Tire shake

Discussion in 'PSI Superchargers Tech Questions' started by racecar1517, Apr 10, 2016.

  1. blownapex

    blownapex Member

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    I bet you end up with a 1.98 to 2.15 1st gear ratio
    or 8.50 to 9.25 ratio with a roots blower
    that 1.68 is screw blower ratios
    id do 1.98 and pull timing if wheel speed is too fast
    make sure your tires don't have more than 20 runs
    mike can help more than me
     
    #21
  2. racecar1517

    racecar1517 Member

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    Thanks for everyone's input and help. I still can't get the wheel speed numbers up but I really haven't changed much other than taking timing out at the hit.
    Last weekend it shook the tire for the first time. Not fun. Live and learn, from the seat of a funnycar. Life could be worse. Thanks ITA!
     
    #22
  3. Mike Canter

    Mike Canter Top Dragster
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    If you put in max advance and can't make more power then it is time to change the gear ratio in the transmission. If you have a Lenco then you can find used gear sets. Mick Snyder of Synder Motorsports sells new and used Lenco gear sets
     
    #23
  4. Nitro Madness

    Nitro Madness Super Comp

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    I know you are probably getting responses on this thread from clutch and converter racers...but since I assume you have a converter the 1.69 x 4.29 gear ratio is 7.20 overall in first gear....probably too much gear....Like Mike says take out timing or change the gear....for much smoother launch....we fought this issue for years trying to "tune it up" to get rid of shake like the clutch guys suggested.....ended up listening to Mick Snyder when he said that tuning up a converter car just increases the shake (multiplies the torque even worse)....
    With the alcohol set up I ended up with a 1.44 x 4.10 for overall first gear ratio of 5.90...so I suggest an overall first gear less than 7:00 for sure....low to mid 6:00 would be better....
    Now for then next issue....this less gear ratio increases the converter temp and is pretty hard on trans and converter parts....I think timing control is easier if you don't have taller ratio trans or rear gears laying around....just my .02....
     
    #24
  5. racecar1517

    racecar1517 Member

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    Mike, for the last run that shook I had 5 degrees out at the hit for .250 and all in by .750... Total timing of 24 degrees. It shook at .320. I don't think it's set on kill.
    Nitro, I am looking into a rear gear chg from the 4.29 to 4.11 or 3.89. I am shifting and crossing at 8300 (3 speed) if the rear gear changes do i need to change the shift point?
     
    #25
  6. Mike Canter

    Mike Canter Top Dragster
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    Let me ask this question.....if you can't get your wheel speed up now with your current rear end ratio of 4.29 then why are you switching to a 4:11 or a 3.89. It would seem to me that you should stay with the 4.29 and change your transmission gears.
     
    #26
  7. racecar1517

    racecar1517 Member

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    The local guys are screw-players. I keep thinking lower is better.
     
    #27

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