OK for 95% of my driving these rotors have no added value. But for that 5% man are they cool and represent the epttimy of if it is worth doing then it is worth over doing.

Click to view attachment

Would Make a Nice Clock Face

Looking good! I had the rotors turned on my old Lightning once, the guy told me for $15 more they would slot and drill - Done, and not so ricer. Just don’t put those fake calipers on to make it look like the big boy brembos.

those would be terrible track rotors only street or show ....

What makes them terrible for track?

Not questioning the statement i just dont know enough about track equipment to put the rationale together.

Well i have no way to confirm, but these are supposed to be made to resist warping and have a lifetime guarantee against warping and wear. Overall the quislity seems good. Nicely finished and coated but only time will tell.

Do tell us why you think they are terrible for the track.

If I am not mistaken, cracks will develope between the holes during high heat cycles, disks with only slots will resist cracks and dissipate heat.

The holes vent the gas build up between the pad and rotor making them far more effective for high speed stopping which is why they are used extensively on race cars .

You are correct that eventually there will be small cracks propagating from the holes but these generally don’t cause any problems and only show up after many very high speed stops.

Jeff B

They will, but anyone who takes racing seriously will inspect the rotors and brake pads daily while on the track, if not even several times a day.
Having holes in them is good, having cracks between the holes is bad.

When i was working the pits for Tom van Overbeek we replaced rotors on a regular basis.

They will be more prone to cracks if the holes are drilled. But I'm sure Mr. Ablesnead from the United States will enlighten us with his knowledge.

mgphoto is correct, - post #8 Further more, the holes remove metal which reduces the disks heat sink capacity, it's primary function.

No doubt you introduce weakness and the potential for cracks. But with a lifetime warranty I don't see a down side.

Of course there are ways to do the process that help reduce the cracking but it can not be completely eliminated.

Technically these holes won't vent any pad out-gassing since the rotors are solid so the holes are blocked on both sides with pads vs. venting to the webbing in a vented rotor.

They do look cool though and IMHO you can't go wrong with a lifetime warranty!

Technically, they still vent the gas as soon as the holes have moved past the pad area.

And they give the gas somewhere to compress into rather than the brake pad acting like an air-hocky puck

Post #8 is a legitimate risk, but holes/slots vs. solid is a balance.

Once you have heat soaked the mass you must be able to shed the heat or the brakes will fade.

If mass is all that mattered, vented rotors would be solid in the middle to add mass.

Nice info, but you guys are overlooking the real issue here: epitome.

HAHA!

Yep! Should not drink and poste! Yes the previous was meant to be funny.

I was recently told that pad materials have advanced enough that the holes are no longer necessary for venting gasses. Porsche still installs them on new cars for aesthetics even though they perform poorly (prone to cracking). I find it hard to believe that Porsche would sacrifice performance and safety for looks.

Don't overlook the reduced surface area for the pads to come in contact with and don't overlook the fact that (stockish) 914's don't go fast enough to use brakes on a track Then you have to consider that you won't see too much of this fancy rotor behind a stock 914 wheel either.. "lifetime warranty".. is great.. as long as they don't cost you your life.

If Porsche does something, there is usually a reason. Looks cool maybe, but i wpuld suspect that there is some advantage if they did it. Mercedes makes the ceramic pads that are harder than the metal so the discs are out of tollerence on the second change. Basically requires new discs after anout 45k. Some of the advancements in braking systems are quite interesting.

...as Someone mentioned earlier...the latest pad formulations don't develop a gas that can float the caliper ..so the holes provide no function , the slots are still used ...I am not clear of their purpose..drilled rotors crack all the time , almost every tracked car will have experience the cracks at some point ...I heave seem many rotors discarded for the cracks , that would be otherwise still in spec...some tech guys , will inspect for cracks and not allow you to run...thats in porsche club !...I also have seen the shrapnel from an exploded rotor lying on the track ....harmless , but .....

The holes are not for gas. The do however provide a cooling function. Compared to modern rotors that often have a dual surface with an air space between the surfaces, solid rotor make up of the 914 rotor can use a little extra cooling. The debate will rage for years as to just how much cooling the holes can add as it is minimal at best.

But given the more modern alloys these are made from they are more Rest ant to crack than just drilling the stock rotors. How much? I got a C (Barely) in Materials Mechanics so i cant even offer a guess.

But i have to think compared to stock there are some advantages and disadvantages. Never going to race this car. AX maybe. But if they crack i will return them and get the slotted and dimpled versions. Dimpled has the same pattern as the drilled but not all the way through the rotor.

On a street car I doubt if cracking will ever be an issue.

At least I hope so as my fronts are drilled, but I got new german 911 rotors for half price, no shipping, they're small and chamfered.

I doubt the cooling function..but agree that harmless and look cool for a street car...