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F40 Brake Rotor Photos, ands what's this thingy?

Discussion in 'Technical Q&A' started by Steve, May 19, 2004.

  1. Steve

    Steve Formula Junior

    Nov 1, 2003
    901
    Seattle, WA
    Full Name:
    Steve Jenkins
    Three photos, two questions.

    First, can anyone tell me what the little inverted dome is that's stuck to the roof of my F40 interior (1st photo)? Is it a dome light with the bulb broken? A sensor of some kind? I can't figure it out...

    Also, notice the cracks around the drilled holes in my front and rear rotors (2nd and 3rd photos). How serious is this? My dealer pointed them out today - I was surprised that the dealer who did the PPI on the car when I bought it last month didn't catch this.

    Were the stock F40 brake rotors drilled AND slotted like this?
     
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  3. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,491
    MO
    Cracks are common on drilled rotors. Its nothing too bad. These cracks seem to still be minor compared to what I have seen on some pcars. I think as long as you are not too aggressive (ie no track days) you will be fine for a few miles still...but still recommend changing them ASAP.

    I have no idea what that dome is.
     
  4. GOB

    GOB Karting

    Dec 22, 2003
    63
    Panama
    Full Name:
    Gus
    I am no expert, but these cracks are pretty common on drilled rotors. It is my understanding that you just have to keep an eye on them and avoid from the hairline cracks extending from one to another. All drilled rotors have this happen to them, even the ones that the holes are cast into the rotors. Sorry could not be of further help.
     
  5. WJHMH

    WJHMH Two Time F1 World Champ
    Silver Subscribed

    Sep 5, 2001
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    I wouldn't chance it. Replace your rotors ASAP.
     
  6. maranelloman

    maranelloman Guest

    I don't think drilled AND slotted were standard, but could be wrong. Cracks don't look that bad to me.

    The thingie on your ceiling is a temp sensor for the A/C system, I believe.
     
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  8. Steve

    Steve Formula Junior

    Nov 1, 2003
    901
    Seattle, WA
    Full Name:
    Steve Jenkins
    I don't think it's a temp sensor. The manual says nothing about it, and the system is "old school" like my 328, where you turn the knob to red for hotter and blue for cooler.

    Any other F40 owners in here have this in their car? I'm wondering if it might be a sensor for the aftermarket Halon fire system.
     
  9. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
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    The dome is the cabin temp sensor for the A/C.

    I've got a 308 in at the moment with big brakes fitted to the front. It's turns out it's discs are F40 and they too are slotted and drilled. I needed to replace them due to cracking, and the new ones are not slotted, but the drillings are better spaced and are nicely radiused like Porsche parts.
     
  10. TOM B

    TOM B Formula 3

    Jul 24, 2003
    1,038
    Orange County, NY
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    Thomas Buckley

    I think it's a sprinkler head. You don't smoke, right Steve ? :)
     
  11. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
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    Malcolm W
    Standard F40 brake discs are drilled only, there were slotted discs available which were mainly for track use. Heat cracks are very common on F40, and from experience they are usually very shallow.

    The inverted dome is an a/c sensor.


    MW
     
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  13. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,761
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    Brian
    cracks around the drilled holes are common and will not adversely affect braking. We generally keep an eye on them, when they go all way between holes or to the edge, we will change them. Slots are a help to keep surface swept, most manufacturers of performance rotors are offering rotors with both now.
     
  14. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,391
    There is no way to prevent cracks on drilled rotors that are used hard. (period)

    It is not a question of the machine work quality, nor is it a question of the quality of materials usd in the rotor. Drilled holes in a differentially heated and cooled item will crack. simple as that.
     
  15. Steve

    Steve Formula Junior

    Nov 1, 2003
    901
    Seattle, WA
    Full Name:
    Steve Jenkins
    So am I OK tracking the car this year with those cracks?
     
  16. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,992
    socal
    Yes! Generally accepted rule Rotors to be replaced when cracks between holes meet or you have to beat a friend in his Ferrari and you need 100% braking effiencecy to beat him with the truest rotors and race pads.
     
  17. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
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    Malcolm W
    Shouldn't be a problem, generally they are only surface cracks, which dissapear after only a few thou is ground off the disc.


    MW
     
  18. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Time to change is when the outermost drilled holes crack to the outer diameter. At this point, you most likely also have 0.010 inch of lateral runout too, and you'll have a violent pedal vibration.

    Check each session, order spares. Common Brembo racing rotor size, however, a few years ago, Brembo changed the dimensions in the area of the mounting flange. To utilize the racing Brembo, you must remove the small "lip" on the mounting brake hat. Very easy on a milling machine.

    Rotor's the same size as common Nextel Cup (a.k.a. Winston Cup) stock cars.

    For track days, run slotted only, not drilled. Change the mounting screw nuts after a few rotor changes.

    Those are not the original brake rotors, nor dealer replacements.


    Best regards,

    Rob Schermerhorn
     
  19. garysp7

    garysp7 Formula Junior

    Mar 28, 2004
    436
    Florida
    Full Name:
    Gary
    As I am sure you are aware of now, the thingie on your roof is an A?C sensor. I believe you will find one by your feet also.
    The rotors should be replaced. The ones to get are the steel Brembos as you will stop faster. You should keep your hats and on the new rotors drill out the rivets and refit you old hats to the new rotors. I believe that OEM rotors became unavailable about 4 years ago.
    gary
     
  20. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Huh? You mean cast iron. I've seen motorcycles run steel brake rotors, but not cars.
    There are no rivets. Are you refering to the hat to rotor screws? No need to drill, just unscrew. As stated previously, modification to the lip on the aluminum hat will be required when running a Brembo motorsport rotor.


    Best regards,

    Rob Schermerhorn
     
  21. GTB4NART

    GTB4NART Formula Junior

    Jan 17, 2004
    421
    The little dome on the roof is either the A/C temp sensor or it's a the factory satellite linkup to make your slow down lights come on any time Maranello needs extra revenue ;)

     
  22. garysp7

    garysp7 Formula Junior

    Mar 28, 2004
    436
    Florida
    Full Name:
    Gary
    Hi Rob:
    I met you several times at Mancuso's when Richard was restoring his glass 308. I am Richard Messersmiths best friend. I was the one on the Ducati when we all used to ride together.
    He sends his regards and ask how unpleasant was it to have Jeff around?
    Richard was sure he has no screws on his rotors and politely disagrees:))
    Unfortunately Richard can wrench on his F40 but can't log on to the itnernet.
    Is that something?
     
  23. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Hi Gary, nice to hear from you and that Richard's still fooling around with Ferraris.

    Send my regards,

    Rob

    BTW, if you (or Richard) look at the nice rotor photo posted at the top of this thread, that fastener you see is the head of a specialzed rotor-to-hat retaining screw. Remove the rotors, and one will then see the nuts on the other side. I can now see how one may think that's some kind of rivet.
     
  24. garysp7

    garysp7 Formula Junior

    Mar 28, 2004
    436
    Florida
    Full Name:
    Gary
    Thanks for response Rob:
    Richard thinks the world of you and your abilities. I will refer him to the picture which I printed of all of the threads to send to him.
    Can you give me your opinion regarding 550's and 575's please.
    I am shopping for one now and I am using Richard as my go between negotiator. I figure if it can pass his inspection along with a dealer check I know I will have as close to a perfect car as possible.
    Richard and I are discussing whether it is worth moving up in dollars to get into a 2002 575 versus a 2000/01 550. Either way I am looking for a low milage perfect car. Richard feels they will both look the same over the hood. What is your thoughts on this?
    Thanks again
    gary
     

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