72-CLASSIC_RIDE Posted July 27, 2009 Share Posted July 27, 2009 I know this issue has been discussed in previous conversations and I have attempted to understand and use the calculators in order to determine what my correct speedometer reading would require based on the following: In the process of changing out entire drivetrain From 350 CI to 402 CI From TH350 to TH400 Trans. From .273 10 Bolt to .331 12 Bolt Posi Rear Axle Rear tire size remains the same @ 235/R70 w/ 15" Rim Based on my understanding the following applies using the calculator(s) provided: Tire dia. @ 27.95" 331 Rear Axle ratio 18 Tooth Drive Gear The formula says I need to change my driven gear from currently 37 teeth to 43 teeth for correct speedo reading. I believe the driven gear housing will also need to be replaced to a 40 to 45 tooth gear housing. Does this seem correct assuming my calculations are accurate? Looking for a confirmation that I had used the math correctly and not left out anything else that would cause me grief. Not totally confident and don't want to throw money around on something I may have overlooked. All comments and suggestions aprreciated All have a GREAT day..... Doug Quote Link to comment Share on other sites More sharing options...
Heckeng Posted July 27, 2009 Share Posted July 27, 2009 Doug, I think you are dead on. Nice job Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted July 27, 2009 Author Share Posted July 27, 2009 Hey thanks for the confirmation Scott. My first attempt at using this formula and needed some support. Seems like the more I learn, the less I know compared to the experiences you all have had. Almost 30 years at the same job and when any of the newer guys raze me about my knowledge, I simply reply (I have advanced so far beyond that point, I have already forgotten what you are just beginning to learn). I know how they feel when I solicit questions in this forum. Much appreciated! Doug Quote Link to comment Share on other sites More sharing options...
footballubet Posted July 27, 2009 Share Posted July 27, 2009 Almost 30 years at the same job and when any of the newer guys raze me about my knowledge, I simply reply (I have advanced so far beyond that point, I have already forgotten what you are just beginning to learn). Doug I need to remember that line! Quote Link to comment Share on other sites More sharing options...
Andreas Posted July 27, 2009 Share Posted July 27, 2009 Sounds perfect, Doug! Quote Link to comment Share on other sites More sharing options...
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