Adding Park to the transmission

The transmission work continues.

Last year, while in the car, discussing possible ways of making a parking pawl for our transmission with John Frana (the maker of Seven’s custom gears and differential), the ring and pinion gear broke…which was terrible and great at the same time. Terrible for obvious reasons and great because it allowed us to brainstorm many more ways of incorporating Park into the trans now that it’s broken and we can’t really hurt it.

The new design reused the custom differential and modified the custom gear set to allow for a wider ring and pinion gear, somewhere between a 200-300% increase in contact area for the new gears, and extended the shafts. We had originally trimmed them down to remove the section where 5th gear was (we weren’t using it anymore), to add 5th gear back in. Why put the original 5th gear back in? Well, if you engage two gears in a manual trans at the same time you lock up the transmission, creating Park. And yes, it only took 8 years to realize that adding Park to a manual trans may be that easy.

Now, it’s not perfectly smooth and it does roll a little bit when in Park and you may have to roll the car a bit to ‘find’ the spot where park will engage, but it’s really no different from my first car or most other pre-1975 vehicles. For a one-off first try, I’d say we hit this one out of the park!

Beats the parking chocks we were using.

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