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View Poll Results: Any Quality Difference between dealer OE Zimmermann rotors vs aftermarket Zimmermann?
Yes, Porsche quality is a bit better.
6
31.58%
No. Quality is the same.
10
52.63%
I've never replaced rotors with Zimmermann.
3
15.79%
Voters: 19. You may not vote on this poll

Any Quality Difference between dealer OE Zimmermann rotors vs aftermarket Zimmermann?

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Old 03-05-2009 | 08:12 AM
  #16  
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If you're driving on the track, the rotors sold through the dealer hold up a lot better than aftermarket Zimmermans. I heat-cracked a pair of Zimmermans in ~4 weekends where the dealer rotors last about twice that long. The finish on the friction surface is also different.

For street driving, though, the aftermarket Zimmermans should be fine if you paint the hat.
Old 03-05-2009 | 12:11 PM
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Originally Posted by jerome951
If you're driving on the track, the rotors sold through the dealer hold up a lot better than aftermarket Zimmermans. I heat-cracked a pair of Zimmermans in ~4 weekends where the dealer rotors last about twice that long. The finish on the friction surface is also different.

For street driving, though, the aftermarket Zimmermans should be fine if you paint the hat.
I agree completely.

Some years ago, I bought a set of 928S4 rotors for an 89T from an aftermarket supplier. When they showed up, one was an OE Porsche rotor in the porsche box, the other was a Zimmerman rotor. Car was track driven, and the Zimmerman rotor had significantly more heat stress cracking and cracked through while the porsche rotor was still in pretty good shape. The difference was quite dramatic. Discussed this at the time with the owner of Diversified Cryogenics (sold a lot of cryo treated rotors) , and he agreed that the metallurgy of the porsche rotors was different than the zimmerman rotors.

Not sure if that was specific to the 928S4 rotors, or if there are similar differences between other sized porsche and aftermarket (whether OEM or not) rotors.

And I dont know if porsche has changed OE suppliers or if zimmerman has changed metallurgy since then (about 9-10 years ago) - but I have only used Porsche rotors on my track cars after that, and will continue to do so, unless it is proven that the aftermarket rotor quality is now the same as porsche.
Old 03-05-2009 | 01:42 PM
  #18  
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Once again, OE is proven better quality than OEM. Makes sense, though, doesn't it? You would think Porsche standards with suppliers would be a bit higher than those of aftermarket parts distributors. In some parts, it's irrelevant, but with brakes...

Thanks for all the responses!
Old 03-05-2009 | 11:18 PM
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Once again, OE is proven better quality than OEM.
Luis... don't push too much - we're already surrounded. Besides, there is much for us to learn from the modifed guys...;] Bruce
Old 03-05-2009 | 11:53 PM
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BRIT944TS - Can we part out your missus

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Old 03-06-2009 | 05:40 PM
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https://rennlist.com/forums/showthre...ferrerid=15894

Some additional discussion on OE/OEM rotor quality and potential risk...



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