Valkyrie

Boooooooooo. Better brakes aren't going to help you stop faster.

Get better tires.

speedturn

iTrader: (1)

I have been running Wilwood dynalite calipers & rotors on my 1st gen for the last 12 years.
Using a stock rotor, machine away all but the inner face. Machine the OD down, to match the ID of a Wilwood rotor, drill the Wilwood bolt pattern into what's left of the Mazda rotor, then bolt the Wilwood rotor onto what's left of the Mazda rotor. The old Mazda/rotor hub now becomes your hat.

It is even easier on the rear brakes.

Not counting $$$machining and fabrication costs, you can do all 4 Wilwood corners + Tilton master cylinders for less than $1400 parts cost.

Sorry for the low quality photo, this is the only one I had on this computer showing my front rotors. If you look, you can see the Wilwood rotor bolted onto the stock Mazda hub.

GTRay

umm... no. the rotors aren't larger so they can disipate more heat rather, they are larger because it creates a larger surface area to create more friction which allows for more heat to be generated. adding another caliper won't cause too much heat to develop in the rotor it's simply going to create more friction in a shorter time period (distance). this amount of grabbing force will lock the brakes in an instant basically negating all efforts put towards enhacing the brakes. the brakes are only as good as the traction and a single caliper system on a car the size of yours is going to work just fine.

Ray

peejay

Well, to be *fair*, you can dissipate all the heat you want with proper ducting and such. But you don't dissipate heat while braking, you dissipate it on the straights. Rotors don't cool off as fast as you put in the heat like radiators, they are more of a store/release type system. (How many seconds of braking do you have per lap? It's a really small fraction) More mass means you can store more heat in the rotor while braking, before going overboard. Some of the drag cars I play with at work have some funky brakes: small, non-vented, heavily cut-out rotors, with small 4 piston calipers. Almost look like motorcycle brakes except bike brakes are bigger. (No exaggeration!) They weigh next to nothing, and do a fine job of hauling a 3000lb car down from 130-odd mph... but they only have to do it once per run, and have a *generous* cooling-off period.

But the larger rotors allow more leverage against the hub, which is also very important. A 9" rotor might have a center of leverage around the 8" mark, while a 12" rotor might have it at the 10" mark. That's 25% more leverage for a given amount of friction, so you can stop harder for the same heat input, or heat the brakes up less for the same whoa-power. If all else is equal you should have better braking feel, too, so you can make better use of the traction you have.

DamonB

Yes they are. That's the only reason to ever make the rotor larger.

http://www.scirocco.org/faq/brakes/p...oorrotors.html

https://www.rx7club.com/suspension-wheels-tires-brakes-archive-112/do-rotors-lines-pads-really-make-big-difference-231994/

https://www.rx7club.com/suspension-wheels-tires-brakes-archive-112/more-drilled-vs-slotted-rotors-480082/

Kentetsu

Hmm, I agree that a larger rotor would help with heat dissipation, but I would also think that the increase in "leverage" would also be a good reason for larger rotors. More leverage would mean less pressure required to stop the car, which would also result in less heat buildup. Am I missing something here?

DamonB

First you have to understand the Law of Conservation of Energy. This states that energy is neither created nor destroyed, it's merely converted from one form to another. Brakes work by converting kinetic energy into heat energy. The more kinetic energy you convert, the more heat you create. If you want to slow a given car from 100 mph to 50 mph you have to convert 50 mph worth of kinetic energy into heat. No matter how big your rotors are, how many brake pads you have, how big your brakes pads are, how many pistons are in your calipers, how big your brake pedal is etc you still have to convert that same amount of kinetic energy into heat to decel the car by 50 mph. That kinetic energy will create a given amount of heat every time, no matter how you design the brake system.

The reason "big" brakes exist is because more massive rotors have greater heat sinking area and can therefore maintain lower brake temps over a given period of time. This is the only reason larger brake systems exist except for those who don't understand or are merely trying to market something. Read the links I posted earlier.

Shoey

we used to run 2 calipers on the rear of our car to help with the launch at the track. It was a turbo foot brake car (no transbrake). It held me on the line alot better and had great holding power.

On the front it would work also. Bentleys have 2 calipers stock. A rx7 is so light it's not needed. What your doing is adding to the friction surface. You hit the brakes you have 2x the surface area stopping you. It would build up less heat than one caliper. But, if you went to a Willwood Nascar style size and thickness rotor it would be better yet.

Your pretty much just getting "wow" factor out of it.

Fish

Looking at pictures there are a couple of cars that run twin brakes. The only difference is that on is a parking brake, not a normal type brake.

I know that Jaguar, Aston Martin use this, not sure about Bentley.

Fish

tims

Damon thank you again for the physics lesson. I hope everyone was paying attention as the explaination was spot on. thanks.

Kentetsu

DamonB - Not meaning any disrespect here, and I agree with 90% of what you are saying, but I'm still trying to wrap my head around this.

Are you telling me that a car with a 5" diameter rotor (if that was even possible) would brake just as effectively as a car with a 10" rotor (assuming that pad area was the same) if heat buildup was not an issue? That just doesn't make sense to me.

Leverage is leverage, and more leverage equals more force (or power, whatever). Based on that simple premise, a larger rotor would have an advantage even without taking into consideration the heat buildup issue. Am I wrong?

photopaintball

I think he means its irrelevant assuming you have enought force to stop the wheel in the first place.

If you can slam the pedal and lock up the wheels w/o ABS at any given speed. Then it doesnt matter what size the rotor is. And the stock rotors are big enough to do this I would think. Therefore, if you already have enought leverage to stop, its pointless to get more leverage

Kentetsu

But what about control, modulation, and feel? If it takes all she's got to stop the car, then you won't have any of those. My Audi has far more braking ability than it needs, but it also has the best feel and more control than any other car I've ever driven.

On the other hand, my wife's van has enough brakes that you can lock them up, but the feel is terrible and the wheels lock up easier due to the lack of feel and control.

I always hear people saying that if you have enough brakes to lock up the tires, then you have enough brakes. I don't buy into that theory at all. Bigger/better brakes also give you better feel and control which allows you to stop faster.

DamonB

Kenetsu, read all the links I posted earlier as well as the one below. They answer your questions.

Grassroots Motorsports Everything You Ever Wanted to Know About Brakes

Kentetsu

Will do...