I've had these on for a litte while now and I haven't seen any commentary by anyone so I thought I'd share. I saved like 36lbs over stock just in the front. Does anyone else have these? Seems like everyone has Stoptech? Well, just wanted to see what you think.

 

Here are some links to discussions about these brakes from corner-carvers.com, NSX Prime, and corvette forum. I actually had a dicussion with an engineer that was trying to sell me on these at a party at SEMA this year. IMO, I don't believe these rotors have adequate thermal capacity or swept area to be effective on a street or track car. I'm not trying to hijack this thread...just posting some sources.

http://corner-carvers.com/forums/sho...s&pagenumber=2

http://www.nsxprime.com/forums/showt...ght=ZMI+Brakes

http://forums.corvetteforum.com/zerothread?id=683918

 

I would buy 4 wheel set of brakes if they could do one thing. Stop at least as good as stock (I do not track the car so I do not need better stopping/fade power). The only thing I need that is important to me and the one thing that would get me to buy brakes is that they are very light compared to the stock brakes. I would prefer them to have the stopping power identical to factory brakes to keep cost down as all I am concerned about is weight at all four corners. Which kit is right for me?

 

Why is weight a concern to you if you are not tracking the car? Not trying to be smart just curious what you're looking for. If you're going to spend the money to upgrade the brakes you might as well go with a package that stops better and resists fade (in case you decide to track at a later date).

 

"IMO, I don't believe these rotors have adequate thermal capacity or swept area to be effective on a street or track car."

J. just curious has Stoptech done any testing on these... they seem to work fine for me. Is there something I should know that no one is telling me?

 

It will see the 1/4 mile. The suspension is finished with the S-Tune forever. It handles as good as I want it to now. I will never be going to autocross maybe a road course once in a year's time. It really only needs to be able to slow down from 120 at the most at the end of a quarter mile. A four wheel drum setup can do that without issue. Less unsprung weight, to me, means better performance no matter what the circumstance. That's why I bought wheels. I thought the stock ones looked fine. But I wanted a nice looking (yes) set of light wheels. Don't get me wrong, if higher stopping power is unavoidable with a lighter kit, I'll take it! But it is not part of my evaluative criteria when comparing the competition. Only weight. So which is the one for me?

 

ZMachine,
I'm not going to comment here. If you would like to contact me privately, feel free to do so. I do not want to publicly criticize a competitor's product. We try not to do business in that fashion. Thanks.

 

The gist of the situation is as follows:

Brakes work by converting energy to heat. They will fade when the rotors heat up to a temperature that is high enough to cause the pads to debond, or when they transfer heat to the fluid and cause the fluid to boil, or when the rotors start to melt.

Typically, the first limit is the surface temperature of the rotor causing pads to fall apart. Therefore, the main goal of aftermarket brake rotors is to keep the surface of the rotor cool, and therefore it will be the primary focus of this post. Keeping the surface of the rotor cool is accomplished in a number of ways:
1. Large rotor mass - a large mass of material will heat up less than a small mass when absorbing equivalent energy.
1a. Specific heat of material (amount of energy it takes to heat a specified mass a certian number of degrees)
2. Use pads that are effective at higher temperatures. Well, this actually sidesteps the heat issue by using a pad that is able to handle the higher temperatures. The problem here is that it is difficult to have a pad effective @ both high and low temperatures, and therefore if you have a high temperature pad on the street it may not perform well.
3. Heat dissipation - by cooling the rotor quickly, it will be ready to absorb more heat. This is accomplished in three ways:
3a. Conduction - heat is conducted away from the rotor face into the rest of the rotor and then into the spindle, etc.
3b. Convection - the heat that has been conducted to the inner surface of the vented rotor is pumped out by air flowing across the vents. It is also convected by air flowing across the external faces of the rotor.
3c. Radiation - The hot surface of the rotor is constantly radiating heat to the outside world.

So, knowing all this, we can see some POTENTIAL areas of concern with respect to these ZMI brakes:

First, lets look at the material property of Ti (pure) compared to cast iron:

Specific Heat - Ti = 522 J/kg/K
Specific Heat - CI = 1X-2X that of Ti (depending on type, from Machinery's Handbook Vol. 25)
Thermal Conductivity - Ti = 21.9 W/m/K
Thermal Conductivity - CI = 80.3 W/m/K
Density - TI = 4510 kg/m^3
Density - CI = 7800 kg/m^3

(all data from http://www.memsnet.org/material , except where noted )

1. Low mass - the very characteristic that makes them attractive from a handling aspect is what makes them "iffy" from a braking aspect. Compared to a stock or Stoptech or Brembo rotor, these have much less mass. Therefore they will reach a higher temperature when absorbing an equivalent amount of energy (unless they can dissipate the heat very quickly). Also, the specific heat of Ti is no better than cast iron (and possibly even worse). However, let us examine their ability to dissipate heat.

2a. Conduction - Ti has poor thermal conduction, and therefore will not transfer heat away from the pad surface as quickly as a cast iron rotor would.
2b. Convection - This brake has very nice slots, and lots of surface area, but compared to a standard vented disk, which basically has a built in air pump and four faces to convect from, I suspect that this brake will dissipate heat no better than a stock brake.
2c. Radiation - would depend mainly on surface area and temperature of the rotor face. Since the rotor surface of these brakes has many holes in them, there is actually less area available for radiation than the stock brakes, and therefore I don't see these brakes radiating any better than stock ones at an equivalent temperature.


So, given all these reasons, it seems unlikely to me that these brakes would perform better than stock ones AT A ROADCOURSE when fade is a problem. However, for street or drag stip use they may be very good, since fade is almost never an issue in those applications.

I would be very interested in hearing any impartial reviews on these brakes to see how poeple like them, and if their experiences are similar to what it seems like theory would show.

-D'oh!

 

That's exactly what I was gonna say!

 

You poor bastard. The person that convinced you to buy those should be drawn and quartered.

 

sorry for the ignorance, but what brakes are they?

 

2003z did you get the springs? Everything cool?

 

 

ZMI Brake Systems?

http://zmibrakes.com

 

Droideka- why the comment? Is that really necessary? These forums could really do without that type of mentality.

D'Oh- I must admit they work pretty damn good so far... I've done some track time and yes they do run a little hotter but I ran a race pad and didn't have any problems. I thought the point of the rotor was to get rid of the heat as fast as possible not hold it in. Isn't that what iron isn't doing? It's holding it in and you need more mass to hold it in. My stock rotors would stay hot long after I stopped where I can touch these ti rotors minutes after.

 

LOL Best comment ever... You could of just told ZMachine, "check your PM" and told him this information privately. Your trying to act like a HERO by posting what you did. I feel "you" as a stoptech REP are being shady about this. Their are many ways you can show why these brakes are good/bad or why your brakes are better in a professional manner without being shady. Hey, its competition and if your professionally educated to show the statistics than its not bad to state REAL facts as it educates the members. The way I see it is, if your product is superior and you did your homework than you can show that professionally no need to get crazy or throw the other company under the bus. Just the way I see, cause it seems like your being a coward cause either way your talking $hit. Only behind doors...

 

Sensing bitterness, anything to do with this thread?
STOPTECH vs. ROTORA

 

Bitternes? Im not the manufacutre of ROTORA they are up for the challenge I asked them here call Richie here is their number (626) 369-0401 Tell them its a brake shoot off. They are very confident about their product. I been racing my car nothing but excellent results with their brake system, no hype just the truth. All I was trying to say is the truth may hurt to some companies but hey its Business. ROTORA never backed out, im not the one in charge... I don't work for them just representing their awesome brakes. If you want to challenge, ask questions, or anything else I gave you their number they will be happy to answer any of your questions and are not scared so Im not bitter

 

Hey Wicked,
I didn't want to get into a 40 page dissertation on brakes, so I posted a few links that contain arguments for either side of the coin. I wish I had time to do a post like that, but I only have a finite amount of time. I have done some extensive posts in the past addressing technical issues.
Some of the people in those posts I supplied links to defend the ZMI product, while others don't like them. I gave my personal opinion, and left it up to zmachine to talk to me privately for more details. I actually debated on not saying anything at all, but I figured people could make up their own minds by reading those posts I linked. You're right...I should have probably just posted the links, and not given my personal opinion. Brakes are a safety item however, and I want people to have as much info as possible. Typically, I try to post helpful information and technical info. I felt that the topic was beaten to near death in those threads, so I didn't feel the need to beat it any further.

Take a look through my post history, and then talk to anyone on this board, or any other board that has done business with me. Shady is not a word that is used to describe me, and surely not StopTech. Calling me a hero, a coward, or shady is absolutely ridiculous. You don't know anything about me.

As for shady...shady is taking down pictures of a product that is poorly designed and F'd up...and then deleting those pictures when someone pulls your card and points out the fact that the product is screwed...so nobody can find them. That's what Rotora did (the company whose awesome brakes you are "just representing") so please don't liken my post to something like that. IMO, that's shady.

Take a look at my posts on I-Forged wheels. I did the same thing that I did in this post. I didn't rant about what an awful company they are...I just provided some background info that people didn't have, so they can form an opinion. I posted links for others to read and research. That's what these forums are about. I am here as an enthusiast that happens to work for StopTech. I don't claim to know everything about brakes, and I learn more each day. I was on these boards long before I was employed by StopTech. I don't come on the boards and "hard sell" and push our product on anyone. I try to stick to the facts as much as possible, and correct errors or misconceptions people have about our product. I tried to get a job with StopTech for over a year, because I believe in the company and the product, and I wanted to be part of it. I finally succeeded in getting the position, and I am proud of that. I love racing my car, and I love hearing people tell me they love our brakes. I also love the 350Z, and I'm pushing to round out our product offerings for the car...since that's how I got in touch with StopTech in the first place...trying to get them make brakes for the then upcoming Z (roughly Nov. '01 when I took my place on the waiting list for preorder).

I am a founding member of this forum, and I've owned my Z since Aug. '02...one of the first in the country. I post on all boards by the same name (J Ritt...honda-tech, s2ki, bimmerforums, z06vette.com, lancerforums, etc.), and any number of people in the racing and automotive community can vouch for me. I don't hide behind fake names and aliases, and I give people my honest opinions. Do a search on any of those boards, and you won't find anything I'm ashamed of. For you to try and defame me (or StopTech) over something like this is absurd. I don't appreciate having someone who doesn't know me call me names. I won't return the favor, because that's not what I'm about. I was merely providing some information on one of the many topics that has gone round and round on various automotive forums...not sure how that is getting "crazy" or trying to "throw the other company under a bus." Maybe I am crazy for not understanding how my post deserves a personal attack.

 

Dude, you have to chill. Your post alone sounds defensive/bitter. Let's just share knowledge and have a good time.