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360 A/C Effecting Smoothness

Discussion in '360/430' started by MATT360, Jul 14, 2007.

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  1. MATT360

    MATT360 Karting

    Jun 8, 2007
    54
    London
    Full Name:
    Matt
    #1 MATT360, Jul 14, 2007
    I have definitely noticed that using the A/C is having an effect on the smoothness of the gear changes(6 speed manual) down low in the rev range, around town etc. With the A/C off the shifts are very smooth and not at all jerky, anyone else noticed this ?
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,220
    Mount Isa, Australia
    Full Name:
    Pap
    #2 PAP 348, Jul 14, 2007
    That sounds odd matt, probably because you have your windows down and you can hear your exhaust would make you shift smoother IMO :p
     
  3. MATT360

    MATT360 Karting

    Jun 8, 2007
    54
    London
    Full Name:
    Matt
    #3 MATT360, Jul 14, 2007
    Strange, I was thinking that too, will need to check it out.
     
  4. Langers

    Langers Karting

    Apr 13, 2005
    163
    #4 Langers, Jul 14, 2007
    Makes perfecr sense... with AC on, there is additional drag on the engine, hence it takes longer to spin up, and spins down quicker. Guessing the F1 gearbox mapping is done for cars with AC off, hence it does not match gearbox output and road speeds perfectly with AC on.
     
  5. MATT360

    MATT360 Karting

    Jun 8, 2007
    54
    London
    Full Name:
    Matt
    #5 MATT360, Jul 15, 2007
    That also makes sense, perhaps its a combination of the two ? I'll try opening the window with the A/C on away from the lights and see if its a sensory thing, I'm leaning toward Langers explanation though.
     
  6. MATT360

    MATT360 Karting

    Jun 8, 2007
    54
    London
    Full Name:
    Matt
    #6 MATT360, Jul 15, 2007
    Ok, just back from a drive and its definalty the A/C drag on the revs. the shifts are really smooth, down shifting is great too and the power delivery feels better. This is not a problem in that I just have to shift from 1st to 2nd early and from 2nd to 3rd quickly which irons out the jerks. Perhaps as Langers pointed out, that this is why the 360F1 trans is jerky ? contributing to clutch wear ? I wonder if it gets better with the A/C off ?
    Driving without A/C, apart from warm up and cool down is a bit out of the question as its around 40 degrees C at the mo.
     
  7. Langers

    Langers Karting

    Apr 13, 2005
    163
    #7 Langers, Jul 15, 2007
    I haven't had any seat time in a 360, but what you described is something I have noticed across a range of sporty cars (i.e. cars with "grabbier" clutches which don't as readily absorb rotational differences). If other owners notice the same thing, then I wouldn't worry about it - unless we're talking about the car being *seriously* jerky.
     
  8. gjockey

    gjockey Rookie

    Feb 3, 2004
    14
    Miami,FL/Austin,TX
    Full Name:
    John
    #8 gjockey, Jul 15, 2007
    You pretty much notice it with every manual... curious what the explanation is for the extent of the abruptness. I believe that turning on the A/C saps horsepower and increases gas mileage a bit. It's my understanding the A/C compressor runs off the engine.

    The thing I don't get is the extent on the shifting feel. The A/C may affect horsepower and gas mileage by say 5%... but the shifting feel is affected much more than that in the Ferrari and every stick car I've owned.

    The revs seem drop a lot faster when you lift off the gas with the A/C on so you need to shift a lot faster to make sure it engages before the RPMs fall too much. Ie. if you use your normal shift speed and try to give the normal time for the clutch to engage smoothly, you get an abrupt shift from the greater than normal rpm drop.

    Anyway, the fact it happens doesn't surprise me. What surprises me is the magnitude of the effect. With A/C on, the rev drop rate seems to be more than a 5-10% difference high up in the powerband. -- John
     

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