Hi, I have all 4 Drilled Zimmermann rotors sitting in the garage waiting for me to install them, I'll take a photo when i get back from work and post it.

Paid $332.00 US for all 4. :)

Do me a favor and measure the over all diameter of the Zimmermann Rotors and then measure them to the size of the stock ones and tell me what size they are. They should be slightly larger.

Nope. They are 1-2 inches larger and don't require any other upgrades. I have some on my car and the only other mod I did was to add better/newer pads. Everything fits.

Now there are some rotors out there that are massive and do require complete stystem upgrades like Bear and Brembro performance packages, but those rotors are somewhere in the neighborhood of 17-18 inches in diameter. My aftermarket ones are 1.25inches larger than the stock ones. :cheers:

I'm going to let you think about that some more for a bit. ;)

so what I am hearing is that Porsche, Lambo, Ferrarri, etc put stock drilled rotors on just for looks, and a solid rotor is better.

I understand the logic as to why drilling has its problems, but I really hate to believe porsche puts drilled rotors on a GT-3 strictly for marketing, when solid is better.

Hummmmmm.....

I don't get your point? I asked him to measure the stock vs. the Zim. ones because I know they should be bigger. When I say "they" I'm reffering to the aftermarket Zim. ones. Mine are not this brand but are aftermarket. Since I thew away my stock rotors and can not find the exact size of the O.E.M. ones. I only remeber they were at LEAST 1inch larger in diameter because I held them up next to each other. Does this help clarify? :D

Ditto, I couldn't have said it any better. It's obvious that all of the "S" types including the Boxster come with better brakes, and I hate to think that the crossed drilled ones they come with are useless. Makes no sence. :confused:

If they were a inch bigger then they wouldn't fit the brake caliper.

check out the ones they actually race. earlier in this thread is a photo of a GT3 RSR. solid rotors. cross drilled were all the rage for awhile, but time and experience have shown that in racing applications, there are better ways to go. for the street / light track, drilled rotors are fine & they look cool. in terms of performance, they're simply not the best option.

porsche986spyder:

check your measurements. a rotor that's 1.25" in diameter larger than stock will hit the caliper. even if it COULD fit, your pads wouldn't sweep the outermost portion of the rotor. also, the largest sports car rotors i'm aware of are 15.7" / 400mm diameter. a 17" / 18" disk w/ caliper won't fit inside the wheels. not to mention the inertia starts to really work against you when you go too big on rotors.

You must be thinking in terms of thickness, I'm talking about overall diameter/circumferance. The calipers fit just fine. The thickness is the same for stock and aftermarket. I know they were at least an inch taller when I rolled them up nex to each other comparing the sizes.

I give up, I don't want this to turn into a long arguement. I just know that my aftermarket ones are definatley larger than the stock ones. When I mentioned 17-18 inch massive rotors I was not speaking of ones made for our cars, but just that there are some out there for other cars. :)

I think this is where there is some question in this thread... haha... 17-18" diameter... when the OP mentioned for you to think about this... i think he was referring to this part of what you said. Picture this... 18" diameter Rotors would be equivalent to my 18" diameter WHEELS. :D

They can't. Look at the specs I posted earlier in this thread between the 'S' and the base model. The difference in diameter is less than an inch. The 'S' is also slightly thicker. Yet, the 'S' rotors won't fit on the base model with it's calipers. Also, Zimmerman is the OEM supplier to Porsche. For their aftermarket discs, they are essentially taking a solid OEM disc and drilling it - they're the same size. That's also why the 'S' and base have different model numbers.

Also consider this, even if you could do what you've stated, why would you? What would you gain? You've not increased the swept area because your pad size is the still same as a result of the calipers. You'd get no additional benefit - and actually lose some.

You're hearing correctly. Porsche (and Ferrari) are a couple of the best companies in the world when it comes to marketing/selling their product. They know their market and what it wants very well.

Just for reference, here's another good link that talks about brakes for those that are interested:
http://www.rennsportsystems.com/2c.html
From the link:
"Porsche used cross-drilled rotors with mixed success. The Zimmerman rotors used on the 930 Turbo brakes were very soft and crack prone, even though the holes were chamfered. The later Brembo rotors will also show some wear when used with most performance brake pads. Some of the best rotors in the world are made in Britain by AP and Alcon. Those rotors, when properly adapted, seem to be superior to the Brembo ones in terms of wear and crack resistance. All drilled rotors will crack sooner or later if overheated. Slotted rotors are more durable in this regard however they are heavier. One reason that most large iron rotors are cross-drilled is to save some unsprung weight. Since nice big, light, carbon rotors cost $1000 each, saving some weight without bankruptcy, is important. Plus, carbon rotors possess very little friction until they reach 500-600 degrees F. Porsche's PCCB ceramic matrix rotors while very light, seem to have mixed success when used for track events."

Hey, no worries...my car has cross-drilled rotors too. :cheers:

HI, Here you go all 4 rotors (discs) :)

http://i167.photobucket.com/albums/u...r/Photo104.jpg

http://i167.photobucket.com/albums/u...r/Photo103.jpg

http://i167.photobucket.com/albums/u...r/Photo100.jpg

The dimensions for the new Rotors, Front 11.75" diameter X .950" thick and the rear
11.500" diameter X .800" thick.

Sorry I don't have any time to remove and measure the OEM'S on the car right now, I've been taking care of my dad for the past 3 weeks, he got operated for intestinal cancer and needs motivation to get back on the horse, maybe next week. :)

Franco:

Best wishes to your Dad.


ddb

Hi, I just finished installing the rotors and the OEM'S are the exact diameter as the ZIMMERMANN and there's no way to fit bigger diameter rotors unless you put spacers to bring out the calipers to compensate for the increase in diameter size and that would be useless unless you used bigger pads.

Anyway they look nice and I'm happy :)

It's 1:25 AM and I'm exhausted goodnight

PS: The install was a real joke :p


ddb, Thanks

Actually you'd get two benefits: 1) longer moment arm and 2) more thermal mass.

you don't get a longer moment arm unless you move the caliper / pad out to the edge of the larger rotor. otherwise, you're grabbing a larger rotor at the same radius you would a smaller rotor. more thermal mass helpful, but its affect is secondary to the longer dwell time air moving through the rotor vents.

on the downside, increased polar moment of inertia, more rotating mass, more unsprung weight.

I agree, I was assuming the aforementioned "spacer" to relocate the caliper out to the edge of the rotor...