Valentines Day Update [John]

Parts found

Found a salvage yard in South Dakota that had some of the stuff we need, parts I wasn't sure we could ever find. We got and installed used letters for the tail gate,

All in decent shape, not perfect, but suitable for this car.

the missing S for the hood,

New S matches perfectly. All letters are now fastened down.

and chrome towers for the wiper arms:

Most glaring need for parts now is the rear fender moldings that we've never had with this car.

First steps on interior

Some of the seams on the front seat had come unstitched and stuffing was starting to pull out. Resurrection Upholstery, a local shop, pulled the cover off and repaired it with new stitching and backing material. Nice shape for its age, but it is pretty old. Also had the front armrests rebuilt and recovered.

To fasten letters to the tailgate we took it apart. It has been repaired, a bit crudely, but seems structurally OK now. It had clearly been rusty. There are still visible rust stains around the hinges, so we will probably revisit this later. Cleaned up the renewed wood paneling in the rear compartment and replaced several missing or rusty screws. There is a bolt shop just down the hill from here (Ababa Bolt) that has had every stainless screw we have gone looking for. Might have to buy 40 or 100, but they have them. We will be back.

Making it run

When I last posted, the engine had left us stranded a few times when warm. The battery was new, and on one occasion of no cranking, light jumper wires from the main battery junction block to the coil and a nasty, untaped joint in the cranking wire started the car. A new ignition switch arrived, and when we replaced the old one, we replaced or repaired all the old wires that serve it. That seems to have resolved the failure to start. 

Finally got around to installing the new spark plug wires, insulators. and distributor cap. The rotor looked new, and besides, CarQuest didn't have it in stock. We've had these parts for months. The wires came in assorted lengths, and we eventually figured out where to put them to get a neat installation. No cutting at all, but we did have to assemble the insulators and the terminals for the distributor cap.

Neat, and easy enough -- once you get them matched up. 

Phil found and bought Firedome plug wire covers, but we haven't painted them yet, so installing them will wait. Maybe we ought to refinish the the valve covers to match. The plug-tube gaskets around each tube are hard and brittle, so we plan to replace them. 

We checked the agreement of wires to distributor cap towers with firing order three times, just to make sure we had it right. Dwell measured 33 degrees, close enough, I decided. When we fired the engine up, it ran like new. Runs smooth, idles, fast response to a throttle blip. Why didn't we do this sooner? The old wires were either misconnected or several were broken. I think at least two cylinders must not have been firing at all. The car now cruises up the hilly streets in our neighborhood and accelerates smartly at freeway speeds. Be nice if it had a higher gear though -- I think its rear end would be perfect for 50 mph gravel roads. We don't drive on those much in San Diego. This engine work was all done last weekend.

Now, about that transmission

Today we got out the shop manual and began diagnostics on the M6 Tip-Toe Shift semiautomatic. The M6 is a four-speed, with two manually selected driving ranges (L and D). Each driving range has an under drive via a countershaft in the main box and a direct drive. The driver selects the driving range with the gear lever, depressing the manual clutch whenever the lever is moved, and an electrical - mechanical - hydraulic system shifts between first and second if in L and between third and fourth if in D. Theoretically.

On this car, upshifts of 1 to 2 and 3 to 4 seemed to work normally. But down shifts were very rare. The driver instructions note that you can drive all day in D, letting the control system select third or fourth as needed. But not on ours. It almost never downshifted at full stops, let alone when speed dropped below 10 mph. Starting out in fourth is disappointing.

The shop manual tells you in a dozen simple steps how to diagnose any M6 difficulty. We used a voltmeter instead of the insulated test lamp it calls for. The problem turned out to be fairly simple: there was no power being supplied to the control elements (solenoid, governor, interrupt switch) and what wiring there was was damaged and incorrectly connected. In a couple of hours, Phil and I made up the wiring harness we needed and ran the checks.

The little box at the coil contains a 20A circuit breaker (top) and a 10 Ohm resistor (bottom). Current from the  BAT terminal on the coil supplies power to the control devices on the transmission through the circuit breaker. One of these, the interrupter switch, momentarily shorts the DIST side of the coil though the resistor, killing engine ignition during automatic gear change. We found none of this connected. 

At the transmission, power from the circuit breaker arrives at one terminal on the solenoid. The other is connected to the single terminal on the governor. There are also leads to an interrupter switch under the right-most round cover in this photo.

If engine speed is decreasing from 15 to 8 mph, internal points on the governor close, grounding one side of the solenoid (on the left). This energizes it, it opens a ball valve, causing oil pressure on the shifting piston to fall. The shifting fork moves rearward, shifting the gear set to 1 or 3, depending on whether driving range L or D is selected. When the fork moves, it activates the interrupter switch, killing engine power briefly to ease the shift. None of this was correctly wired, but it is now.

The checks indicated everything was as it should be, except that this '56 engine lacks a kick-down switch and an anti-stall device on the carburetor. Driving it confirmed that it all works as it should. As a bonus, we were able to show that if you connect a test lead to the governor's single terminal, and you ground the other end of the lead while in second or fourth, the transmission instantly downshifts to first or third. I think we might add a push-button switch on the dash to force this kick-down on the relatively rare occasions it might be needed.

So, how's it look?

Given the improved engine performance and the functioning transmission, I think we should forget about motor or transmission swaps. We need a few days to think about what's next.