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Old 03-26-2007, 12:07 PM   #67
Rob Levinson * UUC Motorwerks
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Join Date: Dec 1969
Location: GA
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My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by jpr View Post
So to summarize, your assertion is that it can be done, but nobody does it?
That's not what I said at all.

1) It can be done. Fact.

2) Your list of aftermarket brands that are drilled is accurate.

3) OE-manufacturer perforated rotors are made with different methods and standards than aftermarket drilled.

Quote:
The only reason the distinction matters is due to the internet "bandwagon" that says drilled rotors are bad, but this particular rotor is okay because the holes are cast not drilled, so you should buy it. But if in fact nobody makes a cast rotor and they are all drilled, then that is not a valid basis on which to select a rotor.
Yes, but none of the aftermarket brands you list are advertised as cast-perforated, are they?

Quote:
As for the assertion that are all perforated rotors are drilled, not cast, if it is a myth as you say, it should be take very little effort to debunk it. All somebody needs to do is provide a picture of a rough casting with holes or a picture of a mold or a patent or some other sort of evidence.
There's a good reason you don't see it... vented rotor casting technology is often quite complicated, and if not patented (as some methods are), then is at least a closely protected manufacturing technique. Think about it... you're casting a relatively large piece of iron with multiple channels, and it has to be done in a fairly precise and balanced way. If company A has a better method than company B, they're not going to post pics on an internet message board.

Quote:
If somebody is actually making a cast perforated rotor and it offers a genuine technical advantage, you would expect them to market it as such. At a bare minimum, you would expect them to admit its existence - if they are making cast perforated rotors why in the world would they describe them as drilled?
The OE-level manufacturers in question make several lines/grades of product. OE-level, A, B, C - tier stuff depending on the price point of the market. They're not going to say "Our OE stuff is made better than the service replacement stuff" as that shoots their marketing in the foot for the high-volume and higher-profit replacement parts. That's just common business sense.

Additionally, the OE manufacturers do not list the product as drilled, always as "perforated". And, as you and I discussed in another thread, a single instance of a marketing brochure saying "drilled" does not obviate the hundreds of other technical brochure listings as "perforated". Not to mention, the secondary "interference layer" of translation from German to English.

- Rob
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