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312mm discs on a 288mm disced car - Advice needed please

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by AndymacA4, Nov 30, 2008.

  1. AndymacA4
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    AndymacA4 Member

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    Okay, I'm bored of poor braking, I am going to bite the bullet and upgrade my 288mm disc to 312mm discs.

    I need a set of caliper carriers (Got these sorted)
    Discs and Pads.

    I have noticed that many firms list the same pad part number for both 288 and 312 disc application, which makes sense, as I'll be using the same caliper. But which part number!!!

    I'm after a set of good quality pads like brembo or feredo. Anyone got correct part numbers? (I tend to use these people for parts

    I also need discs, I'm looking at Nitrac cross drilled discs, they should be easy to source.

    Finally, will I need a new fitting kit/spring set? - I was advised to replace the spring tensioners on my old Alfa every 2 pad changes as good practice, does this apply to Audi too?

    Many Thanks

    Andy
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i jsut fitted this upgrade to my B5,

    The B5 has a few different part numbers depending on age and wether it has wear indicators, however i suspect all the B6 pads are the same (and probably the same as the B5 pads with wear indicators)

    I didnt use a new "fitting kit" its just a bit of sprung wire, but they're only a few quid from the factors if you want to change them.

    I used standard motorfactors disks (Brakeworld) and mintex pads.

    If your looking to spend proper money on pads i'd be looking at mintex1144's or ferodo ds2500's

    As for the disks, in my opinion the disk is just a lump of cast steel, and theres not really any advantage of fitting fancy drilled/slotted/grooved disks over standard plain disks. I've also heard stories of drilled disks cracking between the holes, and i'd rather avoid that tbh.
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  3. AndymacA4
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    AndymacA4 Member

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    I'm not too fussed about disc design. Any ideas on feredo pad part number?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    FCP1323 - DS2500 as far as i can tell.

    MDB1826 M1144 for the mintex pads, again as far as i can tell
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  5. AndymacA4
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    AndymacA4 Member

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    Okay, I have been looking around again, I have found some Mintex kits on flea bay. I have found these.

    http://cgi.ebay.co.uk/AUDI-A4-FRONT...10372QQcmdZViewItemQQ_trksidZp1713.m153.l1262

    I am after 312mm discs and the correct pads to fit into my existing 288mm disc setup calipers! Is this kit correct? I thought the calipers on my car should be ATE jobs.:confused:

    I am going slowly mad :jester:with the range of different part numbers and applications that I am being advised on by different places![FONT=&quot]
    I have found a part number for correct pads in Ferodo DS Performance, it is [/FONT] [FONT=&quot]FDS1323. These run to £100 though!:think:[/FONT]
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  6. coyote
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    coyote Member

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  7. james0808
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    james0808 Active Member

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    Although this is an upgrade it is only a very small one.You would be better upgrading to B5 or B6 S4 front brakes,both are excellent and can be had for less than the cost of going for the 312mm which still use the crappy little calipers.
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    tbh the piston surface area between the A4 and S4 calipers is the same anyway, if it was larger you'd need to change the master cylinder or you;d end up with a really long spongey pedal, so they just use two smaller pistons to give the same surface area

    Most of the gain is simply down to the larger disks, although the larger pad area on the S4 calipers will help a little bit
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  9. james0808
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    james0808 Active Member

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    No its not,you get alot more clamping force with the S4 brakes and i didnt notice any difference to pedal feel,they are more than a little bit better than the weedy standard brakes and 312mm.
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    wtf? go take a ruler to the pistons then...

    You'll find that the piston surface area is pretty much identical.

    If they were larger, then yes you would get more braking, but you would require a different master cylinder to supply the extra fluid for the larger pistons surface area. The S4 and A4 master cylinders are the same.

    You cant get more clamping force unless you move more fluid (ie fit larger pistons) however if you were infact moving more fluid, your pedal would move a lot futher as the master cylinder is the same. The fact that the pedal feels exactly the same, tells you that your moving the same amount of fluid, and generating the same clamping force. Its just that because that force is being applied further from the centre (because the disk is larger) you generate more torque.

    As i said, most of the gain will come from the larger disk, although some of it will be attributed to the larger pad area that the S4 caliper has.
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  11. james0808
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    james0808 Active Member

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    Its not just about the piston size.
    Piston area may be similar but a more even force is applied across the pad surface on the twin piston set up than the single one.
    You also get much better cooling using the bigger and thicker discs than the thin 312mm ones.
    [​IMG]

    I know which ones i wouldnt choose.
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  12. AndymacA4
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    AndymacA4 Member

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    I have asked the e-bay dealer I looked at for a point of reference and was pointed here

    http://webshop.tecdoc.net/ows/en/60...6649B8B7E991D1EB6A0181?view=VIndexFramesetJspMintex online catalogue

    My brake code is shown from my service book so that gives pad numbers, disc numbers etc.

    I'm going to have a set of standard mintex 312mm discs and standard pads for now. If they don't help then ferodo DS perfs. The DS perfs are more than the combined price for discs, pads, and fitting from this place!
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  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    andy: good stuff, be good to see how you get on.

    james: ye the pad pressure is more even, but your still not really clamping any harder. The thicker disks will help under pressure, as you say they'll cool better with the bigger vents and also will take more abuse before they actually get too hot in the first place.
    I'm not suggesting the S4 brakes arent going to be better than the 312's, ofcourse they are, but its only 8mm of difference in diameter, and as such i think the 312's offer a cheap upgrade thats going to improve things a lot with minimal amounts of work.

    Also, your pic is comaring 321mm S4 disks with 288 disks, which isnt exactly the comparison we're making here!

    This reminds me that i need to check the inside of the nearside disk, as i noticed not long after i fitted them that it appeared not to be wearing evenly and hoped it was just a bedding in issue!
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  14. AndymacA4
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    AndymacA4 Member

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    General info for anyone who is interested. I have been e-mailing the firm listed on E-Bay who supply the Mintex kits. They have put together the following kit for me to include the correct 312mm discs and Teves/ATE specific pads for the conversion from 288mm to 312mm discs.

    Might make sourcing quality bits easier in future for those going down this route.

    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=230314688806

    Many Thanks for peoples views

    Andy

    PS My order is in, hopefully they'll be with me before the Christmas hols so I can have a play then!
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