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Denny's Driveshaft builds custom steel and aluminum driveshafts for your high performance car, street rod, race car, van, pick up or 4x4 truck

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Denny's Driveshafts - Speed Calculator

When building a car or truck for racing or street use this handy Potential Speed Calculator will help you to decide whether to use an overdrive transmission or not and which tire diameter to choose and what rear end gear ratio to pick by telling you what the potential speed of the application will be at a particular engine rpm when you are done. It’s great to be able to select a rear end gear ratio for instance and know that it will perform the way that you intended without making the costly mistake of buying the wrong ratio from the start. It seems that everyone at some time has made a gear change and regretted it because it was too much or too little gear to get the job done as expected. This is just one way this calculator will help you.

Also it will tell you if an overdrive transmission will be better for your particular driving than a non overdrive model in the same vehicle. The tire diameter is also very important and this will also help you to decide which one to choose. As little as one inch in diameter can make a difference to your top speed. It will also let you figure your road speed for a given rpm. It is also a great way to determine driveshaft speed, in relationship to critical speed, and your road speed. This is a great tool to help you make an intelligent decision as to what you need to achieve the desired results. This will help take the guesswork out of building your project. Use it to get some answers and tell your friends about it too.

FIRST Enter your engine rpm. It can be your top engine rpm or any rpm that you want to figure. Try your top engine rpm first to see what the potential top speed will be then try various other rpm numbers to see what the engine will be running at various highway speeds. It’s very interesting to see what will be going on at what rpm.

SECOND Enter the tire diameter. The outside diameter of the tire is what you need to enter here. Try selecting various diameters to see what the speed changes will be for various rpm ranges.

THIRD Enter the rear end gear ratio. It’s interesting to see the difference a small change in ratio will make.

FORTH Enter the transmission high gear ratio. For Non overdrive transmissions (Enter 1.0) and many overdrive ratios will be (Enter .7) for instance. Check your model for ratio and enter it in here.

LAST After you enter all the info... Click on the Calculate button to see what the top speed of that particular application would be.

TRY DIFFERENT THINGS Try it by changing the rpm lower and do it once again. Try changing the rear end ratio and do it again. Try changing it from a non overdrive (1) to an overdrive (.7) and see how much the top speed increases. You can spend a lot of time playing with this and you will find the answers are very helpful and if nothing else its entertaining. Enjoy!! And don’t forget to tell your friends about this site.

Potential Speed Calculator

Enter Maximum Safe Engine RPM
Enter Tire Size Diameter
Enter Differential Gear Ratio :1
Enter Transmission Gear Ratio :1

Potential Calculated Vehicle Speed MPH

Special Thanks to for the use of their Potential Speed Calculator Script. - © Copyright 2023-Present

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