Front drilled rotors

[Trust Me]

Just a question. Is there ,or is there not a right and a left when buying Drilled rotors? I just bought some from a guy and it appears that I have two right front. Now, I would think they would have the opposite pattern like these on ebay. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33564&item=2430721232 Can you please help.
I don't want to give him a hard time. But, I want the correct rotors. Once again I bought fronts, not rears like the picture shows. Same exact pattern though.
Please help.

[JP911]

I know that there is a distinct difference between a left and right rotor when they are slotted, but I have not heard of a difference with drilled rotors. I personally avoid drilled rotors based on the possibility of cracking. That said, I think the likelihood of cracking a cross-drilled rotor on a street driven car is pretty slim.

[Trust Me]

Jp911, Do you see what I mean in the pic? The rears have the opposite pattern. Why would the front not?

[ChrisBennet]

The inner vanes determine the the "direction" of the rotor. The holes should reflect that as well.

Rotors that are drilled after the fact (like these) won't pass tech in my PCA region because of their tendency to crack. SC rotors are pretty thin to start out with. The non-Porsche racing rotors (Alcon etc) that drilled are beefier and more crack resistant. Consider getting some solid ones if you go to the track.
-Chris

[Trust Me]

Chris, Thanks. No track for this one. The 77' maybe. So I am I wrong in saying that they should be opposite patterns in the front as they are in the rear?

[rattlsnak]

Yes they should be is the short answer. But you need to look at the interior vanes, its possible that someone drilled them the wrong way, or that they are correct, and they just didnt turn the pattern around.

[Eagledriver]

Rotors only became directional in the last few years. The "vanes" are symetical and go straight out fromt the center. The drilling pattern may be different per side but for a street car who cares?

-Andy

[89911]

I just got these back from Brembo as part of a custom 930 conversion. They are nice enough to stamp a big "R" and "L" on the correct rotor. The definetly should have a different orientation from one side to the other.

[Trust Me]

I guess I am looking for a yes or no answer. Should the drilled fronts have a right and left? They have a pattern to them. Not just a bunch of holes. Sorry if I sound frustrated. Car is sitting on jack stands. AHHHH!

[Trust Me]

Thank you 89911. This is what I mean! Can you show a pic of the other side? It would tell the tale.

[Frostie]

I feel your pain, my 911 is on jack stands also…

Mine are different on each side just like the ones the pic at e-bay. If you got a good deal on them I wouldn’t sweat it. I really don’t think it will make much difference in performance and I’m sure they will still look cool on your 911.

[Trust Me]

Frostie, It's the point. You know what I mean? It's my Porsche. Not some Ford Pinto! ( Sorry Ford guys ) They should be right.

[Frostie]

Yah i understand where you are coming from...

I too would be pissed...

[JP911]

Trust Me-
I think the answer lies in the post that mention the direction of the interior vanes. Because your rotors are vented they are designed move air for cooling in a certain direction. It's the direction of these vanes, and not the drilled holes that matter. I wish I had a cross section that showed the direction the vanes should take. Can anyone help / post a pic?

[Trust Me]

JP911,That would be great.
The guy I bought these from seems to be an ok person. I am not trying to prove him wrong. I lust want to be right! Don't want to be driving around and have someone say " why do you have a right rotor on the left?" ya know?

[Chuck Moreland]

930 brakes are left and right. "A" rotors are not, their internal vanes are straight.

However, it appears these have been drilled after the fact with a directional pattern. The pattern should be left and right, the guy probably sent you two the same in error.

Not that it would impact performance, just appearance.

[89911]

Originally posted by Trust Me
Thank you 89911. This is what I mean! Can you show a pic of the other side? It would tell the tale.

That is a left. The right is just the mirror image. The drilled holes should be arcing toward the rear at the top of the rotor.

[Hugh R]

In the above picture from 89911, it shows one painted wheel lug. Mine are similarly painted (one lug) What is the significance of that one painted lug, is it to line up the tire valve?