Trans trouble
- Thread starter jerdan
- Start date
grumppyoldman
Well-known member
Check the kick down linkage from the carb. to the trans. that's how it engages. May be out of adjustment. Al
I have a '53 with a Fordomatic and my friend who rebuilt both the engine and the transmission went out on lengthy rides with me to get it all dialed in. He definitely didn't baby it, to find out how it was going to act. I recall somewhere in a Motors Manual or service bulletins reading about how to do the adjustments to get all the right shift points. It's out there. And when adjusted properly, it's pretty sweet. Nothing like a new transmission, though. If I can find something somewhere, I'll post again. Good luck.
AnthonyG
Well-known member
How many miles on it? As said make sure kickdown linkage is not gunked up. Could be time to refresh. If no slippage try a reverse flush via Wynns machine will clean flush insides & Free everything up. After that drop pan clean & replace gaskets. Can’t remember if they have screen filter ( think so ) if do renew as well.
Last edited:
rotorwrench
Well-known member
The old FOM single range transmissions were products with a new technology that wasn't set up to work like the transmissions that it eventually evolved into. There was no vacuum modulator yet. Being a single range transmission, it had no sprag free wheeling unit for the planetary toward the rear end of the trans internal drive. The control system had to work just right to get the downshift function and it had to do the required pressure changes quickly. This is the major difference between the old single range FOM/MOM and the later dual range Cruise-O-Matic that came out in 1958.
The transmission throttle valve and governor are what control the shifts. As was already mentioned, the adjustment of the throttle valve control system has to be set with special tools to get it in the ball park for final adjustments. Manzel made tools to adjust the interface linkage with the engine throttle control for the carburetor. It was just a simple gage to set against a machined surface on the engine to get proper adjustment on the bell crank. There was another protractor type tool that was fit to the transmission to measure the position of the trans throttle valve. This was used initially to set the long control rod length to nominal. All of the procedure and pressure check procedure is contained in the FOM/MOM service and adjustment manual put out by FoMoCo. It also gives the governor and shift speed points when performing a drive check of the transmission. There is a troubleshooting guide that indicated what components to check when the transmission doesn't meet the operational requirements. Sluggish or slow band actuator function or clutch pack piston function will result in problems. There are plenty of things that can go wrong in these units or any other automatic of that era. When everything is right, these old units work pretty smooth. It's not quite like a COM dual range 3-speed but it will motivate those old cars just fine.
Just to add: If you drop the pan for an oil change or inspection, don't throw the filter screen away. Some of the new filters are some kind of crappy felt material and the old filter screens can be cleaned to work again.
The transmission throttle valve and governor are what control the shifts. As was already mentioned, the adjustment of the throttle valve control system has to be set with special tools to get it in the ball park for final adjustments. Manzel made tools to adjust the interface linkage with the engine throttle control for the carburetor. It was just a simple gage to set against a machined surface on the engine to get proper adjustment on the bell crank. There was another protractor type tool that was fit to the transmission to measure the position of the trans throttle valve. This was used initially to set the long control rod length to nominal. All of the procedure and pressure check procedure is contained in the FOM/MOM service and adjustment manual put out by FoMoCo. It also gives the governor and shift speed points when performing a drive check of the transmission. There is a troubleshooting guide that indicated what components to check when the transmission doesn't meet the operational requirements. Sluggish or slow band actuator function or clutch pack piston function will result in problems. There are plenty of things that can go wrong in these units or any other automatic of that era. When everything is right, these old units work pretty smooth. It's not quite like a COM dual range 3-speed but it will motivate those old cars just fine.
Just to add: If you drop the pan for an oil change or inspection, don't throw the filter screen away. Some of the new filters are some kind of crappy felt material and the old filter screens can be cleaned to work again.
rotorwrench
Well-known member
I can't answer that question since I'm only moderately familiar with the design through reading the Merc-O-Matic service and adjustment book that I have in my collection of Ford publications and my work on the later Cruise-O-Matics. There is no set length adjustments in the book since they use the tools to adjust the nominal length. They don't recommend any adjustment over 3 1/2 turns from nominal when adjusting for shift tendencies.
Your transmission may respond well to adjustment of the rod but there has been a lot of water under the bridge since those transmissions were in the main stream. Rubber parts only last so long and eventually one actuator piston or another will start to leak around its seal. They lasted a long time in service but no equipment likes to set idle for too long. 65-years is a long time in car years.
If the rod is adjusted, try to mark it so you know where you started from. Lengthen or shorten it in small increments and try it. If it gets worse, go back to the original mark and try the other direction. That's all a person can do without going through the whole diagnostic procedure with adjustment to nominal of the control, adjustment of the bands, and a thorough pressure test. The pressure test will generally let you know if there is a hydraulic control system problem.
Whether you do your own work or go to a transmission shop, it's a good idea to get all the publications you can find for these units so whom ever works on it will have the info in hand. A lot of transmission guys may never have worked on any of the old ford units. In that case, they will need all the help they can get.
Your transmission may respond well to adjustment of the rod but there has been a lot of water under the bridge since those transmissions were in the main stream. Rubber parts only last so long and eventually one actuator piston or another will start to leak around its seal. They lasted a long time in service but no equipment likes to set idle for too long. 65-years is a long time in car years.
If the rod is adjusted, try to mark it so you know where you started from. Lengthen or shorten it in small increments and try it. If it gets worse, go back to the original mark and try the other direction. That's all a person can do without going through the whole diagnostic procedure with adjustment to nominal of the control, adjustment of the bands, and a thorough pressure test. The pressure test will generally let you know if there is a hydraulic control system problem.
Whether you do your own work or go to a transmission shop, it's a good idea to get all the publications you can find for these units so whom ever works on it will have the info in hand. A lot of transmission guys may never have worked on any of the old ford units. In that case, they will need all the help they can get.
Last edited:
Merc Cruzer
Well-known member
This is just a FYI and an observation but not necessarily a recommendation: Since both of our cars (mine is a 53' Merc with the Merc-O-Matic) share basically the same transmission. They have no modulator. I found that if you extend the length of the kick down shaft (turn the "Y" connector at the top of the shaft counter clockwise), the down shift will return, by pushing the accelerator pedal all the way to the floor. But the transmission will shift harder. If you shorten the shaft (turn the "Y" connector clockwise), I lost the pedal kick down (but still can pull the shift lever down to Low and it will give you the downshift) but the transmission shifts softer. I have been told by my local transmission person that if over shorten the shaft the transmission will slip.
Read and follow rotorwrench's prior post above. Be sure to mark the starting point on the shaft before you begin any adjustments. This will allow you to get back to square one. The 3 1/2 turn limitation from your starting point should get you there.
Read and follow rotorwrench's prior post above. Be sure to mark the starting point on the shaft before you begin any adjustments. This will allow you to get back to square one. The 3 1/2 turn limitation from your starting point should get you there.
Attachments
Last edited:
