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Old 05-27-2011, 10:51 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
Posts: 20,360
Mein Auto: 02 BMW 525i M54 auto 130K
A rotor, by any other name, will still stop the same!

Quote:
Originally Posted by Fudman View Post
When you say "meaningful difference", I am assuming that you are referring to braking distance
Good point!

I left 'meaningful' undefined because I wasn't sure what was meaningful.

I do agree, probably the 'most meaningful' metric is stopping feel & distance.

Quote:
Originally Posted by Fudman
Any performance differences in fade, cooling, etc. would be due to design, mass, etc.
Sounds reasonable that an OEM-shaped rotor would perform as OEM shaped-rotors do.

Quote:
Originally Posted by Fudman
Things like brake warping, out of round, etc. are quality issues outside the scope of this discussion.
I'm not so sure that's out of scope.

When I chose my first E39 replacement rotors, I simply researched the brands that you guys recommended - and simply selected the least expensive (taxed and shipped to my door) of those.

If it had been 'warped' (in quotes because what I think you meant was the faces were not parallel due to lousy manufacturing tolerances), or out of round (I'm not sure what that means), I would not have been happy.

So, I would disagree here and say that meeting the OEM specs would be as important a criteria as performance (i.e., stopping ability).

Quote:
Originally Posted by Fudman
Other issues like brake squeal are probably more dependent upon the brake pad used, vice the rotor
Agreed.

Quote:
Originally Posted by AnotherGeezer View Post
coated rotors don't corrode as quickly as non-coated
I'd lump that under cosmetics and not 'meaningful' in a performance sense.

Quote:
Originally Posted by AnotherGeezer View Post
the rotors balance well
Presumably you mean even distribution of weight.

Is weight imbalance (as opposed to size tolerance) a common problem?

How would we know if a rotor is not weight 'balanced'?

For example, following your recommendations, I noticed, in post 91 of the brake thread, that my new and old rotors had a weight-balancing slice taken out of the edge:
- What is this slice taken out of my rotor (1)

Note: Ignore the text on the picture - we found the answer (it was for weight distribution):

Quote:
Originally Posted by AnotherGeezer View Post
a rotor is probably a rotor
Intuition says the more the marketing guys try to tell us otherwise, the more the case is that, yes, a (recommended brand) rotor of the OEM fitment will perform like any other (recommended brand) rotor of OEM fitment.

Quote:
Originally Posted by AnotherGeezer View Post
A rotor by any other name will still stop your car.
Nice!

A rotor, by any other name, will stop just the same!

Quote:
Originally Posted by bmw_n00b13 View Post
I wouldn't order a Chinese brand
Seems reasonable.

Are any of the recommended rotors Chinese brands?

Last edited by bluebee; 05-27-2011 at 10:58 AM.
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