[Biturbos4] Zimmerman brake discs in the UK?

Andy Turner andy at palomar.demon.co.uk
Sat Oct 23 09:28:24 EDT 2004

Admittedly some of it is how it looks, but I'm trying to reduce the
brake fade that has always annoyed me about the S4. I'm told that
surface features such as the grooves or the holes help to dissipate
gasses that build up underneath the pad as you brake - is this
rubbish? A few places have said it. I've always presumed that the
drilled ones *are* literally drilled, but most manufacturers talk
about cross drilling (ie not directly downwards), which helps retaing
the strength, chamfering the edges and re-machining the surface to
avoid any premature pad wear. 

I've never had them before so I may well regret it - that's it I get
hold of some in the first place!


On Fri, 22 Oct 2004 18:12:10 -0600, Quincy Chiang <b5quattro at shaw.ca>

>Just curious, why do people like cross-drilled discs so much?  Most x-drilled discs you buy out there are basically blank discs with a bunch of holes drilled.  Even if they treat the drilled discs somewhat, they're still more prone to stress cracking around the holes and subsequently warpping the discs.  Also by removing material, you're lower the thermal mass capacity of the discs which makes them the brakes fade easier (although there may be extra cooling due to the holes, not sure how much of an advantage that is).  Lastly the x-drilled discs eat brank pads up much faster.
>You may say that Porsches have drilled discs, but AFAIK their discs are casted with holes in them and they are treated afterwards to strengthen the structure, very different than some vendors going at a bunch of blank discs on a drill press.
>No bashing here, just stating what I know and curious of what others think on this subject.
>----- Original Message -----
>From: Andy Turner <andy at palomar.demon.co.uk>
>Date: Friday, October 22, 2004 7:47 am
>Subject: [Biturbos4] Zimmerman brake discs in the UK?
>> Anyone know of any stockists in the UK for Zimmerman cross-drilled
>> discs (rotors!) in the UK? GSF Car Parts get mentioned a lot, but they
>> don't have any. I've got a 2000 S4, and I believe my discs are 321x30
>> on the front and 256x22 on the back - is that right or am I asking for
>> the wrong thing? (which might explain them not having any!)
>> Cheers
>> andyt
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