Progress on Avanti transmission swap.

[gordr]

I now have mostly completed the swap of the 700R4 transmission into the McKinnon-powered '63 Avanti that formerly had a leaky TH350 in it. Got in a good road test today. A lot of changes had to be made. Rear mount, changed. Exhaust manifolds, replaced by original ram's horn style off a real McKinnon engine. Head pipes, hand made to fit. Had to cut a small window in the transmission tunnel to make room for the band servo hump on the right front of the transmission case. Had to alter the bottom end of the Powershift lever to make it straight, instead of having forward-pointed hockey stick shape. Installed a cable throttle. Anchored the bottom of the steering column solidly to the firewall. Sorted out some wiring errors, and made on of my own. How does it drive? In a word, great! Much more jam off the line, holds first to about 20 mph, the shift to second, shift to third. When fourth comes in, converter locks up as it should. Push throttle about 3/4, and it kicks down to third for passing. No leaks, no scary noises. The car feels quite different, much sportier. My wiring error? Somehow, I got the power feed to the shift quadrant indicator lamp (replaced by LED) from the right side turn signal, and signalling a right turn makes the shifter lamp blink. This will be easy to fix.

[bensherb]

Cool! That all sounds about like what I did on both our Studes. I don't like how the converter locks IMEDIATELY upon the fourth gear shift though. So, on the GT, I just re-wired my trans and installed a delay I built to keep the converter from locking up until some time after the fourth gear shift. It's adjustable up to 30 seconds, I set it at 11. My fourth hits at 40 mph while driving normally, at that speed lockup will be 660ft down the road. Chances are I'll "fine tune" that once I get the rest of the car back together and drive it some. I do also have a switch to defeat the lockup system or force lockup in any gear if I want to.

[gordr]

Yeah, the forced fourth-gear lockup is a temporary expedient. My plan is to have a vacuum switch, wired to unlock the converter clutch if engine vacuum drops below 7" or so. I think I can build an adjustable vacuum switch by using a distributor vacuum modifier rigged to operate a microswitch. I have a bunch of NOS vacuum modifiers on the shelf. Such a rig could be made adjustable, too. My transmission harness also has a wire that runs direct to the TCC solenoid, so I could force lockup in third, if so choose. I'm thinking maybe for that, use a latching relay wired to un-latch if vacuum drops below 7", or if the brake pedal is depressed. Use a simple push button to "set" it. Not unlike cruise control. I could see third lockup being useful for driving urban boulevards, etc. at 35 to 50 mph. Also would have the brake pedal release the lockup in 4th gear, maybe with a time delay for it to re-engage?