z/28,
Tell me about your axle. I have a lot of guys who club race on those GM10 bolts and Ford 9 inches. To use a non-floating caliper in the rear the car we need to use a floating hub. Even the pressed in bearings used to remove C-clips have a tendency to walk around under lateral loads. This makes running non floating caliper like A Dinalight almost impossible. The rotor wanders around inside of the caliper housing causing drag. The rotors just won't stay centered enough to make clearances and tolerances work with That kind of caliper. So we have two options. We can change the axle out to a full floating unit, or we can put a floating caliper on the rear end. I'm afraid adding shims won't get us there.


I'm going to include a fixed first floating caliper picture those crudely drawn and Microsoft paint. Just in case there is someone who doesn't know the differences.

I have Bear's Performance Pro Street Axles.

Does that mean I should replace the entire rear brake kit with a floating caliper kit or I just need to get a floating caliper only?

I am tired of these aftermarket parts. I have the wilwood kit and have no way of telling what the offset is. I could not find the part number for it

[OG_Racing]

Hi and thanks for trying to tackle all kinds of braking questions.

I tend to cringe at these sort of threads as they throw out a ton of information in an unorganized fashion. I generally tell people to read a book or read the StopTech white papers. Most people don't really understand what makes a braking system good, so best of luck.

http://www.amazon.com/High-Performan.../dp/1613250541

http://www.stoptech.com/technical-su...l-white-papers





Please make sure you're describing things clearly, thoroughly and accurately. Lots of people find these kind of threads and use them as references.

Your initial summary should include the the mechanical leverage of the brake pedal with respect to the direction force is applied. You do mention the pedal later and I appreciate that you talk about keeping the pedal at or near 90 degrees. Line pressure is also increased by the master cylinder and by other outside means like vacuum or hydraulic assist systems. "Rotor diameter" should be replaced with effective radius. The placement of the pistons and shape of the swept area of the pad will determine the effective radius. Yes, for most cases the rotor size will define the other components people will use. People often don't realize that a smaller annulus pad can be used to increase the effective radius of the system. It's a common trick for dyno testing. These are all small, differences, but I feel they are important for better understanding.

I like the following StopTech explanation that goes through the system in a serial manner:

"1) Line pressure can only be increased by either increasing the mechanical pedal ratio or by decreasing the master cylinder diameter. In either case the pedal travel will be increased.

2) Clamping force can only be increased either by increasing the line pressure or by increasing the diameter of the caliper piston(s). Increasing the size of the pads will not increase clamping force. Any increase in caliper piston area alone will be accompanied by an increase in pedal travel. The effectiveness of a caliper is also affected by the stiffness of the caliper body and its mountings. It is therefore possible to reduce piston size while increasing caliper stiffness and realize a net increase in clamping force applied. This would typically improve pedal feel.

3) Only increasing the effective radius of the disc, the caliper piston area, the line pressure, or the coefficient of friction can increase brake torque. Increasing the pad area will decrease pad wear and improve the fade characteristics of the pads but it will not increase the brake torque."



Your overall balance sections reads confusingly. In your example, it sounds like the more immediate issue was that you locked up your front brakes (two black marks, right?) I realize this was just sort of an introductory summary, but it was not made clear that the front brakes should perform a balanced amount of work that is proportional to the normal force on the front tires (assuming equal coefficients of friction for front and rear tires.) A discussion of weight transfer must include the consideration of the height of the center of gravity, wheel base, and the expected maximum rate of deceleration as determined by the coefficient of friction between the ground and tires. I'm sure you'll get it all covered though. A discussion about dynamic brake balance and Z-critical would be impressive.

It's not my goal to discourage or be a pedant and pester this thread with small additions. Just please do a good and thorough job in your explanations. It sounds like you have a good foundation and lots of practical experience to help people with. I think this can be a really good thread.



In evaluating brake systems, I encourage people to look at three questions.

Is the amount of brake torque at a given pedal effort appropriate to stop my car?

Is the system balanced or can it be balanced?

Does my brake system have sufficient thermal capacity for my car's intended use?


And perhaps as a corollary,

Is it not terrible? (avoids excessive knockback, terrible pedal feel, being unreliable or unsafe, etc)

You nailed it brett, You're absolutely right. I am trying to put the information into layman's terms. There are thousands of technical books all written by engineers that cover the same topic. I find that more people will relate if i can add in a few stories, take the long way to explain things, and even curse once in a while. When I build a brake kit it's more of an interview, and i'll ask hundreds of questions just to get it right.

[OG_Racing]

No thoughts on my little Cougar project? LOL

Andrew

Andrew,
Sorry, it's been a busy day. Not knowing exactly what the dimensions are of your cougars front suspension, I'm not ready to suggest that kit.. If it's going to be driven on the street, your braking demands will be very small. You would be well off using the rotor option that came on the Mustang originally. Combine that with the proper proportioning valve, and a good set of pads. should give you adequate braking power.

If you want to go something more high-performance. I can recommend a ZR34 four piston caliper with the two piece rotor.