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Gear ratio adjustments

Sabrewings

Sabrewings

New member
So I'm using a stock L67 file as the basis for my top swap. I thought I did a mass copy of all tranny tables (to include the gear ratio tables) from one of my L36 files to make sure I didn't have any tranny problems. After a couple drives the tranny started banging in to gear and I got a code for an incorrect gear ratio.

My Impala has a 3.05 FDR. Can anyone (Trannyman maybe?) confirm if these three values are all I need to change and that they're correct for a 3.05 FDR?

Calculated Pulses Per Revolution: 25
Pulses Per Mile: 23310
Drive Sprocket Ratio: 1

Those are the values from my stock file, but I still seem to get that incorrect gear ratio code when used in a L67 file.
 


What tuner are you using? As much as this doesnt make sense, you cant simply copy tables from your stock file to a supercharged file that was intended for 2.93s. I know you probably have copied all of the numbers correctly but there is more to it than that and I am yet to see it work. Here is where a little math comes into play, but it depends what you use to tune with. If you are using HPT I can help out, if using PT then sorry I cant be of much help as it does things a little differently.
 
DHP PT. Unfortunate I guess. I'll go ask around at the Powrtuner forums to see what happens. Thanks for the input, Trannyman.
 
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Whelp, by looking at some math suggested for going from 2.93 to 3.69, I think I've come to the right answer.

I copied the sprocket ratio (1) and pulses per mile (23310) from my factory file. Then, I used the following math.

2.93/3.05 = .960656
1/0.960656 = 1.04095535

So I used the PT to increase the value by using the percent tool and putting in 104.095535% on the 22.29 stock L67 PPR. That gave me 23.2 PPR. I guess this will work...
 


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