Transmission Modification - Change the Gear Selector Pattern

 (Making a Two Speed Gearbox From a Five Speed Gearbox)

One of the neat things about electric motors, like those used in electric vehicles, is the amount of torque they produce. In MR02EV, which has a standard Toyota gearbox for convenience, the plentiful torque means that only 2nd and 3rd gears are used when driving. 2nd gear gets the car smartly of the line and 3rd gear is for cruising above 60kph.

However, in a manual gearbox shifting between 2nd and 3rd gear is a “dog leg” which is pretty annoying after a while. So with the help of two fellow AEVA Sydney members, one a mechanic and the other a gearbox design engineer, I set out to modify the MR2 gearbox. The process went a little like this:

• Dismantle the MR2 gearbox and investigate its construction.
• MR2 gearbox declared un-serviceable and used as a test-bed.
• Test modifications that enable a direct shift between 2nd and 3rd gears.
• Source a replacement gearbox, a Corolla gear box in this case.
• Dismantle the replacement gearbox.
• Remove reverse gear.
• Grind the teeth off 1st, 4th and 5th gear.
• Modify the selector shafts.
• Rebuild the gearbox.

This is the main shaft having the 1st gear removed. And now 1st, 4th, 5th without teeth.

Rebuilding the gearbox with the modified gears. 1st gear gone. 4th gear gone. 5th gear gone.

This is the gear selector modified so that it cannot move along the shaft, and with the lug enlarged.

This is the modified selector moving the selector shafts together.

The end result is a two speed gearbox where we are able to shift between 2nd and 3rd gears directly. The Corolla gearbox reassembled and ready to install.