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I'm getting ready to order the gears for my 3rd member this week and I'm not too sure what direction to go. The car weighs 3200-3250, cal tracs, 28'A/275's, 388 cubic inch, pt106 g trim with a 1.0 housing. Th400 with a Neil chance promod bolt together converter. We are hoping to make around 1200 HP. Any help or info is appreciated.
 

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Std ratio gear set in trans? If so you will be forced to go to fairly low numerical gear. Marty Chance once told me not to go over 7.50 starting line ratio with a high powered car or it will be hard to control and inconsistent. I wouldn't go a whole lot higher or lower than this. I am changing over to a Rossler th400 with 2.10 low gear and trying to stay with same 3.70 gear but this exceeds what I have just told you but I'm going to try it anyway. I have a 3.40 center if this doesn't work.
 

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Will you be running mostly 1/8 mile? If you're running a 9" rear, a 3.25 gear would be a good ratio to start with if the trans has stock gears in it.
 

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Discussion Starter #4
I'm assuming it has a standard gear set in it. It is a Neil chance transmission as well, but I bought it from a friend after he had it freshened and I'm pretty sure he said it had a standard gear set in it.
 

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Std ratio gear set in trans? If so you will be forced to go to fairly low numerical gear. Marty Chance once told me not to go over 7.50 starting line ratio with a high powered car or it will be hard to control and inconsistent. I wouldn't go a whole lot higher or lower than this. I am changing over to a Rossler th400 with 2.10 low gear and trying to stay with same 3.70 gear but this exceeds what I have just told you but I'm going to try it anyway. I have a 3.40 center if this doesn't work.
In your hands and with the capabilities of newer boost control systems those are guidelines gone by. Good luck with the new tranny. Might have to rescale the car. Good luck.
 

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All the "non-pro" gears are about the same in my experience. Id use around a 3.5 ratio.
 

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If you're racing it in the 8th I highly doubt you will shift out of 2nd with anything numerically lower than a 3.60 or 3.70 unless you shift it at 6000rpm.

6% slip on my old turbo car, 3.08 gears 26" tires and shifting at 6400rpm and limiter at 6600 I was on the limiter in between the mph cone and 660' cone in 2nd. I had a 4l80e same ratios as a standard Th400 ratios. I put a 3.55 in it and with that I was crossing at 6000rpm in 3rd shifting at the same shift points.

I think you're going to need to run at least a 3.70 if not a 3.90, but then your going to have more trouble getting it off the line.
 
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