What ratio is needed here?

Discussion in 'Got gears?' started by jimmy, Dec 5, 2005.

  1. jimmy

    jimmy Low-Tech Dinosaur

    A friend has a 69 GS with 455. It runs 6.90's in the 1/8 mile. The rpms at the traps is 5500, tire size is 30" X 9", 4.11 gear now and car is going 98 mph what gear ratio would put the rpms at 6000 to 6200 through the traps? 4.56?

    Thanks
     
    jimmy, Dec 5, 2005
    #1
  2. gusszgs

    gusszgs Well-Known Member

    Jimmy, I don't have the answer to your question, but he could go to a 28" tall tire, which would bring his RPM up going through the traps. Just a thought.
     
    gusszgs, Dec 5, 2005
    #2
  3. jimmy

    jimmy Low-Tech Dinosaur

    We thought about the same thing but the smaller tire will have a smaller foot print and he has lot of power and wants to go with a 10" tire also.

    I am sure there is a formula out there for me.

    Thanks
     
    jimmy, Dec 5, 2005
    #3
  4. jeff bullock

    jeff bullock Dare to be different !!!

    Hey Jimmy,www.drivetrainspecialists.com have a formula to figure out exactly what you need.Go to the FAQ section at the top of the page then scroll down.You'll find the formula there.It's easy to use,just plug your numbers into your calculator.
     
    jeff bullock, Dec 5, 2005
    #4

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