Rev Matching/Double Clutching Question | FerrariChat

Rev Matching/Double Clutching Question

Discussion in 'Vintage (thru 365 GTC4)' started by karmavore, May 13, 2004.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. karmavore

    karmavore Formula 3

    Dec 29, 2002
    1,641
    Hell
    Full Name:
    Karmavore
    If you're rev matching why do you need to use the clutch at all during sifting? I understand (from experience) that releasing the clutch releases the pressure on the dog teeth and allows you to move into neutral, but I don't understand why? Also, if I'm in neural and I rev match and theoretically I have the input, lay, and output shafts all spinning at the same speed shouldn't I just be able to slide the dog teeth into place with out the clutch? In fact, doesn't releasing the clutch cause my RPM to drop and through the the shafts out of sync?

    http://auto.howstuffworks.com/transmission4.htm

    I love How stuff Works.

    Thanks for the help!

    Luke.
     
  2. dretceterini

    dretceterini F1 Veteran

    Apr 28, 2004
    7,289
    Etceterini Land
    Full Name:
    Dr.Stuart Schaller
    You don't have to use the clutch! The problem is that it is hard to rev match. For example, if 3000RPM is 60 mph in 5th, and 5500 in 3rd, it is difficult to match revs exactly, especially as you are usually slowing down when downshifting. Lets say you are doing 60 in 5th, and have to slow to 30 for the corner. In 3rd is 30MPH 7500RPM?...is it 7800RPM?..etc. If you don't get it exactly right and not use the clutch, the car will judder. If you double declutch, it won't...
     
  3. karmavore

    karmavore Formula 3

    Dec 29, 2002
    1,641
    Hell
    Full Name:
    Karmavore
    So if you don't have syncros (or they're shot! :) double clutching allows you to get close in RPMS, but not exact. If you could get them exacly right then you wouldn't even need the clutch. Correct?

    Luke.
     
  4. dretceterini

    dretceterini F1 Veteran

    Apr 28, 2004
    7,289
    Etceterini Land
    Full Name:
    Dr.Stuart Schaller
    Yes, that's pretty much it. Pre-war cars didn't have syncros, and many cars didn't have syncros (on 1st and sometimes 2nd) until the 1960s. Plus teh fact that on many pre-war cars, slipping the clutch at all was a no-no...they were pretty much in or out...
     

Share This Page