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Cummins clutch

Discussion in 'The DIY Room' started by bobdog2o02, Jun 4, 2016.

  1. mdavlee

    mdavlee

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    I've killed a 3850 CB. The levers break after a while. Peter from South Bend clutch told me it wouldn't last. 28k and I had to put another pressure plate in. 94-95 hydros are bigger than the later ones.
     
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  2. Horkn

    Horkn

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    Lol, yeah, I was at the AMA Superbike race roadraces Friday - Sunday. I heard quite a few loud ducati dry clutches there.

    Nice work bobdog! TROGDOR could've given you a hand heating up parts and using that big beefy arm to R&R that Cummins clutch super easy.
     
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  3. mdavlee

    mdavlee

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    The big pulling trucks are running triple disc and even some 4 disc set ups.
     
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  4. ironpony

    ironpony

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    NHRA top fuel and funny cars run 6 clutch plates with 5 floaters and burn them up completely in a sub 4 second pass. They slip them the first 660 feet then lock up solid after that.
    Guesstimate is 12,000 HP.
     
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  5. MasterMech

    MasterMech The Mechanical Moderator

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    Fun trivia, that engine is pretty much spent after one pass. Anyone care to guess how many times it rotates during that pass? Excluding idle time and burnout of course.
     
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  6. ironpony

    ironpony

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    rev limited to 8000 rpm, 4 seconds runtime so

    8000 divided by 60 =133.333333 revs per second
    4 second run 4 x 1.333333 = 533.333 revolutions
     
  7. ironpony

    ironpony

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    also if you follow it closely, the teams shoot for 1 minute 20 seconds run time before staging. this is to regulate the engine and clutch heat build up. they try to be consistent because of clutch heat mainly. the engines are started on alcohol and then switched to nitro. at full fuel load the engine is in hydrolock.

    if a Haybusa, the fastest street bike, was to run flat out across the starting line to trip the lights a funny car from a standing start would catch it and pass it by half track.

    the intake exhaust valves have a lift of over 2 inches.
     
  8. MasterMech

    MasterMech The Mechanical Moderator

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    Most people put many times more than that on their engines before they get out of their driveways! :D
     
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  9. MasterMech

    MasterMech The Mechanical Moderator

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    How the hell do you tune with such short run times? :eek::jaw:
     
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  10. ironpony

    ironpony

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    it takes 1000 hp to drive the blower
    it burns 22.75 gallons of fuel in a pass
     
  11. ironpony

    ironpony

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    engine HP is controlled by timing, head gasket thickness and fuel curve. This is minimal because if you decrease the HP to much you induce tire shake, so they slip the clutch, which causes the tire into a controlled slipping.
     
  12. Horkn

    Horkn

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    Fwiw, all stock bikes, even hayabusa's are electronically limited to 186 mph.

    That's stock though.

    Still, these top fuel dragsters are insane. It's a purpose built machine, meant only to annihilate quarter miles at a time.

    An all around, will never beat a purpose built machine unless it breaks.
     
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  13. ironpony

    ironpony

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    on a good run a funny car will be traveling 280 mph at the 1/8 mile.
    top fuel is quicker ET, funny cars are faster MPH
     
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  14. bobdog2o02

    bobdog2o02

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    I love the place my thread wandered to, cool stuff.
     
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  15. MasterMech

    MasterMech The Mechanical Moderator

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    One of these days, when the boys are old enough, I'm gonna take them down to a drag strip for some top fuel action.
     
  16. TurboDiesel

    TurboDiesel

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    They're gonna love that!
    :yes:
    A pic of my desk
    PART_1465354877854_1465354877981.jpg
     
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  17. ironpony

    ironpony

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    if you want to see what happens when things go wrong google
    Beckman makes highlight reel with big boomer

    broken camshaft, ignited all the fuel in the manifold
     
  18. bobdog2o02

    bobdog2o02

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    One thing being learned.... the extra rotating mass on the trans side is reinforcing the need for for double clutching.
     
  19. ironpony

    ironpony

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    yes, need to learn to shift again........
     
  20. MasterMech

    MasterMech The Mechanical Moderator

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    Perhaps that's why the stock hydraulics die so quickly actuating one of these? Stiffer diaphragm and 2x the cycles = death of a slave cylinder?
     
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