Chassis heat tolerance after engine fire. | FerrariChat

Chassis heat tolerance after engine fire.

Discussion in 'Technical Q&A' started by Joe90, Aug 16, 2018.

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  1. Joe90

    Joe90 Rookie

    Oct 26, 2009
    7
    Zurich, Switzerland.
    Over the years I have seen steel framed cars for sale with severe fire damage, (anything from and F40 to an F360) and wondered if the chassis can be re-used after such an event? Does it need some heat treatment?
    Any input or pointers to restoration threads appreciated.
     
  2. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,289
    socal
  3. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    5,942
    Indio Ca/ Alberta
    Full Name:
    Grant
    As,usual it depends on the fire.
    If car is cheap it needs new subframe etc
     
  4. CarbBoxer

    CarbBoxer Formula Junior

    Oct 7, 2008
    841
    Houston
    Full Name:
    PW
    He asked about steel frame cars not aluminum. But then mentioned a 360.

    I agree an alum frame would be damaged a lot more then steel.
     
  5. Joe90

    Joe90 Rookie

    Oct 26, 2009
    7
    Zurich, Switzerland.
    CarbBoxer, correct I was initially thinking about steels. I guess this in part comes down to asking if the alloy steels used are heat treated. So mentioning the 360 was a mistake. However, using Aluminium 7075 as an extreme example as it is more sensitive, it comes in various grades, -0 (no heat treatment) -T651 which is the same composition of alloys but heat treated, with around 50% more tensile strength (wikipedia). Given that the frames are obviously welded during manufacture, any heat treatment would presumably be lost or at least modified at the welds. Also fire services spraying a car with water will mess up temper. In which case I did wonder if the entire chassis was heat treated after fabrication (this would need a massive oven)? If so, is it standard practise to repair, crack test, and re-heat treat a chassis after a major fire?
     
  6. 335s

    335s Formula Junior

    Jan 17, 2007
    870
    SF Bay Area
    Full Name:
    T. Monma
    Specificity is required: was this a 'flash" fire caused by a leaking return line, or, a banjo fitting's fiber
    sealing washer?
    Or, was it an electrical short circuit straight to ground(effectively "welding" with the amps available from a Boxer's battery-or as I jokingly refer to as: "the MAIN fuse"....)
    With an engine bay fire: The DURATION of the burn is as critical a piece of the puzzle as is the temperature of the flame.
    A carb fire-which you present....is a time value function so to speak(by the way THANK you for the fellow who posted the decay chart for the 7075!
    Nothing like baseline points of reference so that there is little to NO confusion about what we are discussing.I digress), as the actual fire,is really a vapor flash fire-not nearly as hot as you think....the additional "stuff" which might ignite as a consequence of the flash is more information you would accurately be required to submit in order to GUESS.....Accident reconstruction is far more detailed than one might think at first glance.
    The GOOD news is that the frames in those cars are essentially built like a tank....they are considerably overbuilt for what its being asked to do....this is not an assessment of inherent design with respect to flex and torsional loading issues-strictly how stoutly they are from a static perspective in base material size and the materials inherent strength.
    This I'm happy to opine: if the car burned hard-with gusto-for 10,or 15 minutes...the steel has probably annealed, and forget about it...
     

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