|
Re: Rear Gear Ratio
Wheel diameter plays very little in the calculations. However overall tire diameter is the missing key variable you need to consider. Not to be cliche, but this is "where the rubber meets the road". Your final drive ratio is the only consideration you need to measure in order to meet your goals of "efficient drivability".
The previous mentioned website is a good way to calculate multiple options. I created an Excel workbook to do this 14-15 years ago when determining the optimum rear end ratio to install for my '34 Ford Tudor behind a 383 small block with a ZF-6 Speed (.49 gear or 51% reduction...29.5" tire, 4.11 gears, 100mph = 2,300rpms). You really need to decide what your typical driving will be (highway, street light-to-street light, or light cruising). Then compare your engine design (torque motor or RPM) and add the complimenting rear end ratio which will make the most of your choice. The higher torque you have (383, 396, 402), the lower your tranny final gear can be. In contrast, the more de-stroked your engine is (302, 327, etc), the higher your final gear should be because your engine won't be able to handle the load effectively and will force you to up shift or you will dangerously "lug" the engine.
Kudos to you for asking now rather than later. Most realize too late they made the wrong choice.
Posted via Mobile Device
|