Gear Calculator
User & Collaboration Guide

How to Use the Live Gear Calculator & Chart

First, figure out what gears you have in your car now:

  1. Top: Red Line Max RPM – enter your max permissible RPM .

  2. Middle: Shift Point Line RPM – enter the upper RPM at which you'd like to shift, in order to keep the engine in its power band.

  3. Bottom: Peak Torque Line RPM – enter the peak torque RPM for your engine.

    – If you don't know what this is, search online for the year and model of your Porsche engine.
    – This number also depends on the cam shafts, modifications, etc. Call us at 510-907-9700 with any questions.

  4. Enter your Tire Diameter in inches.

    – If you don't know what your tire diameter is, scroll down and use our optional Tire Size Calculator. Enter the tire width, aspect ratio. If you don't know these look on the side of your tire to find these dimensions.
    – Once calculated, enter the number into the Tire Diameter box.

  5. Enter Ring & Pinion tooth count.

    – If you don't know this number, you can look up your gearbox type number online and find out what ring and pinion your car came with (assuming it hasn't been changed along the way). 

  6. Enter the tooth counts for all of your Gears, from 1 up to 6, to produce your gear chart. 

  7. Feel free to email this to yourself using the email and subject fields at the top-right of the Calculator.

Next, repeat the Steps 1-4 once again. In Steps 5 and 6, enter the ratios that you might like to use to produce a new gear chart. 

How to Collaborate in Real Time

With the Retro Sport Interactive Gear Calculator you can collaborate with your mechanic and race team, or with our Porsche racing specialists, to find the perfect gear ratios for your car and application. 

Here is how it works:

  1. Scroll down and click on the red Real-time Sync button.

  2. Secret Key: Enter a key word – this must be at least 7 characters long and will be shared with your collaborator (so please don't enter any private passwords or other info you don't want to share).

  3. Your Name or Email: Enter your name (this will be shown to your collaborators) and click Share

  4. Ask your collaborators to go to the same Retro Sport Gear Calculator (Check the URL to make sure you're all looking at the same calculator). 

  5. Ask them to enter the Secret Key word (see Step 2) and their name, then click the blue Connect button. 

  6. Once you and your team are connected, any changes made by any team members will be visible to everyone else in real time. 

  7. Feel free to use the email fields at the top of the chart to and share your calculations with anyone. 

  8. Once you are done working, remember to click Disconnect.

If you'd like to collaborate with us, please contact us at 510-907-9700 so that we can set a time to work together online in real time and find the best fit for your application.