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Black Diamond discs

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Caesium, Jan 29, 2007.

  1. Caesium
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    Caesium My BM is fixed! VCDS Map User

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    [Jan 29, 2007]
    Anyone had any experience of these discs? I need to replace my fronts soon and these seem real good value.
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  2. silver75
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    silver75 Big Ron

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    [Jan 29, 2007]
    mixed reports on these
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  3. Caesium
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    Caesium My BM is fixed! VCDS Map User

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    [Jan 29, 2007]
    care to elaborate?
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  4. silver75
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    silver75 Big Ron

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    [Jan 29, 2007]
    Some say they are good. Some say they are not.
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  5. Caesium
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    Caesium My BM is fixed! VCDS Map User

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    [Jan 29, 2007]
    very droll....

    any recommendations then?
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  6. silver75
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    silver75 Big Ron

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    [Jan 29, 2007]
    ...wasnt being funny, Ive heard they are good from some people and I have also heard they are just standard discs with black paint on from others... how about tar:eek:x or zimmerman?
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  7. Dan Gliballs
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    Dan Gliballs Active Member

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    [Jan 29, 2007]
    I had them on 205 GTi's years ago and they were absolutely fine :)

    Quite a few of the Cavalier Turbo boys use them and give rave reviews.

    Just make sure you avoid Red-Dot and EBC LOL!!
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  8. silver75
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    silver75 Big Ron

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    [Jan 29, 2007]
    was going to get the "turbo grooved" discs by these guys untill I heard a few horror stories.. its all subjective imo just like the "which tyres should I get" threads :shrug:
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  9. dan_b
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    dan_b Member

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    [Jan 29, 2007]
    The only way you'll ever really improve braking is to increase disc diameter and thickness (bigger discs), with more clamping force acting on the disc (multi-pot calipers), with a higher friction & higher temperature pad, with higher boiling point fluid, all put through wider tyres.

    If I were you, unless you're going to do a proper upgrade as above, just stick with stock. In fact, things like x-drilling a stock size disc can actually worsen your braking performance: by reducing the mass and surface area of the disc you're reducing its thermal capacity - therefore you'll get overheating and fade.
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  10. Caesium
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    Caesium My BM is fixed! VCDS Map User

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    [Jan 29, 2007]
    I just need to replace my discs as they are showing signs of advanced wear now, I don't want to spend 2 grand on porsche calipers or any big brake kits particularly.

    I have driven cars with stock sized discs that are cross drilled, and the reason for them to be cross drilled is so that the gas vapours generated by the friction on the disc have somewhere to vent out through the middle of the disc taking the heat with them.

    Your description of the holes causing overheating is very unlikely unless being used at the track and thats not something I'm likely to do.
    There was an issue with drilled discs cracking between the holes but this was in their infancy.

    Thanks for the advice though, but i'm not really concerned with the application information, just information on the product's quality.

    I never knew that EBC or Red Dot were to be avoided... how so?
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  11. silver75
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    silver75 Big Ron

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    [Jan 29, 2007]
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  12. Caesium
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    Caesium My BM is fixed! VCDS Map User

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    [Jan 29, 2007]
    Nice 1 mate, i think i'll go for the BD ones, they certainly aren't the cheapest but at least they wont rust on the hub eh!
    #12
  13. dan_b
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    dan_b Member

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    [Jan 29, 2007]
    Yeah, the problem is though that brake pads don't out-gas these days so there's no need for it. The only reason pads used to produce significant volumes of gas was when brake pads were made of organic materials -this is back in the 60s/70s we're talking now and the friction surface of the pad would literally boil. It's purely a marketing ploy these days I'm afraid. You don't see x-drilled discs in any form of car motorsport. (you still get them on bikes as a weight reduction technique but bike brakes have different issues - they're not trying to haul down several tons of mass).

    My description of overheating is valid and I've seen it with my own eyes/ feet. A friend had a VW Passat. He "upgraded" to a set of x-drilled, and slotted, but same sized discs. Net result was worse brake performance - he was blue-crazing his discs and getting fade issues through the same daily drive to work. Only possible cause was a reduction in thermal capacity of the disc due to the so-called improvements of x-drilling and slotting.

    As you also quite rightly mention, x-drilling is a quick route to cracking discs, which again is not good.

    Slotting discs can have a benefit if your driving style leads to repeated glazing of the disc/ pad surface, as the slots help to shave the pad surface and keep them "clean". This of course increases the rate of pad wear, and also can lead to brake vibrations!

    You don't need to spend >2k on a brake upgrade either. I put Porsche 4-pot calipers, with the associated bigger discs and better pads on my old S2 for less than £500 all in.

    If you do want better braking for not much cash, one of the best things you can do is invest in better tyres. Getting a softer, sticker tyre compound will, as well as giving you more cornering grip and traction under acceleration, it will also give you better braking. A wider set of front tyres will also help.

    An S2-owning friend of mine modded his S2 by sticking 255 section 18" tyres on the front, with 235s at the back to give him better braking. Along with the 365mm discs he put on with his AP 6-pot calipers, he measured more than 1G in braking effort. Which ultimately bent the struts as they weren't strong enough!
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  14. john2garden
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    john2garden Gonad

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    [Jan 29, 2007]
    Ive got EBC discs and Red Stuff Pads and I cannot report any problems at all.

    Done abour 3k in them so far. And not a snifter of a problem as yet
    (Touch wood) , seem to be really good to be honest.
    #14
  15. a4_23
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    a4_23 sleeper hatch

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    [Feb 4, 2007]
    if you do alot of hard braking then avoid the BD drilled and grooved just go with either just the BD grooved or the BD drilled, just passing on what i seen

    but its up to you IMO the drilled and grooved look nice
    #15

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