If a design like that was good Formula 1 would have it. I'd like to take a set to the track and see how they last :D

 

Maybe we can get ZMI to sponsor you a set John. That would be a great point. Then again, if they haven't put them on someone's car already there might be a good reason... ;)

 

I think I'm going to :U

You guys do realize these will perform worse than stock, right? Or are you driving motorcycles? And for that price you could buy a real set of brakes that would be a significant improvment?

If all you want to do is cruise main and impress the kids driving Civics, I guess they're "cool." :rolleyes:

I certainly hope the Vendor selling these and/or ZMI put a disclaimer on them to everybody who buys them that limits them to that use.

Or the first time some newbie puts these on "because they're cool" and goes to a roadcourse and kills himself, there will probably be some legal action.

 

:cool: looking rotor. Durability & reliability might be questionable though.

 

Perform worse as in pure stopping power is reduced with increased braking distances, and/or worse ability to resist fading? I don't doubt your statement, just curious as to what mode of failure could occur with these.

I have to agree that if you don't see them on race cars, then there must be good reasons, but those reasons may not be engineering reasons, but homologation rules.

 

Also, in formula one and other race cars the rotors are carbon fibre. Those can only be used under race conditions, so they are no option if you still want to drive to the track.
So if there are no homologation restrictions, in a race car you would use carbon fibre. If there are homologation restrictions, they may rule out titanium or ceramic rotors.

Till



[Modified by till, 7:48 AM 11/20/2003]

 

Fading. Nearly any brake (including stock) can stop you from 60 as well as your tires can grip. Once. After that is when things get interesting. Although, it wouldn't surprise me if these faded during a single stop from high speed.

The ability to remove heat from the pad surface (where it's being generated) and absorb it into the rotor is vastly compromised. Gray cast iron roughly six times as high Thermal Conductivity (670 X 10^-6 (Btu-in)/(in^2-sec-F) vs. 81-111) as various Ti alloys. Not to mention, the caliper pictured above will not use a large portion of the available swept area on the rotor, making things even worse.

Second, how much heat can they take before they get hot? Ti has roughly the same heat capacity as cast iron (.11-.13 Btu/lb-F, depending upon exact composition). So you've removed, what, 80% of the mass? If so, the stock rotors can absorb 5 times as much heat and still be at the same temperature these would be.

Third, how does it get rid of this heat? "Active cooling?" Hello, we've had that ever since we've had vented rotors. The vanes in the stock rotor act like the impeller of a turbo or centrifugal supercharger--they suck air in from the center, pump it through the rotor and out the edges. All the while the vanes are also acting like the vanes on your radiator--transfering heat to the air via convection. While the cuts in this rotor may cause some local turbulance in the air, they are going to have about zero pumping efficiency. They simply won't transfer the heat they gain to the air very quickly at all.

So in summary, they won't do a good job removing heat from the surface of the pad. Even so, they will heat up very quickly because of the tiny heat capacity. Once they do, they won't get rid of the heat very fast. Pad fad, boiled fluid, etc will happen much more quickly than with the stock system.

If you offered me the chance to drive two cars, one with this braking system, one with the stock system on the track (or to be an assclown on the street), you'd have to put a gun to my head to keep me from choosing the car with stock brakes.

 

Jon,

Good engineering discription, and very valid. I too would be scared to run these rotors under any conditions and I told them at the SEMA show. But then what do I know.

These Ti rotors are also only 3/8" thick!

One of you can be the first to take them into Trun 5 at Elkhart Lake from 150 mph.

LG

 

Jon AA. My original post in this thread was in reference to these rotors: http://www.madvet.com/shop?store=2&category=244&frame=5119 as opposed to the ZMI's as an alternative. These rotors utilize the stock venting 2 piece design that the ZMI's don't. The ZMI's got sucked into this discussion becuase of the uniqueness of their design. The Stock style ti rotors are very expensive though. Although not as expensive as carbon rotors. :thumbs:


[Modified by ArKay99, 11:58 PM 11/20/2003]

 

Lou, I'm hitting 160+ @ the #3 braking marker, you were hitting 160+ and being conservative, breaking before the #5.

Your point taken...that those rotors are mainly pretty and pricey...not for hard core performance.

 

I realize that. But the ZMI's are being carried by a "supporting vendor" and they're even worse, so I thought I'd comment.

The rotors you're talking about won't be as bad, but they won't be good either. They still have much less heat capacity than stock. And the reduced thermal conductivity will affect these even more because in order to make use of the vanes in the center pumping air, heat must be conducted from the pad/rotor interface to the center of these (thick as stock) rotors. Cast iron does a much better job of this.

Sure, Ti is tough. These things will probably last forever. But you'll be melting your calipers right off of them under conditions in which the stock brakes would perform just fine.

Now look at the price. Why on earth would you spend that much money for a downgrade in braking performance?

Bling! pure and simple. Nothing more, nothing less. If the ability to brag about "My car has Titanium Rotors!" is worth $4K to you, do whatever makes you happy. Just remember you're paying all that money for that right alone and don't take the car to any track I frequent, please.

 

Say NO to crack

 

Would be nice if we got some real hard proof for or against, in this thread
there is one guy testing them on his Porsche race car. http://forums.corvetteforum.com/zerothread?id=681587

Sometimes there is a big diiference between theory and real world practical use (goes both ways)

I would love these things to work , even if they are close to stock braking, because the reduced unsprung weight.
BTW. i put my rotors on the scale last night, weight 18 pounds

And i think Brembo or Movit is even heavier, so with a total rotor weight of.
less than 6 pounds, i would save 12x4 pound of rotating mass, equal to
almost 200 pound off the car (rotating mass is 4 times worse than onbord weight)


Lets get someone to put these brakes to a test, L.A.P.D should assist us and get them tested :-)

 

Jon AA is absolutely right. Please do not bring a car equipped with Ti rotors to any track that I'm on either!!

Brakes work by converting the forward energy of the vehicle into heat. To work most effectively, the rotor must be able to absorb large amounts of heat very rapidly. The less heat the rotor can absorb, the less braking power available. When your rotors get too hot, you call it brake fade. It is really just a case of the rotor being unable to absorb additional heat. (Yeah, there's also the issues of the pads outgassing, depositing pad material on the rotor, and other stuff, but the single most important issue here is heat capacity)

Along with absorbing heat, the rotor must dissipate it also. It cannot dissipate it faster than it absorbed it, and it takes much longer to cool the brakes than it did to heat them.

Bottom line, Ti rotors, pound for pound, will fade sooner than cast iron, and will continue to exhibit fade long after an iron rotor would have cooled sufficiently to allow full braking power. All because of Titanium's poor thermal conductivity.

On a race car, reducing unsprung weight is an important goal. Remember though that a race team has engineers available to tune the spring rates and dampers as unsprung weight changes. Most of us don't have the luxury of altering spring rates, and few of us have adjustable dampers either. Reducing unsprung weight does not automatically give you better handling. In fact, you may get worse handling (effectively you now have a "stiffer" suspension that may hurt wheel-to-road contact on uneven surfaces) unless you tune the springs and dampers.

As far as the overall weight saving for the car, there are much better ways to get it. For example, a full tank of fuel is about 110 pounds .... if you're going to be running 20 laps ... say 2.5 miles per lap ... 50 miles .... start with about 6 galllons of fuel in the car and you'll have saved about 75 pounds of weight.

The tradeoff here is reduced braking in return for an unknown gain/loss in handlling, and an arguable change in performance.

Take the money you would have spent on these brakes, pay it to a good driving school, and you'll be a MUCH faster (and safer) driver than the guy who put Ti brake rotors on his car !!

 

Hey guys,

That was me trying the ti rotors on my Porsche racecar. I am considering selling these brakes to my customers (I own a Porsche race shop), so I really hope these work for most people.

They have a different feel than cast iron rotors; they require more pedal effort as you decelerate. To achieve iron braking performance (which is possible), you use more brake, which led to pad fade on my car. On the plus side, they are very light and probably last for a very long time. I could feel the lighter weight turning in, and accelerating off the corner. Not to mention that they completely changed the setup on my car.

My verdict is that they DO work, but not on my car.

My car is not a fair test, but probably a worst case scenario. My car makes 684rwhp (max. boost) and weighs 2200 wet, plus we were at Carolina Motorsports Park (VERY tough on brakes). I think a lightweight, small displacement race car could easily use these on the front. Almost any car could use these on the rear, which is what I am qoing to do.

BTW, my car is pretty fast: 1:36 CMP, 1:55 VIR, 1:26 Road Atl, 1:14 Summit Point.

I think these brakes would probably work great on a drag or street car. Saving that much rotating weight on a drag car would make a difference in ET's. I would not hesitate to put some on my Z06!

Andy

 

That's interesting, Andy. However, people should keep in mind most C5's will weigh in a thousand pounds heavier than your car. And many will achieve top speeds very close to yours on the straights.

 

Um,

2200 lbs and 684rwhp = 3.2lbs/hp

2200+1000 = 3200/3.2 = 1000rwhp,

so to get "very close" would probably require somewhere in the neighborhood of 900rwhp, if his numbers are accurate........ :eek:

 

Uhm, no. The faster you go, the harder it is and the more power it takes to go any faster. Diminishing returns. Take a 250 RWHP car that traps 100 MPH in the 1/4, do you think it will trap 200 MPH with 500 RWHP? Not even close. By the same token, if I doubled my RWHP (which I could do if I felt like spending the money) would you expect my speed of 135 MPH or so through Turn 1 at Pacific Raceways to double to 270 MPH??? :eek: :eek:

No. Not in my wildest dreams (or nightmares--which that would definately be!).

Once you're close to the 400 RWHP mark on a roadcourse, it takes a lot of HP to significantly increase the speeds on the straights. Don't get me wrong, more HP will go faster and will be significant for laptimes. But we're talking about a speed difference that would make up for a 50% weight increase and the difference in kinetic energy that the brakes would have to deal with. That will take a TON of speed. Not quite 50% due to the V^2, but it's going to take a lot.

A heavy, high HP car is murder on brakes even if it isn't as fast as a lighter high HP car.

Brakes similar to this work great for motorcycles. The fast ones have HP:Weight ratios we can only envy. But they don't need as big brakes. Because they weigh a fraction of what our cars weigh.

 

For every day guys- id go with aluminum hat rotors. Remember, just the hat is Ti, not the whole thing! if it was- there would be problems to say the least

Ceramic wont fade- it can absorb an INCREDIBLE amount of heat before it is saturated. much more than cast iron. Hency why its on the space shuttle.

22lbs is for all rotors together. I doubt you'd notice it in braking or handling unless you have one insane car or autox for 30-40 min at a time. You'd be hard pressed to have brake fade in a C5 under normal agressive driving.

cross drilled/slotted vs blank
First off- its a bad idea. Odds are your rotors will crack. The rotors are asymetrical, there are a prime number of vents in the rotor in order to reduce a number of noise issues. Now to drill and slot propperly, you need to do so symetrically to keep balance. thats going to be a mathematical nightmare because you cant drill into a vent. if you do, well- lets just say i wouldn't drive a car with holes drilled in the vents :no:

Second- your braking capabilites have been DEMINISHED after cross drilling and slotting. Did he just say that? Yes he did. If you want my 3 page techincal brake (pun intended) down, i'll be more than happy to dig it up, copy and paste.

:cheers:


[Modified by TreyZ28, 8:40 AM 11/22/2003]

 

First of all, the http://www.zmibrakes.com setup is ALL titanium.
Second, its not 22 pound total weight reduction, it is closer to 48 pounds.

48 pounds rotating weight is close to 200 pounds lighter car, ie no driver :-)

Third, i can still run 6 gallon gas, and reduce even more weight :-)

But as Jon AA pointed out, IF htey are not capable of transferring heat, they will fade quickly.........

So again, we need someone to test ZMI or the other TI rotor with the right pad and see what they perform like in a real world test.

L.A.P.D or anyone ??????


I would love to test them, but it is wihnter in Norway, car is back in thousand pieces, to be cleaned and tuned for next years races :-)

BTW, i have tried three sets of rotors, they all cracked up.......

So if a TI rotor does not crack i will be happy......