Well, I started disassembling some things and working on my dual caliper setup and have encountered a potential problem I hadn't thought of. The dust shield. If I just rip it off would there be any real side effects or should I fab a new one to fit around the dual calipers?

 

Is that a Contra avatar / icon?

The dust shield keeps dirt & debris off of your calipers & rotors. It's important. Are you going with an aftermarket brake upgrade or just swaping from the regular to heavy duty RX-7 FC3S suspension setup (4 piston caliper fronts)?

 

Yeah, contra...

I'm working on an upgrade for S4 SE cars. All the brake upgrades out there are for 5 lug cars. I'm trying to fab a bracket to mount two 4-lug calipers to the front rotors.

I think it would be nice if there was more available for the lightest FC's made.

 

ummm,..........thats kinda a waste of time, your not going to get anything out of it, the front disks are still going to be an inch smaller then the 5 lug, not to mention the 5 lug 4 piston calipers are aluminum and weight less then the single piston calipres,.. especially 2 of them, you just increasing unsprung weight,.. also there isnt much for the 4 lugs because there not really a sporty model,.. there a base,.. with small brakes and soft suspension. the sport models weight within a few pounds of the bases,.. If your serious abour performance just do the 5 lug swap, grab some sport/gxl/t2 sway bars while your there and youll be pretty good to go with alot less hassle and something that is alot more functonal.

 

Thank you for this well writen, yet miserably misguided and pointless (as well as unwanted and ridiculously off topic), post.

 

contra? really? i thought it was double dragon...

anyways, you finially picked up a 2nd gen? and id also like to know what not haveing the dust shields will do in the long run. recently i saw in nopi street that they took them off of one of the project cars they are working on. i mean if you clean your car regularly i wouldnt think removing them would be that much of a problem, unless brake dust eats away at rubber, but i dont think it does.

 

I've always had an FC ...just not a running one. I'm looking at picking one up very soon and I'm starting a couple projects on the two SE's I have as parts cars.

 

On Mazdatrix' website they say to remove the dust shield as part of the process of installing rear steer elliminators. So I removed mine last week and if there are any negative effects I'll mention em

 

cool. I honastly can't think of any real reason except for maybe shielding the brake lines from heat or moving parts or something.

 

i just thought of what its for! its for pissing you off when all of a sudden when you are driving and turning you hear this grinding and clanking noise, after spending lots of money and time trying to figure it out you notice that the shield is loose and hitting the rotor while turning!

 

yeah mine are going because they look like **** against my painted rotors

 

i didnt remove mine completly, rather i took them off when doing brake work and cut them back all the way to the bolt holes then stuck them back on. this way you still have them protecting the hub and bearing from dirt, but they dont look *** ugly hanging out over your rotors where all they do is deflect brake dust.

 

A couple years ago when I did a track school I received a booklet and they mentioned something on this topic: (Ian Law Racing Track School, pg 2) "Secondly, you can try to improve the airflow over and around the brakes to aid in cooling. This can be as easy as removing the dust cover behind the rotors on some makes of cars." I tend to think that this step wouldn't be suggested if it was highly detremental in other aspects.

 

It's an interesting concept that you're proposing with putting a second caliper up front, but it won't do what you want it to. First of all I'll go over the advantages of a real big brake kit:

1) Calipers: more rigid (better feel), more pad area, lighter (sometimes)
2) Rotors: Larger diameter (more torque {force*radius}), higher thermal capacity (sometimes), larger surface area for cooling

For the brakes not to fade the rotors and calipers must absorb all the energy (heat) that you're generating from braking and not transfer it to the fluid (to slow down you dissipate your kinetic energy by turning it into thermal energy). For this you need to have large rotors and calipers. The amount of heat they can absorb is a function of their weight and the properties of the material. What you want is for the rotors and calipers/pads to absorb the heat from braking and then dissipate most of it before the next corner, with at no time the heat of the brake fluid approaching the boiling point. For this you need airflow to hit the surface of the rotor (which you'll block with the 2nd set of calipers), you can increase this several ways, increase airflow, increase surface area, or both.

There are many problems with what you're doing. First of all the bias will be all off: twice as much brake fluid will to go to the front, giving twice the torque and generating twice the heat, and you'll get front lockup, and stopping distances will increase (the rears are now doing less than half the work they should be). Second, they'll fade very quickly: you'll have twice the heat, less airflow and only slightly increased mass to absorb the heat. Thirdly it'll increase unsprung weight, and for this kind of "upgrade" it's not worth it, most of the "good" big brake kits have much lighter calipers and rotors with aluminum hats to minimize weight.
You can only brake as quickly as traction allows, if you can lock up your tires now, then you'll not notice any improvement in stopping distances no matter how big you go.

This is not worth your time, just get the bigger brakes from a 5 lug car with the 4 piston calipers, it'll perform better, and look better too. Beleive me, I'm a mechanical engineering student, and I've read alot about this subject.

 

You're right to tell him not to go ahead with this idea, but I want to touch on some of your elaborations, as they went a little deep on the wrong tangents.

<< It's an interesting concept that you're proposing with putting a second caliper up front, but it won't do what you want it to. First of all I'll go over the advantages of a real big brake kit:

1) Calipers: more rigid (better feel), more pad area, lighter (sometimes) >>

The primary advantage in superior calipers is to apply more force, more quickly, and yes, over more pad area. Sometimes they are lighter, but the addition of pistons increases the amount of hydraulic advantage while also allowing it in more locations: As the pistons are wider, they will travel less distance and do it slowly, however, their force will be much higher. The less distance traveled and slower travel is compensated in caliper cylinder design, and the addition of extra pistons in the first place.

<< 2) Rotors: Larger diameter (more torque {force*radius}), higher thermal capacity (sometimes), larger surface area for cooling >>

The larger surface area's primary function is for force transfer. For the calipers to have a better grip to stop the rotor from turning. More surface area is advantageous for cooling, however cooling is better achieved in design by ventilation between the rotor surfaces (these are the vents between the two sides of a front rotor, and often times they are directionally oriented) and the metalurgy involved in the contact surface and where the surface area meets the hub.

Too much heat results in brake fade, which is a temporary condition when hot pressure manifests between the pad and the rotor, which is more difficult to contact through, and will malaffect the car's braking until thermal activity is reduced. Some combat this by drilling holes or machining slots into the contact surface. This is a trade off between heat removal and compromised grip due to a reduction in surface area.

<< For the brakes not to fade the rotors and calipers must absorb all the energy (heat) that you're generating from braking and not transfer it to the fluid (to slow down you dissipate your kinetic energy by turning it into thermal energy). >>

Brake fluid will almost never boil. It has for very long been the highest liability fluid in the car, and it has been designed industry wide to be highly resistant to heat. The rotors themselves can catch fire and the brake fluid won't boil if it remains pressurized (and it definitely is under extreme pressure) in the seal system. The user will never have to make any design changes to combat this. Thereby, it is no goal of the user to try to overcome this "boiling" by changing rotors and calipers, which would be a simple fix to say the least if such a condition did exist (heaven forbid).

The energy transfer goal in which a caliper stops a rotor from turning is to turn kinetic energy into potential energy, not thermal energy. The energy in the braking process is not heat by rather mechanical force. Thermal energy is a negative byproduct, and we try to reduce it whenever possible. I've discussed how this is done. The caliper will absorb none of this energy, hopefully, but simply oppose it, as the rotor and then the tire and then the road and car frame equalize the rest.

<< For this you need to have large rotors and calipers. The amount of heat they can absorb is a function of their weight and the properties of the material. What you want is for the rotors and calipers/pads to absorb the heat from braking and then dissipate most of it before the next corner, with at no time the heat of the brake fluid approaching the boiling point. >>

Once again, the boiling point and pressure propreties of the brake fluid are a nonissue. The rotors will absorb the heat, but not the calipers and definitely not the pads. In fact, the biggest threat to a pad surface is heat, often heat from the brake fade phenomenon, which will burnish its friction surface and compromise its ability to hold off. Ironically, the rotor dissipates its heat while turning, not while standing still while being held by a caliper. This is one reason why ABS braking is the preferred method, as one reason why it releases the rotor is to allow it to cool in the microsecond intervals between it being held.

Obviously, the primary purpose of ABS is to allow the user to steer the car during maximum braking and in adverse road conditions.

<< For this you need airflow to hit the surface of the rotor (which you'll block with the 2nd set of calipers), you can increase this several ways, increase airflow, increase surface area, or both. >>

We would prefer that more air go "inside" the rotor, through its designs. And that the air that passes over the the surface be primarily effective in blowing the hot gasses present in brake fade away.

<< There are many problems with what you're doing. First of all the bias will be all off: twice as much brake fluid will to go to the front, giving twice the torque and generating twice the heat, and you'll get front lockup, and stopping distances will increase (the rears are now doing less than half the work they should be). >>

Hopefully, a competent techinician will install a proper metering valve to prevent lock up as a result of bigger brakes in the front. A properly configured hydraulic modulator will assist this in an ABS system. A correct thing to do would also be to proportionally change up the rear brakes, and add the correct proportioning valve to boot.

Torque is not at issue here, as it is not the means by which the caliper grabs the rotor. It is in fact the means by which the rotor opposes the caliper's goals. Torque is the obstacle in a braking application.

<< Second, they'll fade very quickly: you'll have twice the heat, less airflow and only slightly increased mass to absorb the heat. >>

Larger calipers mean larger pads, which means reduced fade. However, the rotor wear will be more. And yes, the old / smaller rotors would warp from the heat.

<< Thirdly it'll increase unsprung weight, and for this kind of "upgrade" it's not worth it, most of the "good" big brake kits have much lighter calipers and rotors with aluminum hats to minimize weight. >>

For this kind of upgrade, the change in unsprung weight is a nonissue, as it will compensate for its own momentum in stopping with its increased stopping capibilities (which will only really be increased if this is done right). The weight would effect emmisions in driveablity much more than it will effect "acceleration power."

<< You can only brake as quickly as traction allows, if you can lock up your tires now, then you'll not notice any improvement in stopping distances no matter how big you go. >>

Yes, a tire upgrade would be best done at the same time as a brake upgrade.

<< This is not worth your time, just get the bigger brakes from a 5 lug car with the 4 piston calipers, it'll perform better, and look better too. >>

Highly, highly not reccomended. Dangerous at worst, compromising to your over all system at least. Spend the money and go to a competent ASE Brakes techinitian who is in the business of doing brake upgrades right.

<< Beleive me, I'm a mechanical engineering student, and I've read alot about this subject.[/QUOTE] >>

Oh.

 

You claim that brake fluid won't boil? On what basis is that. I've seen the bubles in brake fluid from it being boiled (I'm not talking about all of it boiling, you just get little bubbles from some of it boilling). Racers know all about fluid boiling and if you don't design the system correctly then the fluid will boil. Also you say that once the heat goes away the fade will too. That's only true for pad fade (when the pad gets too hot and looses friction), not fluid fade (fluid boiling). I've been to the track and I've had some fade (just a few tiny bubles). You speak of the pads off gassing causing fade. This hasn't been the case for pads in decades. Many people still have drilled and slotted rotors as an "upgrade" but you will have less braking force and you'll crack your rotors under hard use (the holes are stress risers and detract from the surface area able to make friction). Also you say that heat is a byproduct and the brakes turn the kinetic energy into potential energy. That is 100% WRONG! How can you get this potential energy back? Where does it go. Rub your hands together and they get hot. That's the friction causing heat. This is how brakes work. WHile alot of cooling does happen on the inside of vented rotors, there is still alot of cooling that happens on the outside surfaces of the rotors. Also with unsprung weight, that's not for stopping, that's for handling, rotating weight affects stopping. You say that torque is the enemy of braking? I am talking about the torque that the caliper exerts on the rotor, slowing it down and assuming the tire's connected to the road, the car slows down. How does a car accelerate? You apply torque to the drive wheels, so stopping is the same, you just apply the force in the opposite direction. Lastly you say that doing a 5 lug swap is dangerous, but why is that? I mean replacing the hubs, rotors, calipers, everything (MC if it's different too). This is not dangerous when done properly, and many people have done this withought any ill effects.

I am a mechanical engineering student, I've been to two high performance driving shcools, I've attended two SCCA club races as a member of a pit crew, and I'm involved in our university's Formula SAE team. I Know what I'm talking about.

This is a bad idea!

Plus they'd probably sell 2 kits at the most, as it's geared towards some of the oldest and cheapest 2nd gens out there, and FC owners are notoriously cheap.

 

Go ahead and remove them. They can effect cooling under severe braking conditions, which CAN CAUSE THE BRAKE FLUID TO BOIL. It usually turns dark brown/black after being boiled, and pedal feel is severely crapified.
The only good use of the dust shields is that they can be adapted to be fed from ducting for better cooling. The dust shields are more for keeping brake dust off of parts than protecting the brakes from road dirt and debris.

 

<< You claim that brake fluid won't boil? On what basis is that. I've seen the bubles in brake fluid from it being boiled (I'm not talking about all of it boiling, you just get little bubbles from some of it boilling). >>

Whenever you see bubbles in brake fluid, the brake fluid needs to be bled because it has recieved air from outside of the system, or it has aerated air that was previously hidden in the system. Otherwise, there was moisture in the brake fluid (water--brake fluid is hydrophillic) that is boiling. As long as it stays sealed in the system, it will behave as a hot liquid under pressure and not boil; the same as coolant. We are talking about a consumer used, commercial system here. Not a racing application. Brake fluid won't boil in this kind of application. The way these system are designed, brake hosing will sooner melt and spray the fluid onto the hotter part of the system and cause the fluid to burn outright. And sure, it will boil once it's hot enough to burn. But in no commerical system will brake fluid boil and then continue to be used in a system. It never comes up in daily operation.


<< Racers know all about fluid boiling and if you don't design the system correctly then the fluid will boil. >>

We're talking about an RX-7 with the modification listed in this thread. Brake fluid boiling is not an issue in this situation. A regular consumer will never design their system to this effect. Racers even hardly deal with it.

<< Also you say that once the heat goes away the fade will too. That's only true for pad fade (when the pad gets too hot and looses friction), not fluid fade (fluid boiling). >>

In the professional term and diagnosis for brake fade, "fluid fade" is never denoted. So, yes, I am correct.

<< I've been to the track and I've had some fade (just a few tiny bubles). >>

That's your absorbed moisture boiling or the heat accentuating an air presence. I have no idea if you or the technicatian correctly isolated your brake fluid from either. Personal experience is as best as a customer's diagnosis and worthwhile to me only as a goal of replicating the complaint. I can't do that here.

<< You speak of the pads off gassing causing fade. This hasn't been the case for pads in decades. >>

It's an issue even now, it's a major obstacle to overcome while engineering a pad and caliper assembly. *shrug* You're simply incorrect.

<< Many people still have drilled and slotted rotors as an "upgrade" but you will have less braking force and you'll crack your rotors under hard use (the holes are stress risers and detract from the surface area able to make friction). >>

As I mentioned before, the loss in surface area due to slotting or cross drilling a rotor is a compromise to be contended with by whomever performs the operation. Obviously, if it's done incorrectly, what you listed can result. If the rotors are designed to be cross drilled or slotted or whatever in the first place, the engineer will apply the correct metalurgy and machine surface to match and ideally minimize the negative consequences. If you go and slot or cross drill any given commercial rotor, you probably have little or no metalurgy figured into the process, and the same applies for machining.

<< Also you say that heat is a byproduct and the brakes turn the kinetic energy into potential energy. That is 100% WRONG! >>

Not so. Heat is obviously a byproduct of the braking process. It's produced by braking. I don't know what else you want me to tell you. You yourself seem to think that this heat is so surmountable that it will boil your brake fluid. Which is inconsequential.

Kinetic energy is present in the rotor while it spins. Kenetic energy is the energy of motion. When you take moving object and stop it, you are opposing it with the potential energy of the road and the frame of the vehicle. When one kind of energy type is met or opposed by another energy type, energy transfer occurs. Thus, kinetic energy becomes potential energy.

<< How can you get this potential energy back? Where does it go. >>

When you have a heavy car sitting up hill and ready to go downhill, it is potential energy. When you push it with kinetic energy, you transfer its potential energy into kinetic energy, which is its primary energy type when it is going downhill. When it has reached the bottom, and stopped, it has become potential energy again.

<< Rub your hands together and they get hot. That's the friction causing heat. This is how brakes work. >>

Yes, friction makes heat. We want as much friction as possible with as little heat as possible. We create heat in the braking process but do not want to. You seem to think it is a goal of the engineer to make as much heat as possible.

<< Also with unsprung weight, that's not for stopping, that's for handling, rotating weight affects stopping. >>

Unsprung weight is considered for all kinds of things. Including stopping. It's not for or against anything. You want to minimize just like you want to minimize all other kinds of weight. That's a stupid distinction.

<< You say that torque is the enemy of braking? >>

When a rotor or wheel is spinning, it has torque. Torque is rotating energy, force as it is rotated. You must oppose this to stop a wheel or rotor or shaft from spinning.

<< I am talking about the torque that the caliper exerts on the rotor >>

The caliper certainly does not exert any torque onto a rotor. The caliper exerts force onto a rotor. It grips. Torque can only be achieved by twisting.

<< How does a car accelerate? You apply torque to the drive wheels, so stopping is the same, you just apply the force in the opposite direction. >>

Stopping is the opposite, not the same. If I apply negative torque to a spinning wheel, it will spin the other way. Not stop. Different process.

<< Lastly you say that doing a 5 lug swap is dangerous, but why is that? I mean replacing the hubs, rotors, calipers, everything (MC if it's different too). This is not dangerous when done properly, and many people have done this withought any ill effects. >>

Even when done properly it is an amature modification of the original design of a primary safety component (where the wheel meets the hub). Go ahead and do it correctly with an aftermarket engineer. Most people don't. It's professionally discouraged.

<< I am a mechanical engineering student, I've been to two high performance driving shcools, I've attended two SCCA club races as a member of a pit crew, and I'm involved in our university's Formula SAE team. I Know what I'm talking about. >>

Arguing from authority isn't very advantegous when discussing solid rules of physics, it's wiser to reserve an argument from authority for a social issue or opinion debate. You don't have much professional experience, as you are only a student and make a lot of assumptions this negates your authority over the subject.

I am an ASE Master Certified Automotive Technitian, including braking systems, am Master NATEF trained, and hold an automotive degree. I have extended specialization in ABS braking systems and traction control, among many other things. I see more brake jobs and brake damage a day than you've probably seen total.

I am an active member of SAE and SAT, and I too, am a mechanical engineering student.

Rarely ever do I say I know what I'm talking about, since experience has taught me that I am always learning in this industry.

 

I really don't feel like arguing this right now, but I'll reply later. All I have to say now it that nearly everything you say is complete and utter BS. Enjoy your ignorant/malinformed exisstance. While all of my arguments may not be 100% correct, the overall concept/logic is still correct.

 

<<Whenever you see bubbles in brake fluid, the brake fluid needs to be bled because it has received air from outside of the system, or it has aerated air that was previously hidden in the system. Otherwise, there was moisture in the brake fluid (water--brake fluid is hydrophilic) that is boiling. As long as it stays sealed in the system, it will behave as a hot liquid under pressure and not boil; the same as coolant. We are talking about a consumer used, commercial system here. Not a racing application. Brake fluid won't boil in this kind of application. The way these system are designed, brake hosing will sooner melt and spray the fluid onto the hotter part of the system and cause the fluid to burn outright. And sure, it will boil once it's hot enough to burn. But in no commercial system will brake fluid boil and then continue to be used in a system. It never comes up in daily operation.>>

Riiiight, cause you see people at the racetrack having their lines melt and spray fluid everywhere so often. I’ve never in all my life heard of the lines melting and spraying fluid everywhere, no engineer in their right mind would design a system so that catastrophic failure would occur before a gradual reduction in performance occurs. You can still stop when you have fade, if the lines melt, you’re screwed. Also the boiling occurs INSIDE the caliper, not up in the lines. It happens at the back of the piston(s) where the piston transfers heat from the pad to the fluid, so the lines don’t get that hot anyways. The only place you can get air into the system is if there’s a leak (in which case fluid will spray all over the place when you apply the brakes and you’ll have no brakes really soon), at the bleeder nipple (closed when driving, so it’s sealed, and again it’d spray fluid), and the master cylinder (unless it’s broken you can only get air at the top of the reservoir, and it won’t make it into the lines). It’s true that water lowers the boiling point, and that makes it easier to boil it, but their in solution, so the boiling point is a function of the ratio of brake fluid to water. You’re talking about commercial applications in day to day use; this thread was about a “high-performance” upgrade where people would be likely to be hard on their brakes with it. You cannot assume that all consumers will be average, people take their street cars to the track, it’s a fact (hell I’ve seen a Toyota Prius at the race track).

By the way read this:
http://www.se-r.net/car_info/brake_performance.html
The author writes for Sport Compact Car and he’s a smart guy.

<<In the professional term and diagnosis for brake fade, "fluid fade" is never denoted. So, yes, I am correct.>>

See above

<<That's your absorbed moisture boiling or the heat accentuating an air presence. I have no idea if you or the technician correctly isolated your brake fluid from either. Personal experience is as best as a customer's diagnosis and worthwhile to me only as a goal of replicating the complaint. I can't do that here.>>

I bled the system with my dad; we are both competent mechanics (he’s been doing it for over 30 years). I know what I saw; there were bubbles in the fluid as it came out of the caliper. It doesn’t matter what boils, it’s still fade.

<<It's an issue even now, it's a major obstacle to overcome while engineering a pad and caliper assembly. *shrug* You're simply incorrect.>>

If you insist on using crappy pads then it may be a problem. If you use any descent semi-metallic or better pad it’s not an issue at all. This is mostly an out of date problem that not many people ever have to deal with, it’s mostly an urban legends propagated by the corporations so they can sell you more expensive rotors.

<<As I mentioned before, the loss in surface area due to slotting or cross drilling a rotor is a compromise to be contended with by whomever performs the operation. Obviously, if it's done incorrectly, what you listed can result. If the rotors are designed to be cross drilled or slotted or whatever in the first place, the engineer will apply the correct metallurgy and machine surface to match and ideally minimize the negative consequences. If you go and slot or cross drill any given commercial rotor, you probably have little or no metallurgy figured into the process, and the same applies for machining.>>

You think that engineers are actually involved in the cross drilled rotor business? Wake up and smell the scam. Most of these companies that “make” drilled and slotted rotors buy them wholesale, machine them and sell them. It would be prohibitively expensive to cast the rotors with the holes in them and there would still be the stress risers present, no matter how well radiused the holes are.

<<Not so. Heat is obviously a byproduct of the braking process. It's produced by braking. I don't know what else you want me to tell you. You yourself seem to think that this heat is so surmountable that it will boil your brake fluid. Which is inconsequential.

Kinetic energy is present in the rotor while it spins. Kinetic energy is the energy of motion. When you take moving object and stop it, you are opposing it with the potential energy of the road and the frame of the vehicle. When one kind of energy type is met or opposed by another energy type, energy transfer occurs. Thus, kinetic energy becomes potential energy. >>

Heat is the main product of the braking application. There is at no time any kinetic energy being converted into potential energy. Boiling fluid is NOT inconsequential. The road and the frame have no potential energy to oppose the motion of the car. Potential energy is the stored ability to do work. How can you do work with this potential energy that you think is generated by the braking process? There is no way you can re-use the energy lost in the braking process.

<<When you have a heavy car sitting up hill and ready to go downhill, it is potential energy. When you push it with kinetic energy, you transfer its potential energy into kinetic energy, which is its primary energy type when it is going downhill. When it has reached the bottom, and stopped, it has become potential energy again.>>

You’re correct right up until the stopping part. Again, how can you get this potential energy back? You can’t because it’s not there! Sure the car has potential with respect to a lower elevation, but it has negative potential with respect to the hill (you must use a constant origin!).

<<Yes, friction makes heat. We want as much friction as possible with as little heat as possible. We create heat in the braking process but do not want to. You seem to think it is a goal of the engineer to make as much heat as possible.>>

In general heat is proportional to friction. You want the most friction possible in brakes for many reasons. It would be nice not to generate any heat while braking, but that’s not really possible right now without having a hybrid or electric car (regenerative braking, but that’s a completely different process).

<<Unsprung weight is considered for all kinds of things. Including stopping. It's not for or against anything. You want to minimize just like you want to minimize all other kinds of weight. That's a stupid distinction.>>

Unsprung weight does affect braking, but rotational weight affects it more (rotational inertia).

<<When a rotor or wheel is spinning, it has torque. Torque is rotating energy, force as it is rotated. You must oppose this to stop a wheel or rotor or shaft from spinning.>>

Torque is force x length of the lever arm. You’re talking about rotational momentum. And you must oppose this with a torque applied by the caliper to the rotor (You know that guy Newton? Every action has an equal and opposite reaction). When you apply this torque, the rotating wheel, tire and rotor do apply a torque onto the caliper in the opposite direction.

<<The caliper certainly does not exert any torque onto a rotor. The caliper exerts force onto a rotor. It grips. Torque can only be achieved by twisting.>>

Torque is force x length of the lever arm.

<<If I apply negative torque to a spinning wheel, it will spin the other way. Not stop. Different process.>>

And it does this instantaneously? It must decelerate to zero before it can spin the opposite way, and in the case of brakes, the torque to slow down the wheel is dependant on the wheel spinning, so when it reaches zero velocity, there is no longer any acceleration on the wheel.

<<Even when done properly it is an armature modification of the original design of a primary safety component (where the wheel meets the hub).>>

Umm, you replace the wheels too, you can’t put 4 lug wheels on a 5 lug car, that’s not what I’m talking about. Other than the hubs and the brakes, everything is the same on the 4 and 5 lug cars (I’m talking about the parts applicable to the swap: stub axles etc.). So with your logic all the 5 lug cars are inherently unsafe and should have crashed long ago when the hubs go flying off the cars.

<<I am an ASE Master Certified Automotive Technician, including braking systems, am Master NATEF trained, and hold an automotive degree. I have extended specialization in ABS braking systems and traction control, among many other things. I see more brake jobs and brake damage a day than you've probably seen total.

I am an active member of SAE and SAT, and I too, am a mechanical engineering student.

Rarely ever do I say I know what I'm talking about, since experience has taught me that I am always learning in this industry.>>

So? I’ve seen a lot of dumbass technicians, just because you’ve done brake jobs doesn’t mean you know how they work.

Go talk to one of your engineering Profs that has an automotive interest (or racing experience or whatever). They can probably explain it all to you. Do some research online, read racing books (you’ve probably never read Carroll Smith have you?), read your texts, do anything, just get informed about how it really works so you don’t end up looking like an idiot! I don’t have time to argue with you anymore, I have better things to do. I’ve made my argument, stated the facts, and I’m done.

 

I have witnessed the steel backings on brake pads become hot enough from braking to physically melt and deform to the shape of the caliper pistons. With a metal brake caliper conducting heat energy, do you honestly not believe that the fluid will boil?

If brake fluid does not boil, then why do all manufacturers of brake fluid give a boiling temperature directly on the bottle? Why list an arbitrary number?

Give your head a shake and get a clue.

 

Finally someone else has joined the fight to educate this guy!

 

And now back to tenth grade physics; brakes are designed to convert kinetic energy into thermal engery. It's what they do. Not potential energy.

The only way you get get potential energy out of braking is if you were slowing the car down by winding a spring. Once you top, you can let the spring go, and have it accelerate you up to speed again (but not quite as fast was you were going originally.

IIRC, ford was designing something like this for their trucks; when you hit the brake pedal, a good portion of the braking was done by a compressing air into a tank. When you let off again and stepped on the gas pedal, the compressed air would be used to get you moving again. That really REALLY helped with the overall running efficiency of the truck.

 

i think its cool to make a bracket for 4 piston calipers for the 4 lugs....but im just converting to 5 lug because of more wheel options and i just want five lug even tho i like my painted phone dials

 

Putting the 4 piston calipers on the smaller 4 lug rotors would make alot more sence than putting 2 calipers on IMHO.