Question about transmission and tire size

Discussion in 'PSI Superchargers Tech Questions' started by Dusterfränky, Nov 13, 2012.

  1. Dusterfränky

    Dusterfränky New Member

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    Hi, I will run an older ProMod chassis in DYO classes. Engine is a KB 526, Brad fuel heads, 14/71 HHR, 6" set back, 30% over, makes 31lbs at 7600rpm. Trans is a B&J converterdrive. Tire size is 34.5/17/16, Diff. is 4.56. In the beginnig I'm looking for 7.50 class and I don't want to spin the engine over 8000rpm.
    Behind the B&J I have the choice to run a 4-speed lenco(1=2.40, 2=1.70, 3=1.33) or a 3-speed lenco(1= 1.90, 2= 1.38). Also i would like to go to a 33/17/16 tire, the 34.5 is very near to the body and 4-link(rubber marks). Most times we will run on bad drags.
    So what will be the better choice, 3-or 4-speed???

    Thanks ITA for posting.
     
    #1
    Dusterfränky, Nov 13, 2012
  2. Mike Canter

    Mike Canter Top Dragster
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    Have you verified that your rear ride height is correct. That is a very critacal adjustment. Who made the chassis? If you know you should contact them and get the front and back ride heights. I find it hard to believe that a chassis would be built that would allow a 34.5" tire to rub. The other thing is that the springs are too light in the back or the compression is too loose on the shocks. You should not be running a 4 speed with a converter on a blower motor. I beoieve the 2.40 first gear is way too much gear for a blower car with a 4.56 rear.
     
    #2
    Mike Canter, Nov 13, 2012
  3. Dusterfränky

    Dusterfränky New Member

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    Thanks Mike for answer, I will check the things. Good luck with Adam at the races!!

    Frank
     
    #3
    Dusterfränky, Nov 15, 2012

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