Gears

#1 04-30-2008, 05:23 AM

I run a fuel altered with 390 rear gears and a 19% first gear lenco. We run 36" tyres. We have a KB up front. We never run a computer last year but were wondering at what point we should have shifted. What would a different gear % do in the Lenco say a 37%. Thanks for any info,
Tony.

#2 04-30-2008, 10:43 AM

Tony,
This is like asking what cam we should run in our BBC? There's a lot that factors into the equation. For you, the most important factor should be staying within the power band so you're always pulling without over-revving. If you are jumping into your next gear at a point where you lug it below your power band, you need more gear or a higher shift point. If you are running it out into "nose-over" mode, you need less gear and your RPM through the traps should be a very important factor.

Start with the end of the track and work back. Get your RPM at the top end where you want it with your trans at 1-to-1, rear end gears and tire size fixed then work your way back to the starting line where your chosen first gear ratio makes your 60 foot times their best. From that point divide your gear ratios evenly between for shift points and shift at a point where you still have power band at the end of the last gear and into the next.
Hope that helps. Sheer numbers are worthless without all the info. That's why we cheaters use computers.

#3 04-30-2008, 12:32 PM

Thanks Bobby yes all helps. We have a computer for this year so should help a lot. I have just been told by Lenco that I have a CS1N and can only go to a 25% with that case. So may have to look at another Lenco or change rear end gears.
Tony.

#4 04-30-2008, 01:08 PM

May I suggest you call Mike Strasburg at B & J transmissions. His number is 866-781-1064. You won't be sorry you called.

#5 04-30-2008, 01:29 PM

Thanks Bobby

#6 04-30-2008, 01:43 PM

With a 390 rear, 36" tires and a 1.19 low, you are really on that clutch for quite a while. You must really cut a fair amount off each pass. A lower first ratio will get you out of the clutch quicker and lock it up quicker. With a blown KB, you should have the torque to get you over a pretty steep gear change, but even at 25%, that is not steep.
What times do you run, what is your class, etc.

#7 05-01-2008, 11:24 AM

Our class is fuel altered. We ran 6.44 at 215 last year. We are allowed a 20gpm pump / 20% overdriven 1471 / twin Cirello 7.8 amp mags /

Gears

Gears

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