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rotorwrench · 01-15-2019, 12:42 PM

The FOM operates on pressure. There was no vacuum modulator till the 1961 Cruise-O-Matics came out. The Throttle Valve (TV) rod operates the pressure. More throttle equals more pressure since they correlate to each other. The TV rod may need to be adjusted to firm up the shift a little more. Soft shifts are OK as long as it doesn't slip. Slippage is indicated when rpm rises from normal as was previously stated. A low pressure situation like this indicates a need for a pressure test. The pressure should be tested through the range. Low pressure that can not be brought up within a little adjustment of the rod is generally due to some other problem inside. It can be a seal leak on a clutch piston or a band piston or even a damaged internal fluid tube or seal ring. In any case, that needs to be checked before the clutches get fried. Any slippage on a clutch will fry the plates if they are still the old metallic types.

If you do an oil & filter change, you will be able to quickly tell if something has slipped too much inside. The oil will smell burned and there will be metal in the pan. Clutches are steel and bronze in the old FOMs so the particles can be either. The bands can be adjusted too if they need it and the oil looks OK.

The Ford-O-Matics and the Cruise-O-matics both have a similar valve body. The fit of the valves inside the body it close tolerance. If any particles of crap get in there then the valves get sticky. When they are cold the valves get sticky. After they transmission warms up they work just fine but when still cold, they are quirky to shift. When they are right, they work really well but when something is wrong, they talk to you and it's isn't always a polite conversation.

01-15-2019, 12:42 PM	#7
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,010	Re: 55 vicky transmission misbehaving The FOM operates on pressure. There was no vacuum modulator till the 1961 Cruise-O-Matics came out. The Throttle Valve (TV) rod operates the pressure. More throttle equals more pressure since they correlate to each other. The TV rod may need to be adjusted to firm up the shift a little more. Soft shifts are OK as long as it doesn't slip. Slippage is indicated when rpm rises from normal as was previously stated. A low pressure situation like this indicates a need for a pressure test. The pressure should be tested through the range. Low pressure that can not be brought up within a little adjustment of the rod is generally due to some other problem inside. It can be a seal leak on a clutch piston or a band piston or even a damaged internal fluid tube or seal ring. In any case, that needs to be checked before the clutches get fried. Any slippage on a clutch will fry the plates if they are still the old metallic types. If you do an oil & filter change, you will be able to quickly tell if something has slipped too much inside. The oil will smell burned and there will be metal in the pan. Clutches are steel and bronze in the old FOMs so the particles can be either. The bands can be adjusted too if they need it and the oil looks OK. The Ford-O-Matics and the Cruise-O-matics both have a similar valve body. The fit of the valves inside the body it close tolerance. If any particles of crap get in there then the valves get sticky. When they are cold the valves get sticky. After they transmission warms up they work just fine but when still cold, they are quirky to shift. When they are right, they work really well but when something is wrong, they talk to you and it's isn't always a polite conversation.