I am starting a new thread for this hoping that it sees more traffic than my Father Son Falcon Project thread. I have read every thread I can find on the HAMB regarding Ford-O-Matic transmissions, but I didn't see anything specific to this 2 speed. We have a 61 Falcon with either the PCL or PCM style transmission. It's a 2 speed, and it will not shift into second gear while driving. I have verified that the Vacuum diaphragm unit holds a vacuum, and that the fluid level is good. Also, the linkage appears to be correct, and it's the style as shown in this pic. The motor is a late 70s 200 straight 6, and was put in well before I owned the car. The car also just got back on the road after sitting for 11 years. Does anyone have input on what the problem could be? Any other helpful advice is appreciated.
A couple of questions: 1) Does the transmission seem to go into a "Neutral" type state when the shift should occur? 2) Or does it seems to be in LO all the time, and when it is supposed to shift and you let up does it deaccelerate as it would if you put the transmission in Lo? The first scenario points toward the direct drive clutches or annular piston seals. The second scenario points toward governor, vacuum modulator, stuck shift valves, and possibly a stuck LO band servo.
Shifting on this transmission is a balance between throttle pressure (vacuum modulator) and governor pressure. If you have no or very poor vacuum available to the vacuum modulator you will have a late to no shift. On the other hand, if there is a problem with the governor pressure, it will never shift. There is an easy way to check the vacuum modulator as there is a tap on the transmission to check internal pressure. You need at least a 250 psi gauge. With the engine at idle and at least 15 in vacuum on the modulator, you should have 40 - 50 psi. If you drop the vacuum at the modulator the pressure should rise to 150 psi or above. It is proportional to the vacuum level, the less vacuum the more pressure you have. The chart I have lists the pressures in D-L-R. I'm not sure there is any pressure in N. Unfortunately there is no port to measure governor pressure. If the modulator tests good with a pressure gauge, you have to pull the tail housing and physically inspect the governor. If the governor is intact and the weights move easily, it's time to pull the transmission as the high clutch may have a problem. I suppose the downshift valve or the 1 -2 shift valve could be stuck, but stuck valves in the valve body point to other problems (contaminants) in the transmission.
The short rubber hose to the vacuum modulator cracks and leaks on a C4. Modulator is good , but doesn’t function without that hose.
Also, needs manifold vacuum not ported vacuum. That linkage needs to be adjusted correctly too for it to shift.
I had the same problem with a Powerglide ... no matter how hard I tried, I could NOT get that thing to shift into 3rd.
Used trans that sat for 11 years? Probably answers your question right there. Lip seal get hard, servos stick, valves stick.
About 60 years ago I had a '53 Ranch Wagon with a fordomatic. As I recall, whether it shifted or not didn't make much difference.
Wow! Thanks for all the replies. Let me answer some questions... Yes, Vacuum is good. I took the line off at the carb and pulled 30inches of vacuum, and it held for several minutes. Yes, I believe so, even though the motor has been changed. I can post pics if that will help. Trans is tuck in low. The hose seems fine. It has manifold vacuum. I think the linkage is adjusted property, but I will need to check that. This may be the reality, I hope not, but it makes sense. I may end up rebuilding it myself. I heard its not terribly difficult.
The vacuum line on mine developed a leak, rusted, in the line, no shift for me! Emergency cure was a small bit of hose and a couple hose clamps.
How much vacuum are you pulling at idle? Are you pulling vacuum from a fitting on the intake manifold or a fitting on the carb?
First off - Thank you all for the constructive comments and input. I really appreciate it! We got the car to shift, and it was such a minor problem. There is a small piece of rubber vacuum hose that goes from the trans modulator to a steel line that runs up to the carb. You couldn't see it without taking it off, but a small piece of that line melted and fused shut. So even though I could pull a good vacuum at the carb, it wasn't reaching the modulator. We cut off the bad section and now the car shifts. I will replace that hose as soon as I have a chance to grab some fresh vacuum line.
I have the same problem in my 1959 Edsel 2 speed,it was working fine for 3 yers, and stopped 2 days ago, no second gear.
I had a 64 Falcon with a 170 engine and a 2 speed, there were days when you could run a egg timer out waiting for it to shift. Especially on big hill climbs. IMHO 2 speed tranny's need big HP to impress...
You dont happen to know if this trans in a 60 Falcon could be flat towed at a decent speed without damage, do you? I know it has a rear pump and can be push started. i need to get one about 30 miles. thanks, -rick
If you are sure it has a rear pump, it shouldn't hurt to tow it in neutral. The only literature I have on that model is Motor's Transmission Manual. According to the oil circuit diagram, the rear pump supplies the exact same systems as the front pump. That means that it will be charging the lube circuit so you should be good to go.
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