I like the brembos for the front but I hear they are noisy with greenstuff pads. What about Zimmermans? What are you all using?

 

I have powerslot slotted front rotors with the greenstuff. No complaints as of yet

 

Use the stock rotors or something non-slotted to keep dust to an absolute minimum. Slots increase dusting.

 

With the Greenstuff pads the above statement is not true. The dust is at a minimum no matter what rotor you use, BUT a slotted/drilled rotor is BEST for Greenstuff pads as they tend to warp sub-par cheap rotors, as they do heat up more than standard pads. I have used Greenstuff pads and Redstuff for the past 5 years, the ONLY rotors I have used with 100% success are the EBC slotted/nippled rotors, Powerslot, and Wilwood. DO NOT use Zimmerman, and definately do not use stock rotors. Also NEVER use on unvented rotors as well.

 

Wilwood doesn't make rotors for stock apps.

I have never seen a non vented rotor for this car, is there one? What was it on?? Old MINI maybe but I thought all the new ones were vented.

 

For instance....



Alex

 

Anyone had any experience with the stock app slotted stoptechs? I just noticed these were offered a while ago. People seem to like stoptech's BBK

From what i've heard, powerslots are great quality

 

I know alot of people are doing this. Are the Brembo slotted worth the extra money?

 

I just put Brembo CD&Slotted rotors on the front and I wouldnt go back.

 

I was reffering to past applications I have used from them such as their 13.1" Big Brake Kits, of which I used Red Stuff pads with no problems.

Also in my VW days the rear rotors used to be non-vented, they were all solid, and those warped instantly.

The above Brembo's are a great set, but I strongly recommend Slotted and Drilled, as the quicker the cooling, the less chance of warping with these pads. I have warped cheap drilled and non drilled rotors with these pads, and know from experience slotted & drilled seems to be the best...

 

Is it really that big of a difference? You are just changing the rotors

 

I even saw that combo being sold on ebay some time ago. I dont know how justified the price of the brembos is...."you get what you pay for" tends to be true in these cases

 

Do not use cross drilled. Slotted, dimpled, or a slot dimple combo. Cross drilling is very old school. Way over rated and not good for the street. If you must have cross drilled for the look insure that the holes are cast and not drilled. They will crack. Not a matter of if, but when. Slots, dimples, and cross drilling is to relieve gas pressure from the pads, not cooling. Cooling is a byproduct of the gas vents. Check out some current race car brakes. You will be hard pressed to find cross drilled rotors.

 

I have even heard of some dimpled ones(moss) cracking with use at willow. Slotted are definitely your best bet

 

can anyone actually show proof or at least seat of the pants show that slots do help with brake cooling? and is it worth the money to lower the surface area of the discs? sorry for such a simple question,

 

All I know is every big brake kit, high performance kit, Porsche, Audi, Formula, GT etc. all have (cast)/drilled and or slotted rotors. The air being forced through the vents to the holes does help cool, and is being used for a reason. But I can say from experience whenever I have upgraded brakes, the slotted and/or cross drilled (cast) brakes with EBC pads have all been far more superior than upgrading just the pad and not the rotor.

Do what you feel is best, as it is your vehicle, I am simply putting out my experience, R&D and advice to help someone make a better, educated decision. It sucks when you have to do something twice to make it work, and my advice was to eliminate that guesswork

 

Both the Ferrari and Porsche came with Slotted Brembos from the factory. The braking is surreal!

The set on my Porsche lasted me 42,000 miles too!

 

The holes are for venting gas. Cool air does not pass through them. By venting the gas the rotors and pads are able to cool faster. The holes do not take in cool air, then push out hot gas. You have to go back a few years to see competitve race teams using "drilled" rotors. Cast holes will typically last longer but they will crack. Simple facts. Use what you like but from experiece (25+ years racing, designing, and building) slotted is your best bet.

 

Actually cool air would be drawn through the holes. Given vented rotors cool via the center air gap. Proper air ducts are pointed at the hub for this very reasaon. From here the air is 'spun out' from the center and pushed through the holes as well. Thus the dusting is more too. It does also remove the boundary layer between the pad and rotor too as you state. The down side is the cracking- due to uneven thermal expansion of having both a compromised surface and cold air on a hot surface.

And because it was mentioned, an active offer on the table for four months:

I've offered a $200 reward for proof of the long running rumor of 'cast holes' in Porsche rotors. Nobody in the industry I know has proof of this internet story. In fact one Brembo engineer laughed when asked and called it a great American rumor. I'm waiving the BS flag high until I see a pic of the mold or an un machined rotor to prove this. Just the mold alone would be an outragous making. Want the money?

 

LOL - they are drilled, Todd is right, ask the engineers!

Alex

 

so..... $200 for a picture of a mold core that is used for production? or just a mold core? how 'bout a photoshopped pic of a core? how about a pic of a CAD model of a core?
Sorry couldn't resist the opportunity to be a smartass but really, I can get the last 2!

 

What I know on this topic of cast holes, is what I know of the racing brake rotors that I sell. They are "Cast for Holes" What this means is that the vanes in between the rotor section on the front rotor as made in such a way so they do not interfere with the drilling of the holes. I know that because of this, the racing brake rotors are less likely to crack along the holes as many other OEM Drilled rotors are plagued by. I have had my rotors for over 10K miles, with track, and auto-x with out any sign of cracking as of yet.

http://www.piloracing.com/shop/prodd...PACKAGE&cat=12

 

Always a fun topic of conversation....

Show me a rough casting with holes in it to be cleaned up. Not dimples, holes. Light from the OTHER side! Or show me the mold used to produce this part.

I talked at length with a guy in Germany who insisted that this was a cast part- holes and all and swore he'd get me more info- pics, or letterhead at the least to prove it. I'm still waiting. And then I bumped the pot from $100 to $200!

Won't say it can't be done, just that its so impractical that it's laughable. The mold would be an ungodly thing- and of course you'd need TWO for each rotor size....Still the parts would require drill work clean up.

Did a Porsche day a few weeks back too. Looked very close at the rotors....guess what; mostly square cut drill marks on the outer surface and as could be seen the inner section as well. So much for the rumor mill.

Drilled and chamfered holes? Ok here's a teaser for you engineer types. If we drill the rotor (me too) how many surfaces are compromised? Two? The inner and outer side of the rotor? Wrong. FOUR surfaces- the inner and outer of each cheek of the rotor. Now then when we chamfer the two visible parts what is done to the inner vented area? Nothing. I'll grant you that two chamfered surfaces are better than none. That's why we do it. (well except for those Boxster parts, they just do smaller holes)

No slap at any product here. Just food for thought.

 

casting the holes would be simple! the mold to cast those holes would only need a different core, to put the holes in. tolerances would be an issue, and the holes would probably be, more often than not, short-filled at the outside of the plates (braking surface for those not familiar with the terminology). I've stated this before, and it is the one thing that I GUARANTEE drives this out of the realm of possibility, tool wear would be tremendous; how many holes would you guess there are in a 'standard' 12" rotor, 36?, 48? 64? more? how many times do you think a tool can withstand an impact from an interrupted cut? how fast can you push the machines while making those cuts(RPM)? how much material do you think you could remove each pass? cycle time would be outrageous, in order to reduce tool fracture, and unless these were done on a machine with no less than 100 tools dedicated just to cutting the braking surface, I think you'd eff-up the cycle time even more with tool changes.
in response to your question about compromised surfaces...if you clip any of the fins, you could compromise even more than 4.
on a practical note, a forged, solid rotor, with forged holes could be a practical solution to putting holes in a rotor without compromising the surfaces or the microstructure of the iron.
finally one last comment about airflow through rotor fins and the cored area of a rotor. in order for this to truly happen, even with directional vanes, or any of the multitude of patented 'increased-airflow' design fins out there; there has to be a low-pressure area on the outer radius of the rotor, and another on the putside of the wheel. there also has to be room for air to flow between the hub and the inner radius of the plates. I have seen a multitude of studies on airflow through the vanes of a rotor, and even the very best designs only aid airflow by 5-10%. when the low-end of this flow is typically less than .01cfm, even a 10% increase doesn't help much.
sorry for the length.