I've been talking a little about the paddle shifter I am making for my non turbo automatic 850 and have them nearly completed so I figured its time for a post. Last night I did some test driving with my oscilloscope to verify the shift patterns and particularly the line pressure solenoid control strategy.
I have seen paddle shifters done before on electronically controlled automatic transmission but each attempt has left some real considerations untouched. No overshift protection, failure to control the line pressure solenoid, no provision for tuning, failure to include standard auto shifting when you don't want to use the paddles, etc.
So I started with running wire:
As you can see I also installed a perfect power 6 at the same time, although this is for fuel/ignition tuning and has nothing to do with the paddle shifters.
I also rewired the economy/sport selector on the center console so that when 'sport' is selected it hands over shift control to the microcontroller I'm programming (PIC16F628). Below you can see the harness extension that I am running to the microcontroller. The harness has 7 wires in; one for shift solenoid 1, one for shift solenoid 2, one for the torque convertor clutch solenoid, two for the trans output speed sensor, and two for the line pressure control solenoid.
The microcontroller will use inputs (two paddles) to control the shift solenoid activation and will also provide a PWM signal to control the line pressure solenoid. The paddles will select both up and down shift and provide for some 'programming' to change the line pressure on the fly in +10% intervals as the user selects them. The microcontroller also looks at the transmission output speed and then calculates the RPM based on the current gear selection and the gear ratio thereof. By doing this it can calculate the projected engine RPM of the next gear (either up or down) and can prevent shifting that would over rev the engine.
By pressing the right paddle you select a higher gear, while pressing the left paddle you select a lower gear. By pressing both paddles at the same time for more than 2 seconds you select 'programming' mode and by pressing the right paddle you add 10% to the line pressure for each press. To exit programming mode press the left paddle for 2 seconds. Once you switch back to 'economy' mode on the selector switch, the paddles are deactivated and normal automatic transmission operation continues.
Well thats enough for this post, I'll have more pics tomorrow and video a day or two after that. For the prototype I have disconnected the washer squirter function and the high beam function (temporarily) and used those functions on the stalks as my paddles. So now when you pull the right hand stalk back you upshift and when you pull the left hand stalk back you down shift. This is just for testing and I'll most likely replace them with some fabricated paddles later, but it was too perfect not to use in the mean time