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    Default Cooked Disk Rotor

    Finally had a chance to remove the disks from the front of my car after Sandown last weekend. Looks like its been to a BBQ! The other side is cracked too - although not as badly as this one. The pads are Ferrodo DS2500's but I've clearly had them out of their heat range...
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    Yep they have well and truly been cooked. Did you have trouble with the brake fluid during the day? What fluid are you using?
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

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    Hi, Jim!
    Have you dropped out the bolts solution for clamping the wheels? It seems to me you're using nuts, isn't it? Thank you.

    Cheers,
    Cristian.
    Alfa Romeo 155 Q4 WB '95
    Alfa Romeo per sempre !

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    Steve,

    i am using the best fluid that money can buy - AP 600 - but I still boiled it - I need brake ducting and I don't have any....

    Cristian - yes, I am using thread in studs - with normal wheel nuts - so much easier to get the wheels on and off because the wheel sits on the studs..

    jim

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    Jim, could you please give me (us) some more details about thread in studs that you have on your Q4? Maybe some pics if you have.

    At a local wheel shop here they have managed to "fix" 2 holes on the hub (because I am using wobble bolts for 4x100). I would really like to go for thread in studs solution and get 4x98 rims.
    Alfa Romeo 155 Q4 WB '95
    Alfa Romeo per sempre !

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    Default

    Just watching the F1 build-up for quali at Singapore, and they have just had a closeup of the Mclaren front brakes. Vented, but not grooved at all. I know they are carbon ceramic but surely some of the brake disc tech is transfereable.

    So are all these grooved and drilled discs really any better in terms of outright performance or are the grooves etc there to over come something else (glazing of pads)
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

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    Grooves were invented when the Honda CB750 with a stainless front brake disc had trouble in the rain. Cars have dry internally vented discs and don't need grooves at all. It's just something that people figured would be better, because it once made sense on a motorcycle 40 years ago.

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    do not buy the ferodo's it's crap, just like the ds3000

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    From what I'd read, modern pads, which contain a resin to hold them together, give off gas when the pads are hot and the brakes applied, (the resin holding the braking material together vaporises) If this gas doesn't have a route to get away from between the pad and disc it forms a layer and you get a similar effect to Aquaplaning where the pads float over the surface of the disc.
    This is the reason for the grooves, to allow the gas produced to vent away from the pad.

    How true all of the above is, or how much of a problem it causes is up for debate. Although it can't be that much of a problem, otherwise F1 cars, the extreme end of the performance envelope, wouldn't be using standard non-grooved discs.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

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    Yes, I've read about the gasses to, also that the grooves are to prevent hot pads from glazing by scraping off the overheated layer.

    In the pictures above it's clear the grooves are creating hot spots, which isn't good...bigger brakes or better cooling seems the way forward.

    All I know is that they're damn noisy and I won't be fitting them to a road car in future

    wrinx
    My Q4 in the Garage

    www.alfaromeo155.co.uk ............................ □□□-V-□□□ .................................. www.ilmostro.co.uk

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    Had to look them up, but here are a couple of mine cooked discs.



    It was all the way through, except for the centre heart of the disc.

    Close up
    In a world full of compromise...
    ...some don't.
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    Opel Astra Sports Tourer 110HP 2017
    Alfa 147 1.6 16V 120HP
    Alfa 155 Q4 2.0 16V turbo

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    looks a lot like mine - mine also has a fair bit of hairline surface cracking. Looks like they are only good for one season - at least the way I use em...


    jim ~

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    Too many groves and too deep. They only need to be 0.9mm.

    The last of the Fiat Coupes have drilled rotors from new.

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    - Yes, I am getting some brake ducting sorted. The car stops pretty well as it is - but at Sandown I was braking from 220 kph 20 times in one session - really way over what the braking setup I have can reasonably expected to do. If I can get the cooling setup correctly I think it will make a big difference..Will try DS3000 pads next time instead of the DS2500's

    Already got the new rotors - less than seven days from order till delivery from the UK.
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    Wheel stud pictures for XTI (Cristian)

    There are the studs that I use on my car - I have removed then because I can remove the disk rotor more easily if they are out...They have a 'hex' drive in the front that makes them easy to put in. You have to be careful not to put them in too far or they will foul the front of the hub upright..


    cheers, jim..
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    Very kind of you Jim, thanks a lot!

    Do you also use some chemical liquid to prevent unscrewing bolts from the hub? Or it is not necessary because of the constriction force applied by screwing the lug nut?

    Cheers,
    Cristian.
    Alfa Romeo 155 Q4 WB '95
    Alfa Romeo per sempre !

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    Quote Originally Posted by jimnielsen View Post
    You have to be careful not to put them in too far or they will foul the front of the hub upright..
    Does that mean you leave them loose in the hub?

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    Technically, studs are stronger than bolts due to the way they clamp whatever they are screwed into, provided they are inserted correctly.
    You need to make sure they are tightened up correctly to ensure that whatever they are screwed into is compressed between the treaded part of the stud and the shoulder of the stud.
    I'll try to find a pic which will explain it better.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

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    the layer on the disc is pad material and you do need that! because that is making more friction, just like on the track where there is rubber on the track you have more friction, so more grip. the cracking is due too bad disc and pads!

    and don't buy the ds3000 it's the same crap or maybe wurse

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    Quote Originally Posted by jimnielsen View Post
    - Yes, I am getting some brake ducting sorted. The car stops pretty well as it is - but at Sandown I was braking from 220 kph 20 times in one session - really way over what the braking setup I have can reasonably expected to do. If I can get the cooling setup correctly I think it will make a big difference..Will try DS3000 pads next time instead of the DS2500's

    Already got the new rotors - less than seven days from order till delivery from the UK.
    First, the DS2500 pad is a semi street/race pad, you should use the DS3000 (or switch to Performance Friction) if your car is an only-trackday Q4.

    Second, are you really import the discs from the UK while you can buy one of the best disc locally ?
    Last edited by jNk; 03-10-11 at 23:15. Reason: range expansion
    1995 Alfa Romeo 155 Q4 , 1995 cc Standard Standard Black

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    Hi jnk - dba cannot supply the fiat coupe vt20 305mm disk in any format. The ones that I was using were the last pair that they had and they did not have another production run. I could certainly purchase the product in the dba 4000/5000 format but they have never made any. The ones from the UK are so cheap that I can replace them once a year (and will probably need to....)

    Steve - Yes, the studs are 'loose' but I do put thread locker on so that they don't free rotate. They were quite still to get out because of this....

    jim..

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    So dba has stopped the production of all versions of the 305x28 disc ?

    Sh.t , I thought that I'm going to buy the dba discs next year when my brake upgrade is planned.
    1995 Alfa Romeo 155 Q4 , 1995 cc Standard Standard Black

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    no, you wont be able to get them from DBA. They only ever made one batch of them. The rotors do not suit ANY car that was ever actually cold in Australia (to the best of my knowledge) - so they are not keen to make others..


    jim..

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    If you use road discs on a modified track car you are always going to have problems - the sight of those discs alone would have me upgrading immediately to something better suited to the job and not going down the same route again....

    I would suggest moving on ASAP to some separate bells (or top hats if you like) and good quality (AP) 32 x 315 discs

    If you carry on and don't learn from what you are seeing you are heading for a big accident, I've got better brakes than you on my Fiat Coupe road/occasional trackday car, I (and others around me) appreciate being able to stop reliably. Good brakes are as important, if not more so than a bigger power output.




  25. #25
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    On a slightly different note, how do you find the wilwood calipers?
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

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